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  1. #1
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    High speed stability

    I am not a "high speed" kind if rider/racer. I'm pretty comfortable up to about 40mph, start disliking speeds greater than 45mph, and really hate it at 50+mph.

    I was on a Cannondale SuperSix, it kind of bobbled around a bit at high speed, the sensation was as if I were really cold and shivering, but I this happens in all weather conditions - cold, warm, hot. I wasn't actually shivering, that's just what the bike felt like. Anyway, I blamed the bike.

    I'm now on a new Specialized Venge and it does the same thing. So the problem might be me!

    I clinch the top tube with my knees. I try to relax. But I'm pretty tense at high speed. I've tried pushing forward on the bars and pushing down on the bars, tried moving forward to put more weight on the front, tried scooting back a bit, but the bike seems to bobble a bit and it really makes me nervous. This occurs on many different roads and the friends I ride with tell me "yeah, road might have been a little bumpy, but no big deal".

    Any thoughts on what I might be doing and how I can fix it?

  2. #2
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    It sounds like maybe you are focused on constraining the bars. To ride loose it might help to picture the bars floating in your hands like your hands encapsulate the bars but do not grip them, so-to-speak. It's similar to the way your legs ride loose over bad terrain. Maybe look further down the road as well.
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  3. #3
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    The phenomenon, variously called "shimmy" or "speed wobble", is much discussed and not completely understood. It's a resonance effect, and a too-tight grip on the bars by a nervous rider is definitely one of the things that can contribute. But it's different on every bike, affected by things like frame elasticity, wheel weight, weight placement, and others.

    You say you grab the top tube with your knees. Are you sitting on the saddle when you do that? Try standing, with cranks level (I assume you're coasting rather than pedaling at 40+ mph), lift your butt off the saddle, shift weight back, with body low and arms almost straightened, hands in the drops. And as craiger suggested, look down the road, not down at the bike.
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  4. #4
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    Instead of clinching the top tube with your knees, just lean one of them into the top tube. No need to hold it tight, just slight pressure with one of your legs. Legs at 3 and 9 o'clock and lean the 3 o'clock (forward) leg against the tube. And like the other fellows said, light on the handlebars.

    Are you in the drops?
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  5. #5
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    My understanding is that this is an issue of weight distribution. I had this happen often, on a bike I used to ride prior to getting a real fit. Turns out the seat was 1cm too far back - so much that I never sat on it - which I imagine must've had quite the effect on weight distribution front/rear.

    This has not happened since getting a fit. Velodogs question about you being in the drops is also, essentially, a question of weight distribution. Drops effectively shift your weight forward.
    "That pretty much sums it up. I'm 43 and my max is ~178-180. If that HR chart was mine or Froome's, we'd be on the verge of death. But for you it probably looks like a normal workout." -TLG

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  6. #6
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    Quote Originally Posted by 9W9W View Post
    My understanding is that this is an issue of weight distribution. I had this happen often, on a bike I used to ride prior to getting a real fit. Turns out the seat was 1cm too far back - so much that I never sat on it - which I imagine must've had quite the effect on weight distribution front/rear.

    This has not happened since getting a fit. Velodogs question about you being in the drops is also, essentially, a question of weight distribution. Drops effectively shift your weight forward.
    Oh holly bajeebees.
    I would not even consider doing anything over 40 not in the drops. You don't have a full wrap around on the hoods. Even if you hook a few fingers, it's still not very strong.

    Balance your weight in the drops, chew your stem and hold on for the ride.

    AND DON'T LOOK AT YOUR COMPUTER!!!!

    look at the road
    It's a fire road.............
    I'm on a road bike..........

    They have enough in common to blast down it.

  7. #7
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    OP, what size frame do you ride?

  8. #8
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    Quote Originally Posted by ziscwg View Post
    Oh holly bajeebees.
    I would not even consider doing anything over 40 not in the drops. You don't have a full wrap around on the hoods. Even if you hook a few fingers, it's still not very strong.

    Balance your weight in the drops, chew your stem and hold on for the ride.

