Shimano Ultegra Power Meter FC-R8100-P Hollowtech II Crankset - anthracite/172.5 mm 36-52

Shimano Ultegra Power Meter FC-R8100-P Hollowtech II Crankset

Item number: 84399

The FC-R8100-P Crankset by Shimano - Power meter for Ultegra

With the FC-R8100-P 2x12-speed crankset, Shimano offers the option of double-sided power measurement for its Ultegra road bike series for the first time. This gives you access to information about your overall performance, cadence, torque efficiency, left-right balance and round pedalling. The accuracy of the 24 strain gauges can be described as very high with a deviation of only 1.5%. Thanks to Bluetooth and ANT+ radio protocol, there is broad compatibility with bike computers and similar devices.
The lithium-ion battery is located in control unit on the crank spider, which you can easily recharge yourself. If it is completely full again after about 2.5 hours, it will last for at least 300 hours. By the way, the charging cable is the same as for your Ultegra Di2 shifters. You can also carry out firmware updates via the E-Tube Project. On the housing of the control unit, you will find an LED that signals the battery charge level and a button for easy zero calibration. Of course, the entire construction is waterproof and there is active temperature compensation, so you don't have to worry about the weather. You can attach the magnet for cadence measurement to the chainstay, seat tube or down tube using the included positioning tool.
Apart from these special features, the FC-R8100-P is technically identical to the " normal" Ultegra crankset. It converts your power into propulsion in a highly efficient manner, is characterised by an optimal stability/weight ratio thanks to the Hollowtech II design and inspires with precise, fast shifting processes. The crank arms are hollow-formed, as is the large chainring, which is partly made of carbon, resulting in significant weight savings. Apart from the axle, all essential parts were made of lightweight metal. FC-R8100-P has an asymmetrical 4-arm bolt circle diameter of 110 mm. It produces a chainline of 44.5 mm and has a Q-factor of 148 mm.

Information regarding the return of batteries and electrical equipment:

Information on the return and disposal of used batteries and electrical equipment can be found here.


power meter crankset (dual-sided)
Shimano 2x12-speed
Chainring Mount:
110 mm bolt circle diameter, 4-arm asymmetrical

Technical Information:

Ultegra R8100
Crank Arm Material:
Chainring Material:
Aluminium / Carbon, Aluminium
Axle Material:
34-50, 36-52
Crank Arm Length:
170.0 mm, 172.5 mm, 175.0 mm
44.5 mm
148 mm
Axle Diameter:
24 mm
Compatible BSA Shell Width:
68 mm
Recommended Bottom Bracket:
SM-BBR60 or SM-BB72-41B Press Fit Hollowtech II (not included)
Recommended Chain:
+/- 1.5%
Point of Measurement:
crank arm
Power Source:
lithium-ion battery, integrated
Battery Life:
300+ h
Data Collected:
power, power balance left / right, pedal smoothness*, cadence, torque effectiveness*
Data Transfer:
ANT+, Bluetooth

*not transmitted via Bluetooth connections


Shift/Brake Lever:
ST-R8150, ST-R8170, ST-R8060, ST-R9250, ST-R9270, ST-R9160, ST-R9180, ST-R7170, ST-R7120, ST-RX820, ST-RX610
Front Derailleur:
FD-R8150, FD-R9250, FD-R7150, FD-R7100
Bottom Bracket:
BB-R9100, SM-BB9000, SM-BBR60, SM-BB6700, SM-BB5700, BB-RS501, BB-RS500, SM-BB4600, SM-BB92-41B, SM-BB72-41B, SM-BB71-41B, BB-RS500-PB
CN-M8100, CN-M9100, CN-M7100, CN-M6100


  • very accurate power measurement on both sides via 24 strain gauges
  • integrated, rechargeable lithium-ion battery with long service life
  • charging time approx. 2.5 hours, same charging cable as Di2
  • waterproof construction
  • active temperature compensation (operating temperature range -10 °C to +50 °C)
  • simple zero-point calibration via button on the control unit or bicycle computer
  • control unit with LED display for battery charge level (green, red, flashing red)
  • firmware updates via E-Tube Project
  • perfect balance between stiffness, stability, weight and rotational efficiency
  • optimised power transfer
  • fast, high-precision shifting at the front
  • hollow crank arms (Hollowtech)
  • hollow-formed large chainring made of aluminium-carbon composite (Hollowglide)
  • anodised crank arms and chainrings
  • aluminium chainring bolts


Hollowtech II
Shimano Hollowtech II is a crank bottom bracket system designed to achieve an ideal ratio of stiffness, weight and rotational efficiency. It is based on an integration of the bottom bracket and the right crank arm and works with a 24 mm axle or bearing diameter, which has proven to be optimal in terms of stability. In many cases, the bearing cups are on the outside so that the load is better distributed. High-quality precision seals ensure a long service life.

Second-Generation Power Meters
Shimano second-generation power meters use an improved force vector analysis and are therefore more accurate than their predecessors. Both crank arms have 12 sensors each, which are mounted in such a way that the crank deformation can be compensated for and the acting forces can be identified. The right and left sides are connected via the battery located in the axle, ensuring accurate measurement on both sides. The built-in temperature compensation contributes to the precision. You can easily recharge the battery with the Di2 charging cable EW-EC300. The power meters have Bluetooth and ANT+ compatibility to communicate with bike computers and smartphones. For firmware updates and data display, Shimano provides the E-Tube Project Cyclist App or the E-Tube Ride App. A more detailed performance analysis is possible via Shimano Connect Lab software.

Manufacturer Numbers:

170.0 mm 34-50:
170.0 mm 36-52:
172.5 mm 34-50:
172.5 mm 36-52:
175.0 mm 34-50:
175.0 mm 36-52:


  • 1 x Shimano Ultegra FC-R8100-P power meter crankset (34-50 or 36-52)
  • 1 x Shimano crank bolt
  • 1 x Shimano EW-EC300 charging cable, 1.5 m
  • 1 x installation ring for left crank arm
  • 1 x magnets
  • 1 x magnet cover, black
  • 1 x magnet cover, white
  • 2 x double-sided adhesive tape rolls
  • 1 x Shimano TL-FC40 crank tool for left crank arm
  • 1 x cover cap for left crank arm
  • 1 x positioning tool for magnet


  • anthracite/170.0 mm 34-50: 758 g
  • anthracite/170.0 mm 36-52: 769 g
  • 100 day return period
  • Online since 1998
  • Trusted Shop 4.87 / 5.00


  • anthracite/170.0 mm 34-50, in stock
  • anthracite/170.0 mm 36-52, in stock
  • anthracite/172.5 mm 34-50, in stock
  • anthracite/172.5 mm 36-52, in stock
  • anthracite/175.0 mm 34-50, in stock
  • anthracite/175.0 mm 36-52, in stock

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