Bicycle Mechanics - Sheared B tension screw head
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02-21-11, 06:45 PM
I'm not really sure how it happened, but the head of B tension screw (Shimano DA 7800) got taken off when my chain broke (Wipperman link broke).
It's not a problem now, but at some point I'm going to want to remove the rear derailleur. The frame is Ti and the hanger is not replaceable.
Any thoughts on how to get it out? The top of the screw is flush with the eye it screws into.
02-21-11, 07:02 PM
Are you sure you're talking about the B-tension screw? It doesn't really affect the removal or installation of the RD. The trick is to pull the rotate the derailer as you're installing it so that the B-tension screw lands on the hanger's flat spot.
With the derailer off the bike, you should be able to turn the sheared B-tension screw out with a pliers or small vise-grips and replace it with a new one.
02-21-11, 07:14 PM
You're right - the eye that the B screw goes through is part of the RD, not the hanger. Well that makes me feel better.
and of course, thanks
Also, if the RD is already at the right angle, you may never have to adjust it again, so you might as well leave it be and if anyone asks, tell them you sawed off the screw head to save weight.
02-21-11, 08:46 PM
If you really want to replace the screw, unbolt the rear derailleur and grab the stub of the B-screw projecting toward the front side of the derailleur. Use Vise-Grips or pliers to unthread the screw and replace it with a new one.
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