Shimano's mid-range SLX mountain bike groupset has always punched above its weight, offering a similar level of performance to Deore XT at a much lower price, with a little extra weight the only penalty to pay. There's a new version for 2013, and the big S have wisely decided not to mess with a successful formula.
There's a new clutch-equipped rear mech based on the highly praised XTR Shadow Plus derailleur and it's had a cosmetic overall, but overall the new M670/5 group looks set to continue SLX's solid tradition of high performance at a reasonable price.
Probably the biggest change is the new Shadow Plus M675 rear derailleur. The 'Shadow' tag refers to the way it hugs the cassette to keep out of harm's way (as on the current SLX M660 mech), while the Plus refers to the clutch mechanism. Flicking a switch slows down derailleur cage movement, dramatically reducing chain slap. This is a boon for aggressive riders who regularly ride rocky terrain.
Shimano haven't forgotten the more traditional cross-country crowd, though – a lighter (both in terms of weight and shifting action) non-Plus M670 version will also be available. Both will be available with medium or long cages, and with standard or direct mount fittings – see below for more on the latter.
There's a new bottom-swing front mech design that's been designed to give more rear wheel clearance on 29ers (this will be available for XT and XTR, too), but the most obvious change to SLX is the new crankset – it retains the two-tone look of the current version but has a new chainring spider that draws inspiration from Shimano's higher-end mountain bike groups.
There are three close-ratio Dyna-Sys options – 38-26t and 40-28t doubles, plus a 42/32/24t triple – plus a wider ratio 38/24t setup, which is also now available for XT. The shifters have shorter levers and a mode converter that means they can be used with 2x10 and 3x10 drivetrains.
SLX received a brake upgrade last year so there are no major departures for 2013. There have been some cosmetic changes so that the stoppers match the rest of the group, the levers have shed a little weight, the brakes now come with three-layer Ice Technologies rotors as standard, and OEM pads (ie. those which come with complete bikes) are now the finned Ice Tech version, too – last year these were only supplied with aftermarket brakes. The levers are compatible with Shimano's Ispec bar clamp system, too, if you'd prefer to integrate the brake and shift levers into a single clamp.
Direct mount rear derailleur
As if we haven't got enough conflicting standards to deal with already, Shimano want to introduce another one for 2013: direct mount rear mechs. At present, Shimano derailleurs have a 'B2 body plate' between the top pivot and the bolt that threads into the frame's replaceable mech hanger or replaceable dropout. Under the new system, the B2 body plate is removed and replaced with an 'arm' built into the hanger/dropout. This means the derailleur hangs in the same place but is attached more directly to the frame.
Shimano say the new design was developed with 29ers in mind, following requests from several bike manufacturers. They reckon it makes it easier to get the rear wheel in and out, improves shifting accuracy due to reduced flex, gives a stronger rear derailleur/frame connection – although this isn't necessarily a good thing, in our books, given that rear mechs often take the brunt of crashes – adds flexibility for frame designers (because it allows more space for through-axles and suspension pivots) and gives a cleaner look.
As most modern bikes have replaceable dropouts/hangers, Shimano say it shouldn't mean big changes to frame designs, and they point out that current mechs can be adapted to work with the new system simply by removing the B2 plate. It works the other way round too, so a direct mount mech can be adapted to work with a standard dropout by attaching a B2 plate. Direct mount rear mechs will be available for XT and XTR, too.
Mark Greshon, Shimano brand manager for the UK, tells us: "The position of the rear derailleur is very specific in relation to the cassette for shifting performance. Any other new design to create more space would mean a whole new standard and new frame requirements which bike companies did not want. With this direct mount they have the option but aren’t tied into a new standard."
However, one can also take the opinion that Shimano's proposed hanger design change is merely a way to shift the burden on to frame manufacturers. Currently, that relatively thin B2 plate is a vulnerable failure point in the event of a crash or jammed stick. While this direct mount hanger would eliminate that Achilles' heel, Shimano could alternatively just reinforce that bit and retain the current hanger standard. Greshon points out that a replaceable mech hanger will always snap before the B2 plate.
Mountain bike wheels
Shimano now offer 12 mountain bike wheelsets, including four 29er options. New for 2013 are two SLX-level wheels: the MT66 (Race) and MT68 (Trail). Both are tubeless ready, with UST-profile rims.
The MT66 is 19mm wide and Shimano say it can be used with up to 2.25in rubber. It uses 24 straight-pull spokes front and rear, has a 15mm E-Thru axle option at the front and comes in black or white, with mono tone or lime green decals. Claimed weights are 840g for the quick-release front wheel and 985g for the rear (omitting skewers). There's also a 29er version, which uses 24 spokes at the front (claimed weight 945g) and 28 spokes at the rear (1,080g for quick-release; 12mm axle also available).
The MT68 is wider at 21mm, and can be used with tyres up to 2.5in. It uses 24 butted spokes and comes with a 15mm axle up front and a choice of quick-release or 12mm axle out back. Available in the same colours as the MT66, claimed weights are 910g for the front wheel and 1,050g for the 12mm rear. Both wheels are set up for Center Lock rotors only but Shimano have a new SLX-level adaptor (SM-RTAD05) if you prefer to use six-bolt discs.
Also new for 2013 is a 29er version of the XT M785 wheelset. It has a 19mm, UST-profile rim and is available with a 15mm front axle if required. All three wheels run on cup-and-cone bearings, as is usual with Shimano.
Last up are the new CLICK'R pedals. Aimed at beginners and commuters, these are designed to be much easier to clip in and out of than a regular SPD pedal. In fact, the highest tension setting on the new pedals is said to be similar to the lowest setting on a standard SPD.
Shimano say clipping in requires 60 percent less force, and clipping out 50 percent (at the lowest tension setting). This lighter action is partly due to reduced spring tension but the pedals also have a narrower step-out angle (8.5° rather than 13°) for quicker disengagement.
The T700 (pictured below) is a dual-sided XT-level pedal that's available in black only, while the T400 (pictured above) will come in at a lower price, in black or white. Both have pop-up cages, wide platforms and built-in reflectors for safety, and will come as standard with multi-release cleats. Shimano will also offer a choice of six CLICK'R shoes, designed to be easier to walk in than standard cycling footwear.
Pricing & availability
Pricing of Shimano's new mountain bike kit is still to be confirmed. First deliveries of the new SLX are expected to be made in May 2012, with some parts not available until later in the summer. Here's a quick rundown:
- May: SGS rear derailleurs, M670 and M671 front derailleurs, shifters, brakes, 42/32/24t crankset, MT68 wheels.
- June: GS rear derailleurs, M675 and M676 front derailleurs, 38/24t cranks, MT66 wheels (26in and 29in)
- July: 40/28t cranks
- August: 48/36/24t cranks