Technical FAQ: Stem height and high-speed wobble

Can stem height affect high-speed shimmy?

Feedback on shimmy:

Dear Lennard,

With regard to the recent speed wobble question, I’ve been riding a Steel IF, which I had built 4 years ago, a Crown Jewel. When we built it up I had our local shop guy leave an extra inch on the steerer to give me more room for a more upright position on the bike to alleviate some lower back issues. I had my bars set about 1.5cm high.

I had problems with speed wobbles descending for a couple of seasons. I’m a relatively big rider at 6-1 and 180lbs so my frame geometry is bigger as well, which I thought contributed in some manner.

Wobbles were primarily in crosswind conditions when I got “tight” on the bike, so I blamed myself for the situation and prepared for it descending in crosswinds. I ride the Dura-Ace tubeless, which have a semi flat spoke as you know.

Then last season I decided to ride the bike at spec and dropped the bars on the steerer as my back was really not an issue. This was the difference. The bike is now so bomber I do not even think about speed wobbles descending anymore. I was amazed at how rock solid the bike became with this small “adjustment.” So to some of your readers, this may help them if they have a similar bike set up.