What Makes A Wobble?
 

Hello All,

The bike: A 90's "Balance" brand mountain bike with no suspension and a basic 3x7 setup. Ridden daily, I have added fenders and a rack.

On Friday, it rode as usual.

On Saturday, it started making a whoosh/rub noise intermittently, but it would only start after being ridden for a bit. The noise really sounds like the front fender rubbing, but I inspected both fenders and tires and saw no evidence. I removed and reset the front fender to be sure. The front tire was a bit low, so I pumped it up.

Sunday and today: The sound persists, and now there is an intermittent wobbling feeling. For about 15 feet at a time, it feels like SOMETHING is wobbling left to right, then it stops.

Neither wheel is significantly out of true, and there is no play in the axles when pushing side to side. The headset bearings have no play, but the bottom bracket cartridge has a very small amount of sideways movement. Neither QR skewer or lever was crooked or loose.

So, assuming that the noise and wobble are connected, anyone have any bright ideas?

First thought is to do the prudent thing and have a set of experienced eyes/hands have a go. The list of potentials is long but I would wonder about the rear axle/bearings. Assuming a rear QR skewer, a broken axle is somewhat "splinted" in place with the skewer so without significant force involved in the test the wheel would remain fairly stationary. Mere speculation on my part though. Andy

I would pull both wheels off and check for a broken axle. If OK, I would remove the fenders, one at a time and see whether the noise goes away. This might help localize the noise.

A wobble you can 'feel' is usually the result of a bulge in a tire caused by damaged casing.

Remedy: replace tire