Much like Microshift did, Sunrace is going big with new 10- and 11-speed wide range mountain bike groups.

The parts group will contain shifters, front and rear derailleurs and new 11-40 and 11-42 cassettes, providing yet another alternative to SRAM and Shimano for those wanting to put together a purpose-built drivetrain rather than hacking the one they have (not that there’s anything wrong with that).

Shift past the break for the details…


The cassettes are made up of two upper sprocket clusters followed by individual rings for the smaller cogs. Two versions are offered, led by the CSMX9 with an AL7075 large cluster that comes in at a claimed 395g for the 10-42. Unfortunately, I didn’t quite get how they were able to put a 10-tooth cog on there, so check for an update soon.

Below that is the CSMS8 with full steel cogs to come in at 429g (11-40) and 465g (11-42). Both use alloy spiders for the two clusters.


Both models are available in black and champagne colors.



To handle the extra teeth, their rear derailleurs get a long cage and offset upper pulley. No clutch mechanism from the look of it…but the rest of the top-level Driven model is worth looking at closer.


The rearward axle placement lets the upper pulley increase it’s space between it and the cassette more and more as you shift to easier gears, much the same as virtually all modern derailleurs designed for oversized cassettes.

2015 Sunrace wide range mountain bike cassettes and rear derailleurs

Minimalist pulley wheels and carbon outer plate keeps weight down to a reasonable 245g.


  1. Interesting that the der has no clutch. Also really interested in how they got a 10t cog on there with no special freehub carrier ala SRAM.

  2. All – we’ll try to catch up with them at Sea Otter if they’re here this week, otherwise some post-show contact will be made for pricing and more info.

    Josh – I just finished building, photoing and racing a project bike (hardtail, lots of new and used drivetrain mixed up) that put a well-worn XX rear derailleur on a 1×10 setup with wide range cassette. Never dropped the chain once in a 6 hour race with some aggressive rock gardens and a few small drops and jumps. Not to say they don’t help (certainly keeps things quieter), but maybe not as necessary as we thought if used with a good narrow/wide or other 1x specific chainring that helps keep the chain in place. Would I do it on a trail bike? No. But for XC it’s worked just fine so far with a new chain/cassette/chainring. The long term review will reveal whether that holds true after things show some wear.

  3. Any update on these parts? A quick look at Sunrace’s site and at Amazon shows no hints of the wide range 10 or 11 speed bits. I’d love to hear an update!

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