Bicycle Mechanics - Free-Wheel hub not so free?
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05-08-06, 09:24 AM
I had a problem on my morning ride. About half way through I noticed that when coasting, my rear Cassette (or Cog-set, I forgot the exact terminology) on my 2005 Lemond Sarthe seemed to want to go forward - this pushed chain forward an inch or two and then the chain would snap back. This would happen a couple times a second, depending on my speed.
I decided not to coast anymore during the ride (good practice if I ever want to ride a fixie) because the chain was slapping to much against the chain-stay that I was afraid of damaging the paint.
What could cause this? I did notice when I got home that my rear wheel is out of true - could this cause the hub to not work properly?
05-08-06, 09:29 AM
Bent rim wouldnt have any effect on freewheel operation, but a bent axle could.
05-08-06, 09:37 AM
First, I'd say it's worth getting a chainstay protector. Black electrical tape works very well for this, and you can take it off and clean the residue with no loss later if you want to.
It sounds like the freehub (which is what I assume you have on your LeMond; freewheels haven't come on nice bikes for almost 20 years now) has its bearings gummed up. These are the bearings that are turning when you pedal backwards or coast while riding. You can replace the freehub body (new ones are around $20-25 for good quality, 8/9/10-speed compatible bodies) or try removing the freehub body and flushing it with thin grease (e.g., ProLink chain lube) and then putting some thicker oil (e.g., Phil Tenacious Oil) in there.
It's also possible that whatever is inhibiting the freehub from turning isn't internal to the freehub, but rather dirt/grease/grit buildup on the outside, on the interface between the hub and freehub body. This is less likely, but possible.
In any case, you'll have to remove the cassette (for which you need a lockring tool and a chain whip) to inspect well. If you want to remove the freehub body itself, for servicing or replacement, you'll need to remove the axle from the hub, and then use a 10mm allen wrench to loosen the bolt that holds the freehub body to the body of the hub itself. This is assuming the hub is a Shimano. I don't have experience removing Campy freehub bodies, and sometimes sealed-cartridge bearing hubs (from Campy or others) can be screwy to work with.
05-08-06, 10:04 AM
....and sometimes sealed-cartridge bearing hubs (from Campy or others) can be screwy to work with.
Does Campagnolo make any cartridge/sealed bearing hubs? All their hubs I know about are cup-and-cone types. AFAIK, both Shimano and Campy are complete holdouts against cartridge bearings.
And yes, sealed bearing hubs can be screwy as the designs and bearing sizes vary all over the place and many of their freehub bodies are proprietary.
05-08-06, 10:31 AM
I thought that a simple truing would do the trick but I guess that the problem is a bit more complicated.
Its a bontrager hub (Campy compatable), so maybe I will just take it down to my LBS
05-08-06, 10:46 AM
Bontrager hubs are likely proprietary, so you may as well go to your LBS. Worth taking the cassette off first (if you have the tools) and seeing what you can figure out from there.
HillRider, over Christmas I rebuilt my younger brother's 2000-model Campy Mirage 9-speed rear hub with a new rim and spokes. It was sealed cartridge design. But I know Campy mainly sticks with cup-and-cone balls. Which do have their advantages.
05-08-06, 02:33 PM
I forgot to mention.
If I just spin the wheel with no load on it, then there is no problem. I thought originally that having a wobbly rim while riding could put pressure on the hub - thus causing the cassette to 'tighten up'.
05-08-06, 02:39 PM
you just need to clean and regrease the free hub pawl mechanism
05-08-06, 02:57 PM
If you spin the rim forwards with no load on it, does it freewheel okay? Or the reverse: does the chain look as if it's getting pushed forward, when it should be static while coasting?
05-08-06, 02:59 PM
The chain only gets pushed forward when I am riding. I could not duplicate the problem just by spinning the wheel by hand.
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