Cyclefiend

My 2019 Madone SLR has a disconcerting speed wobble. I notice it particularly on long, fast (35+ mph) descents. Has anyone else experienced this? If so, have you been able to remedy the problem & how? I am looking for mechanical fixes as opposed to changes in riding technique (as technique solutions usually include slowing down). The bike is a 54 cm, Aeolus 50 tubeless wheels, 110 mm stem, 28 mm tires (80 psi rear, 65 psi front).

Sy Reene

Sorry, nothing specific to recommend. A decent article that has some ideas linked below, including different tires and/or having wheels checked for round.
Stock tires on a Madone are 25s, have you tried these in same circumstances?

https://cyclingtips.com/2020/07/bicy...-to-stop-them/

Iride01 

Have you tried changing where your weight is on the bike when you get near or into situations that cause the issue for you? Are you certain it isn't from something else, like maybe your front wheel bearings are too loose or worn? Is your headset too loose?

Typically on older bikes with the older vintage frame design, some say it shows up more on the larger frame sizes that have really long head tubes and therefore longer steerer tubes. Every time I had speed wobble it was on such a bike with a un-godly long head tube. It's been quite a while since I've experienced it. Certainly not on my current three bikes though I think I get faster on hills than I did before when I lived in a flatter part of the state with fewer decent hills.

Lennard Zinn has quite a few articles about it. Google and see speed wobble lennard zinn

cxwrench

I've had people come in with similar problems for years. It's nearly never the bike. It's nearly always positional, or the ride had a death grip, or something along those lines. I've never had it happen to me nor have I ever actually witnessed it other than a woman riding a Calfee uphill at 15mph that looked like it was getting a weird head shake. It has happened w/ lots of different brands/models. Bikes are stiff enough laterally these days that I can't see it happening w/o some kind of outside influence...rock, pothole, pavement seam, small animal. Wheel balance isn't much of an issue on bicycles, wheel true...maybe. But that would be very obvious. I had an hour long conversation w/ one of the riders on Kodak/Sierra Nevada when I was the team mechanic one night. They were on Serotta at the time and he'd talked to Ben and one of their engineers. They were of the opinion that is came down to top tube/down tube stiffness and also agreed that it took something out of the ordinary to get it started. After 25+ years in the business I'm still basically at a loss for reasons why it happens.

Racing Dan

Speed wobble is well known in motorcycles. All sorts of dampeners are available and they do work. To my knowledge only very little is available for bicycles and sadly doesn't fit most bikes, - but none the less, maybe you get inspired.

https://canecreek.com/product/viscoset/

cxwrench

The most common cause for motorcycles won't have anything to do w/ what happens on a bicycle...front wheel getting really light or coming off the ground then coming down crooked.

HillRider

I know you said you wanted mechanical, not riding position or technique suggestions but I'm going to ignore that. Cxwrench mentioned a "death grip" and that can be a real contributor. At high descending speeds many riders tend to grip the bars very hard and lock their elbows making their arms rigid rods. That can cause and magnify a shimmy.

I've got a couple of hills near me that allow 40 to 45 mph descending speeds and the only times I've felt any incipiant wobble is when I find myself using the above death grip. As soon as I relax my arms and grip the wobble stopped.

base2 

Plus one to rider position & cg placement.

Bike shops as a matter of industry practice place the rider too far back & too vertical with low seat placement & high bar height. The result is very far from the design intent that race bike engineers intend. It is my feeling this is because bike shop customers are generally inexperienced & unsure non-cyclists & this position inspires them to buy based on weight, brand reputation & ignorance on proper fit. Unfortunatly this also sets up the enthustastic novice rider for failure. The abnormally light weight front end becomes subject to all kinds of forces that would otherwise be dampened by a rider in agressive poisition.

I had this issue with my Cervelo at 42mph like clockwork. I slammed the stem, then shortened it to put the bars back to a comfortable reach & the resultant change in body position/cg is such any wobbles have not returned in the last 5000 miles.

Try a different fit.





