rykoala

When on the stand last night I was adjusting shifting (upgraded from 7 to 8 speed) I noticed that the hub appears to have a bent axle. The reason is that the the cassette wobbles on its axis.

It seems pretty straight forward but before I tear into it I'd like to make sure. I have another axle to put in, but I want to make sure my assessment is correct.

Thanks!!!

Retro Grouch 

When you upgraded from 7-speed to 8-speed what, exactly did you do?

z415

A bent axle usually sounds "off" and leads to bad shifting. A good number of cassettes out there wobble *slighty*, including mine, especially if they are not extremely high end stuff.

And to add to what Retro Grouch asked, a number of 7s to 8s upgrade requires a new hub (from freewheel to freehub) and if you don't build wheels, you should have gotten a new wheel. There are exceptions, of course.

rykoala

For the 7 --> 8 speed upgrade, I built a new wheel and put in an 8 spd cassette. I'm just going to pull it apart and check it no matter what. It could probably use to be lubricated. It wobbles in such a way that's hard to describe. Its not like an out of round wheel, it wobbles in such a way that with the cassette not spinning, but with the wheel spinning, the part of the cassette closer to the bottom bracket moves to and from the spokes, and the other side moves closer. I can take a video of it if needed and post a link to it. Its SO hard to describe.

Imagine if you took a long nail and bent it and then tried to spin it in your hand. Put a metal disk fixed on one side of the bend, and now try to spin it. the metal disk would look like a top wobbling. That's how it is. Well I'm going to go work on it now, I'll be back in a bit and report on what I find.

HillRider

Check the tightness of the 10 mm hollow bolt that holds the freehub body to the hub shell. It should be very tight.

BTW, hub axles don't rotate when the wheel spins. If the axle is bent, the cassette could rotate "out of plane" but it shouldn't wobble. The bend would remain in one direction.

rykoala

That makes REALLY good sense, HillRider. I was wondering if I wasn't fooling myself there. I'll have to borrow a 10mm allen wrench from someone and check that. Thanks for the tip.

PhilThee

Bent axle? Are you talking about the skewer being bent?

Please do so with the chain on. Show the rear derailleur and lower part of the chain if you can work it into the shot.
I think I'm going through the same thing https://bikeforums.net/showthread.php?t=374807

z415

A bent skewer is not noticeable except for being really hard to slide in after it is all the way out and possibly seem hard/easy/wobbly to tighten down.