While we tend to think of mountain biking as a young sport, it's actually starting to look quite middle-aged. By way of an example, this year marks the 25th anniversary of the introduction of Shimano's Deore XT groupset, first launched in 1982. Over the years XT has come to be thought of as a pretty safe bet when it comes to component choice - markedly nicer than the ranges below it but without the huge prices of the flagship stuff. With the introduction of an all-new XTR group last year, a revamped XT wasn't going to be far behind, and here it is. The new XT will be available in July. We've got the lowdown on all the parts - we'll take a look at the clicky whirly bits first:

Transmission

Shimano's big new thing is its Shadow rear derailleur technology, and it's actually something that could deliver some tangible benefits. Shadow is all about a narrower profile derailleur, which has two useful results. First, the parallelogram sticks out less far - rather than a big knuckly bit being the first thing to hit the ground or any passing rocks, the whole mechanism sits inboard of the QR nut so the end of your axle will end up taking the impact of a dropped bike.

Shadow rear derailleur sits out of harm's way

The design also means that the mechanism linking the dropout to the cage is considerably shorter. Not only will this save weight, it'll also improve stiffness. In particular, the new derailleur is said to have increased vertical stability which should mean an end to the irritating rattle of derailleur on chainstay. You'll also find shorter, more direct cable routing for improved response.

Interestingly the Shadow mech will only be available as a top-normal configuration "designed to work best with Rapidfire Plus shifters". There'll be short or long-cage versions. Conventional non-Shadow rear mechs will be available in top-normal or low-normal versions. All the new derailleurs will feature the X-shaped outer plate in the style of Shimano's flagship XTR components.

XT will be offered with two shifting systems. Dual Control levers (which, with a low-normal derailleur, is Shimano's recommendation for XC/marathon riding) will be available in hydraulic disc and cable V-brake versions. Rapidfire Plus shifters (recommended with a top-normal derailleur for all-mountain and enduro) will feature 2-Way Release, so you can upshift with either thumb or finger. If you want Multi Release (allowing multiple upshifts with one press of the trigger) then you'll need to opt for the XTR shifters or use XT Dual Control.

Other Rapidfire Plus shifter tweaks include a removable optical gear display and the ability to mount the shifter inside or outboard of the brake lever clamp. It's also been designed to work with suspension lockout levers.

Cassette options are limited to 11-32 or 11-34. The 11-32 has a four-arm sprocket carrier while the 11-34 is stiffened up by a five-arm carrier and a double-riveted bottom sprocket. Completing the transmission is the wide range of front derailleurs - conventional, top-swing, E-type BB mount and so on. Refinements include angled adjustment screws for easier access (swingarms and things often get in the way of the current adjusters) and improved tyre clearance.