Quick question for those of you who may know. I have a Trek 5900 from 2001.. It's nine speed Dura Ace all around. Question is this: will a new 10 speed or 11 speed crankset work with the rest of the groupset.. I would stay with the 53-39 set up. I would need a new bottom bracket with external cups also I believe. I would just like to update the look a little. There seems to be some good deals around for cranksets..Thanks for your time and information.

Chainrings stay as 1/2 pitch, standard.. as the chain thins, as it must to pack in 2 more cogs, the teeth thin too.. so your wider 9 speed chain should be OK.

you could also just buy 2 new chainrings if yours are worn too much, and not change the crankarms , the BBs keep changing too, you may require both ..

Newer 10 or 11-speed cranks will work with your 9-speed stuff but you might get chain rub on the big chainring when in the middle ring and one of the smaller cogs. A 10-speed chain will work fine with 9-speed cassettes and avoid the chainring problem. I'm currently using a Shimano 10-speed Tiagra crank with a 10-speed chain and all else is 8-speed. Works fine.

You may need a 10-speed front derailleur but that's not a given.

Be aware that the 11 or 12 tooth cogs on a 10-11 cog cassette will be almost useless with a 53-39. Flat out too high with the 53 and high wear with the 39.

Yes, a 10 speed crankset will work with what you've got, no problem. You're correct, you will need a different bottom bracket, but that's it.

If you stay with Dura-Ace, you can get a good deal on the 7800 10-speed cranks. With that you can use either a 7800 or 7900 bottom bracket or some other Shimano Hollowtech bottom bracket.

I've tested this set-up extensively. It works very well. It also works great if you put on a 10-speed chain.

He didn't mention changing the cassette from his current 9-speed and already has 53/39 chainrings on the 9-speed (FC-7700 I expect) crank. This is just a cosmetic crank upgrade.

I agree on the uselessness of an 11T cog or even a 12T with a 53T chainring for most riders. However the prevalence of those cogs was well established in the 9-speed era so 10 and 11-speed didn't make it any worse.

Thanks for all the replys and information. I have always ran the 53-39 cranks along with an 11-23 cassette. I don't plan on changing any of the gearing.. The new cranksets are very sharp looking compared to what I have now. I also like the look of the outboard bearings for the bottom bracket. I'm happy to hear that this should be a fairly simple endeavor. Thanks again.