Jim’s Tech Talk
By Jim Langley
Speed wobble, which is also known as high-speed shimmy (and “death wobble” by motorcyclists) – and likely by other names outside the USA, is a dangerous condition that every rider should know about. It can happen on any bicycle, even electric ones. Due to their suspension plus wider and usually knobby tires, as well as the rougher terrain ridden, it’s much less likely to occur on mountain bikes.
It usually develops on descents at higher speeds, such as over 20 mph. But I’ve seen it at less than 10 mph, too. My scariest wobble happened racing down Monitor Pass in the Sierras at over 50 mph during a triathlon.
What Causes Speed Wobble?
What happens is something causes the front end of the bike to start oscillating from side to side. Only the front of the bicycle, the steering is affected. This condition usually begins as a slight wobble and then gets worse and worse because as the wheel moves side to side the elasticity of the frame tubes encourage the wobble to accelerate.
It can become so violent that you might lose control of the bike and crash. The late cycling technical guru and author Fred DeLong wrote about a speed wobble on a tandem in the Alps so bad that he suffered severe bruising on the inside of his legs from the frame.
Now, if you’re lucky, you may never experience a speed wobble. But, rather than be surprised if you’re not lucky and it suddenly happens, today I’m sharing the technique to keep in mind that usually stops speed wobble in its tracks. Even if you never use it, you might ride with someone who can and you can share it.
That’s what I did and why I decided to cover speed wobble this week. While riding with my friend Tom, he said his bike had a small wobble. I told him what to do if it happens again. And that very weekend on our club’s big century, he was able to avoid crashing when his bike wobbled even worse on a fast descent in the Santa Cruz Mountains (photo). He thanked me by text immediately after the ride.
Stopping a Speed Wobble
When a speed wobble starts your first reaction might be to slam on the brakes, but that doesn’t usually help. It might slow you down enough so you can avoid crashing so badly, but it might not help you regain control of the bike enough to avoid crashing.
1. Don’t let go!
The best bet to avoid crashing is to be sure to keep holding on to the bars even as they begin to thrash from side to side. I know that’s obvious but people do panic and let go of the bars, which is the worst thing you can do. That’s what the analysts think happened to the person who was seriously injured riding the e-bike I mention under wobble causes.
2. Clamp the frame with your knees!
As you’re hanging onto the handlebars, simultaneously move your pedals to 3 and 9 o’clock, which will bring your knees to the same height. Once there, bring both knees together and hold them against the top tube of the frame and keep them there, i.e. pinch the frame with your knees. These 2 steps effectively brace the frame and will stop even serious wobbles so that you can regain control.
3. Unweigh the seat
Don’t stand up from the seat to do this. Instead, as you’re holding onto the bars and clamping the frame with your knees, try too, to put more weight on the pedals and less weight on the seat. This is something to practice when you’re not experiencing a wobble. But, it’s similar to lifting yourself a little off the seat so you don’t feel a bump so much. If you can do it when experiencing a wobble it’ll transfer some weight lower and help stifle the shimmy.
Resting a Knee Against the Top Tube
Once you recognize that a bike has a tendency to wobble, if you stop pedaling on descents and position your foot so that you can rest one knee against the top tube that will usually be enough to prevent a wobble from starting. And if it can’t start it won’t worsen and put you at risk.
What If Your Bicycle Doesn’t Have a Top Tube?
Bicycle frame designs vary tremendously so the knees against the top tube won’t work on every bike. But, most step-through frames should have a tube that you can hold with your legs and that’s worth trying to prevent the wobble. And, unweighing the seat will help, too.
Why Do Bikes Speed Wobble?
Many things can cause speed wobble including road conditions. But if it’s bad pavement, the wobble will usually stop once you clear that dangerous part. With one caused by the bike or components, the wobble will continue and worsen.
To help when searching for what causes a bicycle wobble, below is a list of things I’ve seen and experienced that caused wobbles. The way I test for speed wobble is to try riding a bicycle down a slight grade to pick up a little speed and then letting go of the bars and riding no-handed. DO NOT TRY THIS unless you are an expert rider who can ride no-handed – and realize that even then you could crash if the wobble is bad enough. Be sure to wear safety equipment, too, starting with a helmet.
