Hi,
Can anyone tell me what these bolts below the pads in Shimano rim brakes (Ultegra) are for? They seem utterly redundant to me.
Thanks!
BR-R8100-4859 | Manuals & Technical Documents (shimano.com)
part no.9 says its a tyre guide, on some other shimano pads this is molded into the pad holder.
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So it’s presumably meant to stop you from pressing the pads out of the the holder when changing wheels with tires that don’t properly fit between the pads. They still seem useless to me if tire size and rim width are in a sensible relation to one another…
I always thought they were to protect your rim in the case of not noticing your pads are completely worn down, A hard edge will do more damage than a soft rounded screw. This thread I googled seems to say the same I think. road bike - What is the purpose of the ‘tire guide’ screws on shimano brakes - Bicycles Stack Exchange
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Although I would not trust the plastic screws from not irreversibly damaging carbon rims, this explanation makes at least a little sense. (1) Making sure rim and tire width match, and (2) checking your pads for wear and replacing them in time seem more sensible strategies to me than trusting on those screws.
But everyone rides discs now anyway, right? 
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