SUNCORD 4-7 Speed Carbon Tensioner for Brompton Bicycle P/T Line

1. The adapter base features a single bearing aluminum alloy design, paired with a carbon fiber swing arm to prevent deformation of the chain tensioner caused by the chain dragging when the metal swing arm folds. Carbon fiber offers better elasticity and resistance to deformation.
2. The pulley body is made of plastic carbon fiber, with 10T positive and negative teeth made from aluminum alloy using full CNC processing, reducing the chance of the chain slipping off the pulley.
3. For the pulley teeth, we use 6704 thin-wall bearings for rotational movement, enhancing the stability of the pulley. For linear motion, we use universal ball linear bearings as carriers, combined with alloy sleeves. The ball linear bearings are water and dust resistant and can be lubricated for use, offering higher practical performance. This allows the lower pulley to move more quickly and shifts gears faster.