Old 09-28-21, 04:34 PM
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Bikes: 1986 Cannondale SR400 (Flat bar commuter), 1988 Cannondale Criterium XTR, 1992 Serotta T-Max, 1995 Trek 970

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Older friction shifters didn’t have a shifter boss cover. They had a stop that fit over the square boss and kept the shifter from continuing to turn after shifting to the small cog/chainring. For friction, the downtube shape has no impact.

Boss covers, as I recall, didn’t exist before Shimano’s SIS and locked the shifter internals, so to speak, in place so the lever could click into each position.

Shimano did make a flat boss that might work as it is thinner. There might be a slight gap at the radius of the downtube, but shouldn’t be any worse than using a concave cover on an oval tube.

If it were me, I’d file the concave ones to fit. They have no collectibility value to leave original.


Edit Added: Since you mentioned Microshift, from what I can see, they don’t use boss covers.

Last edited by 70sSanO; 09-28-21 at 08:13 PM.
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