Kato, I run a set of Maxm carbon flatties on my PRST1 and they are fine (along with a flat easton magnesium stem), this sorts out the nasty high front end feel. With the stem I use I needed a headset spacer to stop the SFN from getting mangled but muggins only found this out after reshaping the SFN so I now use a Hope head doctor. PS how are the mono's and Chris king headset getting on??
Nah That xc90 is a super fine weave carbon fibre set. I weigh a fair bit and have a habit of driving into rocks rather that round them (target fixation + Fab PRST-4 Front) which gives my bar a real good workout, but there have been no course for concern if any thing they seem to soak up the very high frequency vibration I used to get on top speed descents, you know, when your hands feel like you've been on a road drill. I think the carbon acts as a high frequency damper, I've heard carbon rigid frame blokes say the same but until now hadn't experienced it myself.
Go Carbon! (But only top name/recommended stuff as there is some cheap cr@p about).
back to cranks, I'd thought I'd throw the Middleburn RS7s into the hat. With the various colour combinations on the arm/spider/rings, they look seriously good. I've got a silver arm with black spider and gray (hardcote) rings. Their stiff as hell as well, and strong enough for DH racing. At the moment thanks to a bent axle on my RaceFace BB, I'm debating what to pair them up with, and I'm leaning toward the Truvativ Gigapipe, since I've heard lots of good things about them. They do something very different with the bearings, so they take the load much better. I'm going for the DH version, but there is an XC BB if you're looking for weight saving. I'm more interested in strength tho'
Haven't bought one yet. The LBS I bought my Whyte from are unsure if a King will fit between the top yoke, so they've got the bike at the moment and are checking
xtr are truly awsome, you can feel the difference when you fit them to your bike. putting the bearings further out deffinatly does the job. If you have the money xtr if not the new xt ones that are based on the xtr versions.