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Resident Curmudgeon
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wim said:
Now you got my curiosity up: what are "positive locking adjustment screws" on a bicycle derailleur?
There are 2 screws on each derailleur that limit its side to side motion. on the rear der. the inside limit screw prevents the der. from shifting the chain into the spokes, assuming it's adjusted correctly. The outside limit screw prevents the der. from shifting the chain too far past the smallest cog where it can get caught between the frame & the small cog.

The front der. limit screws do the same thing. If you look closely at these 2 screws you'll see there's a little tab on the inside that the screw bumps against there fore preventing from going farther.

I have bikes with Shimano 105 & Dura Ace. They both work well. IME the 105 is a little clunkier than the Dura Ace. The Dura Ace is like butter. The Dura Ace brakes seem better too.
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