Bicycle Mechanics - Cassette movement?
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03-26-03, 09:43 AM
At work last week some ass hole banged something into the back of my bike. The rear skewer somehow mangaged to snap. Ever since their has been a strange clicking (almost like a scratching noise) coming from the rear of the bike. I took the wheel off I realised thier was a bit of side movement in the cassette. Also when I rotate the wheel it isnt nearly as smooth as it used to be (their is no play when the wheel is attached to the bike). Do you think something has come loose (wishful thinking) or do you reckon i'll need a new cassette? The cassette I have is a Shimano HG-50, 8 speed, 11-32t
Here's the full spec: http://www.specialized.com/SBCBkModel.jsp?orig=intl&minisite=10020&minisite=10020&san=03HardrockInternational&bl=mountain&my=2003
p.s. should you grease a rear skewer before you install it?
Umm....if your skewer snapped, then nothing is holding the wheel on-of course it's going to move......:rolleyes:
03-26-03, 01:54 PM
It sounds like you may have a bent or even broken axle as well.
( I'm sure you replaced your skewer, as most reasonable would assume.)
Grease does keep the rust at bay and the and the adjust-knob turning easier.
If none of your cogs are bent, check the spacing, keep the cassette
Ride with Care
03-27-03, 05:03 AM
If the axel was bent wouldnt you see some odd movement in the casette as the wheel spins?
I found a bent axel by removing the wheel and rotating one end of the axel by hand... you could see the other end of the axel moving (up and down) as it turned.
03-27-03, 06:46 AM
I'm with Pat. If your skewer snapped it seems like there must have been some stress applied to the axle, since the skewer is inside the axle. A new axle is about $10. After such a trauma to the wheel I think I would replace the axle just as a precaution. If your hub uses cartridge bearings they may have been affected also since they are not designed to withstand side to side stress. I guess worst case if you have cup and cone hubs there could have been enough stress to affect the cups which are integral to the hub.
I realize some of these ideas are long shots, and let me stress that I am not a mechanical engineer so I may have misused some terms. These are just things I would check, more or less in this order.
03-27-03, 01:51 PM
Alex, OF COURSE I REPLACED THE SKEWER!
The skewer snapped at the very end (opposite the lever). The axle doesnt appear to be bent. This is the rear hub: Shimano RM-40, 32 hole, sealed cassette.
Anyone got any ideas as to whats gone wrong?
03-27-03, 09:32 PM
First, bearing play that goes away when the wheel is clamped in place is expected (see Sheldon Browns web-site for explanation). The smoothness thing could just mean your bearings need to be cleaned and replaced (if it's not a sealed unit). They would have to be in very bad shape to cause that much noise, but it's an easy thing to check (again, if it's not a sealed unit).
Don't know what's wrong, you didn't give us much to go on. Sideways movement of the cassette is a problem. If that puppy won't tighten down, something is hosed.
If it will tighten down, but the noise remains, you need to do some investigation. I'd start by doing some experiments to narrow down possible causes. Do you get the clicking/scratching noise in all gears? In fact, does it continue when you coast (don't pedal)? What about when spin the wheel and you aren't on the bike at all? If something hit your bike that hard, it may have messed up something in the drivetrain, maybe even bent the frame?
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