The little knob on the end of horizontal dropout adjustment screws.
The cover plate (or whatever you call it; I only mess with them when destructively removing a FW) on old freewheels.
jim
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Cross Check Nexus7, IRO Mark V, Trek 620 Nexus7, Karate Monkey half fat, IRO Model 19 fixed, Amp Research B3, Surly 1x1 half fat fixed, and more...
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SB forever