From the pictures on Cervelo website it does seem to have a very nice gap between the tyre and the bike (just check the Cervelo's home-page and check the main S5 there, you can almost put a finger between the frame and the tyre, never seen that in a real life picture). Anytime I see a real life picture, the gap is very very tight (not possible to see the other side at all)... I'm not sure if Cervelo website pictures are real life pictures or if they're edited on photoshop. If they're real life, then we sure do have some very big quality control issues on the production line, if they're photoshoped, then the bike is probably supposed to run on 21 tyres. On both cases we, consumers have a problem.
I will tell you that I am an S5 owner running Cosmic Carbone SL + Vittoria Rubino Pro 700x23 and the gap is very tight, It doesn't rub on a daily basis, only when I ride on some bumpy roads or something, but really this is not acceptable at all. I always tought it was happening because of the Cosmic Carbone SL ( they´re only 19mm rim width) I always tought that it would be cool with a larger rim wheelset (like Zipp or Hed) but that doesn't seem to be the solution.
From the reports I've heard and pictures I've seen (Cervelo website and other people's bikes), it seems to be a production problem where some bikes have a good gap and others don't... I feel very sorry because I bought my bike overseas, and now that I'm back, there's almost no chance I will be able to have my frame exchanged.
Something I learned, never buy a bike with such tight tolerances... Sorry, no more Cervelo for me, this is not cool for a $ 4,000 bike... Too much money for too much trouble and very low quality control.
TeamS5: I too have rubbing in the exact location on my 2012 S5 team, with the original wheels and tires that came with the bike. The rubbing of the frame actually comes from the tire itself, as opposed to debris lodged between the tire and frame. Are there any S5s that DO NOT rub, or is this an accepted defect?