what size b screw for a RD 7800?
02-03-14, 10:42 AM
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what size b screw for a RD 7800?
I run a 27 big cog and wanted to try a 28. Put in the B screw all the way and almost almost but not quite enough clearance.
What size screw should I buy at home depot?
What size screw should I buy at home depot?
02-03-14, 11:20 AM
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Just take it with you and match it, just 1/4 inch longer. Probably M5 or 6. You can go to the nut selection and use metric nuts to see which one fits the screw (bolt). Get stainless steel if you can. You may have trouble finding the exact type you want, so be flexible about the head type. Hex head, allen head, flat driver head, Phillips head, it doesn't really matter for this purpose.
02-03-14, 11:58 AM
#3
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Your current screw is an M4-12.
12mm is about 1/2" long.
Simple enough to look up in the Shimano tech docs.
https://techdocs.shimano.com/techdocs...H5!-1887296039
12mm is about 1/2" long.
Simple enough to look up in the Shimano tech docs.
https://techdocs.shimano.com/techdocs...H5!-1887296039
02-03-14, 12:45 PM
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You might be able to put your existing screw in from the opposite side and have the head go against the derailleur to gain more clearance.
02-03-14, 02:29 PM
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02-03-14, 02:35 PM
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I'm running a 28T with the backward screw and it works great.
02-03-14, 04:27 PM
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I've had to bend a longer screw after installing it to get the head to hit the hanger tab fully. Andy.
