I have a new Soloist Team (stock edition, Shimano wheels) that I raced last weekend.  The first time I descended a steep grade and got up over 40 mph (65 kph), the bike started vibrating/shimmying and felt very unstable laterally - I thought I was going to lose control and crash, and applied some brake to slow down.  Has anyone else experienced this?  Is it "normal" at high speed, caused by crosswinds, or a problem with the bike/wheels?  The bike has been rock-solid at all other times, but now I'm afraid to take it up to high speed.  Any thoughts would be appreciated.

There was an article on Velonews regarding this: http://www.velonews.com/article/9786

Dear Readers,
As many of you know, we have discussed speed wobble a lot here. Wehave discussed wheels, stiffer top tubes, headset adjustment, increasedfork rake, and losing weight off of the rider as ways to reduce it. I gotthis letter from carbon guru Craig Calfee, however, regarding alignmentof the fork blades being a culprit in high-speed shimmy. Fork alignmentis something that all we framebuilders used to worry about in the era ofsteel forks, as we were building them ourselves, but with suspension forkson mountain bikes and carbon forks on road bikes, neither of which canbe aligned, we all just abdicated responsibility for that and assumed thatthey were right on. Calfee, however, finds that they are not, and he furthermorefinds that he can eliminate bike shimmy by replacing a poorly-aligned forkwith a straight one.
Lennard

Dear Lennard,
Calfee Design has identified a cause of speed wobble (a.k.a. shimmy)and instability that can be prevented. Speed wobble is a dangerouscondition that can cause the rider to lose control of the bicycle and crash.While loose headsets and out of true wheels and frames can contribute tospeed wobble, we have found that fork asymmetry can also cause speed wobble.Fork symmetry is defined as the symmetrical position of the fork dropoutsin relation to the steering axis. Specifically, the equality of thedistances from the dropout faces to the steering axis must be within acertain tolerance for the bike to ride in a stable and confident manner.Traditionally, steel forks were cold set after welding or brazing torealign them after possible distortion caused by the heating and coolingof the metal. A diligent steel frame builder can align the fork bladesto within a millimeter of symmetry.Carbon fiber forks cannot be cold set. They must be molded straightto begin with. We have found that a small percentage of carbon forksby various makers were molded with asymmetrical fork blades. Someare off by a little over a millimeter and others are off by two or more.Forks that are off by over 1.8 millimeters in symmetry have a good possibilityof being prone to speed wobble. A symptom of a fork that is off by1.8 mm or more is a noticeable difficulty when riding no hands at a slowspeed (less than 10 mph). One has to lean to the side slightly tokeep going straight. A bike with asymmetrical forks seems to cornerbetter in one direction but not so well in the other. At speeds of30 mph or more, the bike can develop speed wobble.If your bike has the above-mentioned symptoms, the fork should be measuredfor symmetry. This is difficult to measure without proper tools.Calfee Design measures all forks for symmetry and is equipped to measureany fork. If any Calfee customer wishes to have their fork checked,please send it to us with a letter requesting a fork inspection.Non-Calfee customers may send their forks for inspection for a nominalfee. Replacements may be available for asymmetrical forks, dependingon the individual fork maker’s policy.

Fork Symmetry Measuring Setup:

1. Fork blades must be square to the surface plate
2. Rotate fork in V blocks to measure other dropout
3. Difference between the two measurements must be no more than 1 mm(Calfee tolerance)

 

Craig Calfee

Perhaps it's just the Shimano R500 wheels?  Before I bought my Soloist Team, I heard nothing but negative reviews of the R500s, so I didn't use them on a single ride and sold them at the first opportunity I had.  I regularly ride a couple of 3-5 mile descents @ +40MPH using the stock fork and the bike holds absolutely steady the entire way down, using Bontrager Aeolus or Race X Lite wheels.

My experience is it is almost always caused by me tensing up my arms/upper body. It may not be instictive, but concentrate on relaxing your grip and I'll bet the shimmy disappears. If it doesn't, pinch your knees on the top tube.

Thanks all for the suggestions.  On further search I found the following (exhaustive if not conclusive) thread:

http://forums.cervelo.com/forums/p/490/2394.aspx#2394

It appears the phenomenon is not unique, but also not common/predictable:

1. It seems the Soloist Team is a little more prone to this than many other bikes...which slightly shakes my confidence in Cervelo.

