Wheel building - Differences Between Bicycle and Motorcycle Wheels
Are you a bicycle wheel builder who is considering moving onto motorcycle wheel building? The very earliest motorcycles were literally a bicycle with an engine so wheels for these machines are unlikely to give you any real problems, but if you are intending to build a wheel for any motorbike other than a vintage machine there are several extra things that you will need to know.
The motorcyclist is relying on his wheels
When you are building motorcycle wheels you are taking on a very much bigger responsibility. Motorcycles travel a lot faster than bicycles. Motorcycle wheels will turn a lot faster and the forces on the components are a long stronger. A defect in a wheel that might be little more than an inconvenience to a cyclist could result in catastrophe on a motorcycle. Unless you are extremely confident of your ability as a wheelbuilder do not start to build wheels for motorcycles.
Preparation for rebuilding
Before you dismantle the wheel you will need to take some measurements. Bicycle wheels are almost always built with the rim running centrally between the lock-nuts. On a motorcycle wheel you will usually have the hub without the axle and other fittings attached and you will need to measure the offset. This is done by laying a straight edge across the brake side of the hub and measuring the distance between the straight edge and the rim. Take the measurement in several places and be sure that you are confident that you have this measurement written down accurately before you start to dismantle the wheel.
As when building bicycle wheels it is also important to make a note of the spoking pattern and any unusual features before dismantling.
In this day of cheap digital photography it is also a good idea to take some photographs as well.
Motorcycle spokes are a lot thicker than bicycle spokes so they cannot be flexed. When rebuilding a motorcycle wheel you will not be interlacing the spokes as you would for a bicycle.
You will find that spokes need to be inserted in the correct order. Inside spokes need to be fitted first. If you make a mistake during building it will very likely be necessary to dismantle your work and start again.
You will also notice that the rim is dimpled where the spoke-nipples fit and that the holes are drilled offset. You do not have the flexibility to play around with spoke patterns that you do with bicycle wheels. Motorcycle rims are drilled to fit a certain hub with a certain spoke pattern.
Motorcycle spoke heads are not always set at right-angles. The spoke head angles can be set anywhere from 90 degrees to perfectly straight. Perfectly straight spokes cause other problems as the spoke may turn in the hub during truing.
Motorcycle wheels are often built with more than one length of spoke, or with spokes with different head angles, in the same wheel.
Truing the wheel
Your bicycle wheel truing stand is not going to help you when finishing a motorcycle wheel. Motorcycle wheel truing stands are much heavier, take up more room on your workbench and are of course more expensive to buy.
I'm sure it is quite obvious, but I'll mention it anyway, that you will also need a different nipple-key before you can begin to true a motorcycle wheel.
A motorcycle wheel is usually trued with the bearings installed but with no axle. The wheel is held with cones in the stand.
If you are truing a wheel with an alloy rim it is very easy to mark the rim with the nipple-key. Even more care needs to be taken than with bicycle wheels.
I have tried to show that being able to build a bicycle wheel does not automatically qualify you for building motorcycle wheels. However with care. practice and the extra knowledge contained here, hopefully you will find the transition to be an enjoyable one.
Written by Vince Warner of Colwood Wheel Works
- Wheel Building and Repair | Colwood Wheel Works
Vince has been building bicycle and motorcycle wheels since he was a child. He now owns and runs Colwood Wheel Works in Hailsham, England.