Not seeing how rebound alone could be "too fast" on washboard such to reduce wheel contact. Too fast/too little compression damping yes, as the unsprung mass' inertia will cause it to keep going up after passing over a bump. But rebound will only go as fast as the ground falls away, because the ground is always there as a limiter.
Fluttering like that is usually not because of just "too fast" rebound, but it's a combination of trail speed, washboard frequency, compression damping, _and_ rebound damping. You can get into situations where the wheel floats up after the bump due to lack of compression damping, and the rebound damping lets it then extend at the exact right (or wrong) speed to smack into the next bump such that the wheel gets shot up too much yet again. Slowing down the rebound damping just changes the trail speed that causes the smacks to line up and accumulate. This might feel like less fluttering at a very specific speed, but at speeds similar to what first caused the flutter, the wheel will be in contact with the ground even less than with faster rebound.
A better solution for fluttering on washboards is not to slow down rebound damping, but rather speed it up, maybe a bit more compression damping to keep the wheel from shooting up beyond the bump, and also be active over the bumps: active pressure to keep the bike weighted and not let the bars and pedals flutter, let the suspension work as fast as it can.
Dec. 19, 2024, 11:36 a.m. - Justin White
Not seeing how rebound alone could be "too fast" on washboard such to reduce wheel contact. Too fast/too little compression damping yes, as the unsprung mass' inertia will cause it to keep going up after passing over a bump. But rebound will only go as fast as the ground falls away, because the ground is always there as a limiter. Fluttering like that is usually not because of just "too fast" rebound, but it's a combination of trail speed, washboard frequency, compression damping, _and_ rebound damping. You can get into situations where the wheel floats up after the bump due to lack of compression damping, and the rebound damping lets it then extend at the exact right (or wrong) speed to smack into the next bump such that the wheel gets shot up too much yet again. Slowing down the rebound damping just changes the trail speed that causes the smacks to line up and accumulate. This might feel like less fluttering at a very specific speed, but at speeds similar to what first caused the flutter, the wheel will be in contact with the ground even less than with faster rebound. A better solution for fluttering on washboards is not to slow down rebound damping, but rather speed it up, maybe a bit more compression damping to keep the wheel from shooting up beyond the bump, and also be active over the bumps: active pressure to keep the bike weighted and not let the bars and pedals flutter, let the suspension work as fast as it can.