2. No one has found any consistent cause.  Suggestions have included (a) headset too loose/tight, (b) wheels slightly (if imperceptibly) unbalanced, (c) fork not perfectly symmetrical, (d) handlebars unbalanced, (e) frame poorly made, (f) rider position/grip.

Frankly, I find it hard to believe that rider grip/tensing would cause this problem, although it might make it worse.  When it occurred to me, I feel I was riding as comfortably (all relative) as I do at lower-speeds; the wobble started when my speed increased past 40 mph - and it came on very suddenly.  Also, I've seen quite a few posts (here and elsewhere) describing rock-solid handling at high speeds...it's hard for me to believe that ALL of those riders are relaxed, while the "wobblers" are not.  Moreover, some people have claimed to solve the problem with mechanical changes.

Having to pinch my knees and "relax" - while those may be good general guidelines for descending - does NOT seem to me to be a solution.  That would be like telling a race car driver, whose car skids every time he exceeds 170 mph, to just "steer into the skid."  That might prevent him from crashing, but doesn't solve the problem with the car.

I will be looking at all the possible mechanical solutions.  Checking my headset and handlebars should be relatively easy.  Changing wheels is also an easy thing to try. Measuring fork symmetry is apparently more difficult without precise instruments - and changing the fork problematic/expensive.  What worries me is the apparent predilection for Soloist Team to have this problem...you have to wonder if something in the frame is prone to imbalance, at least under certain conditions (component build, rider position, etc.).

I would check your wheels if this is something new.  tension, stiffness etc.   you shouldent have this issue.  ive decended 60+ mph on my r3 sl and had no issues.  

I've been lurking here on the site for awhile but never registering. I feel compelled too today in reference to the highspeed wobble.

 I own two Cervelos, a 2006 Carbon Soloist with full Dura-ace and an 08 RS full Dura-ace with krysirium ssl's that I purchased new in April. Both bikes were purchased and built by Locomotion in Winter Park, FL.

A year and half ago my soloist broke into a violent speed wobble at 45 plus mph. I don't have to tell anyone here, it scared the *** out of me. I had Jere at Locomotion evaluate the bike, he did and gave it a clean bill of health. He did a thourough investigation including but not limited to looking at the steerer tube and every other part of the bike. It shook my confidence in downhilling on the bike. I slam my stem too. At certain times in the season I will use one stack, but no more.

My RS hasn't broken into a speed wobble, but it has gotten twitchy at speed which is a little disconcerting to say the least. I just returned from my second trip to Blood Mountain, GA and the six gap course and descending does not seem to be either bikes strong point. Climbing and riding on the flats are excellent.

 One of my riding partners is David Milham a two time world champion BMXer and #2 pro, he has bike handling skills that are amazing and he feels his Carbon Soloist has a tendency to wobble at speeds too.

These bikes were professionally built by a leading Cervelo dealer and I have full confidence in their builds and maintenance of the bikes. Dave hypothesis is that with the really short chain stays the front end is just naturally light which may cause the wobbles?! Just speculation, but real in our opinion.

My Felt F1 purchased and built by the same shop never had this tendency.

I enjoy my Cervlo's a great deal and am happy with my purchases, I just make sure I am aware of the limitations and enjoy them much more going up and across than going down.

 

Fitness, I think you are missing my point. On this weekend's century in very hilly area, I was able to create a shimmy by gripping the bars tightly, and eliminate it when I relaxed, at over 40 mph. I thought it was interesting. I have an SLC-SL with a 3T Funda Pro fork. I think the 3T is more stable than the Wolf.

It works for my, may not for you but I think you might find it interesting to try.

This is quite alarming! I have read numerous issues about this "wobble" at high speeds and it is starting to detract me from purchasing an R3. I know I can hit 40+mph easily on a descent, so I am quite concerned about handling issues. I expect better performance for a highly priced carbon steed. AC

I have 2 Cervelos, a 2002 Soloist and an R3

 The soloist is very stable at speeds up to 48 mph which is my maximum and this is a 6 year old bike with a 1" steerer, (Reynolds pro Ouzo fork).