You may have heard to never ride a bicycle no-handed, which is a good safety rule to follow. But know that bicycles should not wobble with or without your hands on the handlebars. And some will wobble even at lower speeds if you ride them no-handed so it’s a good test.
Common Causes
The following are actual issues I’ve dealt with when finding and fixing bikes that wobble. The solution is to fix the problem, so for example for the first one you would lower the stem. The only cure for the superlight frame tubing is to switch to a frame with stouter construction.
- Stem too high lightening the front end too much
- Excess weight on wide dropped handlebars
- Tire not seated (front or rear)
- Defective or damaged tire with crooked tire treads (front or rear)
- Out of true or round wheel (front or rear)
- Seat positioned too high for the rider (incorrect seat height)
- Superlight frame tubing under a rider too heavy for it
- 25-pound e-bike battery mounted on a rear rack (the tail wagging the dog)
My Friend Tom
So far we haven’t figured out what’s causing Tom’s bike to wobble (it’s a Specialized Roubaix equipped with SRAM eTap). I tried my no-hands test and it did not wobble for me. But, it has wobbled several times now for him and he’s losing confidence in the bike. When last we spoke, I told him to try lowering his tire pressure which was slightly above the recommended range. I also asked him to try dropping his stem a little since he said the front end felt too light to him.
Your Turn
If you’ve experienced a speed wobble, it would be helpful if you shared your story, what happened and how you resolved the issue if you did. Together hopefully we’ll prevent others from ever crashing due to a speed wobble, which would be a great thing. And, you might even help Tom solve his wobble.
Jim Langley is RBR’s Technical Editor. He has been a pro mechanic and cycling writer for more than 40 years. He’s the author of Your Home Bicycle Workshop in the RBR eBookstore. Check out his “cycling aficionado” website at http://www.jimlangley.net, his Q&A blog and updates at Twitter. Jim’s cycling streak ended in February 2022 with a total of 10,269 consecutive daily rides (28 years, 1 month and 11 days of never missing a ride). Click to read Jim’s full bio.
I had a speed wobble which ended up being related to a wheelset, not a specific bike. It was a high end Roval wheelset which initially wobbled on my road bike. I put different wheels on my road bike, which solved the issue (I knew it wasn’t a fit issue as I’m professionally fitted). Thinking maybe the wheels would be ok on a different bike, I moved them to my TT bike, only to have a wobble that was one of the most terrifying things I’ve experienced! After extensive investigation with a Roval authorized shop, it was the bearings in the wheel. They were ceramic & fragile & had become damaged on some rough road or something even though the wheelset was pretty new. I replaced them with steel bearings and the wobble is COMPLETELY GONE. Might be worth it to check his front wheel bearings…
News flash ! The use of ceramic bearings over high quality steel bearings for any application on a bicycle is just plain silly and speaks to the cycling crowds endless fascination (and gullibility) with anything “new”, “lighter”, “faster”. It must be better and when I have it and my buddies don’t, it will be my secret weapon to provide victory. That is the opinion of my aeronautical engineer brother.
Sound like this is your opinion also, R. 😉 No need to throw cyclists off the bus, though – there’s another reason lots and lots of riders upgrade to ceramic bearings (at Praxis where I work they are one of the most common bottom bracket upgrades – we spec Enduro). They can last longer and require less maintenance over their lifespan, too.
Jim
I really appreciate you sharing your experience, Melissa. Tom is on Roval wheels so it’s possible you’ve told us where his wobble is coming from. I did suggest he try a different pair of wheels but he wasn’t sure he had any to try. Now that I’ve heard what happened to your wheels, I can’t wait to tell him. Right now he’s traveling and I don’t know if he’ll see your comment or not.
Thanks so much!!
Jim
Melissa, THANK YOU for your comment. On the strength of it, the shop swapped my Roval CX 32 carbon front wheel for a DT swiss r470 aluminum wheel (wheel, hub, disc). Lo and behold the wobble is gone. My acid test was a descent of 40+ mph where the wheel had previously scared me out of my wits! No problem now. Plus, the rattle I used to hear all the time is gone (the shop thought it was my frame pump — it wasn’t!). The shop will get another Roval; I hope it works well.
