Originally Posted by
PeteHski
it depends how much damping there is in that flexible part. It could actually act more as an un-damped spring, which would tend to make things worse at the resonant frequency.
This makes me wonder about bikes like the Specialized Roubaix. Early versions of that had an undamped spring above the headset. The latest version also has a damper.
My point is this: it’s unknowable without knowledge of the entire system at resonance at that instant in time and without some knowledge of the impulse that set the system into resonance.
None of this is due to a single cause or, by now, all of those things would have been eliminated and there would be no resonance/under damped instances in bicycles and this would never happen.
This stuff is always complex and multidimensional. That’s why it’s hard to isolate, replicate and pin down. Every time this happens, I’m sure it scares the crap out the bike manufacturer’s lawyers and engineers (been there done that - different industry). The big guys are going to have a lot better handle on simulation and analysis of what causes this in their bikes than the little guys.