Machining for bicycle and motorcycle components
Two-wheeled hardware lives with vibration, weather and weight in a way most industrial parts never do. A clamp that is 20 g heavier is a marketing problem; one that cracks at the fillet is a warranty problem.
Part families
Hub shells, end caps and axle spacers. Bearing bores must be coaxial to each other and square to the dropout face, or the wheel sits off-centre and the bearing preload is wrong.
Handlebar clamps, bottle mounts, light brackets and caliper adapters. These see reversed loads and are usually made as thin as the material allows, so the fillet radius at the transition is a fatigue feature, not a cosmetic one.
Chainring spiders, cassette adapters and motor mounts for e-bikes. Bolt circle accuracy and face parallelism decide whether the chain line runs true under load.
Linkage plates, shock mounts and pivot hardware in 7075 or steel. Load paths are short and stresses are high, so material choice and fillet geometry dominate the design.
Machined inserts bonded into carbon frames and components. Surface preparation for the adhesive matters more than the tolerance, and anodizing is usually avoided on the bond face.
Materials and finishes
| Part | Material | Finish | Why |
|---|---|---|---|
| Hub shell | 6061-T6 or 7075-T6 | Anodize | Weight, stiffness, colour |
| Clamp | 7075-T6 | Hard anodize | Strength at thin section |
| Caliper adapter | 6061-T6 | Anodize | Stiffness, corrosion |
| Pivot hardware | 4140 or 17-4 PH | Zinc nickel or passivation | Wear and corrosion |
| E-bike motor mount | 7075-T6 or steel | Hard anodize or black oxide | Fatigue and stiffness |
| Bonded insert | 6061-T6 | None on bond face | Adhesive compatibility |
Where two-wheel parts fail
Every sharp internal corner is a stress raiser. A 1 mm fillet where the design allows 3 mm can halve fatigue life for no functional benefit.
A 2 mm wall cannot hold an M4 thread under vibration. A bonded insert or a machined boss is the fix, and it is much cheaper designed in than repaired.
Type II anodize grows about 10 µm per surface, enough to turn a slip fit into an interference fit. Mask the bores or machine oversize.
A clamp that is tightened until it holds can ovalise the bore it clamps. The design needs a specified torque and a wall thickness that survives it.
Small batches are normal here
Bicycle and motorcycle component companies often launch with a few hundred pieces and scale only if the product sells. That suits machining: no tooling, a design change costs a re-quote rather than a new mould, and the same supplier can continue into volume if the product succeeds.
Where volume does arrive, the route moves to casting or forging with machining of critical features, and the machined interfaces stay the same, so the bearing fit does not change between a machined prototype and a cast production part.
| Prototype | 1–5 pcs, 3–7 working days |
|---|---|
| First production run | 50–500 pcs, 7–15 days |
| With hard anodize | Add 3–7 days |
| Repeat order | Same route, shorter lead time |
Industry questions
Yes, from one piece. No tooling is needed, so a prototype is a machining job rather than a project. Design changes between prototype and first batch cost a re-quote, not a new mould.
Yes, to a Pantone or RAL reference. Colour-critical parts are run as one batch per colour, because two anodize loads can differ visibly even on the same alloy.
Around 1.5 mm on a supported section with a proper fillet, and thicker where the clamp is tightened. Below that the clamp deforms before it grips.
We machine the metal insert and prepare the bond surface, but bonding into a carbon structure is done by the frame builder. The insert is supplied with the bond face unmasked and free of anodize.
Send the component and tell us the load case.
For two-wheel parts the fillet and the section thickness decide whether it survives. The quote will flag the transitions that need a larger radius.
From the shop notes
Longer answers to the questions these pages raise.