Shimano Adds New Cranksets and a Derailleur to Their Lineup

Date Mar 25, 2021

With Shimano's 100th birthday on fast approach, they've managed to sneak in a few additions to their lineup before the big day. Fresh off the lot are new 55mm chainline spacing cranksets available in both XTR and Deore guises, along with a shorter-cage XT derailleur. Check the release below for all the details.

Adding versatility to its robust lineup of 12-speed mountain bike components, Shimano has announced new crankset and derailleur options to suit a wider range of mountain bikes and rider preferences. Two new cranks - including an XTR option - feature 55mm chainlines, providing riders with more clearance for modern bike designs that include wider chainstays. Additionally, Shimano has introduced the new Deore XT short cage rear derailleur that offers more ground clearance for aggressive riding while maintaining Shimano’s hallmark fast, smooth, and accurate shifting.


New Shimano 12-Speed Cranksets

To accommodate new mountain bike frame designs and progressive riding styles, Shimano offers two new cranksets (FC-M9125-1 and FC-M512-1) with a 55 mm chainline. This new 55 mm chainline option complements Shimano’s FC-M9100 (51 mm) and FC-M9130 (56.5 mm) cranksets, delivering compatibility for a diverse range of mountain bike designs. Both are designed for use with 148 mm wide O.L.D. rear wheel hubs and feature direct mount chainring installation.


Shimano’s new short cage Deore XT rear derailleur provides better ground clearance for more aggressive trail riding. It also supports faster riding and smoother rear suspension movement thanks to a reduction in unsprung weight of the drivetrain. Shimano’s new Deore XT derailleur still offers all the technologies and benefits of Shimano’s 12-speed rear derailleur platforms such as fast and precise shifting performance, bigger 13T pulley wheel, and stable drivetrain in rough terrain.


RD-M8100-GS - Shimano Deore XT Derailleur - Designed for Shimano’s 10-45T 12-speed cassette - 28mm shorter than RD-M8100-SGS long cage derailleur

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+1 Zayphod
Skyler  - March 25, 2021, 7:53 p.m.

It's kind of amazing how close Shimano came to making the best cranks on the market, and still missed. All they had to do was make direct-mount chainrings for the M8000/7000 series stuff. One chainring series with a 51mm chain line, and another for superboost (57mm?). These would have instantly been the benchmark for crankset reliability, with their 24mm steel spindle, pinch-bolt spline interface, and Hollowtech strength-weight. 

Instead, for M8100/7100 etc, they decided to make the chain line adjustment through different spindle lengths, with spindle washers, and an ultra-narrow Q-factor that means you need to run a wider chain line if your cranks don't clear your frame. And it's so narrow that they don't clear on a lot of bikes! Now they're having to make alternate cranksets for a different ratio of Q-factor to chain line, so that they can clear more frames? What???

This the most complex and annoying solution to a simple problem, imaginable! Are bike shops expected to stock 9 different SKUs of Deore cranks? 

The new short cage derailleur is on the right track at least. From the start, a refinement of M8000 with an 11 speeds 10-45 would have suited me even better. My 11 speed XT with a Sram 10-42 cassette has continued to be far, far more reliable than any 12 speed drivetrain I've had. I've even gone back to 11 speed on my all-mountain bike, after 2 years of frustration with 12 speed.


Gbergevin  - March 26, 2021, 6:32 a.m.

Completely  on the needless complexity and SKU proliferation with the current crop of cranks - cranks are inherently modular, Shimano seems to be willfully minimizing the opportunity to take advantage of that. I've had a lot of Shimano cranks go bike to bike over the years... my 12s stuff won't be able to do that as easily. 

12s has been super reliable, though - I always found Shimano 11s pretty touchy, especially compared to my gold standard 10s XT - the later gen 10s stuff you could set up and it'd be perfect a a couple seasons later. I'd wear out chains and cassettes before I need to mess with cables.


Pedro447  - March 26, 2021, 11:32 p.m.

Nice comparison, spot on. All the sram stuff pretty much pales in comparison to the new Shimano 12spd. I think AXS is kind of it’s own beast because it’s still the first of its kind, but excited to see what we will get from Shimano in that department. Not a big fan of batteries or electronics in general on my bike, but HG+ with the shift quality of AXS and without having to mix components would be baller. Maybe we’ll see some prototypes on the EWS course next year.



Greg Bly  - March 27, 2021, 10:28 a.m.

I guess it's just me . I don't have dirrect mount rotors . They exist but they are not popular. Why do I want dirrect mount chainrings? Forgive my lack of knowledge . Are all dirrect mount chainrings using the same standard?  Glad I stocked up on chainrings for my old standard Saint and SLX cranks.  

Change for the sake of change or fixing a common issue. ? My guess four bolts at the end of the spider will do a far greater job of resisting a chain ring bending.  So I would describe dirrect mount chainrings as a down grade.


Zayphod  - March 29, 2021, 12:54 p.m.

"It also supports faster riding and smoother rear suspension movement thanks to a reduction in unsprung weight of the drivetrain."

Seriously? The difference between GS and SGS for 11spd XT was about 10 grams.


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