Speed wobbles: try these 5 easy ways to stop shimmy

Had a shimmy at 45mph going down Ballingdon Hill into Sudbury on the Dunwich Dynamo at about half past midnight. The bike had one of those big bikepacking saddlebags, which had made the front feel a bit light. Anyway, braking lightly and pressing knees on the top tube sorted it. Only ever had one shimmy before, in 54 years of cycling. The knee trick seems to work.

Funny this has popped back up, read this article the other year and it saved me when this happened to me coming down the Iseran at about 70kph this July. Took a couple of seconds to realise what was happening then what felt like an eternity to remember what to do. Weight off the seat and gripped the top tube with my knees and thankfully that worked. Was seriously shitting myself and thought I was definitely coming off. Don't want to go through that again.

Had the misfortune of a 1980s light weight lugged steel frame racing bicycle that would speed wobble going downhill at about 70 kph. Frightened the daylights out of me but l clamped my knees on to the top tube and very slowly recovered stability. Thereafter I started experimenting. I found (1) weight on top of my rear rack made it easier to develop a wobble (2) the quickest way to reduce wobble was to lift by bottom off the seat, stand on the pedals at 3 and 9 o'clock and get low as possible to the top tube. Please note in my case that weighting the handlebar did not work and some studies have also cast doubt on this. Since then I have had no problems with a Surly LHT and a Specialized Carbon Comp Diverge which both have much stiffer frames than the lightweight steel bicycle which was otherwise a pleasure to ride.

Hi, I had my DWD on the Lautaret (88km)! Survived, tried all those things! Headed to my "local" bike in Valouise, where, he calmed down, made me a coffee and explained what had happened!

Something is wrong he said. He hung my bike from a large strap in the ceiling and then spun it up! It jumped around like someone had shot it! It was amazing! He put another bike on the strap, it hummed like a gyro!  He put my bike on a stand and began to check, frame, wheels etc and finally the tyres! There was the smallest of deviations in the rear tyre. There is always something he said! 

I was amazed by how much he knew about the problem and how simple it was to him to solve. I often check my bike to see if it "Hums", after all, far better it hums than hoping knees, seat etc will bring a satisfactory end to your DWD!

I never had a bike, out of the 9 or 10 that I've had over the years, and most I still own from steel to titanium, that never wobbled, even at speeds approaching 60 mph coming down steep mountain roads.  Even my former 1985 Schwinn Le Tour Luxe when loaded never wobbled.

Enter the newest touring bike I bought in 2019, a Masi Giromondo 700c, when loaded it wobbles at speeds above 14 mph, and I can see the whole frame moving back and forth.  I tried all the stuff mentioned in the article, and comments here and it will not stop other than slowing down, which is highly undesirable when coming down a steep grade loaded.  I tried balancing the weight 50/50 front and rear, I tried 75r/25f, and then 25r/75f, and other combinations, nothing works.  I only carry about 50 pounds of gear, and I only weigh 175 pounds.  I find it very odd that the old Schwinn with smaller diameter tubing and fork diameter, with 27" wheels with 40 spokes each, never once even slightly wobbled when loaded 70r/30f even when approaching 25 mph loaded, and the Masi has larger diameter tubing and fork, but the wheels are cheap Brev M. 23mm internal Tubeless Ready, Double Wall, with just 32 spokes.  I tried moving the seat all the way forward, then all the way back, put on a shorter stem, nothing.

I tried different psi in the original Kenda Drumlins 45c tires, I then switched over to Schwalbe Amotion 38c tires, and played with the psi on those as well; then I tried adding more spoke tension, nothing.

So does anyone here think it could be the wheels causing the whole bike to wobble?  Or is the fork, or head tube?  The fork and head tube would surpise me since it is larger diameter tubing used over the Schwinn, and the Masi weighs about 5 pounds more than the Schwinn did which I can only assume is due to the larger tubing and heavier wheels.  When riding unloaded it rides great even at speeds excess of 30 mph, but add on the 50 pounds of gear and things take a turn for the worse.

