Re: Instability and Speed Wobble: Bikefanclub.com

Hi,

This is an interesting thread even though its a bit old. The age doesn't affect much, though, because the fundementals of bike dynamics still aren't well known.

If you doubt the latter, assemble 3 or more frame-builders to discuss handling and frame/fork design. They'll disagree. The best seem to recognize that more than one combination of design factors can work well and that humans adapt easily to their bikes. So, what's this got to with speed wobbles?

Inputs of some cause cause the wobble, but what are they? The problem with tests to date is that in their attempts to isolate a variable, they limit other variables that may have synergistic consequences. The weight of ones wheels may be a causal factor for speed wobble, but only with certain configurations of bike and rider. The same can be true of the headsets condition/adjustment/fit, or frame flexibility, or alignment of the fork. Proving that one, or a limited set of instances of a mis-aligned fork doesn't prove that a mis-aligned fork isn't a causal factor in speed wobble.

The experienced mechanic or builder will attack speed wobble by looking first for more common and easier to solve solutions and then work towards more difficult and less likely solutions. Speed wobble hasn't a single cause nor a single solution.

If anyone doubts the impact of alignment, think of the last time you pushed a grocery cart with a bent front wheel. It oscillates. Nuff said on that.

In any case, grossly misaligned carbon forks are a crime. For their price, high precision should be expected.

As to technique, someone with more experience and better honed bike handling skills will probably have a better chance of recovering from a wobble. However, no one should become too proud of their skills. That you've never succumbed to a wobble only means you haven't yet met a wobble you couldn't handle. Sort of like someone from New Orleans sayinhg a year ago that a hurrican couldn't wipe out the town. Same goes for your bike, regardless of who built it.

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