Xt spd39s are designed to take the rigours of off road competition whilst also being perfect for cross country trail riding lightweight and high performance using a forged alloy body chrome moly axle and a revised cleat interface for increased stability beautifully constructed with a strong and slender spindle using an 8 mm allen wrench mounting system slim oval axle body housing sheds mud efficiently and reduces stiction sealed cartridge axle system for reliability and simplified