Progress on cornering: berm turns vs. flatland turns

I blogged a little bit about cornering back in August when I started  learning how to pump a flat surface. Practicing pumping flat ground has helped me make some progress in my cornering ability, as you’ll see in the video of  me below riding at Lebanon Hills a month ago or so.

Two of the how-to videos I linked to in that post also had segments about cornering technique, and the one called Hip Flexion by MTB coach Simon Lawton (free Fluidride videos here) recommends a slightly different technique for a berm turn vs a flatland or off-camber turn.

Simon Lawton flatland turn Simon Lawton berm turn

He says:

We want to turn our inside knee and head in the direction that we want to turn. And we want to follow with either our heart or our pelvic region. We want to follow with our pelvic region in flatland turns or off-camber turns and with our heart in berm turns where we’re really trying to accelerate out of the turn.

It’s not too observable the video of me below but I’m just starting to experience the pumping/accelerating motion coming out the turns in the berms.  More noticeable is my ability to lean the bike while aiming my upper body in the direction of the turn, which is why I superimposed a photo of Lee McCormack (Lee Likes Bikes) over a still from the video.  A closer look reveals my tendency (a habit from my mototrials background) to stick my outside knee out instead of keeping it tucked  in which would make it easier to rotate my torso more.   (“Screw yourself!” is the coaching phrase.) Keeping my eyes ahead through a turn is also not yet an ingrained habit.  

hip flexion flatland turn

My hip flexion technique is somewhat noticeable in the section of the video where I’m weaving through the trees on flat turns.  It’s pretty amazing how much more stable and in control I feel when I do that properly.  And that adds up to more speed and more fun.

Update 12/17: In the comments attached to this blog post, we’ve been discussing pedal position when cornering. For more about this, see Simon Lawton’s Cornering Essentials/Dynamic Footwork video.

123 thoughts on “Progress on cornering: berm turns vs. flatland turns”

  1. Clay Haglund wrote on Facebook:

    “Two of the skills I focused most on improving this year were pumping the terrain for free speed and proper cornering. I learned quickly I’d need better cornering technique as I was carrying more speed everywhere from actively pumping…not something I’d really done before reading Lee McCormack’s book last winter. I noticed it was much easier to screw myself into the turn if my inside foot to the turn was to the back. So for instance in a right hand turn my right foot would be toward the back in the pedals level position. Your hips are naturally more open to the turn that way. Where I found real challenge and reward was at Spirit Mountain on Candyland with the rapid series of switchback berms and turns. By consciously having the correct foot in the back position, I was able to screw into the turns more and retain more speed.”

    Clay, at the 1:05 mark of Simon Lawton’s video titled Cornering Essentials, he says:

    “So if I happen to lead with my left foot forward like I do when I ride, as I turn left, I’m going to move my inside knee out and my outside pedal is going to move slightly down and back. When I’m turning right, I’m going to open my right knee and my left foot is going to move forward and down. If I lead with my right foot, which is totally fine, as I turn left, I’m going open with my left knee and my right foot will move forward and down. And as I turn right, and open my right knee, my left foot will move down and back. “

    So he seems to emphasize more ‘down’ with the pedal position instead of just ‘back’ evidently because it allows for more of your weight to be placed on that outside pedal. Notice how for practice, he coaches riders to completely take their foot off the inside pedal to experience the benefits of fully weighting the outside pedal.

  2. You’re welcome, Jeffrey. It was an eye-opener for me, too, as I’d look carefully at the pro rider videos of them railing the berms but without much hip flexion evident. Now I know why.

    I also found it interesting that Lee McCormack doesn’t mention this in his book.

  3. It seems to me that it is an extrapolation of keeping the center your center of gravity over your tire contact patch on flats, where berms allow you to move your mass to the center of the curve with out loosing traction. So you have less mass that is changing vector (direction). Now just to put it practice. 🙂

  4. But using hip flexion wouldn’t change the center of gravity in a berm, would it, Jeffrey? It seems like that’s determined by the angle of the bike’s lean.

    Simon seems to be saying that turning your chest into a berm turn vs your hips gives you more ability to generate energy coming out of the turn.

    Or have I misunderstood you?

  5. I started to answer and when I reread your question I rewrote it!

    Yes, I only mentioned hip flection during a flat corner.

    I implied the other side of the coin, but should have stated that turning your heart into the turn puts more of your mass towards the center of the turn. That energy that is “generated”, I believe, is a combination of conserving some of the energy needed to redirect your entire mass. Also as you lean your mass closer to the ground (basically falling), you gain energy that you direct out of the turn by the berm.

    Very much like the spin that a figure skater does, pulling their arms in to increase the speed of the spin. I believe pulling the bars back to the chest as you exit the berm is part of that energy translation.

  6. I like that explanation! Lee McCormack has a blurb on P. 125 of his book about pumping a turn but he doesn’t go into much detail on the physics of it. He says to go into the turn low and then push/extend/pump at the midpoint.

    When I watch the berm part of my own video above, it’s funny… there’s a bit of muscle memory that gets triggered. I’m not good enough to pump the berms at the beginner pump track in Eagan but I could feel myself doing it a little bit on those small berms at Leb.

  7. Hey Griff,

    This is really interesting stuff. I posted a question for Lee on this a while back and since then have been practicing flat turns like crazy. I’m currently living in Florida where there’s nothing but flat turns. But I did notice huge improvement when I rode trails in the PNW last month. Just leaning the bike I felt tons more confident. It sounds like what y’all are saying is simply pump berms like rollers, but turning your chest and leaning the bike less, then you can push back at the hole with arms and legs more in line, generating more power. Am I correct?

    I’ve also noticed a huge benefit of putting my outside pedal down in flat corners. I imagine this would not be as beneficial in berms as you’d only be pumping with one leg (outside) and one arm (outside) rather than two.

    I just took my chain off last night and I’ll post a video of some flat turning to a ramp on pink bike, tomorrow. I’d love to get feedback.

    Cheers,
    Phil

  8. looks pretty good, Griff, you could still lean your bike more than your body… really push your inside arm basically straight and try to stay almost on top of your bike… google Lee McCormack turns and you will see… you really start to see the benefits when you can use the actual out side turning nobs on your tires… Keep up the good work you have definitely improved 10 fold from when we first met

  9. Philip, when you want to pump a berm you need to imagine it as a roller, shift your weight slightly forward when entering the berm pushing your front tire into the middle, as you approach the middle of the berm start to shift your weight back to the center of your bike and begin to apply force through your legs and ever so slightly shift your weight backwards and you will feel this acceleration through and out of the berm.. it is a great feeling when you get it

  10. Hey Chance,
    Thanks! That’s exactly what I was thinking. I think of it as a rocking horse motion over rollers. I still lean the bike if the berm isn’t steep enough. One more question: We’re dealing with so many pitches on a trail that there’s so much foot and hip-flexion and leaning bike or body that it’s crazy, so I try to just keep it simple -- lean bike, get low, twist hips, lower outside foot. I’ve found that translating my flat turns into berms still generates more power than I used to on blind trails, but I imagine you want the keep the bike right under you if you know the berm is right as that’s when you’d have the right stance for really rockin’?
    Cheers,
    Phil

  11. Thanks, Chance. I have made progress and most of it is due to the Eagan bike park that got created mainly because of you.

    Philip, if you look at the 1:42 mark of Lawton’s video, you’ll see that he DOES have the outside pedal down through at least the first half of a berm turn and then starts to rocket out of it with a pedaling wheelie.

