These spacers get securely installed on a threaded axle between your hub's bearing cones or retaining hardware and lock nuts, making a 120mm spaced track hub compatible with frames having wider-set dropouts.

They are not compatible with hubs that use bolts that thread into the hub (ie: Phil Wood, Mack, Reina, Raketa, Paul, Surly, etc.).

Not all rear track hubs have axles long enough to accommodate 130 or 135mm rear spacing, so do some measuring first!