Speed Wobble

[mrP(Boonen)VT]

[quote]also to reach the brakes

[Tony]

Paul, far from me to judge whether or not you are a big girl's blouse (there are other members of the club both past and present who would more aptly be described as such) but speed wobble can be caused / exaggerated by a mechanical problem with your bike. In my experience a speed wobble requires:

1. Cross wind;
2. Fast decent;
3. Light-weight rider;
4. 'Noisy' road-surface (e.g. loose chippings on tar construction rather than glass-smooth tarmac);
5. LOOSE / POORLY ADJUSTED HEADSET;

The loose headset allows the whole front wheel and front fork arrangement to shimmy from side-to-side. When it happens you feel as though you have bugger-all control over the bike. One of my bikes from a few years ago (which never seemed to have a very good headset adjustment) rather enjoyed a good shimmy at 40+ mph. On other bikes I have never had any issues at all even at considerably higher speeds.

I'm sure other mechanical issues - such as a slightly out-of-true front-wheel or front- and rear-wheels a little out of alignment could cause it too. I'd definitely check for play in the headset (both top and bottom bearings) as a starting point. Otherwise it may recur more readily than you'd expect.

As others have said, if and when it does occur, try and relax and let your body absorb all the vibrations. I wouldn't try and hold the top tube with your knees for the first time when you're in the midst of a big wobble - unless you normally decend that way. You can decend without a speed wobble without having to do that.