    AND DON'T LOOK AT YOUR COMPUTER!!!!

    look at the road
    Damn, that's some bad advice. What happens when you hit a bump? Get low but not that low...that's just stupid.
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  9. #9
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    Quote Originally Posted by velodog View Post
    Instead of clinching the top tube with your knees, just lean one of them into the top tube. No need to hold it tight, just slight pressure with one of your legs. Legs at 3 and 9 o'clock and lean the 3 o'clock (forward) leg against the tube. And like the other fellows said, light on the handlebars.

    Are you in the drops?
    This - one knee on the top tube, light grip on the bars - practice. I think geometry and bike fit might play a role, but don't know enough of that to provide useful help. I have one bike with Zipp 303's that will shimmy bad in wind at high speed, but using he above technique has pretty much knocked it out.

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    Quote Originally Posted by cxwrench View Post
    Damn, that's some bad advice. What happens when you hit a bump? Get low but not that low...that's just stupid.
    I hit the underside of my chin a couple of times on the steerer top cap when hitting bumps, it was not fun, don't do that any more.

  11. #11
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    Quote Originally Posted by velodog View Post
    Instead of clinching the top tube with your knees, just lean one of them into the top tube. No need to hold it tight, just slight pressure with one of your legs. Legs at 3 and 9 o'clock and lean the 3 o'clock (forward) leg against the tube. And like the other fellows said, light on the handlebars.
    This is exactly what I do. Clinching both knees to the top tube really isn't nearly as stable. Plus with one knee pressing hard it makes it much easier to swoop in and out of turns (changing knees depending on swoop, of course).

  12. #12
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    Quote Originally Posted by 9W9W View Post
    My understanding is that this is an issue of weight distribution. Turns out the seat was 1cm too far back.
    It MIGHT be an issue of weight distribution, but that is probably quite far down the list. And certainly moving the seat 1 cm would not shift weight distribution much - you move much more than that on the saddle when descending.

  13. #13
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    Quote Originally Posted by Kerry Irons View Post
    It MIGHT be an issue of weight distribution, but that is probably quite far down the list. And certainly moving the seat 1 cm would not shift weight distribution much - you move much more than that on the saddle when descending.
    Welp, file that under correlation does not imply causation then.
    "That pretty much sums it up. I'm 43 and my max is ~178-180. If that HR chart was mine or Froome's, we'd be on the verge of death. But for you it probably looks like a normal workout." -TLG

    LOLOLOL

  14. #14
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    [QUOTE=JCavilia;5132415]The phenomenon, variously called "shimmy" or "speed wobble", is much discussed and not completely understood. It's a resonance effect, and a too

    That sounds like what I'm experiencing - a shimmy / wobble at speed.

    More info about me: I'm a bit over 6'1" tall, about 170 pounds, ride a 58. According to my LBS, I could have gone either 58 or 60. The 58 felt better to me, so that's what I purchased. My Cannondale had the older (dumb) ENVE 45s. The new Venge has the Roval 50s. Perhaps the larger frame size contributes?

    I ride with guys who are much more confident and skilled at high speed descending (Cat 1/2, some local and regional Pro riders, Gregory Daniels, some former National Champions, and some speed demons who are always seeking new PRs/KOMs), so I'm always trying to keep up. Thus, I'm very conscious of aero and always in the drops over about 35mph, typically don't look at my cyclo-computer until I start getting nervous, mostly looking down the road.

    I practice the "super-tuck" when alone (not in a pack) at speeds from 30-35mph. It scares me death, but my goal is to scare myself so I feel less scared at 45+ on the seat. That may not make sense to others, but it makes sense to me -- do something REALLY scary and other stuff becomes "no big deal".

    Anyway, when I say I clinch the top tube with my knees, it is while my butt is on the saddle. I don't understand why clinching with both knees would be less stable than pressing one knee, but am willing to try it.

