mountain-driv in its standard version is designed for bottom bracket shells of 68 to 72 mm width. Each mountain-drive comes with an aluminum spider with bolt circle diameter (BCD) 110 mm. This allows to mount chainrings with 34 t. up to 53 t.

There is a spider with BCD130 mm available. For BCD130, we can deliver chainrings from 38 t. up to 75 t.

The mountain-drive housing comes either with a torque lever (see photo on the right), that holds the reaction torque of the planetary gearing system.
Or with cone rings, that make installation easy, even if there is no chainstay to fit the anti-twisting bracket.

The unit is designed for BSA bottom bracket, but doesn't need the BSA threads, as it is clamped and not screwed in. The inner diameter of the BSA bottom bracket is in the range of 33.6 up to 34 mm. There are adapters available for larger diameters (m-d with torque lever only).

Photo: mountain-drive with torque lever and clamp for the chainstay