- Over the last decade, mountain bikes have evolved to use the 29er wheel size.
- This is a change from decades of 26-inch wheels, being the norm. But why not go even bigger?
- Despite engineering challenges, some Italians have produced a working 36-inch wheel carbon-fibre mountain bike.
Forget about sock length. Colour coordination. Or even post-ride coffee blends.
The most intense and relevant debate in mountain biking, is always about wheel size.
Unlike road bikes, which have been rolling the same size wheels for decades, mountain biking has ‘evolved’ to use different sizes.
For most of the 1980s, 1990s and 2000s, mountain bikes standardized around 26-inch wheels. A size borrowed from legacy road and touring bikes. And nobody cared. It worked.
But experimentally minded riders and engineers knew that bigger wheels would roll larger tyres. And on off-road routes, with rocks and roots, a mountain bike with bigger wheels and tyres, would be comfier to ride. And easier to control.
Bigger is better, right?
Despite initial resistance to the theory in the 2000s, the bigger wheel size theory has won. Convincingly.
It is now nearly impossible to buy a new mountain bike with 26-inch wheels, as 29-inches has become the default standard – with 27.5-inches as an option.
But if 29-inch wheels work so well, why not go bigger? That is exactly what the Italian mountain bike brand, 36pollici, is doing with its new 36-inch wheeled frame.
From 26, to 29 - and now, 36?
One of the challenges mountain bike designers had in the 2000s, attempting to develop the 29er concept, was the lack of parts. Rims. Tyres. Suspension forks. These were all designed for 26-inch wheels.
Frame packaging is the other issue, as wheel size increases. Bigger wheels and tyres need more clearance. Shaping a frame that can roll efficiently, with excellent balance and riding agility, involves some very tricky geometry calculations.
A unicycle connection
The 36pollici is the world's first carbon-fibre 36er, with matching carbon material wheels. It is a hardtail frame and rolls unicycle tyres on custom composite rims.
VeeTire provides its T-Monster 36x2.25” rubber and these tyres are heavy, at 1400g each – much heavier than a conventional 29er mountain bike tyre.
Rotational weight dramatically influences riding performance and can make a bike feel sluggish to pedal and indifferent to turning. For 36pollici’s engineers, those issues are offset by the sheer obstacle rolling momentum of those huge wheels – despite the bike having no air or coil suspension components.
Built with carbon-fibre components, 36pollici claims the 36er hardtail comes to 12kg – which isn’t that heavy.
Whether the 36pollici concept will herald a new era in even larger wheeled mountain bikes, will depend on suspension manufacturers and tyre companies. And if they are willing to invest in new moulds to create forks and rubber, for those huge wheels.
A big advantage of those huge wheels will be for very tall riders, who often feel awkward on most bikes. Even those with 29er wheels.