Also plus one on headtube length & stiffness. It's the undampened frame twisting action & self-reinforcing undampened oscillations between frame & rider that cause the issue. When descending, make a practice to grip the top tube with your knees to short circuit any oscillations & a loose grip at the bars &/or de-weight the saddle so that the forces have nothing to amplify against.

aggiegrads

I had a bad speed wobble on one of my bikes. I don’t think that I did anything wrong on that bike that I don’t do on any of my other 5 drop bar bikes. Anytime I sat up to rest my hands or get a drink, unweighting the front wheel immediately triggered the wobble. It was worse when I put weight high on the rear custom rack.

The framebuilder added additional tubes to the rack to stiffen it, but it did not solve the problem. I am a mechanical engineer by education and training, and I know that speed wobble is ultimately undamped vibration. There are three ways to fix it - change the mass (not an option), change the spring rate of the system (also not a good option), or add a damper. I ended up getting a Viscoset and that instantly solved the issue. I tinkered with the damping stack until I had a setup that I could easily ride no-handed, but still provided enough resistance to kill the speed wobble. Needle bearing headsets are also a well-known solution to speed wobble, but there are only one or two headsets available for 1-1/8 steering tubes, and none that I know of for 1-1/2 inch lowers.

None of my other bikes need any damping and do not have speed wobble at any speed.

pdlamb

The only two bike mechanic-al things I can think of are misaligned wheels and a wheel out of true. So first, make sure your rear wheel is straight in the frame. Then give the front a spin and watch for wobbles.

Rider-mechanics are often easy to correct, at least in theory. I'll assume you're in the drops (coming off Mt. Lemmon?). It's easy to lock your elbows: don't do that. Consistent deep breaths to stay relaxed may help. At least flex the fingers of each hand, if you're uncomfortable taking a hand off the bars, to remind yourself to stay loose. Just switching hand positions, e.g. sit up to catch some air and grab the tops before you go into a curve, will help you relax.

Crankycrank

A few other things to consider. Check the balance of the wheels by spinning them and checking for overly heavy spots where the wheel always will stop in the same spot. Almost all wheels will be a little unbalanced and no big deal but a really heavy spot could make a difference and if so try rotating the tire on the rim or moving a wheel magnet, if you use one, to a different spot on the wheel to see if you can lessen the effect. If you like your riding position on the bike I absolutely don't recommend changing it by moving seat, bars, etc. around as the other 99%? of your ride time will affected. As mentioned check if your headset is tightened properly. Your tire pressures are probably fine but just for experimentation purposes try adding more pressure to the front and see if the wobble goes away or improves. Even though this is a Trek CF frame which very rarely are not perfectly straight you may have got a bad one so check for alignment. Also I have never heard of complaints of speed wobble with these so you may just have a situation of a perfect storm of small niggles combined that happen to create this situation and removing just one of them may solve the problem. I know you said you're not interested in moving your body around too much to stop this but just pressing your knees together against the top tube often will stop a wobble.

shelbyfv

If your wobble is repeatable you are well on your way to a resolution. Find a descent and do repeats while changing things. Start with your position, both saddle and bars. Change one thing at a time. If needed, move on to tires, then wheels, etc. Good luck! FWIW, though wobble is pretty scary, the old advice to grip the top tube with your knees has worked for me.

davidad

Shimmy or Speed Wobble by Jobst Brandt (sheldonbrown.com)

Andrew R Stewart 

This issue has been known, written about and not well understood for decades and decades. There's all kinds of opinion to be found with well done internet searches. There's VERY LITTLE actual understanding and more to the point, solutions, that work consistently. Hence the revisiting of this issue over and over. Believe me that if the total cause and effect were well understood then no bike would suffer from this as the liability lawyers would see to the design teams doing the "no wobble" design right from the start.

My meager understanding is that a combination of flexibility (frame, fork, wheels, rider), cycles of stress inputs and the harmonic resonance that results from all these factors are the main contributors. Changing any one or more of these factors can change the output (the wobble). Damping the steering, different rotating weight, tire pressures and profiles, rider weight placement and their "grip" on the bike, wind pressure, weight of load location, ability for the load to shift about (or not), stiffening the wheels, frame/fork, are all common methods of solution and in any one case some of these will make a greater or lesser change.

