I was in LP this weekend doing the IM course and ran into some issues on the downhill into Keene. Got a lot of wobble on the front wheel and on one of the loops, heading into a strong headwind, I got enough of a wobble that i was sure I was going to bail. Can someone give me some tips on how to effectively go downhill. I’ve already got the “grow some balls” tip from a friend so now I’m just looking for some technical riding skills type tips. We don’t have downhilsl like that here in Southern ontario…at least none that last for 9K. Any help is great since if I hit a strong headwind again at IMLP, I’ll need to clean out my shorts in Keene.
Been there done that 5X…the word is not to death grip your bars and to squeeze the top tub with your knees. Still scares the shit out of me though.
weight shifted back on the saddle, chest low, knees clamped on the top tube with pedals level, hands near the brakes for increased balance and for just in case, eyes looking far ahead scanning for other riders, road debris, pot holes etc, steer with your body not the bars. After that just let gravity do its thing. If it is windy control your speed with your brakes and with how much of your chest you show to the wind.
If it is just the idea of decending at speed then really the only thing that will fix that is experience, the more you descend the more comfortable you’ll becomes going faster.
You experienced “death wobble”. This is a common phenomena. Some bikes are more prone to this than others. As already described relax your white knuckle grip, unweight your seat and press one or both your knees against the top tube. My early model aluminium Giant TCR was notorious for this. My Lemond is much more stable on the downhills.
Another but rarer possibility is an assymetrical carbon fork. This is more common than most people realize since the carbon forks are molded and can’t be corrected after inspection the way the old steel forks were. Slowman referred to this as the bike industry’s “dirty little secret” that they don’t want to admit.
If the rider position changes don’t work you can get your fork tested by sending it to Calfee.
I’ll repost this from Lennard Zinn at Velonews. It’s a possibility.
Check the alignment
Dear Readers,
As many of you know, we have discussed speed wobble a lot here. We have discussed wheels, stiffer top tubes, headset adjustment, increased fork rake, and losing weight off of the rider as ways to reduce it. I got this letter from carbon guru Craig Calfee, however, regarding alignment of the fork blades being a culprit in high-speed shimmy. Fork alignment is something that all we framebuilders used to worry about in the era of steel forks, as we were building them ourselves, but with suspension forks on mountain bikes and carbon forks on road bikes, neither of which can be aligned, we all just abdicated responsibility for that and assumed that they were right on. Calfee, however, finds that they are not, and he furthermore finds that he can eliminate bike shimmy by replacing a poorly-aligned fork with 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 dangerous condition 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 to speed wobble, we have found that fork asymmetry can also cause speed wobble.
Fork symmetry is defined as the symmetrical position of the fork dropouts in relation to the steering axis. Specifically, the equality of the distances from the dropout faces to the steering axis must be within a certain tolerance for the bike to ride in a stable and confident manner.
Traditionally, steel forks were cold set after welding or brazing to realign them after possible distortion caused by the heating and cooling of the metal. A diligent steel frame builder can align the fork blades to within a millimeter of symmetry.
Carbon fiber forks cannot be cold set. They must be molded straight to begin with. We have found that a small percentage of carbon forks by various makers were molded with asymmetrical fork blades. Some are 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 possibility of being prone to speed wobble. A symptom of a fork that is off by 1.8 mm or more is a noticeable difficulty when riding no hands at a slow speed (less than 10 mph). One has to lean to the side slightly to keep going straight. A bike with asymmetrical forks seems to corner better in one direction but not so well in the other. At speeds of 30 mph or more, the bike can develop speed wobble.
If your bike has the above-mentioned symptoms, the fork should be measured for symmetry. This is difficult to measure without proper tools. Calfee Design measures all forks for symmetry and is equipped to measure any 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 nominal fee. Replacements may be available for asymmetrical forks, depending on 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
Calfee Design
As others have said, although it is hard to make yourself do this you unweight the saddle and clamp the top tube with your knees (even one knee touching can sometimes be enough).
I have often noted that inexperienced cyclists will induce wobble by tightening their grip on the bars and stiffening their upper body and arms so the wobble is transmitted to the bars. I actually had a wobble at Vuelta De Bisbee on the first road stage because it was cold and I was freezing on the descent I actually started to shiver and it made the bike wobble. Getting my upper body to relax helped.
KR
Great advice from all. Descending at speed isn’t an issue since I have gone faster before and had no issues…I think it was the added head wind and the prolonged descent that may have attributed to my “death wobble”. I’m also going to check my headset since I did have an issue with it being loose in the past (and it was tightened) - it may have come loose again. Technique sounds a lot like descending steep inlcines on a mountain bike (I was a MTBer before a road rider). Thanks again. Last thing I need is to train for this race and then experience the same wobble and crash out…not a happy ending!
Thank you for your post. I was going to ask the same question after a scary wobble this weekend. I was descending a hill at about 40 mph and a strong wind caught my bike from the side. I was pushed off the line I was following and the front end wobbled terribly. I have descended much faster and had wobble before, but never like this. It intensified until I let loose of the bars and actually allowed the wind to carry me across the road. I wanted to know ahead of time what to do in the future if this happens again.
ON steep descents, I do what I saw Walton do a few yrs ago. Put my butt WAY back on the saddle–almost sitting on my hamstrings, chest low, hands on the bullhorns. It’s very aero and fast and stable. If you wobble squeeze the top tube with your knees and lift your butt a little. Someone posted a pic of him doing that on here recently.
I have had the speed wobbles many times. Last time was in march and it destroyed me. I already have fear of descending and this was terrible. I really thought i was going down and couldn’t stop shaking. I think the cross wind is what got me too. I am still overcoming the fear that it created. riding hills non stop in tuscany for a week eased up my stress a bit. Not sure what advice to give, I am so scared this will happen again.