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Old 11-09-10, 07:08 PM   #1
boro
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Will a friction shifter solve my autoshifting issue?

Stupid question...

I built a 1x9 out of a new frame and older specialized stumpjumper components. Derailer is an older XTR but seems to be in very good shape; shifter is an XT rapid fire; cable and housing is brand new.

I noticed the bike skipping and autoshifting about a week after putting it together. I fiddled with the cable adjustment en-route and that helped a bit. Later, I readjusted the derailer and put some grease on the BB cable guide, and all seemed well. I replaced the chain (old one grenaded) and shifting seemed to improve even more.

Fastforward to a few weeks later, and again I experience the dreaded autoshifting. I readjusted the derailer again and it seemed fine, but on the way to campus I get the annoying brief shift up and back down.

Am I not vigilant enough with my cable/der. adjustment? I'm considering abandoning the rapid-fire for a bar-mounted friction shifter if that would help, or would I just be throwing parts at the problem?

Thanks
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Old 11-09-10, 07:45 PM   #2
cny-bikeman
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If the auto shift happens in only some gears and others work perfectly it is very unlikely to be any adjustment. More likely friction, hanger alignment or derailleur damage.
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Old 11-09-10, 08:06 PM   #3
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Yes, it's more likely to occur in the smaller gears. Hanger is fine, and I was under the impression that the cage is fine as well, but I'll go take a look right now...
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Old 11-09-10, 08:59 PM   #4
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The ramps and modified tooth profiles on hyperglide cassettes

are generally eager to jump out of the gear you selected, whether you want it to
or not.

I found it so when there were only 6 cogs on currently offered freewheels ,
putting 3 more cogs in virtually the same space
can only make it more so.

older full height teeth worked with some overshifting, and subsequent manual trimming , with the lever..
but stayed put once gear was selected.

newer tooth profiles just shift early.
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Old 11-09-10, 09:27 PM   #5
boro
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I went out to adjust again, make sure the der. cage wasn't bent, etc. and discovered a stiff link. Readjusted everything and it's shifting fine on the stand, but the test will be tomorrow's commute. I'm surprised how finnicky it has been - worked flawlessly on the old bike for years.

Thanks for the advice
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Old 11-09-10, 09:30 PM   #6
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Quote:
Originally Posted by fietsbob View Post
The ramps and modified tooth profiles on hyperglide cassettes

are generally eager to jump out of the gear you selected, whether you want it to
or not.

I found it so when there were only 6 cogs on currently offered freewheels ,
putting 3 more cogs in virtually the same space
can only make it more so.

older full height teeth worked with some overshifting, and subsequent manual trimming , with the lever..
but stayed put once gear was selected.

newer tooth profiles just shift early.
Autoshifting indicates a problem somewhere. It's not something that has to be tolerated, no matter how many cogs are in the back.

You say your setup is 1x9. What's your chainline look like in the extreme gears? If it's way way off, that definitely won't help. Check your alignment in each gear. The derailer pulleys should be directly below the engaged cog, and everything should be vertical. If your derailer isn't vertical, it's probably bent somewhere. Also, if your chain is much too long or much too short weird things will happen. A picture of your setup might help. There are lots of things that could go wrong here.

Finally, you said you just put a new chain on. How old are your sprockets? If they're badly worn shifting problems will result.
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Old 11-09-10, 10:22 PM   #7
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I'll take pictures if the problem persists/returns.

I feared a problem of new chain + old cassette, but there was no problem with the new chain for weeks after I put the new chain on - only recently. I sized the chain via the Sheldon Brown method, so I hope that's not the issue.
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