A little backround- I have been making my own frames for a few decades. Many of my bikes have suffered from some wobble at some times. The touring bikes being the worst. It's no fun riding along on a 100+ lb. bike/load at 11 mph with a consistent wobble/shimmy for miles and miles. Lots of time to think about this issue. I have tried all the usual methods, different wheels/tires. Moving the load about the frt/rr panniers and bar bag (if any). Riding sitting up as straight as I can, sitting as low or forward or rearward as I can. Slowing my naturally high cadence. Bracing the TT between my knees. Back pedaling briefly. Locking elbows, no handed, one handed riding. Yet when I've had a friend borrow my bikes they generally don't ever have any shimmy.

At 5'6" I am no where near the frame size that many talk about being more prevalent in wobblliness. I have replaced various headsets and rode Stronglight roller bearinged units for nearly 20 years (and thus discount the trendy claims of the roller bearings having enough friction/damping to quell shimmy). The same bike with a Campy NY and later a Stronglight A9 wobbled just the same.

So I agree with the rider's aspect and their reaction/response being the most important and what costs nothing to change (but are of course the hardest to change). Andy (who has more to say but will stay put for now)

aggiegrads

Seriously, the Viscoset is magic. A damper has a linear effect on a system, while mass and spring constant have an effect proportional to the square root.

It has only been around for a short time, but I think that it will become the solution of choice when more people know about it and try it.

Cyclefiend

Thanks for all the insight folks. I’m thinking it’s a headset issue, but don’t feel any play that I can feel, but it may be very subtle. It’s one for my LBS at this point. One thing also is the 50mm rims, they’re a definite handful in a stiff side-wind, possibly initiating an oscillation. May try borrowing a set of 20-30mm hoops to see how they work.

base2 

It is not a head set issue.
It is a head tube stiffness issue.
You're trip to the bike shop will not solve the headtube stiffness. That is a function of the bikes design.
There is nothing wrong with your bike.

Proper center of gravity & rider position/technique is the fix.
Pedals horizontal.
Hands in drops, fingers on/over the brakes.
Knees squeezing the top tube.
Saddle de-weighted.
This is the proper descending position on your Trek Madone, & indeed, any other racing bike. Deviating from this position is wrong. Keeping in this position is proper technique & will make you faster.

Engineers struggle to understand & solve the issue in frame design because it is largely not a frame design issue.

Good luck at the bike shop where they'll charge you $80 & reset the headset preload so that they can tell you they did something so that you feel at ease. A less than honest bike shop will take the opportunity to upsell you some new cartridge bearings & maybe even bill you for a total headset replacement with labor. Telling customers about the wrongness of user error is bad for business...& since the real problem is descending technique (which you say in post number 1 that you are not interested in changing,) you'll be back to sell to again.

Good luck.

shelbyfv

Worth trying

Sy Reene

?? So it's a bike design issue and therefore something is wrong with the bike?

This statement suggests that any and every bike will have speed wobbles if its rider has the 'wrong' position on their bike? Or that the same rider will have wobbles on any bike they ride? Some riders could still be pedaling and putting out power at 35mph -- a lot of your suggestions preclude this option.

Wish we could hear back from the OP though, is this his first bike, or has he ridden other bikes past the 35mph speed in the same manner without speed wobbles occurring? What size bike is this? Trek has a practice of not offering enough fork rakes to keep a consistent trail through the sizes offered (indeed, the current Madone lineup has trail figures ranging from 6.8 down to 5.6)

oldbobcat

I noticed that when I demoed one a few years ago. Rode an Emonda SLR over the same route the next day without any issues. It was just like a slightly lighter stiffer version of my 2012 Madone.

