It's a guide and stop for bar end shifter cables. There's probably one on the other side as well. I think you can just see it on one of the pics.
They're more guides than stops, one of them's bent as they're very delicate
@midlife started
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It's a guide and stop for bar end shifter cables. There's probably one on the other side as well. I think you can just see it on one of the pics.