  12. Griff,

    “He says to go into the turn low and then push/extend/pump at the midpoint.”

    Does he say to get low on exit? I have had it explained to me as pushing and then pulling on exit, like the exit is the bump.

  13. Another thought: I’ve taken the chain off my bike to really feel where I’m getting power through flat turns (and I’m curious as to how fast I can get going on flat stretches just pumping flat turns -- I should have a video soon). Right now it’s almost all legs and a bit arms as I exit. As it’s almost all legs & hips I feel that getting the pedal position just right is helpful:

    I noticed if my push my pedal all the way down I’m using just that leg to push and I lose power as I’m violently switching legs. So I’d recommend on pedal position: about quarter down (outside foot-lead or back), on off camber all the way down, bermed a bit down to level depending on pitch of the berm.

  14. Jeffrey, I don’t think Lawton details body position on the exit of a berm but McCormack does and his answer to your question is yes. “Pull hard, pull yourself low” on page 125 as if it’s the frontside of a roller.

  15. Philip, I’m eager to see your video. If you look at the pro rider in Lawton’s Hip Flexion video as he pumps rapidly through the cones on flat pavement (1:20 mark), it seems that he’s got the outside pedal all the way down, just like in a berm turn.

  16. Griff,

    As I practice “Pull hard, pull yourself low” I am not sure whether I am bringing my upper body to the bars or bringing the bars to my chest. The more severe the berm, I think it feels more like I have to pull the bar to my chest. If I pull up hard on some berms I feel like I will take to much weight off the tire as the berm flattens out.

  17. You’re pissing me off, Jeffrey. You get to practice and I don’t! The frozen snow-covered trails here offer other delights, so I can’t complain too much.

    Why is it a problem to run the risk of taking too much weight off the front wheel? You think it’ll slide out?

  18. Yeah I feel like I will slide out, taking to much weight off the front wheel. Particularly as a berm ends and flattens out. Might be variations of berms as they come in all shapes and sizes. It might also come from decades of berm free riding, road or dirt where keeping weight on the front wheel is key. So pull chest down not bars up. I will have to find some place to practice flat pumping. I am on a slight hiatus of MTBing. Small break. No frozen sports to switch to. Kinda new for me, this year.

  19. I like some of James Wilson’s thoughts on this too. When I first started to learn how to corner, I was so focused on making sure that my feet were in the right spot (outside foot weighted/down). One thing that James said that was enlightening was that if you are moving your hips laterally properly, then your feet will naturally follow and be in the right spot, instead of getting your foot right first and hoping your hips follow. This blog post and a couple others of his have really helped me understand the “why” behind all of it: http://www.bikejames.com/strength/why-you-dont-want-to-twist-you-hips-while-cornering/

  20. Outside foot down and pressure on inside hand. Got that from Davis Phiney’s book decades ago. He also says that you need to keep your COG in line with the G forces. Below 60 that is pretty much straight down. So leaning the upper upright keeps more weight on the tires. He was a pro road rider. The same application of COG over contact patch applies to MTB. Only the speeds are lower and traction is lower. One of the comments to James showed a picture if straight outside leg as the wrong technique. Only because of MTB lower speeds and traction. That comment seems to say that with a straight leg you cannot get your hip over far enough to keep your COG in line with the contact patch. I think I still can, but that brings me to something that I have been practicing. Keeping out side foot forward not down. Some friends have had great results with it. My jury is still out as I have to retrain my ingrained habits. But it does twist the hips a bit in the right direction and allow easier hip movement to the outside to control the COG.

  21. Hey Guys,

    Here’s the result of my chainless/flat-ground pumping experiment:http://www.pinkbike.com/video/343934/

    I don’t start from a track-stand in this video -- I push with my feet a few times to about 10km/hr, but I have before. I topped out today at 24 km/hr. From looking at it I think I’m getting a better pump to the left. I’d love any feedback and guesses at top-out speed.

    My thoughts from just experimenting without a chain is I don’t want to push my feet all the way down every turn, I lose strength and energy doing that. But a quarter down squares my hips and sets me up to really push with my legs. Also, with my arms it almost feels as I enter each turn with a tiny counter steer that I’m rowing. It’s a weird but really good and smooth feeling. Then go through the turn (on really good pumps) the ground almost feels like a roller. So that’s what I’m shooting for -- roller feel every time.

    Cheers,
    Phil

  22. Phil, you look really smooth and fast in that video so I can’t fault your technique. (I like how the PinkBike videos can now be advanced one frame at a time with the right arrow key so as to better analyze what’s happening.) Your hip flexion looks perfect.

    One observation about pedal position. You’re in a practice environment on flat pavement where you’re trying to gain speed while flipping the bike back and forth and traction is a non-issue.

    On most dirt trails, however, traction is the main challenge on flatland or off-camber cornering. And most of those corners are much further apart from one another than the ‘corners’ that you’re taking on the street.

    So I’m thinking that while you might lose some strength and energy in the pedal down position, you’d gain a LOT in traction.

    Does that make sense?

  23. Hey Griff,
    That makes total sense. And I look forward to reading more of your blog. Trials background has to help!

    My thought is that you’ve got to scan the terrain to guess what grade you’re going to hit. So if the grade is bad, you push that foot all the way down, but if it’s bermed a bit, save energy and keep it up as much as possible while getting that horizontal hip flexion maneuver in. But then if it’s really bermed forget much hip-flexion mid-berm, just lean over with your bike and pump it like a roller. So bermed turn enter with hip-flexion high tapering to leaning with bike to exit popping a wheelie. I believe arms play a much lesser role other than positioning. That seems to fit with what I see on vids. Am I right?

    All of this is what I think is what makes trails so fun, there’s so much going on there that muscle memory combined with tiny smooth adjustments can mean the difference between really railing and losing speed.

    I’ve got family in Van, BC, so I’ll be taking this knowledge to the trails!

    Great thoughts everyone! A combination of what y’all are saying plus James and Simon is the best I’ve seen on the web. And I’ve been searching for quite some time. Thus all my long-winded comments :).

  24. I finally got out on pavement with these things in mind. I think a big factor is XC vs DH riding. I am a XC rider. Have not adopted a dropper post. If I do not put my outside foot down I can not get my COG over the Contact Patch. The My thigh hits the saddle with the pedals anywhere near parallel with the ground. So I am going back to outside leg down, next time I hit the dirt flat turns. Kinda like this http://www.pinkbike.com/photo/4083974/ But I get my hips way more over the contact patch.

    On berms I may play with outside foot forward on berms.

  25. Griff,
    Just got through the links you posted and some other surfing on James site.

    He says outside foot back to support the hip swing to that side.

    He also says you must lower your seat. I am not currently into that and not likely to change. But that used to be never, so…

    Although I do not use flats either, I have always ran my cleats all the way back (James alternative if you use clipless)

  26. I’m basically on a 26 inch bmx. A DK Xenia I picked up at walmart. i highly recommend it on a budget -- full chromoly and I’ve jumped it like crazy for 3 months without any apparent wear. It has a rigid fork that wasn’t adjusted for suspension height, so I put a 5 inch riser wide bar on it. It’s just more comfortable for jumping. But when I had a 2.5 inch riser on it was better for pumping.

    So the short answer to your question is yes, go wide bars and flat pedals. I used to ride clipless on my old 29er a bit and pumping was pretty much the same deal, but you get to be a little freer with flats and get a leg off if you slide out. I’ve also noticed you don’t need to put your saddle down, but it certainly helps, especially when I’m on my mountain bike -- a SC Chameleon. On the Xenia the seat is so far back I don’t lose much pumping action on flat ground. I would if I was at a track. I hope all that helps.

