Bike Anti-Porn - When Things Go Wrong

Ah, then the problem is caused by the enormously excessive trail combined with a very slack head angle, which means the front of the bike drops when the wheel turns - you have gravity fighting against the castor.

MDCC_Tester,

Yes, you are right. There is a huge trail with a 700c wheel and a very slack head angle. I already look at it. In the flats this is not a problem, but climbing out of seat it wobbles more the front wheel.