Front end bounce - please help

[Guest]

What are all possible causes of bounce in forks? Happening on relatively smooth roads, straight and in turns. I'm at a rally, first real rides and bike is basically unsafe.

Recently had front tire off to clean valve stem. Also replaced steering bearings . No discernable play in stem, fork fall freely to either side when front wheel is off the ground. Had occasional slight bounce before, nowhere near this bad.

Sonic 1.0kg springs, 15wt oil.

[Jonathan]

Describe the bounce more fully? When riding at speed do the front end hammer up and down (out of balance front wheel)? Or is the front suspension under-damped so that road oscillations set the front suspension pogoing? Is it worse at particular speeds or road conditions or is it the same regardless of speed... Do the handlebars flap left and right as well as up and down?

[Dogma]

My guess is a wheel weight fell off. 15wt oil at anything like the correct level should not be radically underdamped. You would be able to feel the damping working just by bouncing the front end. You can check balance there at the rally. Put it on the center stand, then put enough people on the back to keep the front off the ground. Spin the wheel a few times to see if it always settles on the same side. Dragging brakes may need to be removed or backed off to get a good enough read.

A damaged tire, like maybe a bulge somewhere could do it too. If the wheel was off, maybe it didn't get back up on the rim?

[Joe Garfield]

It's a bent stem and possibly bent fork stanchion. Wheel balanced relatively OK, tires look good, etc,c. Bwringer noticed some marks on the forks, put some weight on it and said they're binding. So I had unequal travel in the forks and they were fighting each other. Loosening and turning the stanchions helped enough to make me feel dumb enough to ride it again today. Having fun but tired of gripping for dear life to hold the steering straight. :/

[Buffalo Bill]

Have you tried loosening the axle bolts, bouncing the fork a few times so they can find their own place, then re-tightening the axle bolts?

[Joe Garfield]

I didn't loosen the axle bolt. I will try that, thank you

[Joe Garfield]

The front end was finally made right on this bike. I installed the straight stem and got the bearing pressed in correctly; no more bounce.