RD collides with cassette.
07-05-16, 10:23 AM
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RD collides with cassette.
I am rebuilding a mid 80s Schwinn High Sierra mountain bike. I am setting up the RD and I am having it collide with the cogs on the rear wheel. I have changed nothing about the bike except the shifters. Why would there not be enough clearance now between the cogs and the RD?
Parker Anderson......from my phone
Parker Anderson......from my phone
Last edited by Thumpic; 07-05-16 at 10:27 AM.
07-05-16, 10:43 AM
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07-05-16, 10:46 AM
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Parktool on B screw: Rear Derailleur Adjustment | Park Tool
07-05-16, 11:14 AM
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Did you really change only the shifters? If it cleared before and doesn't now something else has changed. Chain length? Cassette? Cable slack?
As noted, the B-screw is the probable fix.
As noted, the B-screw is the probable fix.
07-05-16, 11:24 AM
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Everybody already said B-screw, that is the specific means for adjusting RD/cassette clearance. No idea why it might have cleared before but be hitting now.
If screwing in your B-screw all the way is not sufficient, take it out, go to any hardware store, and buy another longer bolt with the same threading.
If screwing in your B-screw all the way is not sufficient, take it out, go to any hardware store, and buy another longer bolt with the same threading.
07-05-16, 11:45 AM
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Everybody already said B-screw, that is the specific means for adjusting RD/cassette clearance. No idea why it might have cleared before but be hitting now.
If screwing in your B-screw all the way is not sufficient, take it out, go to any hardware store, and buy another longer bolt with the same threading.
If screwing in your B-screw all the way is not sufficient, take it out, go to any hardware store, and buy another longer bolt with the same threading.
07-05-16, 11:56 AM
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I don't think so -- if the spring were shot, the RD would sag downwards away from the cassette. If it's pushing up, then you've got a spring working against gravity.
07-05-16, 01:38 PM
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If you changed the shifters, did you mess with the cable? The rear housing loop acts like a spring that increases the force of the B-knuckle spring. If for some reason you removed the wheel, that could also be an issue since horizontal dropouts are used to adjust the gap as well.
Edit: Wrote A instead of B. Learn the difference, it could save your life.
Edit: Wrote A instead of B. Learn the difference, it could save your life.
Last edited by 2lo8; 07-07-16 at 11:27 AM.
07-05-16, 01:46 PM
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rear housing loop as add'l spring, I like that hypothesis.
07-05-16, 01:51 PM
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Is the chain sized correctly? It looks like it might be longish?
07-05-16, 03:25 PM
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I am rebuilding a mid 80s Schwinn High Sierra mountain bike. I am setting up the RD and I am having it collide with the cogs on the rear wheel. I have changed nothing about the bike except the shifters. Why would there not be enough clearance now between the cogs and the RD?
Parker Anderson......from my phone
Parker Anderson......from my phone
07-05-16, 03:49 PM
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It's hard to count exactly but that looks like a 32T big cog; I don't think it is original to a bike from the '80s. Not sure of the specs of your rear derailleur but it might not clear a cog that big.
07-05-16, 06:06 PM
#13
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It's hard to tell from the blurry pics but the B-screw looks bent, like the derailleur was installed without cocking the derailleur so the B-screw didn't clear the hanger.
07-07-16, 06:50 AM
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Shortened housing....swapped to smaller cassette...voila!
Last edited by Thumpic; 07-07-16 at 06:53 AM.
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