    "It sounds like maybe you are focused on constraining the bars. To ride loose it might help to picture the bars floating in your hands like your hands encapsulate the bars but do not grip them, so-to-speak. It's similar to the way your legs ride loose over bad terrain. Maybe look further down the road as well." seems like good advice. I ride/race mountain bikes very successfully and understand the importance of riding confident/loose, but am not there yet on the road bike. Something about asphalt that amps up my anxiety.

    Moving forward or backward on the seat has not solved the problem for me.

    I didn't have an opportunity for anything over 40mph this weekend, so I tried some of the suggestions, didn't have a speed wobble, but it typically starts at about 45mph, so not having the issue when I don't usually have it anyway is not conclusive.

    Traveling for work this week, so I'm open to more feedback and next chance to implement will likely be Saturday.
    Last edited by multirider; 03-13-2017 at 08:00 AM.

  15. #15
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    [QUOTE=multirider;5133763]
    Quote Originally Posted by JCavilia View Post
    I practice the "super-tuck" when alone (not in a pack) at speeds from 30-35mph. It scares me death
    If you really wanna scare yourself, do the "super-tuck" with some 82mm wheels....
    I've done it with a pair of 808s and have not done it since.

  16. #16
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    I practice the "super-tuck" when alone (not in a pack) at speeds from 30-35mph. It scares me death, but my goal is to scare myself so I feel less scared at 45+ on the seat. That may not make sense to others, but it makes sense to me -- do something REALLY scary and other stuff becomes "no big deal".
    As someone who is reasonably comfortable coasting at 45-50 mph (on known roads and in good conditions), and who does not experience your sense of panic at high speeds, I have to say that makes absolutely no freaking sense to me. But if it works for you, great.

    I'm not going near that "super-tuck". That stuff is crazy, IMHO.
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  17. #17
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    [QUOTE=multirider;5133763]
    Quote Originally Posted by JCavilia View Post
    The phenomenon, variously called "shimmy" or "speed wobble", is much discussed and not completely understood. It's a resonance effect, and a too

    That sounds like what I'm experiencing - a shimmy / wobble at speed.


    I practice the "super-tuck" when alone (not in a pack) at speeds from 30-35mph. It scares me death, but my goal is to scare myself so I feel less scared at 45+ on the seat. That may not make sense to others, but it makes sense to me -- do something REALLY scary and other stuff becomes "no big deal".
    Instead of trying to scare yourself "straight", so to speak, maybe just put that effort into relaxing on the descents and not thinking about crashing. Get in the habit of touching a leg to the top tube whenever you are coasting on a downhill. If you turn the crank for a curve, switch to the other leg. Create good habits by acting in a controlled manner, exorcise fear, don't introduce more.

    Any unease, most highly, transfers itself into a death grip on the bars, contributing to the shimmy.
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  18. #18
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    Quote Originally Posted by multirider View Post
    ...typically don't look at my cyclo-computer until I start getting nervous....
    I think that says a lot right there, for some reason you are getting nervous, tense up, and the rest is inevitable.

    I would concentrate on the basics before worrying about being super aero and not sure if scaring yourself when trying not to be nervous is the best way to go about it. At this point in time you are probably waaaay overthinking everything which is just contributing to your anxiety about it all.

  19. #19
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    [QUOTE=velodog;5133838]
    Quote Originally Posted by multirider View Post
    Any unease, most highly, transfers itself into a death grip on the bars, contributing to the shimmy.
    This has been my experience as well. Once when a bus was passing me closely (major potholes to my right, nowhere to go without crashing), I got my bike to shimmy on flat ground when I wasn't going much more than 21 - 22 mph, because I had a death grip on the bar.

    There's lots of factors involved, though, so your situation may be different. Just something to try - relaxing your grip, I mean.

    ----------

  20. #20
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    [QUOTE=D&MsDad;5133907]
    Quote Originally Posted by velodog View Post

    This has been my experience as well. Once when a bus was passing me closely (major potholes to my right, nowhere to go without crashing), I got my bike to shimmy on flat ground when I wasn't going much more than 21 - 22 mph, because I had a death grip on the bar.
    The exact same thing happened to me, a semi truck on my left shoulder and a curb less than a foot to the right of my tire. I'm lucky I didn't snap my bars I held them so tight, and a shimmy like I've never experienced.
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  21. #21
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    Quote Originally Posted by multirider View Post
    I am not a "high speed" kind if rider/racer. I'm pretty comfortable up to about 40mph, start disliking speeds greater than 45mph, and really hate it at 50+mph.