I wrote an email to Haro bikes 2 weeks ago about the problem since the frame has a lifetime warranty, but so far no response.

Any ideas would be appreciated.

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I've found releasing my fingers but keeping my thumbs braced helped ie stopping the natural push/pull effect of the deathgrip.

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Glad I've never had a speed wobble - it sounds proper scary.

That's over 6+ road bikes, high/low profile wheels and a lot of descending at speed, which I love.

I'm usually relaxed descending, pinning the top tube with my knees like a jockey with a light grip on the bars, just letting the bike find its way ... or maybe just lucky so far

"Your instinct in this situation is probably to grip the handlebar tighter to regain control, but the harder you grip the bar the worse it gets."

I've done a fair bit of gliding and this sounds similar to a phenomenon called "pilot-induced oscillation" (PIO). This is where you overcorrect and then overcorrect the overcorrection the other way, building-up an oscillation. (This can particularly affect trainee pilots while being aerotowed by a powered airplane.) The solution is to relax your hold on the control column and let the glider naturally stabilize.

Nothing to add really, except loosen your grip and slow down.

On a related note, I rode the RideLondon last Sunday. Following the hour and a half walk to the start line, during which I got colder and wetter, I eventually set off shivering. The first downward section into a tunnel had the bike wobbling like crazy because of my shivering. Miserable ride.

 I think I've had it twice two different bikes but the same thing stupidly sprinting on tt bars.  First time I sprinted through it but the 2nd time I wasn't  so lucky and lost a bit of  skin (fortunately the bike didn't even get a scratch.  I resist the urge now to sprint in the tt bars and touchwood it won't happen again

it's probably a consequence of steeper head angles for lively steering. Get a bike/frame with longer wheelbase and slacker head angle.

Have experienced this on 3 different bikes all of which were good bikes. Definitely me and not the bike. Each time it has been because I have tensed up. Happened yesterday coming of a steep hill at 30mph and started to get nervous and tensed up because I could feel a cross wind pulling at me. As the video above shows this is very scary and I have came close to losing control which at speed is going to be nasty. Later descended another hill at 40 mph without incident but main difference was I stayed relaxed. If this ever happens again I will try gripping the top tube with my knees as recommended above but key thing is to stay relaxed and avoid it entirely.

If you have excluded other possibilities, try replacing your fork. I experienced a pretty serious shimmy on my Lynskey Ti (and at lower speed similar though less aggressive symptoms) some months after a collision whcih superficially did not appear to have caused any damage. On replacing the fork, I have not had this problem -

However, unpredicatble and strong sidewinds at high speeds on straight descents can always cause problems, esp if you are not pedalling - so I try to keep my speed down in these situations now

Surprised you didnn't mention cross winds as a possible cause.

I have experienced shimmy on a couple of bikes. 
A steel tourer, which is very prone to it on any sort of fast descent.  But my best (Ti) bike only once, coming off the Pennines and getting hit by a sudden crosswind gust started it off.

I find single knee application - hard - against the top tube deals with it and feels more stable than trying to grip with both knees.

I've had it I think twice on TT's I think.  Typically in the past I've stupidly saved too much for the finish and found sprinting on the tri bars wasn't a good idea.  First time I managed to power through it but the second time on another frame I wasn't as lucky.  Subsequently I googled it and would try the knee techique if it occurred again but touch wood it doesn't as i pace my self better on TT's

I've always found that shaving off some descent speed helps - it's never happened to me below 65 mph.

I had a speed wobble on a moulton APB while using a Tri Bar. (Scott AT4) Irrecoverable, woke in ambulance...

I attributed it to the damping being unevenly applied, but perhaps it was just me...

Had this a couple of times on the same bit of downhill on my road bike.  Found that moving my weight forwards slightly on the saddle stopped it.  Anyone else tried that?

I think there are different reasons for the dreaded wobble therefore a different fix for each...

I get wobbles and I know they're selfinflicted - it happens when I go down a steep hill and I need to apply the brakes, I find myself tensing and I need to take a deep breath and tell myself to relax. This always works for me. It isn't speed related as if I'm descending a lower gradient and pedalling  I can easily go faster without getting any wobble.

