Northern California - Speed Wobbles

After experiencing this on Carson Pass at 46ish mph, I've now read everything I could find about Speed Wobble or Shimmy.

This video is great. Wobble (http://www.youtube.com/watch?v=xODNzyUbIHo)

It makes it less frightening to see someone intentionally induce and then correct the wobble. Before reading up, I had no idea how to correct it. I lucked out on Saturday! :twitchy:

That was pretty intense - although it seemed to correct itself by him just grabbing hold of the bars again, not sure how representative that is of "real world" speed wobble? I've only ever had one close call with that - I hit a personal best 53mph on Guadalupe Canyon (San Bruno) and got hit with a side wind. Knees on the top tube and gently reducing my speed seemed to do the trick, but I got a nice 20bpm boost in HR for my trouble.

Shimmy is scary. It used to be common with older bikes, newer ones with stiffer front ends are way more stable. Front wheel balance and truing are also critical factors. But sometimes it's also due to the rider from too much tension in the arms. The video is really extreme but pressing the knees against the top tube and relaxing the upper body help a lot.
I was apprehensive on Monitor Saturday but didn't feel any hint of wobble even at close to 54 mph.

Yeah, I was fine on Monitor. Maybe fatigue, cold, a bump, whatever got it started on Carson. I had never heard about it. Got lucky that I managed to slow down to a complete stop. Weird thing was that as I slowed from 45ish, around 20mph it was more pronounced. I didn't know what else to do, so I just held on and lightly held the rear brake until I was able to get off the bike. Took me a minute to reset.

Could also be due to lack of tire pressure. I noticed my front wheel had a flat this morning so I surely had air slowly leaking off this tire on Saturday, could also be your case. Rider shivering would amplify any wobble, that's for sure. What troubled me the most down Carson were the cracks crossing the road every few yards. My R-Sys wheels performed fantastic all day long but their stiffness and my added weight on the front wheel from fatigue, I guess, amplified the shocks.

I had the same experience descending Carson. I had read about it, but never experienced it before. At first it felt like my back wheel had tacoed, but than I realized it was high-speed shimmy. It went away as I slowed down and shifted my position.

I attributed it to my slight shivering and tenseness due to being cold and wet. I had been faster going down Monitor, yet everything felt solid.

When I first got my Ritchey, I discovered that it developed a wobble at >40 mph. Scared the crap outta me! Then I had a professional fitting, which raised my butt and moved it forward, and dropped the bars just a little. That effectively shifted more weight onto the front wheel, and since then it's been rock solid to as fast as I've been able to go - a little over 45 mph drafting a car... :innocent:

If you can stay relaxed then you won't get shimmy. Some bikes or setups shimmy easier than others, and sometimes crosswinds or shivering can start it, but in the end it's due to having your arms too tense.

Elbows bent and knees on the top tube, and you won't have a problem.