just different colourways?
no. different levers, SLX don't have the pad clearance adjustment, and different calipers - XT are one piece, SLX are, a two-piece construction.
also 2008 slx don't have servo wave
What does Servo wave do? And do you want a one piece or two piece caliper? Whats the advantage of the number of pieces?!
SLX do have servo wave but don't have the adjuster.
A one piece caliper is stronger and the servo wave allows the pads to sit further from the rotor as it alters the effective length of the brake lever as you apply it.
In theory, servo wave is just a fancy name for the alignment of the lever, and the rod attached to it that pushes down the master cylinder piston within the bake lever setup. The idea being that when you initially pull on the lever, the alignment means that you get a very quick push on the brakes pads that brings them out to meet the disc, and then as you continue to pull the lever, the alignment changes to mean you you get more leverage ( and hence braking power ) out of the brakes.
Most normal brakes have a pretty linear lever pull to pad movement ratio. The servo wave tries to vary that ratio through the stroke of the brake lever to get the pads moving at different rates.
1 v 2 piece calipers. There is a fair amount of force generated by the hydraulic fluid when you pull on the brakes. If you have a 2 piece caliper, then you have 2 bits of metal clamped together which have to hold that pressure and transfer it to the brake pads. In theory, some of that pressure can be lost by the 2 piece calipers seperating slightly, thus in theory you'd be losing some braking power. A 1 piece caliper doesn't have that problem, and so the caliper wont try to split under the pressure, and the power all goes to the brake pads.
How much of a difference that really makes i personally think is marginal at most. If 2 pieces were to lose that much power by trying to seperate, then i think we'd see more issues of fluid pissing out between the caliper halves ... not the most common complaint i've read about on here.
2 pieces are easier to manufacture ...
Thanks people, so effectivly for every say 1mm of lever I pull the pad moves say 2mm. XT levers break new ground in ugliness stakes though, still I shall not care about that if they save me.
I have just got the XT ones and think they look better on the bike than in the pics of them.
I got the XT brakes for my new bike and was with you them being a little ugly but having been running them a while now I reckon they look spot on and actually make most other hydro levers look really big and clunky in comparison.
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They work really well too and have great feel. The easy reach adjust is a great bonus too. I doubt I will go for anything else in the near future.
Thanks for the piccy they are quite small, or smaller than I thought. What kind of rotors do they come with, splined or 6 bolt. Do shimano make vented 6 bolt or am I making that up?
i have both SLX and XT on different bikes. I am not sure that I would bother spending the extra again on XTs though (although they look better, have neater calipers and say XT on them)