man, im having drivetrain issues as of late. running a 10 speed triple with 8 speed cluster and chain, seems great 90% of the time. every once in awhile in the middle ring, the chain seems like its sticking in the back, to the point of lurching forward. i thought maybe a freehub issue, but ive gone to town back pedaling and it seems fine. im running out ideas....also the chain and cassette are a bit old. casette more so then chain so perhaps those could stand to be changed. any ideas??