    I was on a Cannondale SuperSix, it kind of bobbled around a bit at high speed, the sensation was as if I were really cold and shivering, but I this happens in all weather conditions - cold, warm, hot. I wasn't actually shivering, that's just what the bike felt like. Anyway, I blamed the bike.

    I'm now on a new Specialized Venge and it does the same thing. So the problem might be me!

    I clinch the top tube with my knees. I try to relax. But I'm pretty tense at high speed. I've tried pushing forward on the bars and pushing down on the bars, tried moving forward to put more weight on the front, tried scooting back a bit, but the bike seems to bobble a bit and it really makes me nervous. This occurs on many different roads and the friends I ride with tell me "yeah, road might have been a little bumpy, but no big deal".

    Any thoughts on what I might be doing and how I can fix it?
    So shimmy starts at 40 mph? That's really fast for a bike. Do some tests.

    First, try relaxing the hands on the bars, so when they shimmy it isn't amplified in your arms and shoulders. If the front wheel still shimmies, it could be you've got too much weight over the front wheel. That'll cause shimmy at any speed. If the bike is on the small side, reach is short and bars are dropped lower, so going down a hill at 40 mph the rider is right up over the front wheel. So slide back on the saddle, which holds the back wheel more firmly on the tarmac, lowers the center of gravity, and takes weight off the front wheel.

    If it still shimmies, something is out of alignment on the bike or there's an integrity issue. It could be a loose quick release skewer, out of true front wheel, bulge in the tire inducing out of balance wheel, rear wheel not tracking front wheel or out of true. Take a string and run it along both rims. See if the string is touching at two points on each rim when it is dead straight. If not, you'll see an alignment problem which might be the culprit. When riding, take the hands off the bars. The bike should hold its line.

    Does the bike steer freely when holding it on your shoulder and poking the handlebars side ways? They should swing freely. A binding headset could cause shimmy that would resonate when more weight is transferred on the front wheel in a descent. especially if you weren't relaxing.

    If all these tests don't find the problem, then it could be wimpy wheels or frame flexing too much. A heavy rider needs a stout bike that stays true under his weight when all of a sudden he's going at motorcycle speeds! Punching through that 40 mph wall of air definitely challenges the bike's structural integrity not noticeable below 30 mph.
    Last edited by Fredrico; 03-13-2017 at 08:38 PM.

  22. #22
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    Quote Originally Posted by Fredrico View Post
    Does the bike steer freely when holding it on your shoulder and poking the handlebars side ways? They should swing freely. A binding headset could cause shimmy that would resonate when more weight is transferred on the front wheel in a descent. especially if you weren't relaxing.
    Actually the proponents of needle bearing headsets suggest that the less free spinning, so to speak, of the front end help in reducing shimmy. The needle bearings, having more drag than ball bearings, are more able to reduce shimmy. I have found this to work for me.

    I have a low trail bike, 30mm on paper, that tends to want to shimmy. It is a 1" threaded headset with an IRD headset, which has lower needle bearings and upper ball bearings. I originally had the headset adjusted as I would a ball bearing headset, so that the front end would spin freely as Fredrico explains and there was some shimmy. I adjusted the headset down, snugger than I would feel comfortable on a ball bearing headset, and the shimmy is significantly less. The needle bearings can take significantly more load without binding, than can the ball bearings, allowing them to keep the front end more solid, and less apt to shimmy.

    I have a headset with needle bearings, both upper and lower, that is in reserve that will eventually be fitted to the bike. But with over 9,000 miles on the current headset, and showing no sign of wear, even though it's adjusted quite snug, that headset will remain on the shelf.