I videoed the ride so that in case there were still problems I could show the shop. If you’re curious — https://www.youtube.com/watch?v=y7jsaG5Jg1A
Tom
I have an all-road bike with 48 mm tires that sometimes wobbles, especially when loaded. It is definitely linked to the interface between the tires and road, because it only happens when I have really good grip. It doesn’t happen on gravel, nor when I swap out my smooth tires for ones with small knobs. I suspect the knobs allow enough squirm to damp out the feedback.
Shivering on a cold descent can cause a speed wobble.
That’s a frozen wobble, Kevin.
Yes, that’s a good one, Kevin – self induced wobble. Seen that in cold races and it’s scary in a pack!
Thanks a lot,
Jim
Yes, I’ve experienced it on a cold descent of Carson Pass, clearly related to body shivers transferring to frame, and significantly reduced with knee on top tube.
I’ve had several occasions of dealing with speed wobble. Once was also from shivering, one was from the rear wheel not being properly set in the drops, One happened in a race in the Catskills Mountains that occurred in the same exact spot two years in a row, so I’m guessing it was due to road condition. Another ride had the same issue at the same spot in the race. Others I have no idea what the cause was. I definitely agree that the most effective remedy is to brace your knees against the top tube.
My shimmy experiences always felt like the back end had broken loose. The effect was like I had a very large tire go flat. Since my last such experience, when descending, I do clamp the top tube with my knees. I also ride in the drops and shift my weight forward. The article mentions too much weight on the drops. However, it also mentions un-weighting the saddle. I guess since what I do “works” (no shimmy in many years), I guess my solution is more un-weighting the saddle than weighting the bars.
Thanks, Richard. Just to clarify and prevent any confusion for readers of comments, what I said was not too much weight on the drops, I said too little weight over the front end from having the stem or bars too high.
Jim
I recommend adding a ‘steering damper’ to the bike. I use a short section of old MTB inner tube. Slip the short section of inner tube over the steerer tube when the fork is removed from the bike. When you reinstall the fork, position the section of tube so it covers the lower headset bearing, touching both the fork and frame. This can add just enough damping to the system to prevent wobble. It also prevents road grime from entering the lower headset bearing. My bike has an external headset so this solution works well. It’s possible the shape of the frame and fork on a newer bike with an internal headset might make this solution difficult to execute. Good luck.
Thanks for sharing this old trick, Kelly. It’s a good one and it might help on some bikes for sure. There have been mechanical dampers – not sure anyone sells them anymore. They work just like motorcycle dampers, connecting the fork to the frame.
Thanks a lot!
Jim
I had the first year carbon Specialized Roubaix that wobbled on all mountain pass descents. It would only start on a curve when it got upset by imperfect pavement or a gust of wind from the side, and only on higher speed. I checked all your suggestions and also made sure the wheels were balanced and the headset was not loose. I found two other riders had the same problem with the same model bike. They were all large frames. The smaller frames would not wobble. I contacted Specialized about this , but got nothing but excuses. The next year of Roubaix had a redesigned, much more massive headset. Is this not an admission of guilt? I gave up and replaced the bike as Specialized would not admit that they had a flawed design.
Sometime in the late 1990’s, I was riding a 1985 bike of Tange 2 steel tubing, a good but not great bike, down a hill in New Hampshire that warned it was a 16% grade. I’d never been on it. My speed exceeded 45mph, and the bike started to shimmy. It was not the extreme wobble described in the article, but it was definitely unnerving to say the least. I felt sufficiently in control and the curves were gentle enough just to let myself freewheel down; I thought braking might create a bigger problem.
My solution was to buy a new bike, which I wanted anyway; and the experience of that descent was a good excuse (along with merely wanting to convert from 7-speed friction down-tube shifters to 9-speed shifter-levers). I bought another steel bike, but this one had Columbus TSX Ultralight tubing. The following summer, I descended the same hill on the new bike. It was solid as a rock, and the descent was a great, smooth, shimmy-free cruise. Obviously, when comparing two bikes, any number of differences between the two could be the culprit that caused the wobble. My instinct is always to look for the simplest solution first, and I suspect the difference was the new frame.
I would not go so far as to advise anyone experiencing wobble to buy a new bike. On the other hand, a new bike almost always makes one happy whatever the excuse or reason.