I recently bought a CAAD12 and it is an EPIC machine (Ultegra, rim brake) it is light and it is fast. Since it is still quite new to me I have to go into descents slower so I can build my confidence on it and it's working!

My impression is that 99% of the time it is rider. Maybe even higher proportion than that. I help a lot of beginner riders. Some get speed wobbles down a hill at 25 mph. They insist it's the bike. I get on the bike and ride it a t 25, 30, 35 mph down the same hill, go no hands.... no speed wobble. If someone says "some of my bikes do it" I'm sorry, it's inevitably the rider. I've been riding competitively for 30 years. I've ridden dozens and dozens of bikes, frequently over 50 mph. I have never had a bike give me speed wobbles since I was on a sit up and beg when I was 10 years old, except in one circumstance. If you want speed wobbles, simply unload the front wheel at speed down a hill. Sit far back on the saddle and lean back so there is little weight on the front wheel. You will get speed wobbles every time which will disappear as soon as you put load back on the front wheel. If you hold the handlebars with a death grip you may get speed wobbles on some bikes. Unclasping your hands from around the handle bars, leaning over the handlebars and placing your hands lightly on the tops will cure it, in my experience, 100% of the time.

My bikes occasionally do it, but infreqently.  My Plan A is relax grip on handlebars and shift your seat back a bit and grip with both knees on top tube, to calm the whole thing down and lighten the weight on the front (which is one of the things that is whipping the wheel back the other way).  If that doesn't work straightaway, Plan B is shift forward slightly and apply weight more on one pedal and brace other knee on frame - that changes the loading on the frame - more weight on the front, a twisting load from one side and a damper from the other - that stops it pretty much instantly if Plan A didn't work - ie two strategies - dampen and lighten the front, or load, twist and dampen.  The latter is scary, because you've got to try and change a position on a bike that has a different agenda and has already told you to eff off once.

I have seen this caused on a few occasions by wheels, in particular the placement of a speed sensor magnet on a wheel. This is probably less common now, as many people are using GPS computers without the need for a wheel magnet but still, here is my experience.

It often happened with new wheels, which had a magnet installed by the rider. The natural instinct it seems, is to place the magnet opposite the valve stem, thinking it would balance the wheel.

In truth, most rims are pinned and welded at the opposite side to the valve hole, so is actually the heaviest part, adding the magnet puts a really out-of-balance point to the wheel.

I cured this issue on at least three occasions by moving the magnet round the wheel to the lightest part (found by letting the wheel settle after several spins in a jig, and finding the most favoured place to stop; lightest part will be at the top, or at least heaviest is at the bottom!).

Don't go too fast and periodically apply brakes to shave of acceleration

I've read and considered this thread carefully. Death Wobbles seem to be the ghost in the machine. There are no specific causes or complete fixes. 

At 53 years old I had my first real experience with this event on a hill I had ridden before. I did everything wrong. I tensed up, held a death grip on the bars, and grabbed my brakes. I thought I was about to become hamburger going down this roughly surfaced road at around 30 or 35 mph.

I've lost more than a little confidence just weeks before a 580 mile trip around Lake Ontario.

I wonder if the limited flexibility in my lower back contributed to the opportunity for the wobble to arise? I sit a little tall in the saddle. Add to it my undersized Fuji frame a trunk on the back end and I'll bet I might expect more of the same.

Any ideas on back flexibility would be appreciated (yoga is against physician's suggestion). I took care of frame size and now ride a Trek 720.

Had my first one today coasting into a bend at 52mph. Should have known better - first  time on upgrade wheels that are definitely twitchier and I think I tensed up and shifted my weight, unsettling the bike as I went into the corner. I somehow managed to save it without hitting the hedge but it lasted for about 50 metres.

Instict told me to just ease up without breaking and I just rode it out. I was really lucky. The mountain biker I overtook on the way down said it looked well scary from behind. I can confirm it definitely was!