Kit di riparazione per ruota libera e pignone da mountain bike - Pignone in acciaio cromato 11T/13T nichelato + temprato 9 velocità per 11T

[Precision Gears] Laser-cut chrome-plated steel teeth with a hardness of 55 HRC—reduces chain slippage by 90%, optimizing shifting performance on mud and uphill. [Anti-Drop Design] Tooth profile and asymmetrical notches actively guide the chain—preventing chain slippage during off-road and endurance riding. [Plug and Play] Directly replaces the 9-speed freewheel. Installation in 5 minutes. [Abrasion Protection] Double hardening (deep freeze treatment + nitriding) extends service life—resistant to sand corrosion and chain abrasion. [Lightweight Optimization] Precision balance (±0.01g) eliminates vibration at speeds of 40+ km/h.