An alloy barrel means it'll be in service for many years too

Tip: Combine Amino Ultra Endurance and Amino Explosive Power for combined strength and endurance sports

which can be useful on stubborn tyres

A Fibreglass shaft

Race Face Crank Boots Pair - Black - Medium - Carbon Virtual Parent An alloy barrel means it'llProtect your carbon or alloy cranks from the abuse of trail riding. These are a must have item when using carbon cranks. We use these boots with our Race Face cranks and they have held up extremely well and have done an exceptional job protecting the crank arms. No more worrying about bashing your crank arms on rough trails! To install, remove pedals and slip over the end of your crank arms. Medium Carbon Compatibility: Sixc Cinch Sixc (24mm Spindle)