None, you really have to crank down on the rear skewer but after It slipped once I had no more problems. Giant TCR - Geometry too small on the Large for me. For the first 200 miles are am very happy with the bike. I am a mountain biker at heart, but I really am enjoying hopping on this and going out for a couple of hours at a time. First time I have ever been comfortable on a road bike.
Rear wheel is diffucult to change due to creativly sculpted rear dropouts.
Might be to stiff for some riders. Zipp 404 sewups. My first frame was great until a bad weld failed while I was leaving a stop light. I really didn't like this frame. I took the bike to the Santa Cruz booth at the Sea Otter Classic and showed it to them.