Senior Member
Join Date: Aug 2017
Location: Kansas
Posts: 171
Bikes: Peugeot PR-10, Peugeot UO-8, Boeris racing bike, AMF Roadmaster Renegade, Gitane Gypsy Sport, various Schwinn muscle bikes, Schwinn Super Sport, Panasonic DX-4000, Palo Alto Campy equipped bike
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Why do pulleys sets nowadays have a different upper and lower pulley whereas on older derailleurs like this used the same pulleys for upper and lower? I've read posts on this and apparently the upper pulley is supposed to be a "guide pulley". I'm thinking Shimano might have started this trend possibly when they introduced SIS: I have an older Shimano 600 pre-SIS derailleur and it has matching pulleys, and then I have a 600 "tri-color" derailleur that has the two different pulleys on it. Can the older derailleurs like my Campy one use the newer style pulley sets that have the dedicated guide pulley, and if so is there a benefit in using them?