Thanks for sharing your shimmy story, Fixieguy. You’ll like this: the bike that went into the high speed shimmy on me descending Monitor Pass was made of Tange tubing, too.
Jim
Jim, that’s interesting, indeed. That was the only bike I ever owned of Tange 2. I’ve owned quite a few of Tange 1. I never did that hill on any of those, but I know I reached 40mph elsewhere on several without any shimmy. Then again, that shimmy has never recurred on any bike I’ve owned; and I don’t miss it.
My one occurrence was at 50 mph on a brand new bike. Took it to my lbs and they tightened the head set. Hasn’t happened since.
My understanding of speed wobble is that it’s basically caused by the ‘pivot point’ of the bike being changed from the head tube to the seat tube. This can be caused by a number of factors, I’m sure, but I find it happens most frequently when I am ‘sitting too heavy’ on the saddle. The unweighting technique seems to fix the issue most quickly, but avoiding altogether is clearly a better option. I think you might want to advise your friend to be sure his weight is well distributed when he is descending, and not to just put all of his weight into the saddle.
I like my traditional diamond frame bike with flat (not sloping) top tube because I can hold top tube between my knees. I do this all the time, it’s a natural descending technique for me.
Makes me nervous to ride bikes where I cannot do this. I feel bikes that have sloping top tubes probably save a few grams for marketing purposes, and look cool (more “modern”) but I don’t like them.
I agree that lifting weight off the seat is also a good tip for this problem if wobble is encountered.
Wobble (or flutter) is mysterious physics/dynamics stuff and it exists in many things besides bikes like aircraft and towing trailers. I get a no-hands handlebar wobble if I have a bag on my stem (feed bag holding a 3rd water bottle for hot rides) but not if I have a handle bar bag with the same weight in it. Dynamics is weird and mysterious stuff for sure.
I experienced wobble (vibration) on the rear wheel while coasting down a hill. As soon as I would start pedaling it would go away. Had the wheel greased at the bike shop … did not help. Changed wheelset…. vibration would go away! My only explanation was how the rear wheel was spoked. The spokes on the cassette side were installed radially instead of criss cross. It must have made the wheel weaker. I changed wheelset and everything is fine.
Had wobble problem that grew increasingly worse on a carbon centurion with what they called a mono seat stay coming from the top tube to the top rear triangle. Got so bad it bruised my legs gripping the top tube. Come to find out the frame was defective as that seat momostay had play in it. Bike was under 5 years old and was warranted. That frame wasn’t made anymore and the centurion name disappeared and I believe diamondback took over and I paid extra and got a titanium frame (read magazine article that Merlin manufactured it[1990s?])
I used to have a bad wobble on my Pinarello. I found that even more effective than clamping the top tube with the knees was to put a lot of pressure on whichever pedal was at 6 o’clock. The torque would instantly resolve whatever frame geometry situation was causing the problem.
I’ve had a couple of high speed wabbles, over 30 mph, that have kept me awake at times. Both times I lost control of the steering of the bike. I didn’t crash thank God because I rode it out by using the knees locked on the top tube and getting my weight as far back on the saddle as I could. A high speed Wable isn’t something I would wish on anyone and it’s beyond scary.
At the end of the day, my wabble was caused by have the wrong rake on my fork for my bike model. Once it was confirmed that the bike shop had sold me a replacement fork with the wrong rake on it and the correct one was put on, I haven’t had a problem.
Jim-
Understandably, slamming the brakes to control a wobble (or wabble, if you wish,) is a no-no, but what braking technique, if any, would you employ if you can’t get the shaking under control?
Thanks
Hi Seth,
I would brake to slow the bike but controllably if possible. Feathering both brakes rather than forcefully applying either one. You wouldn’t want to skid, either. But your main focus should be on trying to control the bike and hopefully stop the wobble. There are a lot of good tips in these comments for that from riders who’ve experienced lots of different situations.
Thanks for the great question,
Jim
Some years ago Craig Calfee published an article on speed wobble. He attributed one cause of the wobble to asymmetry in the fork drop outs. At the time he offered to measure the forks of any Calfee at no charge and to measure any other forks for a nominal charge. My wife suffered a serious wobble on her Calfee and sure enough the True temper forks were seriously asymmetric. The replacement Wound Up forks completely eliminated the wobble.
