9-speed vs 10-speed?

[BleeckerSt_Girl]

One advantage of running Shimano 9 speed is that you can run a mountain bike rear derailleur and a 34 cassette so you get fabulous climbing gear. Although your races may not be too hilly, you may want to do some trail riding on your cross bike and I found the extra gearing really helped me. With Shimano 10-speed, you can only go up to a 27 in the rear. With Campy 10-speed you can go up to a 29 in the rear.

Yes, this is exactly the setup I have! We have no flat rides around here to speak of- lots of hills. I have the mtn rear derailleur and 34 cassette with a triple up front, and that gives me a HUGE gear range. I find I use my very lowest gear often to get up the steepest hills. I love it. But if i lived near fewer hills this setup would probably be overkill.

People make the mistake of thinking a 10 speed will automatically give you a wider gear range and lower gears than a 9 speed. Not true. It just means there are more gears within whatever range you have and less of a jump between them. Theoretically, you could have a 15 speed bike but your highest and lowest gears might still be the same as my 9 speed, depending on your cassette-to-front ring setup. You might just have more gears in the middle with less spread between them. At that point one would likely shift 3 at a time because there would be so little noticeable difference between them. Hope this explains a bit.

Oh, and....10 speed seems to be the "new thing" and so 9 speed parts are not "quite" as easy to get now. So if it's ease of getting parts and swapping parts you want try the 10 speed. If you don't care about swapping much, are good at searching out parts online, and want major hill gears, you might want to consider 9 speed.
Personally, I'm not so sure that 10 speed is here to stay, and I'm happy with my 9 speed setup.