VBC is an acronym for Variable Bolt Circle. The beauty of VBC rings is they allow you to set up various tooth configurations to get the gear ratio you desire. The outer ring is designed with a slotted section and the inner five bolt ring is self centering allowing more options when compared to traditional crank designs with set bolt circle requirements.
We recommend at least a ten tooth difference between the outer gear and the inner gear and a maximum of 24 teeth. The VBC rings can be configured with an off-road ratio and mated to your mountain bike uses the ENO crank arms, or if you have a road frame, use the VBC road crank arms and configure a suitable ratio for road riding.
Inner ring: 24 - 38 (in even increments)
Outer ring: 38 - 52 (in even increments)
We recommend a 10 tooth differential between the inner and outer ring.