Shimano Ultegra FC-R8100 12-Speed Crank Arm Assembly - 160mm
The smartest way to build Ultegra — premium arms, your choice of rings.
The Shimano Ultegra FC-R8100 Crank Arm Assembly gives you the complete HOLLOWTECH II crank unit — drive-side arm with integrated spindle and 4-bolt asymmetric ring spider, plus the non-drive-side arm — without a fixed chainring combination. Bolt on whichever Shimano 12-speed chainrings suit your riding, whether that is compact 50-34T for climbing, mid-compact 52-36T, or standard 54-40T. PDL.Bike is the first Australian stockist to offer the FC-R8100 as a separated arm assembly, paired with our separately-stocked Shimano Ultegra chainring sets.
Chainrings sold separately. This listing is for the crank arm assembly only — no chainrings are included. Pair with Shimano FC-R8100 compatible 12-speed chainring sets, available as a separate listing at PDL.Bike. Shimano BCD is 110mm 4-bolt asymmetric (HG+/12-speed).
What makes this worth it
HOLLOWTECH II Construction
Shimano's hollow forged aluminium technology delivers exceptional stiffness-to-weight in the crank arms. Power transfers directly to the drivetrain with minimal flex, even under hard sprinting loads.
4-Bolt Asymmetric Spider
The integrated ring spider uses Shimano's 110mm asymmetric 4-bolt pattern, optimised for 12-speed HG+ chain compatibility. All Shimano FC-R8100 chainring sets mount directly.
Choose Your Ring Configuration
Sold without rings, this assembly lets you pick the chainring combination that suits your riding. Pair with PDL.Bike's separately-stocked Shimano Ultegra 12-speed chainring sets.
5 Crank Lengths
Available in 160, 165, 170, 172.5 and 175mm to fit every rider geometry. Shorter lengths suit smaller riders or those seeking a more open hip angle at the top of the pedal stroke.
Bearing Pre-Load System
The non-drive-side arm includes Shimano's integrated bearing preload adjustment collar. Eliminates play at the bottom bracket interface and is serviceable without specialist tools.
Ultegra Tier Performance
R8100 sits one tier below Dura-Ace in Shimano's lineup — the same proven HOLLOWTECH II platform and 12-speed compatibility, at a price that makes sense for training and racing.
Specifications
| Brand | Shimano |
| Model | FC-R8100 Ultegra |
| Type | Crank Arm Assembly (no chainrings) |
| Technology | HOLLOWTECH II |
| Speed | 12-Speed |
| Chainring BCD | 110mm Asymmetric 4-Bolt |
| Chainring Compatibility | FC-R8100 12-speed HG+ (sold separately) |
| Bottom Bracket Interface | 24mm spindle (HOLLOWTECH II) |
| Compatible BB Standards | BSA, BB86, BB92, PF30 (with adapter) |
| Crank Lengths Available | 160, 165, 170, 172.5, 175mm |
| Material | Hollow Forged Aluminium |
| Chainrings Included | No — sold separately |
(IFCR8100ARM)
HOLLOWTECH II Construction
Shimano's hollow forged aluminium technology delivers exceptional stiffness-to-weight in the crank arms. Power transfers directly to the drivetrain with minimal flex, even under hard sprinting loads.
4-Bolt Asymmetric Spider
The integrated ring spider uses Shimano's 110mm asymmetric 4-bolt pattern, optimised for 12-speed HG+ chain compatibility. All Shimano FC-R8100 chainring sets mount directly.
Choose Your Ring Configuration
Sold without rings, this assembly lets you pick the chainring combination that suits your riding. Pair with PDL.Bike's separately-stocked Shimano Ultegra 12-speed chainring sets.
5 Crank Lengths
Available in 160, 165, 170, 172.5 and 175mm to fit every rider geometry. Shorter lengths suit smaller riders or those seeking a more open hip angle at the top of the pedal stroke.
Bearing Pre-Load System
The non-drive-side arm includes Shimano's integrated bearing preload adjustment collar. Eliminates play at the bottom bracket interface and is serviceable without specialist tools.
Ultegra Tier Performance
R8100 sits one tier below Dura-Ace in Shimano's lineup — the same proven HOLLOWTECH II platform and 12-speed compatibility, at a price that makes sense for training and racing.
| Brand | Shimano |
| Model | FC-R8100 Ultegra |
| Type | Crank Arm Assembly (no chainrings) |
| Technology | HOLLOWTECH II |
| Speed | 12-Speed |
| Chainring BCD | 110mm Asymmetric 4-Bolt |
| Chainring Compatibility | FC-R8100 12-speed HG+ (sold separately) |
| Bottom Bracket Interface | 24mm spindle (HOLLOWTECH II) |
| Compatible BB Standards | BSA, BB86, BB92, PF30 (with adapter) |
| Crank Lengths Available | 160, 165, 170, 172.5, 175mm |
| Material | Hollow Forged Aluminium |
| Chainrings Included | No — sold separately |
| SKU | IFCR8100ARM |
| Brand | Shimano |