  27. Philip wrote “I’ve never tried this. I’ve heard some pros can pull it off.”

    Try your flat pumping with the other foot forward to see if your week side gets better.

  28. Glad you guys are keeping at this discussion. I’ve been dealing with some family stuff (aging mother) this week. I’ll get caught later this weekend.

    Tech note: I’ve turned on threaded comments, so that you can now comment on a comment, 5 levels deep.

  29. I’d say that James Wilson describes the hip action the best. Brady linked it somewhere in the thread.

    I began pumping flat ground when I saw Lee’s video early this past summer. I still haven’t experimented enough to say I’ve got it down or understand it completely, but I’d say that it’s moving your hips sideways out on each turn (which will twist your navel in the direction you want to go) keeping them over the bike as you tilt the bike.

  30. Interesting. Right now I’m topping out at about 15mph on the bike without a chain, which seems consistent with this comment about the trikke -- Captain Bob says “It will do up to 17 mph on flat terrain and really fly down hills.”
    http://www.amazon.com/Trikke-Series-3-Wheeled-Carving-Scooter/product-reviews/B001CCURWQ

    With the bike it does feel like there’s a push/countersteer/row thing going on, especially from a track stand and lower speeds, but that’s quickly followed by the power in your hips. I like to whip my bike when I jump and maybe it’s similar to that. People who are uber-good at whipping say you actually counter-steer in the air before you twist your arms the way you want to go and then your hips follow your arms, or more your shoulders. I’m not sure about that thought…

  31. Here’s the video of Lee McCormack pumping a flat surface. He’s not dropping his outside foot, either… just like you, Phil!

  32. Hmmm. It’s flat corner. He’s got the bike leaned properly and his outside pedal is all the way down. But it appears he’s not compensating enough with his own COG, not rotating his hips enough. So I’m guessing he’ll slide out.

  33. Phil, I think leaning the bike instead of turning the bars is all about arms but after that, yeah, hips and legs seem to matter most.

    Glad you’ve found the discussion helpful. It sure has helped me way beyond my initial blog post.

  34. Jeffrey, I think James Wilson advises having the outside pedal back so as to support more shifting of the COG. I would guess that Simon Lawton would disagree with him for flatland turns because to keep the pedal level requires putting weight on the other/inside pedal. Hence, Simon’s practice drill of riding flat corners with your foot completely off the inside pedal.

    See what I mean?

  35. Jeffrey, I just read the comments to the James Wilson video/blog post and I saw yours, submitted both in WordPress and Facebook

    I see you just ordered the 30-day cornering solution. Cool! Let us know how it goes.

    I’ve purchased some of his components in the past year or so and like them. I’m a big believer in his holy trio of Kettlebell exercises: Turkish Getup, Swing, Goblet Squat.

  36. Yea, those one legged drills look a lot like what used to I look like cornering. (up until I tried this outside foot forward thing.) I have to see how those one legged drills feel. I am reconsidering going back to my outside foot down. One guy says you have nowhere to go if you slide, I say the bike has more time to slide until your foot gets to BDC. Of course a slight bend is good to take up shock.

  37. The berm is resisting the slide out forces. He seems to be dropping his COG into the inside of the turn, but pointing his hips up. I would say ride too high on the berm and maybe over the lip. Otherwise if the berm ends soon enough he will translate that down energy to exit speed.

  38. I think that kettlebells are great for cyclist. I wanted to get James take on them and delve deeper into cornering. I really feel the Stagger leg Squats. Stagger Halos show that I am less stable on one side. I needed to get off the beach. No big draw for me to ride in the Keys.

  39. Hey Jeffrey,
    When I go trail riding, I will leave my saddle up to get used to pumping with it up. So if you ride mostly cross-country I would recommend lowering until you get the feel of the pump and then raising it to practice. I hope that helps. Also in flat corners on flat or uphill ground, you’ll find you are actually in front of your saddle when you pump.
    Cheers!

  40. Jeffrey, I drop my saddle for these drills and most every other type of challenge. As a former mototrials guy where the bikes don’t have seats, it’s second nature to me!

  41. Griff wrote “I drop my saddle for these drills and most every other type of challenge”

    Some say you get bad habits when the seat is up. But it might just be a different skill set. Or I need a dropper post on my SS rigid 29er. Although that does not seem to congruent with that bike.

  42. Philip, thanks for that link. I especially liked the Manon Carpenter segment from 1 minute thru 1:45, using the slow motion controls to observe her feet and body position.

  43. Weird. Jeff you mentioned a berm in your comment but the photo I was commenting on had NO berm. The photo I see now is one I’ve never seen before. Go figure. And never mind my comment!

  44. I want a dropper post but I do so little racing right now, it’s usually no biggie for me to stop and raise/lower the seat.

    I would agree that you probably would acquire bad habits riding with the seat up all the time because of the effort required to not be limited by it.

    I also think that crashes are more likely to be worse when riding technical obstacles with the seat raised.

  45. Way back when I had a Hite Rite spring. I used it a lot at first. I finally took it off when it was almost rusted in place from disuse. That was mainly for the fall line trails back in the day, not so much cornering skills. Although I may have played around swooping some. I ride my MTB saddle at the low end of my range, for float in the rough. Some folkes take issue with that.

  46. Cheers, what I’m seeing too is riders really adjusting their feet in the up down position due to terrain. But what is consistent throughout their turns, at least the good ones is hip-flexion. It seems like having the foot all the way down is ideal, but that they can’t always get it there, or don’t need to.

  47. Yeah, I’m having some second thoughts about enabling threaded comments while using the Jetpack comments plugin. Thanks for the feedback!

  48. Philip wrote “But what is consistent throughout their turns, at least the good ones is hip-flexion.”

    What ever foot placement enables that for you. My mantra will be “Drive with the hips”

  49. Hey Giff, keep up all the good work…YA GEEZER 🙂 I’ve just started riding in fall of 2012 and it’s been an utter blast, especially learning all the skills. I just happened upon your blog and noticed that we seem to be learning a lot the same skills, visiting same sites and referencing same videos lol. I’ve got a long way to go as I need to get the weight down to ride how I think I want to. Just wanted to drop by to say thanks for the reads, comic relief, and most of all, insight with the different skills! You’re doing great! I’m thoroughly impressed and look forward to reading more of your stuff.

  50. Hey Jon, thanks for chiming in and your kind words. Proofread? Nah!

    Good to know we’re in the same ‘learning’ boat. I look forward to hearing more from you.

  51. I don’t doubt that these techniques help with cornering, but as a former physics student I am skeptical of the explanations involving shifting the center of gravity of the bike and rider. I’m definitely a bit out of practice with my physics, so read the rest of this with a critical mindset. In any case, here are some thoughts I have.

    Firstly, it’s not possible to shift the center of gravity of the bike and rider to an arbitrary position. Only certain positions allow the forces on the bike and rider to stay in equilibrium. These positions lie along a line segment that starts at the contact point of the tire and ground and goes out to infinity. The angle this line makes with the ground is a function of the turning radius and speed of the rider and bike. Shift the center of gravity to one side or the other of this line and you fall over. When the rider moves their hips to the outside of the turn and leans the bike farther to the inside, the center of gravity must stay somewhere on this line. You can easily experiment with this when riding in a straight line and leaning the bike one way or the other while maintaining balance. In the straight line case, the center of gravity must remain directly over the tire-ground contact point.

