I've been thinking of switching from a triple to a double on a 2007 Trek 1500. I have looked at some cranks on e-bay and noticed that most say 10 speed compatible. Will these also work with a 9 speed cassette? I'm not sure what else I would have to change. My bike has 105 shifters, an Ultegra long cage rear deraileur, a 105 front deraileur, and presently an Ultregra triple.