Tubeless conversion for spoked wheels: how we do it

A classic spoked wheel is one of the best-looking things in motorcycling — and one of the most old-fashioned. The spoke nipples pierce the rim, so it can't hold air on its own: it needs an inner tube. A punctured tube deflates fast, and repairing it means pulling the wheel and the tube. Meanwhile, practically the whole modern motorcycle world rides tubeless: safer in a puncture, more convenient, far easier to repair. At Iron Custom Motors in Cascais (Lisbon) we seal spoked rims with polyurethane, so classic, retro and custom bikes keep the spoked look and gain tubeless behaviour. Here's how it's done.

The video

Five and a half minutes: the full conversion, tyre-off to balanced-to-zero, on a Royal Enfield Bear 650. Watch it first, or read on and come back.

First, the spokes

Wheels apart, rim tape off, and the work starts with spoke tension. First by ear: every spoke should ring at roughly the same high pitch, none standing out — that matters for balance. Then a spoke wrench confirms no slack remains; wheel stability depends on it. Critical caveat: we only check the tension, never overtighten. Then a full wash and meticulous degrease — near-surgical cleanliness. The wheels on camera came off a Royal Enfield Bear 650, the same bike as our scrambler build.

Three thin layers and 36 hours

The sealant rule is hard: never construction or sanitary silicone — it shrinks over time, dries out, cracks. We use single-component polyurethane made for load-bearing parts under constant vibration: resistant to aggressive environments and UV, elastic for decades. It cures on atmospheric moisture, so it goes on in three thin stages of 1–2 mm: the spoke cavities first, then two top layers, with 12–16 hours of polymerisation between them and space left for the valve stem. On camera, the first layer had dried after 16 hours; at 36 hours both were dry, smooth and neat. Not fast. Worth it.

The result

We also fit angled air valves — inflating past a disc or hub is far easier at an angle. Then assembly and the leak test: every spoke, and the valve too. Final touch: balanced to zero, and the wheels go back on. The coating stays elastic for decades, shrugs off vibration, doesn't crack. And the method scales: the video shows a classic thirty-inch spoked wheel converted to tubeless — the same machines behind our motorcycle tyre service handle wheels up to 30 inches.

FAQ

Can spoked motorcycle wheels be converted to tubeless?

Yes. The rim is sealed from the inside with polyurethane, spokes included, and holds air without a tube. The classic look stays — only the angled valve gives it away.

How long does a tubeless conversion take?

Three thin layers with 12–16 hours of curing between them — about 36 hours in total, plus leak test and balancing. Days, not hours.

Would silicone work instead of polyurethane?

No — silicone sealants shrink, dry out and crack. We use single-component polyurethane made for load-bearing, vibration-exposed parts.

How long does the seal last?

Decades. The polyurethane stays elastic, shrugs off vibration and doesn't crack; every wheel is leak-tested spoke by spoke.

Can very large spoked wheels be converted?

Yes — the video shows a classic 30-inch wheel converted the same way; our equipment takes wheels up to 30 inches.

What does the tubeless conversion cost?

€100 per wheel. Whether your particular wheels are suitable we assess individually — message us on WhatsApp (+351 917 961 230) or via the contact page.

Wheels, tyres and service in Cascais

Conversion, tyre fitting and balancing all happen in-house in Portugal. The tubeless conversion costs €100 per wheel. Iron Custom Motors runs a full motorcycle tyre service, complete Royal Enfield service, and wheel work for classic, retro and custom bikes. Wondering if your wheels qualify? Message us — we speak four languages.

WhatsApp: +351 917 961 230 · Tue–Sat 10:00–18:00 · São Domingos de Rana, Cascais · Contact us

Fix your ride & fuel your soul.