I haven't read the other responses, so this may already have been covered.
I had the chance to talk to Frank Day
(the inventor and owner of the company
) about Powercranks, and in particular the adjustment period. I had recalled Tim the Nurse
(guy used to be active on Tri-Newbies Online and still pops in on occasion
) and his experiences with them
(basically he'd been a BIG opponent to PC's, and Frank finally told him to put his money where hos mouth was, so Tim tried them, and after a short time paid for them sonce they were doing him so much good
). Well, at the time, Tim had set a record for how few days on PCs before doing a century on them -- something like 2 weeks
(maybe less, I don't really remember, but it was short
). Well, Frank told me of a guy who wanted to get the PCs and said he was going to reset that record, which he actually did
(2 days
), BUT... Frank basiclly doesn't count that record, because the guy trained almost exclusively on a fixie. He said that the benefits of PCs will almost be lost on some one who does a lot of fixed gear riding.
So take that for what it's worth. I interpret that to say that a fixie will give you pertty much the same benefit as PCs, though it may take more time. To be honest, I've only tried PCs once, at a bike expo, and I lasted about 30 seconds on them...