I seem to remember that Craig said something to the effect that if the bike goes straight when ridden hands off its probably OK, but if it tends to wander to one side then you may have a problem.
Yes, I remember Craig’s article, thanks for sharing this, Roger.
Jim
I’m a motorcycle guy as well as being a cyclist.
Any front steered two wheeled machine can have Wobble, or Weave, or Wobble and Weave. Wobble is also known as head shake, and is a simple oscillation of the front fork in the steering head. EVERY such machine has a Natural Wobble Frequency, and in general they occur at some low speed band range, when the system damping (tire dominant) is minimal. Weave is when the rest of the machine oscillates about the steering head axis, and significant chassis deflection can be major in extreme cases. Wobble is common, Weave is not.
I had wobble on my old mountain bike, heavily laden, worn suspension fork, puny weak steering head bearings that were worn, going downhill in mountainous areas on a tour in Colorado years ago.. It always happened at a certain speed. Being relaxed with the arms and upper body is crucial to helping “damp it out”. Fighting it is an invitation to disaster. Crouching down to lower your C of G helps. Stay off the front brake and lightly braking with the rear can sometimes help. Avoiding the triggering speed is crucial, but going through the triggering speed quickly can sometimes stop it.
I’ve only experienced “speed wobble” once and I’ve had several bikes. I released my “death grip” on the handlebars and other wobble was gone. Keeping a light grip is very important. It stops the road “noise” from transferring to your bike.
In my 50 years of bicycle riding, I have had 4 different bikes go in to a speed wobble at various times. The bikes were a Viscount, Cinelli, Colnago, and a Litespeed. The common denominator was a high speed descent with a cross wind. One was set off in a high speed descent while going through a bend and crossing a cattle guard..
Jim Jordan
I’ve had it on bikes before. One was due to a loosely secured load in a saddle bag. The other might have been an issue with some play in the headset, but a new frame with an oversize down tube certainly got rid of the problem! 🙂
It has been noted that this also shows up in motorcycles, but I thought I’d mention that it is not unheard of in aircraft with a nose wheel (as in tricycle landing gear). A small training jet named the Fouga Mageister had this problem. They solved it with a nose wheel tire that had thick ribs on the left and right side and no center section of the tread. i.e. it was the opposite of a tire with a round cross section. This caused some scrub when the tire turned left or right, damping any shimmy or oscillations. A shot of one of these aircraft and the tire:
https://live.staticflickr.com/2662/3725747922_8be9feb8c1_b_d.jpg
Thanks, Steve. Unfortunately I couldn’t open that link but I appreciate knowing it happens on some planes too.
Thanks,
Jim
It can also be caused by a cracked front fork. That was the ultimate diagnosis on the bike a friend experienced speed wobble on. New fork, problem solved. But if it is not equipment related it is usually triggered by unfavorable weight distribution which many have commented on. This can be from a poor bike fit, or too much weight on the seat and not enough on the feet. On a loaded touring bike it can be weight distribution in the luggage between fore and aft.
My husband rode a carbon frame that developed a high speed wobble.
Discovered a small crack in the frame.
The bike had never been crashed, but he was a big man man and had ridden the bike many years, so perhaps the frame had been torqued enough to develop a very small thin crack.
Thanks for sharing your speed wobble experiences and solutions everyone!!
Jim
I have a Specialized Diverge with the future shock system. It has a tendency to speed wobble at speeds of 35+ mph. I sometimes wonder if it’s related to the future shock system. Maybe the suspension system causes weight to be lightened over the front tire? Also, it may cause extra vibration or incorrect damping. I’m not sure. My bike is at the shop getting checked to resolve this problem right now. Also, my Diverge has a offset seat post. I assume that doesn’t help with my weight distribution.
I assume the problem isn’t with me as my road bike with 23 mm tires feels much more stable than my Diverge with 38 mm tires when descending. I’ll follow up if I ever figure out how to resolve the issue.
Yes, please let us know if you figure it out and the issue gets resolved, TN. That’s a very popular bike and it’ll help others for sure to know what fixed the problem.
