A small file and some emery paper? Mask it with duct tape and then go to work to take down the power. First test fit the shifter backing plate to make sure you HAVE to remove some of the PC.
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1 Super Record bike, 1 Nuovo Record bike, 1 Pista, 1 Road, 1 Cyclocross/Allrounder, 1 MTB, 1 Touring, 1 Fixed gear