I am at work and am looking to buy a different stem and I was not sure if the bike comes with a 1.5 or 1.56" steerer? I brought the old stem with me and measured the ID and it is dead on 1.56". Can someone confirm that it is 1.56"?
Your measurement is indeed 100% correct. I can't remember what year that Cannondale switched the Lefty steer tube from it's original 1.56 to 1.5 (2012 ish I think) but your 2002 will definitely be the 1.56"
No problem. Stem choice is going to be pretty limited , especially if you want to use a 31.8 mm bar over the normal older Lefty's which had 25.4 mm ones. They are out there on e-bay though.
Yes, the 2002 Cannondale Jekyll with the Lefty fork uses a 1.56" (also known as "Lefty" or "SI") steerer tube, which is larger than the standard 1.5". Your measurement matches the spec, so you’ll need a stem compatible with the 1.56" steerer. Standard 1.5" stems will not fit.