Running after the bike

Hey everyone, Just did my first Olympic yetesday and it went great. Meaning I finished and wasn't completely dead. Swim went well, Bike went well. But when I got to the run my quads cramped up. I was having some issues with my stomach as well but that was my fault as I kind of mis-timed my nutrition. The reason I am bringing this up is that it happened on my last two sprints as well. It was much worse in my last sprint. Either way, it happened again yesterday. I'm sure it is somewhat common for people to have leg cramps, but was thinking that I must be doing something wrong. My first inclination is that my bike is not setup correctly. Would that do it? 2nd, does having a tri bike do a better job of taking the stress directly off your quads. I averaged about 18 mph. I felt I was moving along pretty well. Almost every person that passed me had a "real" tri bike vs a road bike. I don't think anyone with a road bike passed me. I know this is like the fountain of youth question. Tri vs Road Bike. I'm more just trying to figure out why my legs keep cramping. It never happens on my long run on the weekends. Just after I get off the bike. Its just my quads too. My hammy's are fine. Anyones thoughts/suggestions would be appreciated. Thanks.