Cyclocross - Drivetrain Drivetrain upgrade for '05 Axis (making it "racier")

I am about to purchase an '05 Axis and was after riding a floor model and reading up on the poor drivetrain it has, I was thinking of an upgrade to make it more cross-race worthy... Here's what I was thinking...

Crank --> FSA Compact Cross 38/48, Platinum BB (double cset, stock Sugino bl*ws)
XT Rear Der --> Upgrade to Ultegra 6500 short-cage (short cage will shift better)
Casette --> Upgrade to Ultegra 9spd 12-25 (cross sizing)

My biggest concern is if I switch the cassette and crank right now (but not the der) will they run well w/ the XT rear der? Or do I should I switch out that part as well? I'm not sure how the XT will throw around a chain on 38/48 double crank w/ a 12/25 cassette.

Backround... I'm doing this b/c I can't afford to step up to the Cross Veloce but I can get a good deal on any Bianchi. Going to ride mostly a 20 min. commute, road cross-training miles (I'm a highly competitive runner), and a few road and 'cross races.

The XT rear derailleur actually shifts quite well. If money is an issue don't bother upgrading it. And yes, the rear derailleur will work well with a 12-25 cassette. I even use an 11-21 on my sister's bike with the same derailleur and the shifting is crisp.

In the past the Axis did come with a rather mediocre Sugino crank. It can be pretty flexy especially for a strong rider.

Thanks for the advice. Like I said, I was suspect about the crank. I'll probably just end up swapping out into a 105 or ultegra cassette (12-25) and up the crank to a Truvativ Elita Cross or FSA Gossamer Cross.

I am about to purchase an '05 Axis and was after riding a floor model and reading up on the poor drivetrain it has, I was thinking of an upgrade to make it more cross-race worthy... Here's what I was thinking...

Crank --> FSA Compact Cross 38/48, Platinum BB (double cset, stock Sugino bl*ws)
XT Rear Der --> Upgrade to Ultegra 6500 short-cage (short cage will shift better)
Casette --> Upgrade to Ultegra 9spd 12-25 (cross sizing)

My biggest concern is if I switch the cassette and crank right now (but not the der) will they run well w/ the XT rear der? Or do I should I switch out that part as well? I'm not sure how the XT will throw around a chain on 38/48 double crank w/ a 12/25 cassette.

Backround... I'm doing this b/c I can't afford to step up to the Cross Veloce but I can get a good deal on any Bianchi. Going to ride mostly a 20 min. commute, road cross-training miles (I'm a highly competitive runner), and a few road and 'cross races.


I would think that over time, as the chain wears the shifting with the XT will degrade a lot faster than with the ultegra. the spacing between the chain pulley and the cassette will be greater with the XT, since it is designed to accomodate up to a 34 tooth cassette (instead of 27-29 max for ultegra).

as the chain wears it becomes more flexible sidewise. a tight spacing with ultegra (or other road derailleur) means it deflects the chian at a greater angle. if you combine a worn chain with wide spacing between cassette and pulley, then the deflection may not even be enought to prompt a shift.

I have used XT with a 12-25 or 12-27 cassette, so I am not saying it can't work. but in the long run I do think it's likely that the shifting won't be as good and could end up being a lot worse as the chain wears.

but since you already have XT you could try it and see how it works for you.

Another downside to having a ling pulley cage is that it's more likely to get damaged the longer it is.
so, having one only as long as you need makes sense to me.

i'm not sure what sort of hookup you have. but maybe the shop will do the changes for you as part of the purchase. that way you don't waste a lot of money changing out perfectly good parts and you can get the setup you want.

marc