    But, none of this helps you because there are no head sets, to my knowledge, with needle bearings for threadless front ends being manufactured for you to even try.
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  23. #23
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    I raced motocross for over 20 years. Most of that was in the Pro class. I have not found the transition from motorcycles to bicycles to be easy bicycles feel so fragile and insubstantial and unstable.

    I motocross background as the basis for my approach to scare myself through the super-tuck. Towards the end of my moto career, there was a track with three monster jumps. One of them was 100 foot table, another was an 80 foot table, and another was a 60 foot triple jump. The 100 foot table always scared me to death, wide open throttle in top gear and slamming into the face of it to launch was a frightening proposition for me. But I was very comfortable with the 80 foot table and the 60 foot triple. As I started considering terminating my moto career, I stopped jumping 100 foot table. Within about a month of that, the 80 foot table was scaring me to death. Since I was thinking about quitting anyway, I stopped jumping that too. Soon afterwards, the 60 for triple jump scared me to death. Basically, the "edge of the envelope "followed me backwards every step of the way.

    Anyway, I went for a fast group ride on Saturday, never felt uncomfortable on even the fastest descent, I was very surprised to find that I hit 51 mph. Similar thing on Sunday fast group ride including a canyon descent, never felt uncomfortable, surprised to see my max speed was 50 mph.

    I tried to scoot back on the saddle a little bit, keep a loose grip, and use one knee against the top tube instead of both. It is hard to determine what the primary factor was because I change multiple things at the same time. But I am very pleased that I cracked 50 miles an hour on both days and never felt overly concerned.

    It should be noted that both days were pretty smooth roads. The real challenge will come on a fast descent on a rougher road.

    It did not make sense to me to use one knee instead of both until I started typing this message, but I think trying to clinch with both knees increased the tension in my body which was transmitted into the bike. I think the "one knee" approach is definitely superior.

    My guess is that the primary factor is gripping the bars too tight. It is probably not possible to grip them completely evenly, and an unequal grip could introduce a vibration that turns into a bobble.

    I appreciate all the feedback and help!

  24. #24
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    Quote Originally Posted by velodog View Post
    Actually the proponents of needle bearing headsets suggest that the less free spinning, so to speak, of the front end help in reducing shimmy. The needle bearings, having more drag than ball bearings, are more able to reduce shimmy. I have found this to work for me.

    I have a low trail bike, 30mm on paper, that tends to want to shimmy. It is a 1" threaded headset with an IRD headset, which has lower needle bearings and upper ball bearings. I originally had the headset adjusted as I would a ball bearing headset, so that the front end would spin freely as Fredrico explains and there was some shimmy. I adjusted the headset down, snugger than I would feel comfortable on a ball bearing headset, and the shimmy is significantly less. The needle bearings can take significantly more load without binding, than can the ball bearings, allowing them to keep the front end more solid, and less apt to shimmy.

    I have a headset with needle bearings, both upper and lower, that is in reserve that will eventually be fitted to the bike. But with over 9,000 miles on the current headset, and showing no sign of wear, even though it's adjusted quite snug, that headset will remain on the shelf.

    But, none of this helps you because there are no head sets, to my knowledge, with needle bearings for threadless front ends being manufactured for you to even try.
    Get your point. But you did say "less shimmy" when snugged down a bit tighter than ball bearing headsets. If shimmy is still there, the headset is not causing it, merely dampening it slightly. The problem is somewhere else. When the bike is aligned properly and weight distribution is not too much over the front wheel, the bike shouldn't shimmy. I have a DeRosa like yours with 74 degree steering. I can get it to shimmy in a track stand quite easily. But I'm amazed how well it handles above 30 mph. It moves with great stability, like a motorcycle. I attribute that to inertial mass inherent in all speeding objects. The faster it goes, the light weight becomes less of a determinant in handling. It cuts through the wall of air like a bullet. The wheels spinning that fast amplify the "flywheel" effect, stabilizing forward momentum not as apparent below 30 mph.

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    Could also be an out of balance wheel/tire. While under most normal riding it's not an issue, but as speeds climb an out of balance wheel can start to vibrate.

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