What type of clearance should I be shooting for with the rear wheel cutout? As-is on my frame it seems like it is too close, I can adjust it back if needed but haven’t seen anywhere that lists how much clearance I should give it.
USAT says you need to be able to slide a credit card between the tire and the seat tube. I’ve never seen an USAT official check for this at any race though.
that is a USAT rule? I thought it was just the UCI
I was thinking more for safety purposes than regulations. Is there no problem having it that close to the frame?
When its very close you will occasionally pick up mud/dirt on the tire and hear it scrape on the frame.
When it is TOO close the tire will sometimes rub
nothing dangerous happens in either car.
When training I leave a bigger gap to avoid the frame scrape.
when racing I get it as close as I can such that the tire never rubs.
Sometimes on a hot summer day the tire will heat up quite a bit and the air inside can expand. If you were extremely close before the ride, then it’s possible that the tire would expand to the point of rubbing. Not catastrophic, but it would slow you down.
Enough so that it doesn’t rub. If it’s rubbing, the aero advantage wilol be nullified by the physical drag of tyre on frame.
Note that not all wheels/tyres are perfectly round. There may be a bulge, so remember to rotate the wheel in the frame and check by eye/ear that at not point contact is made.
I’ll definitely check and vary mine depending on the course surface and conditions. I’ll occasionally hear a little “chirp” when the tire picks up a bit of debris and it gets pinched through the gap between tire and frame (i have a strip of chainstay protector along the inside of the cutout to protect the frame finish, so whatever debris is contacting rubber on either side). If the course isn’t swept, or especially if it’s a little wet causing more crud to stick to the tire, then I run a bigger gap.