Had a guy come in over the weekend who needed to replace the brake pads in his Campy Record brake holders. The pads had worn a bit - not to the worn line, mind you - but enough so that the tire guide was scraping on the rim. Not a good idea when your rim is a super spendy Zipp deep section rim. The carbon section of the rim he was using bulged out below the brake track. Just enough that if your brake pads wore, the tire guide scraped on the carbon. Probably not a great sound and definitely not good for the carbon.
He had no idea what that little fin was for on his brake pad holder. I told him it was a tire guide and it was used to help guide the wheel through the brake pads when installing it. Come to think of it, why is it even there these days? I can't think of the last time I fit a road wheel in a frame where the guides actually aided in the install.
I had forgotten about this customer until I saw photos on cyclingnews.com of racers bikes at Gent-Wevelgem. It looks like the mechanics cut off the tire guide. Well, actually, after (ahem) downloading that photo and enlarging it, it looks like the tire guide is still there, just dirty and looking like a bare aluminum spot as if it was cut off.
Regardless, it is probably something to think about if you are running rims that have a bulge profile below the brake track. I'm running a set of FSA RD-420 wheels that I've had for several years that have a round cross section. I have to carefully position the brake pad against the brake track to avoid having the guide scrape on the rim. Maybe I'll cut off the guide on my brake now that I think about it.
What's playing: (KWMR music in the morning)