Originally Posted by brawlo

There is something wrong here that is not the tyres. I would definitely be checking your fork clearance on the front and also checking the clearance on the rear both in between the wheel and the seat tube and in between the chainstays.

I would go back to 25mm tyres in a heartbeat if I could run them on my Felt '12 F4. I was running 25mm GP4000 tyres on A23s on my old bike and they were definitely not any slower than my 23mm tyres. When I was looking at a new bike I had a look at the Cervelo R3. It ended up being too small, but one came into the LBS for repair so I curiously tried putting my 25mm tyred wheels on it. This is supposedly a cobblestone style of bike, made for riding rough roads, on which you would of course run wider tyres??? The front wheel wouldn't turn, the tyre was wedged to the top of the fork and the rear had less than 1mm to the seat tube! So that was the R3, but now onto my F4. I carried over my A23 wheels with 25mm Contis from my old bike. After riding less than 200km, I took the rear wheel off to change the cassette for a 11-28. I noticed the tyres had been rubbing the chainstays. There is only about 1mm of clearance either side of the tyre. If I hadn't noticed this so early in the piece, I could be looking at an expensive repair, replacement or even worse.

My next bike which I have already started researching for will be as stiff as the F4, but I want clearance to run 25mm tyres again. I'm heavily limited with what's on the market due to my size, and the top contender I can't even get here in Oz. So I have some time to find a way to get one here... Canyon!

Originally Posted by adrien

Rode 28s again the other day, with a modest tread (Paselas). I was a bit slower on those, but the gravel road may have had something to do with that.

Originally Posted by Dunbar

I'm itching to try a 28mm GP4000S II on the back wheel of my Roubaix but literally nobody that ships to the US has had stock on them for 6+ months.