Crown Race Base Ring bicycle helmet compatible with tapered fork compatible with mountain bikes

Compatibility: Compatible with tapered fork and headset systems for mountain, road, and hybrid bikes. Fits 29.8mm inner and 39.9mm outer lower bearing interfaces.
Material and Finish: Precision-machined aluminum alloy for smooth steering support; helps reduce play and noise; corrosion-resistant silver finish for easy cleaning after wet rides.
Performance Improvement: Restores correct bearing seat geometry when swapping forks, frames, or headsets; improves contact between the crown gear and lower bearing for consistent handling.
Dimensions and Installation: 29.8mm inner and 39.9mm outer; thickness fits common 40mm lower bearings; push-fit design; installs with a crown gear setter or soft mallet.
Use Scenarios: Ideal for home mechanics and shop service; handles helmet rebuilds, fork upgrades and frame overhauls for trails, commuting, gravel, touring and city riding.