XT has gone 11-speed, and the new Shimano XT Cranksets are spinning on XTR/Dura-ace inspired bottom brackets. They have a smaller bearing size to enhance rolling efficiency and for shaving some weight. They are also better sealed to reject whatever muck mother earth conjures up and tries throw at them.
Shimano BB-MT800 Pressfit Bottom Bracket Features:
- Small Ball Bearings for Better Rotation
- Better Sealing
- Fits PF30 92mm BB Shells

BB-MT800-P
SHIMANO DEORE XT - Bottom Bracket - Press-Fit - HOLLOWTECH II - 89.5/92 mm shell width
For SHIMANO 24mm MTB cranks, the SHIMANO DEORE XT bottom bracket uses high quality sealed bearings and is offered in threaded and pressfit options.
FEATURES
Ride anywhere 11-speed rider tuned gearing
The power to choose how and where you ride
Various choices for bike and riding style
Consistent shifting performance and enhanced chain management
More durable chainwheel teeth
Composite chain ring construction:
Steel teeth/Steel+CFRP body (1x11, 3x11 Middle)
Aluminum plated teeth/Aluminum+CFRP body (2x11 Top)
Optimal balance of durability and lightweight
New 3D composite chain ring's teeth composition is optimized for each chainwheel load out with steel driving gear teeth and aluminum support gears
Aluminum teeth/Aluminum+CFRP (3x11 Top) Steel teeth/CFRP (3x11 Middle) Aluminum plated teeth/Aluminum+CFRP (2x11 Top) Stainless steel/CFRP (1x11)
High efficient and precise shifting
Improved driving rigidity
70 degree spider arm with HOLLOWTECH II technology and Dynamic Chain Engagement (1x11-speed)
Close ratio gear combination for minimum shifting gap and maintaining rhythm
Single spike structure for robust shifting
Enhanced chain retention
Dynamic Chain Engagement (1x11-speed)
Better sealing and better rotation
Small ball Bottom Bracket
Gear combination: FC-M8000-3: 40-30-22T FC-M8000-2: 38-28T, 36-26T, 34-24T FC-M8000-1: 30T, 32T, 34T Chain line 3mm outboard spec available