Derailleur Arm – the arm which extends within the rear derailleur, with pulleys to feed the chain by means of. The derailleur arm is spring-loaded to get rid of slack from the chain when working with scaled-down gears. Cylinder head design has a significant effect on the efficiency of combustion, https://bikeengineparts94898.blue-blogs.com/42470576/what-does-bike-parts-headset-mean