arsed axle, or blown hub?
hiya. this is gonna sound like a complete idiot question but i am really kinda stumped.
i have bike. the bike has a rear wheel. when i put the bike and the wheel on the bike trainer today i noticed that in a certain gear i could hear a clicking/thumping sound, and felt it through the pedals. i thought at first it was the BB but by concentrating on the rhythm found it to be the rear wheel. this drew my visual attention thither and i noticed that the rear hub oscillates up and down on the freewheel side. (the FW dances a bit too but i know that's normal) i made sure the hub was moving and not just the FW. preliminary diagnosis--bent axle. so...i pulled the axle tonight and rolled it on a flat surface. it really didn't seem bent. so i reinstalled and of course the wheel's behaviour hasn't changed a bit. so, is it possible that the axle is bent enough to do that to a wheel but not enought to see/detect? AND--is it possible the innards of the hub are buggered up somehow? the cones? the bearings? the hub really looks fine. the way the wheel is acting on the bike really says bent axle. ie: the axle stays still while the hub oscillates around it. i appreciate your help! mark |
A bent axle wouldn't cause this.
Even if it's bent, it's always in the same position, since it's "fixed". It has to be a rotating part(s). |
Originally Posted by Bill Kapaun
(Post 8329873)
A bent axle wouldn't cause this.
Even if it's bent, it's always in the same position, since it's "fixed". It has to be a rotating part(s). could mismatched bearings also cause this? or a skewed cone? really trying to understand the physics here. thanks! |
I can't imagine a bent axle only giving symptoms in one gear. I would clean and lube your freewheel.
|
Originally Posted by wrk101
(Post 8330538)
I can't imagine a bent axle only giving symptoms in one gear. I would clean and lube your freewheel.
oh and the freewheel is newly cleaned and lubed. :thumb: |
A loose or bent freehub fixing bolt? What kind of hub is it?
If it's a freewheel hub, maybe the freewheel threading is coming apart from the rest of the hub body like in this thread http://www.bikeforums.net/showthread.php?t=505037 |
Originally Posted by Gonzo Bob
(Post 8331536)
A loose or bent freehub fixing bolt? What kind of hub is it?
If it's a freewheel hub, maybe the freewheel threading is coming apart from the rest of the hub body like in this thread http://www.bikeforums.net/showthread.php?t=505037 i'll check on the make when i get home from work. also gonna examine it closely for damage. EDIT: also, would that cause the whole hub to oscillate? seems to me just the end would be wonky in that case... |
It has to be one or more of-
Hub, cone or bearings. Is the noise possibly every 2 revolutions? If so I'd say BB's. Yos simply have to disassemble and inspect. You might want to buy 18, 1/4" BB's (and grease?) from the LBS before you start. |
ok update:
i took the wheel apart, freewheel and all. i took a ruler that measures to 32nds of an inch and measured the disance from the outside (highest) edge of the bearing races to the outside edge/face of the hub. turns out that the freewheel side race is not seated evenly. its a difference of 1/32" from one edge to the opposite edge. one thing i did think of maybe related to the original problem of the clicking/thumping noise--when i have the bike on the trainer it seems alot more stress is put on the drivetrain than if the bike were on the road. for example--on another bike, i had trouble shifting into the biggest chainring when the roller was engaged, but when it was disengaged it shifted fine. i haven't had a chance to test this theory on the bike currently in question, (the theory being that the stress of the trainer exacerbates these minor problems and causes other ones) but i wonder would it be an issue at all w/o the added sress on the drive train. am i way off here or has anyone else noticed this about trainers? or do i just have a crappy trainer, maybe? |
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