I have an ultegra chain and cassette that were bought together about 1000 miles ago. My crankset is FSA mega exo compact 50/34 (about 3 years old). Just recently, I have had two problems: the first is largely corrected; the second is not. The first was that my front changer was throwing the chain all the way over the big ring and onto the crank. It could sometimes be popped back up on the fly, other times not. An adjustment of the limiter screw fixed it for the most part. Now, my second problem is that when I drop down to my little ring, the chain catches the little ring, but, regardless of the gear or how much pressure I'm applying to the pedals, there is no resistance until I go back up to the big ring and back down once or twice. Is this a worn small ring? Cassette? Surely My Campy Eurus Wheelset doesn't have a defective freewheeling mechanism (after less than a year), does it? I'd appreciate any advice I can get.
My guess is that your front derailleur needs to be readjusted. I'm thinking that pulling up the Park tool instructions and staarting at the very beginning with the position of the derailleur on the seat tube might be a good idea.
thanks for the advice--i'll give it a try.