    Secondly, static friction between the tire and the ground is what allows the bike and rider to turn. Static friction is a function of the downward force applied to the tire (and some other things). Assuming all forces on the bike and rider are in equilibrium the position of the center of gravity has no effect on the downward force of the tire on the ground. The force of the tire on the ground must equal the weight of the bike and rider, otherwise there would be no equilibrium and the bike and rider would either fly up into the air or burrow into the ground.

    The only thing that I can think of that changes when the rider leans the bike over farther is the part of the tire that is in contact with the ground and that might have some effect on traction. The knobs on the outside of the tire might provide better lateral traction than the knobs in the center of the tire. You’d think though that tires could be designed to require more or less leaning to achieve this effect.

    In order to find explanations for why this technique works, I think we need to look beyond the simple physics of the bike, rider, and ground. It could be more of a human physiological thing. Positioning the body in the fashion might help the rider to control the bike as it navigates a corner.

    On the other hand, the middle part of a pump does increase the downward force and thus the traction. The catch is that the beginning part of the pump actually decreases the downward force, therefore timing the pump is critical.

    In any case, I’m going to practice some of these techniques next ride. It seems like it should also apply to winter riding in the correct conditions like right now. I was able to hold almost summer-like speeds in the river bottoms yesterday.

  52. Mike, much like I told a brother of mine who’s too brilliant for me at times, always breaking everything biking down to physics and what not, just do as those who know do. The movements of our body understand and execute the laws of physics much better when stop over analyzing it. There’s a reason many have done it this way and continue to do so, it works and works exactly as the teaching tells you. Ive put the teachings to practice and have seen a vast improvement in my cornering (application and confidence) at higher and speeds. From bunnyhops to manuals as well as other skills, my brother who’s tried to understand and thus reinvent the wheel, via physics, has struggled. Me, I’ve simply applied the teachings to mimic those before me and wouldn’t you know it, I’m progressing! Best of luck to you, keep riding!

  53. Mike.

    I think you answered your own query. The goal is not to move your Center Of Gravity to an “arbitrary position”, but to keep the COG over the Tire Contact Patch (moving it inside as the speed goes up or “static Friction” increases, such as in a berm).

    The debate seems t be split into three camps; Outside Foot Down, Outside Foot Forward or Outside Foot Back.

    OFD and bringing the torso upright to move it away from inside
    OFF naturally opens the hips into the turn.
    OFB gives better support to move the hips toward the out side and opens the hips into the turn and lets the saddle clear the inside leg to lean the bike more

  54. Jeff, I dont understand that to be correct. What i understand to be correct is that if the rider positions themselves in a turn such that the center of gravity of the bike and rider is directly above the contact point of the tires and ground, the rider will fall over. During a turn a rider must position the center of gravity to the inside of the turn. The tighter the turn and the faster the rider is traveling, the more the center of gravity must be shifted to the inside. The degree of bike lean and or hip rotation does not change this.

    Jon, I was not debating whether these techniques work. I was just expressing my skepticism about the explanations for why they might work.

  55. Open Question.

    To not drop the chain. I have trained myself for years not to back pedal and use OFD.

    While practising either OFF or OFB, I find it awkward to not back pedal. So do most of you use chain guides as well?

  56. Mike,

    Definitely not arbitrary, then.

    Yes COG over is TCP an over simplification.

    Moving the COG “towards” the TCP may be more accurate. This includes bring the upper body closer to the handlebars.

    As inertia wants your mass to continue forward, maximizing the frictional forces between the ground and the tire, is desirable.

    The degree of bike lean, will determine optimal COG placement “in relationship to the bike”.

    Hip rotation, if the hips swing out, is one way to control where the COG is “in relationship to the bike”.

    When timed correctly, moving COG towards the the outside of the turn “in relationship to the bike” will minimize the energy needed to turn the bike, as the body is changing its vector more slowly.

    Opening the hips to the direction of the turn is using “Body English” to help direct the bike.

  57. Yesterday, I finally got back to some dirt or sand anyway. The Quadrants at Balm/Boyette, less than an hour from Tampa, Florida, are perfect for flat turn practice. I found low upper body very important. I tended to like OFD best. Of course OFD is what I taught my self decades ago.

    In small radius curves, if I could get the timing right to get OFB, I found that I could make and exit them faster, swinging the hip “towards the outside”

    There are so many miles of twisty’s that I actually fatigued all those cornering muscles.

    Lots of palm trees angling out of the ground, like roots. You would have to go over or around, what amount to small logs just out of sight, around many of the curves. You can handle the rough better when balanced on both pedals.

    But all this changing up was far from simple and hard to keep under conscious control, particularly as speed increases.

    But pumping the turn and concentrating on the hip swing over foot placement was doable.

    Fluidly changing from seated carving to standing is paramount. Saddle not lowered.

    Remember I have no dropper post or chainguide and this was virtually flat terrain.

  58. Mike,

    Not being a physicists nor anything close, not to mention it’s been almost 20 years since I last took physics in college, I can’t obviously debate the physics that’s taking place 🙂 I understand and respect that having a physics background, you’d want to understand it from that perspective.

    My point was simply that too much dissection of the physics involved here might actually hinder your application of the technique. As it is, although you acknowledge the technique to be right, you are conflicted because you believe the physics presented to be wrong. Obviously both can’t be right (their technique/physics vs your physics). Speaking for myself, I definitely wouldn’t want the burden of trying to do something I didn’t understand as sound logic, especially if it could lead to me getting hurt. If there’s one thing I’ve learned in MTB that’s utterly important, it’s commitment. Not having it is a recipe for undesired results.

    The human body is phenomenal at interpreting physics when it’s not asked to overly think about it. I think when we break it down to the level of numbers, variables, gravity, angle, velocity, etc, we over complicate very simple things.

  59. Jeff, after reading this article tonight, I think everything both of us has said is an oversimplification of the problem.

    http://en.wikipedia.org/wiki/Bicycle_and_motorcycle_dynamics

    However, I will still hedge a bet that changing the center of gravity with respect to the bike has no effect on the force of the tire on the ground and thus no effect on traction. I hedge a second bet that the technique described above has more to do with maintaining balance via steering than increasing traction via downward force.

    Jon, I hear what you are saying, but my attempts to ride faster and my attempts to understand why I ride faster are two equally interesting pursuits even if improving one is not conducive to improving the other.

  60. Mike wrote “However, I will still hedge a bet that changing the center of gravity with respect to the bike has no effect on the force of the tire on the ground and thus no effect on traction. I hedge a second bet that the technique described above has more to do with maintaining balance via steering than increasing traction via downward force.”

    If changing your COG to the outside did not increase cornering traction, then staying in line with the leaning bike would have equal traction, and I know from empirical evidence that I will slide out at the speeds that I can go with a weight shift, at the same bike lean angle.

    I like to discuss physics. I will read that wiki and see if I change my mind.

  61. Jon,

    Except for years ago, when first applying principles as described in Davis Phiney’s book, this has mainly been a subconscious act. Until this year when a friend mentioned outside foot forward and separately I started riding berms for the first time. My first time blowing off the high side of a berm into a tree, started me thinking again. I obviously had to get conscious about it and look at the differences, which meant revisiting flat cornering. And boy is there a lot more MTB specific stuff out there now and some of it seems to contradict each other. So breaking it down to the physics lets me see why they are similarities are. And that seems to be shiting weight towards the outside, either hip or torso on flat turns. And spinning around your mass that is towards the center of the curve of the berm, manipulated by pumping.

    The hip twist applies steering torque in the direction you want to steer.

