BSA wheels are well designed, but unfortunately the wheels vary considerably from mold to mold. Most of the wheels are not perfectly round and the tread surface is not even.
Our Speed Wheels are official BSA wheels which are sorted by mold number, and then precision machined with a CNC (computerized) lathe for maximum performance. To provide you with an awesome set of wheels, we perform the following operations:
The wheels are sorted by mold number, and any defective wheels are discarded,
The wheel tread is lightly lathed to achieve a perfectly round wheel, and a flat tread surface,
The inside hub is slighted beveled,
The inside edge of the wheel is trimmed, reducing the tread width by 10 thousandths of an inch (approximately the thickness of three pieces of standard copier paper.
Round and smooth wheels roll faster than standard wheels.
Matched mold numbers ensures that the bore diameter and other wheel measurements are identical, maximizing performance.
The molding mark on the tread is virtually removed, eliminating the 'bump' (see Figure 1).
The slight weight reduction provides a faster start.
Usage
The Official BSA Speed Wheels can be used without any additional preparation. However, the following steps can be performed for additional speed:
Polish inside edge - Place a wheel mandrel in a drill, mount a wheel on a wheel mandrel, start the drill, and lightly polish the inside edge of the wheel (opposite the spokes) with a polishing compound or very fine wet sandpaper (minimum 600 grit).
Cone the Inside Hub - Form a cone on the inside wheel hub with the Pro-Hub tool. Click here for more information.
Polish the Bore - Polish the wheel bore with graphite or bore polish. Click here for more information.
Important Note
The lathing operation removes a small amount of tread surface. The serrated edge is intact (see Figure 2). The tread reduction is barely visible to the eye, but is measurable with a caliper. If your race restricts the use of lathed wheels, consider using our specialty tools and supplies to prepare a set of raw wheels.
Technical Information for 4090/4091 Wheels
Wheel Diameter: 1.170 ± 0.001 (Raw Wheels: 1.184 to 1.199)
