Powertap wheel question

They sell the wheel with cassette? Sounds a bit strange - is this from Ebay?

Shouldn't be a problem, as long as the number of sprockets matches (e.g. both 10 speed). You may want to shorten the chain to optimise shifting, but I don't think that it would make any difference (going from 27 to 25 largest sprocket may mean slightly more slack when you are in the small / small combination, but who cares? - you are not meant to use the smallest 3 sprockets with the small chain ring anyway).

When you change to biggest / smallest (53/12), the rear derailleur pulley and jockey wheel should line up vertically.

You could also check the wear on the new cluster and your existing drive train using a Rohloff tool. If it is second hand, who knows how worn it is?

BillM said:

The wheel (Velocity Deep V) I have coming with my Powertap has a Dura Ace 12-25 cassette attached to it. My bike currently has an Ultegra 12-27 cassette on it.....I assume I will not have to change anything to mount this new wheel right?

Should be fine. I swap between a 12-23 and a 12-25 without changing anything, so you should be fine with a similar 2-tooth difference (25-27). DA & Ultegra are completely interchangeable.