DOPPLER is one of the rare equipment manufacturers to offer this type of product.
As in the great era of moped racing, the central mainspring is an essential option for the variator and the clutch pulley.
It allows the progressiveness of the variator to be adapted to the engine speed.I
l gives the possibility of adjusting the hardness of the spring and avoiding slippage.
The mainspring is mounted on a nylon ball joint.