Cranking up the speed

To Chin Swee Road, 36 km. Tech note My Bontrager crank knows its time is up. It behaves well, like some poor guy knowing the axe is going to fall but still keeping his nose to the grindstone. He's been grinding away since Mar 03, on the chain gang for about 15,000 km. I want to change it because I'm tired of trailing behind hardcore roadies. And being whipped by a certain mountain biker. Bikeshop man is amazed at how worn my old crank is. He says I shouldn't wait till it's like shark teeth. He doesn't have the XT model that I want, so I settle for LX. he's My new crank is smooth, real smooth. Front d seems to shift better too. Feels strange though, as if the Q factor has changed. And the chain doesn't seem used to the new chainrings; the crank doesn't make the usual 2.5 revolutions when I spin it by hand backwards. (No. of near accidents: 2)