Mountain Hub
Mountain Hub
Sometimes after shifting gears on my mountain bike, the pedals will just spin? What could be causing this?
The only things I could think of were the hub or the cassette. This is an older Haro mountain bike with a 7 speed cassette. Any ideas?
Thanks.
If the problem comes and goes…fixes itself when it happens…and if you’re not hearing horrible gnashing of gear teeth as the chain slips across the cogs…then the problem is most likely that your freewheel needs to be lubed or replaced.
Sometimes the pawls in the freewheel body stick, slip out of place, or break, and then it doesn’t do what it’s supposed to. You need to remove it from the bike to inspect and/or service it. This will require a couple of chainwhips and the right style of freewheel remover. Check out http://www.parktool.com and look in the “repair help” section for pics and instructions if you need to. Or just take it in to a bike shop.
When you have the freewheel off, remove all of the cogs and play with the ratcheting body for awhile. Feel how it turns….like a bank thief trying to crack the code on a safe. Listen to what it’s doing. If it feels gritty, it may just be dirty and a flush/lube might fix it. If there is grinding or it gets blocked, then you’ve probably broken a spring or shattered a pawl and you’ll need to replace it.
If all seems ok, then try to lube it and try it out again for awhile. If you want to flush it you can, but it’s not always necessary. Soak it in kerosene or paint thinner (something petro-based) for awhile, then swish it around and let it drip dry. Then submerge it in a heavy motor oil, work the ratcheting mechanism while it’s in there, and let it soak for awhile longer. Even used motor oil will work, but if you have some heavier rear-end/gear oil, that’s better. Just be sure to use a petro oil and not a synthetic one (Teflons, silicones, waxes, etc).
Hopefully that’ll help, if not, 7-spd freewheels are pretty cheap to replace. Good luck!
Joytech Road & Mountain Hubs ’09 Taipei Bike Show Video by Downtube.com