    Here are my thoughts after my first experience with berms http://www.mtbepicrides.com/2013/03/tannehill-kwik-stats-2.html

  62. Jeffrey and Mike,

    Definitely understand both of you and your wanting to understand it thoroughly. I’m very much like that as well when it comes to my profession and well..just about everything else in general. It’s never dull trying learn or understand everything from how a stem cell determines its path to how a series of 1’s and 0’s can become audio and video 10,000 miles away.

    When it comes to sports however, I’ve just never given it a second thought. Don’t get me wrong, I’d definitely question those when I didn’t agree with their teachings and wasn’t ever afraid to go against the grain or try something new. Being someone who loved sports/competition, ANY sport for that matter, and competing, when it came down to non mental things that simply required the body to react (just as in biking), I just never gave it much thought. Fortunately for me, it’s worked out as I needed it to. I guess since it’s always worked for me, I’ve never felt the need to look any further 🙂 Obviously this doesn’t make it the right way to learn nor the only way to learn. In the end though, as long as we all reach that common goal, that’s all that matters!

  63. Jeff, again it’s not the observed result that I am skeptical about (i.e. the experimental evidence), it is the explanation (i.e. the theory).

  64. Jeff, since you stated you are interested in the physics, let me explain further what lead to my skepticism. I drew a pair of free body diagrams of the bike and rider where I considered the bike and rider to be a single rigid body. In the first case the center of gravity was inline with the bike (simple lean) and in the other it was to the outside of the bike (hip flex). I observed that there are only 2 vertical forces in both diagrams, gravity pushing down and the ground pushing up. The other 2 forces are the horizontal forces of the ground on the tire and the tire on ground caused by the steering angle. I also observed that both of the vertical force vectors are identical in direction and magnitude in both cases. The only significant thing I observed changing is the angle between the bike and the ground.

  65. Wait… I just thought of something else significant that changes. the moment of inertias of the bike and rider around their center of gravity and the around the center of the turning arc are different due to the mass being distributed differently. Although this has no effect on the vertical forces, it does have an effect on the dynamics of the bike and rider as they rotate through the turn. It might however be an insignificant effect. I think you might have been on to this previously when you were talking about reduced energy to make the turn, however I think you might be using the wrong terms.

  66. Griff,

    I was watching your video. Some things that really helped me to be more comfortable and balanced:

    As far as hip flexion, if I’m turning right and moving my hips to the left, I turn my hips to the point where my left knee is pressed on the frame and vice versa. Although it’s not necessary, it’s really helped me to feel it versus just shifting my rear end originally.

    As far as my arms are concerned, after watching lee get real low, I realized I wasn’t using my arms very much. Whenever I practice now, whichever way I’m turning that arm is straight and pushing down to lean the bike while the other is up with elbows pointing up. I imagine myself pointing and aiming with my arms and eyes. It’s really helped me to really lean the bike, without washing out at a decent speed on sharp flat turns.

    To think, before all this, I figured to turn, all
    I had to do was turn the bar…NOOB!!

  67. Mike,

    I probably use the wrong terms. Particularly Inertia instead of centrifugal force, because I consider them the same thing.

    So reducing the moment of inertia, that the tires have to overcome, would happen “AS” part of the human mass continues past the bikes trajectory in a wider arc. Hopefully, that was more accurate terminology. But I believe we see eye to eye on that point.

    Let me ask a couple questions on those 2 forces to see if I can get what you are saying..

    The vertical force vector. Would that not always be up and down relative to gravity (along the radius of the planet)?

    Same downward force for each model. hmm

    Which was more leaned over?

    I guess I am having trouble seeing how weight further out on a lever has the same force as a weight closer to the fulcrum on that fulcrum, in this case the tires.

    Is the simple lean not as leaned over as the hip outside model?

  68. Jeff, I thought more about tit and came to the conclusion that moving the center of mass farther from the center of rotation while also maintaining the same angular velocity will not change the force required to make the rigid body follow the arc. It’s true that increasing the radius of curvature decreases the force required, however as the radius of curvature increases the translational velocity must also increase if the angular velocity is held constant. The additional translational velocity causes the force required to increase and cancels out the reduction in force required caused by the greater radius of curvature. You don’t get anything for free.

    Also, it occurred to me that, as I said above, the center of mass can not be moved to an arbitrary position while keeping the bike upright. For every little bit it is moved outwards, it must also be moved downwards. The rider could accomplish basically the same thing by just lowering their body while still keeping it inline with the bike. There’s no need to rotate the hips. But since there is no experimental evidence that lowering the center of gravity inline with the bike has a positive effect on cornering success, I’m guessing this is a logical dead end.

    Concerning the free body diagram… yes the force vector due to gravity is positioned at the center of mass and points straight downward. There is an opposing force vector that is positioned at the tire-ground contact point that points straight up. Since these are the only 2 vectors on vertical axis, they must be equal is magnitude. If they were not, there would be a net acceleration of the body along the vertical axis: up into the air or down into the ground. The fact that the bike is leaning does not change this.

    The lever you talk about comes into play when you start considering rotation of the rigid body. In the plane that is perpendicular to the bike (when looking from the front or back of the bike), the components of all force vectors that are on a tangent to center of gravity must sum to zero or otherwise the bike will rotate and fall over (to the inside of the turn or to the outside).

    To figure out the lean angle that results in equilibrium, you have consider the other force on the rigid body. There is a force vector positioned at the tire-ground contact point pointing to the center of the turning arc that represents the horizontal force of the ground on the tires (i.e. the traction force). If you work out all the trig, you’ll see that the faster the bike is going and the tighter it is turning, the lean angle must increase to prevent the rigid body from rotating.

    Note that there is technically no such thing as centrifugal force. What is really happening is that there is a net force on the rigid body because there is no force to oppose the horizontal force of the ground on the tires. This net force causes the rigid body to accelerate and this acceleration causes the rigid body to travel in an arc around the turn.

  69. I’m waaaaay behind on this conversation but will get caught up eventually. Glad to see you guys are still hammering away.

    Just a quick report: several of the singletrack trails in the Twin Cities have been groomed for winter riding and they are currently packed hard and ride fast for both fat bikes and skinny tired bikes like mine (29’er with 2.4″ knobbies, low tire pressure).

    I noticed that in the fast and slippery turns, if I did NOT have my Outside Foot Down (fully weighted) with proper hip flexion and bike lean, I had a tendency to slide out. All three seemed to be necessary. A very unforgiving environment (I have a sore shoulder to remind me) but a great one for practicing proper technique.

  70. Correction, there is technically no centrifugal force in my analysis, because I chose an inertial reference frame. It is a concept that exists in rotating reference frames.

  71. Mike,

    Warning long but overly simplified math and physics below.

    For clarity and expedience I will refer to each paragraph from http://mountainbikegeezer.com/2013/12/progress-on-cornering-berm-turns-vs-flatland-turns/#comment-15000

    P1

    If timed to where the inertia is likely to overcome traction, the bike makes the turn, with less rider mass, at that moment. No free lunch, you choose how and when you pay for it. Correct me if I am wrong, but it takes less energy to make a smaller vector change, like a milder arc and conserve more momentum, the hips in this case. Just like you can take a milder curve faster than a sharper turn. This will not work in a rigid model of course. Your hips act more like a pendulum, maybe. It is often described as a swing.

    P2

    I did not know that you were talking about keeping the bike “upright” , when talking about arbitrary mass position. I did not even consider an upright bike as an possible assumption. You even mention “When the rider moves their hips to the outside of the turn and leans the bike farther to the inside” .

