25mm rear, 30mm will offer a more comfortable ride, but the 25 will get you a much quicker response
Oh & you cannot take measurements on a stand. The bike must be on flat level ground with you on the bike in your natural riding position. This means you need 2 extra people to take sag measurements properly. One to hold the bike while you are sitting on it and one to take the measurements.
You will personally have to help left the bike in the air to get the front & rear wheel off the ground for the unloaded measurements. The guy that does the measuring ALWAYS does the measuring as he is the only person that can insure the points you are measuring from are constant and we are dealing in millimeters here so there is not a lot of room for error.
Last edited by LDH®; 03-15-2013 at 05:29 PM.