Anyone know bicycles?

Synchros shot? Weird noises while shifting? Not sure what needs to be replaced?
SonicHKS
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Anyone know bicycles?

Postby SonicHKS » Sat Mar 30, 2013 5:25 pm

I've got a couple problems with my bike. Its a 21-speed street bike.

First, it slips in 6th and 7th gears, regardless of position of the front gear. Derailer issue I guess? Or possibly caused by the second issue?

Second issue is that the rear wheel won't spin freely. If you spin it by hand through just 1 rotation (360*), it'll catch through part of that rotation. So it'll spin freely for like 320* and catch/bind on something for about 40* of rotation. It also wobbles slightly.

The brakes aren't catching or anything, so I'm guessing the second issue is from a bad axle/hub? I know almost nothing about working on bikes, I barely even know any terminology. Any idea how much this will cost if I take it to a repair shop?

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theholycow
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Re: Anyone know bicycles?

Postby theholycow » Sat Mar 30, 2013 6:01 pm

First issue: If it's good in 1-5 but #6 and #7 are slipping, could be chain stretch, worn gears, or bent derailer hanger. Not likely derailer adjustment, as that would affect all gears, only #1, or only #7. Could conceivably be caused by second issue, I suppose.
http://sheldonbrown.com/brandt/chain-care.html (scroll to "Skipping chain")
http://sheldonbrown.com/chains.html (scroll to "Chain and sprocket wear" and continue to "Measuring chain wear")
http://sheldonbrown.com/derailer-adjustment.html (scroll to "Before You Try To Adjust A Rear Derailer, Make Sure It Isn't Bent!")
I assume it was not always like this. If you've replaced parts, modified anything, or it's always been like this, could be too-long chain or insufficient take-up spring strength or something like that.

Second issue: Sounds like a wheel bearing. Might just need adjustment.
http://sheldonbrown.com/cone-adjustment.html
sheldonbrown.com/brandt/cone-adjustment.html

Do additional research on that site. Sheldon Brown and Jobst Brandt are the real Gods of bicycle tech, more than any of the more famous people who write books and so forth.
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