    If you keep the bike up right in a turn you have to move your COG inside quite a bit in relationship to the bike. I use this technique to turn in sandbox like turns. It was key in winning my first race way back when, in fact.

    I agree that lowering the body is important as it gives inertia a smaller lever arm to apply it’s force on the fulcrum (tires). Taking a higher moment of inertia (higher speed, our goal) to pivot the bike and rider about the tires toward the outside and crash (I think this is another way of saying what you said in P4). That is one reason bring your lower body to the bars is important. I posit that by swinging the hips out and leaning the bike more can lower the body more than in an upright position, even with a dropper seatpost.

    P3

    Wow. The bike and rider are many order of magnitudes different in mass. We are effectively moving on the Earth. The effect of the rider and bike pushing on the Earth is negligible. So using the Earth as a reference point, as long as there is any part of gravity, even a milligram of force, an object would not float away(given no other forces exerting a vector change in a vertical direction, such as a ramp, bumps are ramps) But as that force drops, the friction between the rider and the Earth decrease. So I agree that ” The fact that the bike is leaning does not change this. ” But leaning the bike moves the weight further away from the fulcrum the less force is applied at the fulcrum, the tires, in this case. Take a 200 pound rider. When upright that rider would place 200 pounds, plus bike weight (let’s call it 20 pounds), on the tires.

    Now I know that the riders mass is not at a singular point, but for sake of argument, let’s assume that it is. I am going to over generalize the math. Sorry to mix pounds and meters, but it makes for easier to Visualize.

    Let’s sat the mass is all a meter high when vertical. Let’s now lean the bike and rider over 90 degrees. Rider is on the ground, only a small portion of the bikes weight is on the tires if any, they may even be off the ground. So let’s call it zero weight in the tires.

    So at a 45 degree lean (bike and rider), the weight on the tires has to be more than zero and less than 220 pounds. Let’s call it 100 lbs for ease of visualization, approximately one half of rider mass (again I over generalize) I don’t want the numbers to get in the way. If you move the mass half a meter or 50 cm closer to the tires (fulcrum), the weight on the tires approximately doubles getting more traction. We would hardly move the Earth but the traction (friction) would increase making it harder for the bike to move horizontally in relation to the surface of the Earth (sliding out).

    Mike, I think this is where we do not see the same thing.

    P5

    Are you saying that the traction at the tires has force vector pointing at the center of the turn?

    If yes, then that force is caused by turning the bike, by turning the handlebars and/or leaning the bike. If I understand correctly.

    I understand that ” you’ll see that the faster the bike is going and the tighter it is turning, the lean angle must increase to prevent the rigid body from rotating. ” I believe that the inertial force of a road cyclist lean does not get critical until around 60 mph. IIRC from Davis Phiney’s book. Hence not that much lean at ours speeds. More modern MTB interpretation has use leaning more at much slower speeds. On a road bike I drop into a turn and I believe that as the body falls, accelerates toward the ground, some of that energy translates into the new vector. I would make significant gaps on riders that did not use this technique. I have never done 60 mph on a bike, much less into a turn, unlike descending stars like Phiney.

    P6

    ” Note that there is technically no such thing as centrifugal force. ” I thought someone else saw centrifugal force for inertia. For a moment anyway. 🙂

    If you get tired of our discourse, please let me know. I find it interesting. I find few people that are interested in discussing it. I know my terminology is not up to your level.

    I would like a yes or no answer to the question I asked” Is the simple lean not as leaned over as the hip outside model? ” Asked in regard to http://mountainbikegeezer.com/2013/12/progress-on-cornering-berm-turns-vs-flatland-turns/#comment-14995

  72. Mike,
    I took an easy ride around the neighborhood. I did all kinds of turns, weaving etc. I have been thinking about our discourse. It was in the back of my mind while I swooped around like a kid. It was an easy 45 minute ride, so I did not have to think about much more on the low traffic streets at the RV park.

    A couple things occurred to me.

    1st
    On the faster turns that we are talking about we cannot be like a “Rigid Body”. Some part of our body has to move in relationship to the bike. Upper body, lower body or both must move in relationship to the bike.

    2nd
    Another way of saying that is that the bike has to move in relationship to some part of the body.
    I payed attention to this and that I would lean the bike and leave as much of my body over the tires as I could. Similar to leaning the bike side to side while keeping weight centered over the tires. MIke mentioned this drill, and I have used it to get riders to get the feel for the movement before I bring out the cones.

    These both speaks to the balance aspect, that Mike spoke of.

    These things have been second nature for so long I had to deconstruct them. and separate them from the traction issue.

    3rd
    By keeping more in line with the bike, it felt more like falling into and accelerating through the turn. I had to bring the upper body down to the bars to keep the front wheel from sliding out. We all know this. To me that displays that weight on the tires, keeps them from sliding out, increasing friction, which is traction.

    This is what I have been trying to say with oh so many words.

    Mike, I reread your first post and now realize that you were not say that we “Are” moving our COG to an “Arbitrary” place. You say we can not. This is true. But I do not think anyone was saying we could. We are moving the COG relative to the lean of the bike. The lean may have been implied at times. I think we are all saying that in different ways.

    It is the weight on the tires vs traction, where we differ. My bike will stay on the ground under it’s own mass. But I can overcome it’s lateral traction quite easily. It takes much more force with all my weight on it and it will take less than that to lose traction if I lean some of my weight off the tires, even if I am balanced on the bike to counter the moment of inertia of a turn.

    Yes some tires have bigger side knobs and tires deform under side load to give a bigger contact patch. Road racing motorcycles use bigger tires to increase grip at high speeds and low lean angles. These both help that weight on the tires interface there intended medium, dirt and pavement respectively. Take away too much weight or interface and you slide out.

    And definitely yes, that body position helps control the bike in the turn. Vector change and negotiating the rough terrain.

    Jeff

  73. Jeff, sorry I do not have time to reply in for e. I have a simple experiment you can try. Place a board on a scale. Attach a rope to the board. Keeping the rope perfectly horizontal use it to lean the board at different angles. At each angle, observe the scale reading. You should observe that the angle of the board has no effect on the scale reading. Now imagine the board as your bike and the rope as the centrifugal force.

  74. Mike,

    I am sorry, the scale did not make the cut when we pared down to living in a 40′ motor home.
    Maybe somebody else on this thread could act as my surrogate.

    But barring that, are you saying that, if the forces are balanced, so that the rider does not pivot out or in on the tires, that some of the inertial force that is pulling to the outside is driving the tire into the ground?

    In effect making up or balancing the weight that we took off the tires by leaning?

    If so sufficient friction would between the board and scale would be necessary. Otherwise at some point the board would slip off the scale in the direction of the pull on the rope.

    From Friction worksheet from Cornell http://www.ccmr.cornell.edu/ret/modules/documents/Friction.pdf

    “Even though friction acts parallel to sliding surfaces, the
    maximum amount of friction force depends partly on the
    perpendicular force holding them together.”

    The more you lean the bike/rider unit, the less of that force is perpendicular to the sliding surface.

    Jeff

  75. No it is just the opposite. A horizontal force cannot cause a vertical acceleration. The only force causing vertical pressure on the scale is the vertical force of gravity. For extra credit, try raising your hand so the the rope is above horizontal. The scale reading should go down. Now lower your hand below horizontal and the scale reading should go up. There is a transition point at fully horizontal.

