Deore XT Crank Arms

Deore XT Crank Arms


Regular price Sale price$153.99
Crank Arm Length
  • In stock, ready to ship
  • Inventory on the way
  • Free shipping on all orders $49+


  • Series: Deore XT M8100
  • Speeds: 12-speed
  • Material: Aluminum
  • P.C.D: Direct 
  • Bottom bracket not included
  • Chainring not included

Shimano Deore XT FC-M8100 Crank Arms

  • Hub Spacing:  Non-Boost (135/142mm) & Boost (141/148mm)
  • Chainline: 52mm
  • Q-factor: 172mm
  • Average weight (32t): 620 grams

Shimano Deore XT FC-M8120 Crank Arms

  • Hub Spacing: Boost (141/148mm)
  • Chainline: 55mm
  • Q-factor: 178mm
  • Average weight (32t): 628 grams

Shimano Deore XT FC-M8130 Crank Arms

  • Hub Spacing:  Superboost (157mm)
  • Chainline: 56.5mm
  • Q-factor: 181mm
  •  Average weight (32t): 636 grams


The Shimano Deore XT Crank Arms are compatible with the following:

  • Chain: Shimano HG 12-speed chains
  • Chainring: Shimano direct mount chainrings:  CRM75, CRM85, CRM95
  • Bottom Bracket: Shimano Hollowtech II Bottom Brackets
  • Pedal: All 9/16" pedals

Please reach out to us with any questions you may have on anything we sell. We want to make sure you get the right part the first time. Our lifelong riders at Thunder Mountain Bikes are knowledgeable and would love to talk to you!


We currently offer both economy and expedited shipping options though FedEX and USPS. 

Orders totaling over $49 are eligible to ship for free via an economy ground option of our choice. 

If you're in need of something super-quick, please contact us directly. We may be able to overnight your order with an additional fee and depending on your location. 


Should there be an issue with the item you bought, or you no longer need your purchase, we will be happy to set up a return.

Returns or exchange requests for New or Used Bikes must be requested by emailing us at within fifteen (15) days from the date of delivery. Bikes must be in un-ridden condition. Custom-built bikes may not be returned. Returned bikes have a $200 restocking fee and the customer pays for return shipping.

Returns for most other items may be requested within sixty (60) days of the delivery date. All returned items must be received in new, unused, and uninstalled condition, with the original tags and labels attached and in the original packaging. We cannot accept returns on any items installed or show wear of any kind. 

Clearance and open-box items may not be returned. 


To request a return, please log in to your customer account by clicking the  customer account icon  Profile icon in the top right of any page or visit

1. In the Email field, enter your email address and click Continue.

2. In your email account, open the email sent from our store and copy the six-digit verification code included in the email.

3. Go back to the online store and enter a six-digit verification code to log in.

4. Find and click on the order that you want to submit a return for.

5. If your order has more than one item, select only the items you want to return.

6. Select a return reason and add a note for the store if needed.

7. Click Request Return.

Once your return request is approved, you will receive an email with shipping instructions and a return shipping label. 


We will process your return after we receive your returned item(s) and inspect the condition. Please allow at least seven (7) days from the receipt of your item to process your refund. We will notify you by email when your return has been processed.


If you receive defective or damaged products or if we sent you the wrong products, please contact us using the phone number or email below.


If you have any questions concerning our return policy, please contact us at:

(928) 282-1106   |

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Customer Reviews

Based on 10 reviews
Just needed 165mm crank arms

My bike came with Deore 175mm cranks. Wanted to drop to 165. Definitely didn’t need XT-level cranks. It was just literally impossible to find Deore or SLX cranks in 165. Thunder Mountain happened to have XT cranks in 165 and I caught them during Black Friday for 20% off. Why not! They’re smooth and work with the entry-level Shimano BB already in my frame. Thunder Mountaun shipped quickly!

Only complaint is they don’t come with the VERY specific tool needed to tighten the center lock chain ring in place. Caught me off guard and needed to run to a LBS just to get them to tighten the chain ring in place. Make sure you have this tool handy if you’re installing on your own!

Ken Feldman
Deore XT cranks

Ordered Deore XT 165 cranks. Order was processed and shipped by Thunder Mountain in 2 hours. Unbelievable service and the order was perfect! These guys are awesome!

Barrett Walker
Shorter Cranks, More FUN

Love the shorter cranks, you wouldn’t think 5mm would make that much difference but I really like how they perform.


As described. Solid cranks. Wanted to try 165mm.


Superior product