Thanks,
Jim
So the bike came back from the shop. They checked the headset and trued the wheels. The Diverge headset with the future shock can be a tad weird and become loose at times. Anyway, they didn’t find anything wrong with the bike.
While the bike was in the shop, I rode an old 853 steel road bike with 23 mm tires. That bike felt more stable than my Diverge with 38 mm tires. So there is some correlation to the problem being bike related. In my opinion, the Diverge with the future shock makes the bike feel a lot more bouncy which leads to uncertainty. It does not lead to speed wobble though. I think a lot of the speed wobble for me was rider related.
After a couple weeks of re-acclimating to the Diverge, I haven’t been experiencing speed wobbles as much. I’ve been focusing on keeping a tight tuck on the bike when descending. This keeps my weight forward and keeps the wind from blowing me around. I also try to have confidence that no wind gust or road bumps will necessitate drastic and sudden hand inputs at 35+ mph. At that speed, my momentum is going downhill, I just need to keep the hands steady and slightly shift my weight to stabilize the bike. So far, this has corrected my speed wobble issues.
TN, I find it interesting you have an issue with a Diverge. I, too, have one, and find it exceedingly stable. I have ridden it in excess of 40 mph down steep hills (but nice asphalt) with zero problems. It was *far* better than my road bike (I’m the “Tom” Jim mentions in his article). My model is Diverge Expert; carbon frame but aluminum wheelset.
I have future shock 2.0 on both my Diverge and my road bike (which now has a wheel replacing the defective Roval CX 32, and is now stable again). Both are very stable and the future shock doesn’t seem to affect performance at all.
Perhaps you have a front wheel problem, like I did. Swapping the wheel (wheel, hub, disc) cured it.
Wikipedia has an article on speed wobbles:
“An academic paper that investigated wobble through physical experimentation and computer modeling concludes: “the influence on wobble mode of front tire characteristics, front frame inertia and chassis stiffness were shown. In particular, it shows that [by] increasing front tire inflation, chassis stiffness, and front frame inertia about steering axis and decreasing sideslip stiffness of front tire, wobble mode damping is improved, promoting vehicle stability.”[10]”
Having had it happen twice on my old Merlin titanium at 40mph, I now use the techniques mentioned and generally stay below 30mph. And got a new bike…
I echo the article from Craig Calfee as a outlining a cause of speed wobbles. I also want to add that rear loading ie rack top bags can contribute to the problem as you said the tail wagging the dog. I have in the past experienced speed wobble induced by the headset being too l loose and a handle bar bag loaded with too much stuff. Rode it out but never wanted to do that again. Your advice to hang on to the bars and clamp the top tube is spot on stay safe and keep the rubber side down
I have experienced speed wobble on two different bike. The first is a 2012 Tarmac. At first I thought it was my ultralight Ardennes wheelset. However I changed out the wheels for Shimano Ultegra wheelset and it did the same thing. The Tarmac is equipped with rim breaks so my next thought was that breaking on high speed descents caused the problem. Well, I recently experienced the same thing on a Specialized Diverge with disc breaks and wider wheels. It is obviously something I. Doing, not the bike
I solved a wobble issue by balancing the wheels using small weights: https://smile.amazon.com/gp/product/B08HD1YPTC/ref=ppx_yo_dt_b_search_asin_image?ie=UTF8&psc=1
I’ve done several wheels but found not all wheels need counter weights. Spin the wheel several times in a truing stand or in an upside-down bike. If it consistently stops in one position, it may be a balance issue. Typically the weights are applied opposite the valve stem. The weights referenced above are flexible and have adhesive backing. Clean the rim area to apply weights with alcohol. Cover weights with black electrical tape. Mine have stayed in place for years, are not visible on black rims, improved pedaling efficiency, and eliminated wobble. There are several Youtube videos on this, including: https://www.youtube.com/watch?v=UpSrrVV0XNE
DK
I’ve experienced the issue on several occasions, mostly when getting over 50 mph on specific sections of road that appear to have visual “speed bumps” (i.e. regular black tire marks from cars on the road surface). That’s a big hint that the road surface is an issue. Untrue wheels may also play a role.
Holding the top tube with knees seems to help but is not a panacea. Gradual braking also works but is not great as you’re committing more weight to the vibrating front wheel as you brake. Putting more weight on the rear wheel is good.