It is a basic build eith 105 groupset and Aksium wheels and I TT and race it and it is a great bike.

My R3 is the same, very stable.  I did the Etape with it this year and descending Tourmalet was a pleasure at speeds up to 50 mph.

I think that if one has speed wobble to look at all possibilities including:

1    Proper meticulous build of the bike, especially front fork alignment and headset set up.

2   Wheels are true and balanced.

3   Riding technique

4   Brake caliper alignment.

hope this helps

 

 

I find it hard to beleive that a company with the highest concentration of engineers, does more testing than 95% of all bike companins and works with some of the best Professional cyclist in the world would have a wobble issues!  I regularly hit 50mph and have hit 62 with absolutly no issues.  I have had issues with some wheels not being strong enough and therefore causing a 'mushy' feeling and unstable, but never wobble.   you should have no issues with your cervelo

Speed wobble due to a tight grip and tense arms has been my experience as well. In fact I'd say it's not just the hands and arms, but the whole body. It is a bit counterintuitive, but I find that if I relax and let the bike track as it was designed to do, it's very smooth. I can see that speed wobble is a dynamic problem, probably with lots of causes and contributing factors - which I suppose is why it's impossible to come up with one answer/solution. But, for me, the tension=wobble equation rings true.

i was completely relaxed when my carbon soloist went into a violent speed wobble. i done the descent  reaching speeds of 57mph on other bikes. I never once had a problem. I think the Cervelo's are great bikes, I own two and purchased one after the episode on my carbon soloist (by the way it's got the alpha Q fork).

 

The wobble was so violent my friends I've ridden with for years were behind me and pretty much wrote me off. I believe I saved it by not tensing up. I've ridden motocross since 1973, so I know about a relaxed grip on the bars.

 

there are too many accounts of the wobble issues to act as if they don't exist. I don't blame Cervelo for not acknowledging the issue if they are aware of it. The way people want to sue and not take personal responsibility. I consider the Cervelo a race bike with an aggressive angles, so if I have to be a little more careful I will, but as I stated before, my Felt F1 rode the down hills and mountains like it was on rails.

While I don't know the answer, my gut (and head) tells me it's not just "upper body tension."  When it happened to me, it started as I increased speed above 40 mph - the tension in my grip hadn't changed.  Also, once it started I admit my grip tightened tremendously (!), yet it stopped as soon as I applied enough brake to get below 40 - even though I still had a death grip (I was pretty scared at that point) and was still descending.  Maybe "relaxing" would've stopped it too, but I can't help sensing that speed (and something in the bike's reaction) was the cause....I admit that it's hard to imagine Cervelo - which prides itself on speed and outfits top racers - being "responsible" for such a problem...but ignoring it - even if it's caused by non-Cervelo parts - is NOT a good answer.  I'm going to keep investigating - online and with my bike - but my confidence in my new Soloist (and by extension Cervelo) is somewhat shaken....Although there appear to be reports of wobble with other brands too [perhaps suggesting that frames are not the culprit], I'm so far getting a non-scientific sense that the Cervelos (esp. Team Soloist) are more predisposed....

I have no reason to doubt Republicanrider's or FitnessCC's experiences. Sounds scary as hell. As I said "I can see that speed wobble is a dynamic problem, probably with lots of causes and contributing factors - which I suppose is why it's impossible to come up with one answer/solution". I don't think anyone said or implied it doesn't exist. I can only speak from my experience, and mine does not include a mechanically induced speed wobble (SO FAR...can't say it will never happen). I've got a 56cm RS, which is pretty close to square, with rather ordinary 73 degree angles, and longish 41cm chain stays, 3T Funda fork. Not exactly aggressive. Extremely stable for me. So obviously, the cause of the wobble is not necessarily inherent in a particular brand, model, or size for everybody. Again, too many variables, especially once you add the rider (weight, position, etc). I guess this is the beauty of a forum - lots of different experiences and perspectives. Not always a right or wrong answer available.

I've been participating in cycling forums for about 12 years now, and this speed wobble thing comes up all the time. I've yet to see a definitive single answer or an agreement as to cause.

Great discussion