We brought you an early look at Shimano's all-new 2008 Deore XT groupset a while ago (part 1, part 2). Since then we've been to some bike launches and had a chance to get some riding time in on the new parts - expect to see a lot of XT on 2008 bikes.
We'll start with the things that don't really feel any different from the saddle. Perhaps slightly surprisingly, the new XT cranks stick with the twin pinch-bolt arrangement for the non-drive side arm rather than the new XTR style of an axial bolt and bearing preload doofer. The arms are a new shape, which most people (us included) find a little disappointing in terms of appearance - the current cranks are quite distinctive, but the '08 ones, well, aren't. Durability should be improved, though, especially with the introduction of a steel/carbon fibre middle ring instead of the old aluminium one. It'll come as no surprise to hear that the front shifting is swift and snappy.
The innovative stuff is elsewhere. The big news is the rear Shadow derailleur, with a low-profile design that not only promises a number of benefits but looks likely to deliver. Once you see one actually mounted on a bike it makes a great deal of sense. The fixed part of the mech lies entirely inside the end of the QR nut, so is less likely to get bashed if you fall over. In most gears, the front end of the parallelogram is inside the nut too, but even when it isn't, that's the bit that moves in and out - hit it and it should just swing out of the way.
Also very welcome is the more direct cable routing. Rather than the big loop of housing of old, the Shadow design uses a short, straight length (along very similar lines to SRAM's mechs, only without making a turn around a cam on the mech itself). The whole thing looks very clean, and works a treat (although we had to do a bit of fiddling, what with manufacturer's launch bikes often being assembled in a bit of a hurry...).
Driving the mechs are new shifter pods. They're along very similar lines to the already-popular XTR ones, but don't have the Multi-Release feature that lets you shift multiple gears in both directions. You get a bi-directional trigger that you can operate with finger or thumb, but the current shifters have that too. The new ones are much neater-looking and are just fine in use, but expect to see a fair few bikes getting an upspec to the XTR units to get Multi-Release. We didn't particularly miss it ourselves, but then we haven't really managed to get the hang of not getting two gears at once on XTR when using our thumbs to upshift.
Finally we have the brakes, and this is the other place where XT gets the innovation. The calipers are very XTR-esque, and the levers are clearly also closely related. But the XT levers incorporate Servo-Wave - a variable leverage ratio through the lever stroke. From rest, moving the lever a small amount drives the pads a long way, allowing them to sit further from the rotor to reduce drag. Once they've reached the rotor, a cam in the lever gears up the action to move the pads less for a given lever movement to increase power.
The system also incorporates what Shimano calls "free stroke adjustment", altering how much lever travel there is before any actual braking occurs. Combined with the usual reach adjustment you should be able to get the feel that you want. The brakes take a little getting used to, though. Initially there's a sense of nothing happening for ages and then all the braking at once, but once you get the feel of it they're really rather good. Shimano claims a 20% power increase, but the most obvious difference to us is how much quieter they run in grotty conditions. That little bit of extra pad clearance certainly seems to pay dividends.
So first impressions are good. The big question, of course, is how well all this stuff's going to last. A big box of XT stuff is winging its way BM-wards right now, so we'll keep you posted...
