SRAM's ever-expanding empire now includes forks, brakes and cranks, but it's still transmission stuff that it's best known for. We're huge fans of SRAM's thumb-only trigger shifters but we've never got on with Gripshift, which means that until fairly recently our views on the company's rear derailleurs were coloured by having to use SRAM shifters. But now that we don't have to use Gripshift we've been getting the miles in on an X-9 rear mech.
X-9 is second-to-top in the SRAM component heirarchy, with the carbon-fibre-enhanced X.0 occupying top slot. The X-9 retains most of the Terminator styling of the top-end kit, with a distinctive open design. Unlike the first generation of SRAM mechs, the X-9 (along with its cheaper X-7 sibling) uses an alloy knuckle joint for strength - these days you have to kit 'em hard to break them.
A couple of key features distinguish SRAM's derailleurs from the benchmark Shimano product. Actually it's largely things that SRAM does without. There's no barrel adjuster on the derailleur, and the cable routes in from the front to eliminate the oft-troublesome last loop. The angle of the guide lets it work well with seat- or chainstay-routed cables. The inner wire runs around a cam before anchoring under a bolt in the usual way.
The other thing that you don't get is a spring in the knuckle joint. Shimano derailleurs have a hefty coil spring hidden inside that pulls the derailleur body forwards, thus splitting chain-tensioning duties between two springs. SRAM doesn't use the top one, relying solely on the cage spring to keep the chain tight. The upshot of this is that the derailleur body doesn't arc back and forth under normal use, making it a great choice if you're troubled by your derailleur clattering off the frame, not an unusual situation on some chainstay-pivot full suspension bikes.
The big difference between Shimano and SRAM, though, is the thing that means you have to use SRAM shifters with SRAM mechs - acuation ratio. That's the amount that the cage moves for a given amount of cable pull. SRAM uses a 1:1 ratio, so if you pull 1mm of cable the cage moves 1mm. Shimano mechs are geared up, so 1mm of cable pull moves the cage 2mm. The theory is that the 1:1 ratio makes the shifting more tolerant of gungy cables, and this does seem to be the case. The shifting action is very light and very accurate and it stays that way for ages.
Drawbacks? Somehow we keep managing to make the top jockey wheels sieze up on SRAM mechs. Certainly our bike-cleaning technique tends to be fairly component-unfriendly, but Shimano mechs deal with it just fine. It's no biggie, though. A timely squirt of lube stops it happening and if we forget, a quick strip-and-clean gets things going again.
Other than that, the only criticism we can come up with is that the X-9 model doesn't seem to offer all that much extra over the £15 cheaper X-7 except more silveriness and a little less weight. Then again, you could say much the same about LX and XT. And you have to use SRAM shifters but since we love the triggers we don't have a problem with that...
 Light, accurate shifting; funky looks; no clatter
|
 SRAM shifters not to everyone's taste, ham-fisted cleaning can make jockeys stick
Verdict
|
PERFORMANCE
|
|
VALUE
|
|
OVERALL
|
| |
