It has a try all axle with shimano bearings, the axle is 22 mm diametre and the bearings are 24 so i made a pice on a lave, you can chose some bearings in general the ones used in bmx bikes who come in 22 mm. i have chosen this tipe becouse they are cheap and wanted to test the idea, next will use some campagnolo 50g a set and an titanium axle. so its will be light and rigid