    Solving a rigid body problem where the body is in static equilibrium starts with breaking all the forces down into their x, y, and z components, setting the x, y, and z sums to zero, and then solving the equations for the forces. This is something civil engineers do a lot of when designing bridges and buildings and such; albeit they do it with computers these days.

  76. Mike,

    I assume you are answering the questions above and not the statements. Like I said no scale in the RV. But I did not think the horizontal force could push down on the tires. Only contribute to a slide out in the horizontal plane, on a flat turn of course.

    So, then, what you are trying to relate to me is that no matter what the lean the full weight of the rider and bike are on the tires?
    As long, of course, that the inertial forces and lean angle are balanced.

    If this so I need to find a scale!

    So are you also saying we never slide out, we only fall down?

    Jeff

  77. Q. So, then, what you are trying to relate to me is that no matter what the lean the full weight of the rider and bike are on the tires?
    A. Yes, all vertical force components must sum to zero

    Q. So are you also saying we never slide out, we only fall down?
    A. No, all horizontal and rotational force components must also sum to zero.

    The rotational force components come from the fact that the ground pushes on the bike tires and not the bike-rider center of gravity.

    However, a thought did occur to that I don’t think we can assume that the rider rides the bike through the in a perfect circular arc. Perhaps crashing on turns is sometimes caused by a loss of control followed by a sudden sharp turn to regain balance that leads to a slide. I.e. it’s a a dynamic bike stability thing rather than a simple static rigid body thing.

  78. “Q. So are you also saying we never slide out, we only fall down?
    A. No, all horizontal and rotational force components must also sum to zero.”

    At some point, speed for a given curve, “moment of inertia” we slide out. Even on pavement with road tires on a perfect circle. I assume the forces will sum zero, but we still slid out. If so, it is not about the forces canceling out.

  79. “I.e. it’s a a dynamic bike stability thing rather than a simple static rigid body thing.”

    We are definetly talking about being dynamic on the bike. A static model cannot cover it all, for sure!

  80. It’s been two years. Time to revisit this discussion! I got this email from someone named Leonard:

    I’m reading through your blog on flatland cornering and I’m still not quite there yet…

    I can do the basic cornering form, ie lean the bike not the rider, outside foot down, body facing where you wan to go, but I’m loosing speed on flat land corners. The moment I exit, I already lose a significant amount of momentum even if I enter at the correct speed.

    People ask if I do pump tracks because its just the same -- pumping the flat corner as if it were a transition. Yes I can pump and modesty aside, I can get the timing correct repeatedly any time of the day on the PT. Thing is, I’m missing something on flat land cornering 🙁

    While watching the fluidride vid, Simon talks about snapping the corner. This is where I can’t get my head around with. I know there are subtle skills that I need to work on during the split second events of the cornering action, but I can’t quite dissect the movements.

    I can see that you’re able to ‘debug’ yourself and get the motions dialed in. Can you help me out what I’m missing and why my speed is being sapped when I corner?

    Thanks,

    Leonard

  81. Leonard,

    A couple things come to mind for the flat corners:

    1) Are you sure you’re using hip flexion and not hip twisting? See this vid for the difference: http://www.bikejames.com/strength/why-you-dont-want-to-twist-you-hips-while-cornering/

    2) I don’t think you can pump or ‘snap’ a flat turn/corner like you can a berm on a pump track. If you look at the Fluidride videos, they’re not exploding out of flat corners. They’re just maintaining their speed until they can’t start pedaling again. Hence, the one-footed drill turns.

    Any chance you can post a video of your attempts?

  82. I found a lot of help here and from Lee at http://www.leelikesbikes.com/pumping-flat-ground-in-the-real-world.html. I actually feel like I can generate increased momentum out of flat corners. Two things seem to be going for me. I throw my hips into the turn, increasing pressure on front and rear tires while keeping the bike under me. 2nd I lean the bike to keep it totally under me and dip my outside foot. As it’s been a few years now of doing this I’ve noticed I don’t have to drop the foot all the way and a good rule of thumb is to simply keep your pedals level with the ground, not the bike. So if I’m really leaning the bike, then I really dip my outside pedal in relation to the bike not the ground. ALL OF THIS SAID, I’m still not exactly sure I’m cornering correctly -- especially in berms (as someone said I needed to get lower keep my pedals level, go figure), but it definitely feels better than the way I used to corner.

  83. Hey, Philip, good to have you back chiming in… and to hear of your progress. You got me thinking!

    I blogged twice a couple years ago about my marginal ability to pump a flat surface after seeing that video of Lee McCormack doing it.
    http://mountainbikegeezer.com/tag/pumping-a-flat-surface/

    I guess I’ve seen that as an exercise to practice my hip flexion and not something that I’d use to try gain speed on a trail with flat turns where the traction was slippery. But now that I think about it, I may be mistaken.

    I can’t wait for spring to try it!

  84. I remember watching your vids and studying them. That’s around the same time I started trying it. So far as gaining speed I put a cheap walmart computer on my 26 inch djump bike (fully rigid) to see what kind of speed I was getting. I would pedal up to about 10mph and then get up to 17mph purely pumping. I even took the chain off at one point with the same result.

    But, it’s a little finicky to figure out how this translates to the trail as I’m doing this in Florida on asphalt and while it’s flat and there is a tiny grade. Going “uphill” I couldn’t get much past 15. On the trails here, which are very drifty with sand, it really helps in simply holding the right line.

    Also in the past couple of years I’ve been out to the Pacific Northwest 3 times (even getting to Coast Mountain Gravity Park -- where every corner is bermed so maybe not as applicable) and I did notice I was way more comfortable on downhills with wet rocks roots and tons of flat-to-off-camber turns. I don’t think I was gaining speed much through turns as much as I was simply attacking turns more confidently and not losing speed. Low pressure in the front tire helps a lot ;).

  85. Philip, I’m delighted you raised this issue of how pumping on an asphalt parking lot translates to the trail.

    Yesterday, Lee McCormack (LeeLikesBikes) added a comment to one of my other blog posts about pumping a flat surface, linking to a newer YouTube video of him pumping in a parking lot:
    http://mountainbikegeezer.com/mtb-skills-i-thus-far-still-suck-at-pumping-a-flat-surface/#comment-23527

    My comment to Lee:

    It seems like it would be helpful to see a video that shows pumping circles or a figure-8 on a flat dirt surface, like a gravel parking lot, ie, something that would more closely replicate the conditions of a flat corner on a singletrack trail. Are you aware of any? If not, could you create one? I would try but we’re snow-covered here in MN.

    Philip, can you find a gravel parking lot in Florida and try it?

    My thinking currently is aligned with you, ie, practicing pumping a flat hard surface can really help to develop the hip flexion habit which in turn builds confidence to maintain speed/hold a line through a flat corner on the trail. Does that sound right to you?

  86. I think so. I’m no pro so I’m not positive whether it puts you in just the right position. On the parking lot, I’ve done figure 8s but not on gravel. I can definitely try and get you a video on a loose surface.

    Another thing I’ve found that my be informative, but am having trouble finding at the moment are videos of bmx street guys riding without chains. Some of them push their bikes like skateboarders, but the smarter ones have learned to pump with hip flexion. My guess is you can get going close to 20mph like that if you’re really good. In my experience it’s also a great feeling when you get near 15mph, something clicks and it really does feel like the flat road is now curved, much like regular rollers on a pump track feel. It’s super fun even if the neighbors look at you weird ;). I’ve thought it would be cool to have flat chain-less races with obstacles.

