Originally Posted by
himespau
I have it tightened as far as I can by hand, It dropped about an inch yesterday when I rode it for an hour. Should I be using a wrench on the nut? As it is I have a hard time closing the QR.
How much bigger should the tube be than the seatpost when not compressed by the bolt?
The seatpost should not slide when riding the bike. Looks like you have two possible causes:
1. QR skewer. Exposed cam skewers like the one on your bike require more hand force to achieve the same amount of clamping force. An enclosed cam skewer will help, or just get an allen bolt. Not as convenient, but possibly less chance of getting your seatpost stolen.
2. The seatpost shouldn't be any smaller than the inside diameter of the seat tube. Of course it has to be slightly smaller to fit, but there should be a little friction when sliding it down. If there's not any friction it can still be ok, but there should definitely not be a big amount of wobble without the QR tightened. You should not be able to see or feel a gap between the post and tube. If you can, you bought a seatpost that's too small.