I currently have a specialized roubaix pro that I have had professionally fitted for triathlons including clip ons, and a shorter stem to get more compact (not as stretched out). While at IMLP doing the downhills at keene I couldn’t go over 40 mph without an unbelievable wobble-shimmy of the front end. I’ve had the wheels (zipp 404) checked out etc.
My question is, is this problem a function of my road bike being converted to a tri bike, and would I be better off switching to a tri bike?
(Due to a bad neck, I can’t have a really aggressive position on the aerobars.)
You’re describing “death wobble” which happens on certain bike/rider combos. It was quite a serious problem with my medium frame Giant TCR on fast downhills. I switched to a Lemond frame and have no such problems since. It’s something to do with a resonating vibration that gets going. Maybe somebody on the forum with a physics background can explain it. Putting on the brakes only makes it worse.
The solution is to hug the top tube with your knees and unweight your saddle a bit. Also relax your grip on the bars. When I did this the wobble on my Giant would stop almost immediately.
It’s very unnerving but can be brought under control this way. The only other consideration is make sure your headset is tight as this can also cause a problem.* *