  87. Philip, I’ve not seen videos of BMX street racing without chains, just the competitions on a pump track like:
    https://www.youtube.com/watch?v=wmKZuDgQT2U

    That BikeRadar cornering video is a good one. I’d not seen it. But did you find it odd that he didn’t make reference to the difference between bermed vs flat corners? The video shows both but he didn’t indicate which techniques work best for which. Or did I miss it?

  88. Hi Griff, thanks for entertaining my email and inquiry… really happy to have found your blog.

    Just this weekend I was attempting to practice this bit and I sort of hit or miss a flat land turn session, (ie not so much radius, wiggly movements, losing speed). From the sessions last weekend, I think I’m getting somewhere.

    With regards to hip movements, I think you’re hitting something. I do recall myself hearing the front tires do the ‘brrrrt’ sound whenever ‘I think,’ I’ve done the right push on the handlebars and hip displacement. I feel a bit of acceleration that sort of tingles the senses -- a combination of speeding up, falling sideways, and suddenly stopping (ie losing speed, which is what I’m trying to get rid of). It’s still sort of hit and miss for me though perhaps due to: inconsistent body position and fatiguing muscles. I don’t really have much upper body strength compared to legs.

    Overall, what I can say is, ‘I think’ I’ve dialed a bit of the movements, but I lack power, hence the small turning radius and sluggish turns. I still got a ton of troubleshooting and refinements to do and a lot of weekends ahead of me to session.

    I’ll post a vid soon.

  89. BTW, I forgot to mention that in one of the videos of Ryan Leech free tricks, he was able to pump flat lands without exaggerated movements. From a viewers POV, his ‘flow’ looks so fluid and effortless with no snappy movements, yet he pumps flat lands…

  90. My hunch is he didn’t reference it as he wasn’t hitting any high berms where you essentially ride it like a roller, sideways. For most berms we hit on trails, hip-flexion, leaning bike, pedal down is most efficient. With a high berm and more vertical (like most pump tracks) my guess is you go in pedal slightly down leaning bike not body but then start to lean body with bike pumping with arms to legs (peddles level) and popping out pedals level body neutral. Does this seem right to you?

  91. Hey Leonard, glad you made it here, that you’re seeing some progress, and that you might have a video soon. We’ve had some melting here so I’m hoping to dust off the cobwebs and do a little flatland pumping myself later this week.

    I took a look at Ryan Leech’s Fun & Easy Bike Tricks Online Course that you mentioned (affiliate link) and see one called Trail Flare in which he writes:

    “Stop being so stiff out there, add some flare to your riding form! It’ll add a little extra energy and effort but it adds way more fun! Pumping the trail! Basically push the bike into every little dip in the trail and suck up the bike (absorb) every bump -- if you get good at this it’ll actually help you go faster, and you’d be surprised at how small the undulations can be for this to work!

    Is this the one you’re referring to?

  92. Philip,

    I’m not sure but that seems right, looking at the Fluidride videos of a high bermed corner.

    Your “for most berms” comment makes me wonder: I’ve been treating this as an either/or situation, (ie, corners are either high bermed or they’re completely flat) but it seems like we encounter many more corners on the trail that fall on a spectrum somewhere in between those two. So for us non-pros, it would seem that it’s best to use hip-flexion while leaning the bike for most of the corners we encounter on singletrack trails. Ya think?

    FYI, I didn’t include ‘outside pedal down’ because instructors seem evenly divided on that.

  93. I agree with you about it not necessarily being an even/or thing and that that might be why pros spend so much time working on corners, as they’re working to nail the right body movement on a really fluid spectrum of body and weight positioning. For example if you go from flat into a high berm, when do you want to be leaning body with bike? My guess is you enter with a pedal down then bringing them level by the apex of berm, while at the same time moving from just leaning the bike (mostly) to leaning body at the apex, and moving from pumping through hip-flexion to pumping with your arms and then legs, then reversing it all back to exit. If I’m right, that’s a lot to think about. Allowing this to became muscle memory is what probably even separates the pros from one-another!

    I have a nice trail near the house along a creek (where most our decent trails in central Florida are) with everything from a fair amount of natural berms to off-camber turns. For almost all of these leaning the bike more than body, hip flexion-pump and (for aft pump when I can), looking where I want to go and having the pedal a little to all the way down does the trick. I only mention it as I was thinking about it a lot as I rode. What I do know for-sure is that pumping on flat ground immediately gave me a boost of confidence in corners I’d never had before.

  94. Hey Griff, it’s actually the Flintstone Power video (8/23) -- I should have mentioned that earlier.

    The way he pumped isn’t really how Lee and and Simon does it in their videos. His was more mellow, a little bend from the extremities, yet he still moves. Obviously it’s not as dynamic as Lee’s and Simon’s, hence the little movements -- but he (Ryan) can still move in spite of the minimal effort. I’m guessing if he does what they do, he’s gonna gain a lot of speed.

  95. Philip, when you’re at a pump track, can you experience the feeling of getting a small burst of speed as you exit a bermed corner? And if so, did you first experience that before or after pumping flat corners on pavement?

    I’m intrigued by your report that your confidence in bermed corners has grown from your confidence in pumping flat ground.

  96. Hey Griff, I do if it’s not a full 180 degree berm. And I did experience it before, but not to the extent I do now. But this would apply to mellow berms, not higher berms, which I find less at pump-tracks and more on the trail. With higher berms I feel way more stable, but haven’t figured out the pump yet. Someone remarked I wasn’t really diving into them with the lean of my bike, which is counter what I’ve learned on flat ground. Their advice could have been wrong though… Here’s a video that I found addressing some of the nuances of cornering -- in this the say to keep the same positioning as in a flat corner (but then they could be wrong :)). https://www.youtube.com/watch?v=jKIBr8IpORw

  97. Just watched Simon Lawton at Fluidride (great tip thanks!), and it’s hard to argue with how much speed he carries out of berms here: https://www.youtube.com/watch?v=YM5IrbocyUY&index=1&list=PLt1vXTcxRuLrM0JlIWq2kF2YlrKgdj0bc You can see where the snap occurs, a beautiful thing. But it gets more complicated here as he says with berms you essentially lean body with bike https://www.youtube.com/watch?v=kjx7ZSE-OMo&index=20&list=PLt1vXTcxRuLrM0JlIWq2kF2YlrKgdj0bc At first he seemed to contradicting himself a bit. However, watching them twice now, I see that he’s still saying the more speed and power you want to create in a berm the more you’ll want to employ body-bike separation and dipping the outside foot. On a really vertical berm this may take a ton of skill, don’t know.

    So my conclusion for now, at least for the trail (not pump tracks as much) is to keep employing the pedal work and lean the bike. Less extreme when I have a berm trying to really snap it with for aft motion and hip flexion, and more extreme on flat employing more hip flexion to get power. I should get a few video shots to show on the trail. I’ll try and do that soon.

  98. Philip, my reading of the first Simon Lawton video you cited is that he makes a differentiation on speed and the position of the pedals, ie, the more speed through that series of bermed turns, the more it helps to get the outside pedal down:
    https://youtu.be/YM5IrbocyUY

    My reading of the second video of his you cited is that he makes a differentiation on body lean depending on the amount of berm available, ie, the flatter the corner, the more the body becomes upright while the bike continues to be leaned:
    https://youtu.be/kjx7ZSE-OMo

    The latter doesn’t seem to fully jibe with what you wrote above:

    “However, watching them twice now, I see that he’s still saying the more speed and power you want to create in a berm the more you’ll want to employ body-bike separation and dipping the outside foot.”

    See what I mean?

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