Abstract: Apparatus for retaining contact of a wheel having a first and second sidewall includes a first roller having a tapered body, the tapered body of the first roller having a larger diameter at the first sidewall of the wheel and having a constant or curved taper to a smaller diameter towards the second sidewall of the wheel. The apparatus further includes a second roller having a tapered body, the tapered body of the second roller having a larger diameter at the first sidewall of the wheel and having a constant or curved taper to a smaller diameter towards the second sidewall of the wheel, the first and second rollers being disposed adjacent to each other, wherein the taper of the first and second rollers enables the rollers to maintain contact with the wheel at varying rotational speeds.