The Shimano Ultegra FC-08 brings refined Hollowtech II engineering to the serious road cyclist, pairing a 52/36T chainring combination with 165mm crank arms for riders who want race-level performance and precision. Hollow-forged aluminium arms and a Hollowglide outer chainring reduce rotating mass without compromising stiffness, making this an ideal upgrade or build component for 11-speed road drivetrains.

Highlights

• Hollowtech II construction: Integrated spindle interface transfers power directly to the drivetrain with minimal flex and reduced weight.
• Hollowglide outer chainring: Precisely profiled teeth and reduced material weight improve shifting speed and front derailleur response.
• 52/36T gearing: Versatile double chainring combination suited to road racing, gran fondos, and mixed-terrain riding.
• 165mm crank arm length: Ideal for riders with a shorter inseam or those seeking a higher cadence position with reduced hip angle restriction.
• 110mm asymmetric BCD: Consistent with Shimano's R8000/R9100 series, enabling straightforward chainring upgrades.
• 43.5mm chainline / 146mm Q-factor: Efficient pedalling geometry that keeps legs tracking naturally through the pedal stroke.
• HG-EV and HG-X11 chain compatibility: Works with Shimano's full range of 11-speed road chains for reliable, precise shifting.

Hollowtech II and Hollowglide

Shimano's Hollowtech II system integrates the bottom bracket spindle into the right-hand crank arm, eliminating the traditional separate axle and reducing the number of interfaces where energy can be lost. Hollow-forged aluminium crank arms remove material from low-stress zones, keeping overall weight to 681g for the 52/36T 165mm build. The Hollowglide outer chainring uses a specially shaped tooth profile to guide the chain smoothly onto the ring and reduce the force required to shift under load.

Geometry and Fit

A 43.5mm chainline and 146mm Q-factor place your feet in a natural, biomechanically efficient position that suits the majority of road riders. The 165mm arm length suits riders with a shorter leg length or those who prefer a more open hip angle at the top of the pedal stroke — commonly chosen by riders moving from mountain to road, or those following a bike-fit recommendation for a shorter lever.

Compatibility & Fit

Designed for Shimano 11-speed road drivetrains. Compatible with Shimano HG-EV and HG-X11 11-speed chains. Requires a Hollowtech II outboard bottom bracket (sold separately) in a 68mm, 70mm, or 86mm shell width. Not compatible with 10-speed or 12-speed groupsets. Bottom bracket not included.