What's wrong with my rear wheel? Wheel moves about 1/4" front to back when brake is fully applied, cassette seems a bit wobbly, some rubbing noise

Question

I first started inspecting my wheel because I noticed when I applied my brake while not riding, I could push my rear end and the wheel would turn forward and back about 1/4"-1/2" each way (but the brake is still locked tight) . I took my wheel off and saw that my DT Swiss center lock was loose, so I bought a Park BB tool and tightened it up, but I still have the problem but less now. I see that the wheel is moving @ the center lock just a bit.

Then as I was messing around with the bike upside down, I noticed that my cassette is wobbling ever so slightly.. Is it possible/probable that this is related? There is also some rubbing noise that is not coming from the brake that is difficult to locate.

Is this likely my axle? Hub? Cassette? Thanks!!

Answer 1

I've seen this issue in the past and the culprit was the axle (not the skewer) in the hub had snapped.

Fortunately, the bike was still rideable to a certain extent, as the QR skewer was holding the two broken sections of axle in place. Note that even when the wheel was removed from the frame, it still wasn't immediately obvious that the axle had snapped, until the skewer was removed from the hub. However the whole wheel was replaced ASAP for safety reasons.

Due to the age of the wheel (15-20 years), it was more economically viable to replace the wheel than to rebuild the old wheel with a new hub.

Answer 2

I'm not 100% certain how the DT Swiss centerlock works but it seems like its a way to attach a 6 bolt brake rotor to their hub. What may have happened is that since your center lock was lose:

1. it allowed the rotor to work against the 6 posts on the adapter causing some wear
2. it allowed the adapter to work against the hub, also causing some wear.

I'm not certain, but the freehub body might be the same material as the hub shell (the adapter part). I've heard of the splines on freehub bodyies (from other manufactures) getting worn down, causing the cassette to wobble. In these cases, the freehub body was always soft aluminum. Inspection of the splines on both the freehub side and the centerlock side will tell you if they've been worn out.

Answer 3

You could also be getting some play in the fork (assuming you have a suspension fork). To verify this, put your finger where the stanchion meets the lowers of the fork, lock the front brake and rock the bike back and forth. Every fork I've had has just a little play there.

It's not likely that the play in your cassette is related to your front wheel. That play could be from the cassette ring being a little loose, or the fit of the cassette on the freehub (likely) or just a bit of play in the hub itself. If the cassette ring isn't loose I wouldn't worry about the cassette play...unless you think it's affecting your shifting.