My guess it was about the flex dynamics of the frame and my weight distribution over the wheels. This was a shorter, taller stem than what I normally use. Since swapping stems and spacers is so epic with these bikes, try riding in the drops to lower your CG and move it forward. See if that changes anything.

base2 

If it were a design issue, there would be a recall. Headtube/top tube stiffness is what defines the liklihood of resonance. Modern bikes with their large headtube diameter, & large tapered (conical) design & complex shapes are such that an undampened standing wave setting up in the system is unlikely.

Everything has a resonant frequency. So, yeah, any bike could have the speed wobbles given the right conditions. Large diameter tubes & ridiculously stiff frames just don't have enough "spring" in them though.

The OP intimates the anomoly has happened several times & is repeatable & recoverable. That it is repeatable & recoverable says a lot. This suggests the rider changed something and did indeed have influence on conditions in some way.

The variable is the rider & his/her interface with the system. A bike rider still on the hoods putting out power is a different condition.

Racing bikes are designed with racing position in mind. Bike shops sell bikes with unskilled & unsure novice riders in mind. Bike fit of highest & most rearward center of gravity is the best way to set the OP up for failure. This is the opposite position of the engineers assumptions.

Anecdote: I used to own a Kawasaki KZ1000 police bike. The engineers discovered that it would develop speed wobble during high speed left turns. The kind that would only occur during a police chase. It turned out the culprit was a small & relatively light radio box above the rear wheel. Mounting that box on a damper decoupled it from the system enough that the speed wobble never returned & that bike went on to be synonomus with "police" on a cultural level.

One damper, one object, high over the rear wheel.

Racing Dan

That is what have been done in MCs for decades..Im betting the viscoset doesnt fit the Madone tho. Then what?

aggiegrads

It looks like he Madone has a proprietary headset (integrated 1-3/8”) but it also has an Isospeed damper in the top tube. I would see if other inserts are available (maybe a stiffer one) just to change the characteristics of the system.

I also had a different bike that developed a speed wobble after I installed fenders. It wasn’t bad at all, it only happened for the first time when I sat up no-handed on a long descent to take a drink at about 30mph. It was a set of long Honjo fenders and I left a long section below the front stay (you have to drill the fenders to add the stays). The long section of unsupported fender vibrated and induced speed wobble, so I re-drilled the fender to lower the stay and the problem went away. That bike has about 10,000 miles in that configuration and it has not had speed wobble since then.

I disagree with the assertion that it is caused by poor form, or rider error. Some bikes just don’t match the riding style and position of the rider. Many experienced riders have encountered at least one bike that produces speed wobble for them. Some experienced riders have never encountered a bike with speed wobble, and attribute their superior skill as the reason that they have never experienced speed wobble. It is as frustrating to me as those who say that cramps are a result of poor conditioning. Some people are just more susceptible to cramps, regardless of how fit they are.

Racing Dan

I forget about the isospeed. I believe its in fact adjustable right out the box, by moving the insert, - see the link (takes forever to load, sorry) .. I think I would play around with the settings. Also, possibly a 1 cm longer or shorter stem could change the dynamics of the system just enough to not trigger the resonance. Or it would just move the frequency a bit

https://cyclingtips.com/2018/07/2019...ject-one-icon/

Im sure its not reasonable blaming the rider, but this video is fun and interesting and does show body position can help save the day if you experience wobble on a MC

.

DaveSSS 

I'd put more pressure in the front tire. My michelin 28mm tubeless say 73 minimum, but I get by using 70 on my gauge, since I weigh 135-140.

Modern angular contact headset bearings need some preload on them. I don't use a torque wrench for such small amounts, but the only way to know that the preload is too great is when the front wheel doesn't automatically self-center after a turn. Also be sure that the top cap is not touching the steering tube and preventing preload from being applied.

I hit speeds of 48-54 mph on nearly every ride. I don't unweight the saddle or put my knees against the top tube. I pedal up to about 42, then get low with my hands in the drops and fingers ready to brake when there are curves ahead. Those deep profile wheels may be a problem. I refuse to use them, since strong cross winds are always a possibility. I have fulcrum racing 3 disc brake wheels on both of my bikes.