There aren’t many times a replacement part actually improves your bike but put one on your bike and you’ll wonder why you didn’t install a NINJA sooner. The bearings are housed in an alloy shell and wrapped with plastic and fibre. This fusion of the three materials provides the bearings a solid platform to sit on and extends their lives. A lot of people would be satisfied with this, but they went even further by extending the alloy shell so the right and left sides lock together. This locks the frame, cranks and bottom bracket together and provides unparalleled stiffness.