650b’s not dead, says Hunt as it bucks the big wheel trend with its overhauled Adventure wheelset

In the world of bicycle wheels, where bigger is regarded as better almost without exception, Hunt appears to be going against the flow with a new, completely overhauled and redesigned version of its Adventure Carbon Disc.

But why?

The current narrative in the mainstream bike industry might be that 650b is dead, with 32in wheels emerging as the next big thing, but Hunt says the core alt cycling community knows better. “At Hunt, 650b never left,” it claims. “Enjoying the benefits of massive, high-volume tyres shouldn't require buying an entirely new frame. Honouring the rugged roots of gravel cycling, the 650b concept allows riders to unlock a plush, highly capable ride on their current setups.”

To rewind, 650b wheels played a major part in the early gravel boom a decade ago because the outer diameter of a 700c tyre (40-45mm) and a 650b tyre (2.0-2.2in) are very similar. In the case of 650b or 700c, swapping wheelsets for different types of terrain didn’t drastically alter a bike's geometry. But then frames started to get more clearance, 700c came back, and now the huge 32in is looking unstoppable.

“We see this overhaul as a love letter to ‘old’ bikes,” says Hunt. “It’s about keeping your favourite gear running longer while unlocking the sheer fun of riding big rubber.”

So how are the new Adventure Carbon Disc 650b gravel wheels different from the originals? In a nutshell, they’re 71g lighter at a claimed 1,390g, the internal rim is 1mm wider and the maximum tyre size increases to 65mm, while the carbon rim has been redesigned for greater impact resistance. Hunt has incorporated its H_Core technology into the new rims, which means using a pultruded carbon core within the rim sidewalls. “Pultruded” splices pull and extruded and is a process that pulls reinforced fibres through a heated mould filled with liquid plastic resin. Hunt says this reduces porosity in high-stress areas and improves impact resistance, making a set of rims that it says are built to withstand the “harshest singletrack beatdowns, even on a fully loaded rig”.

As for the dimensions, the old rim had an internal width of 26mm and was 33mm wide externally. The new one has 27mm internal and 32mm external, so the new rim is fractionally wider internally and narrower externally by the same amount. The new profile is designed for supporting bigger tyres: Hunt says it’s optimised for 45-60mm tyres, and it works with rubber from minimum 35 to maximum 65mm.

Hunt has also used preformed carbon angular spoke patches to protect against spoke pull-through, while the 28-spoke build uses Sapim D-Light double-butted stainless steel spokes and brass nipples with the conventional J-bend interface.

The hub is upgraded from an older six-pawl version to a 36-tooth, nickel-coated ratchet system with extra sealed bearings for increased durability.

Claimed weight is 1,390g for the pair. The price hasn’t changed: £949, as before.

It’s refreshing to see a brand let consumers stick with an older standard and upgrade a compatible product rather than making it obsolete, as the cycling industry is often fond of doing. And of course, extending the life of a bike rather than persuading us to throw it away and buy a new one is the kind of sustainability message that's too often missing.

Meanwhile, from a practical point of view, some aspects of the 650b standard can’t be beaten, even by 32in. A wheel with a smaller rim can have a lighter overall weight – Hunt’s new wheelset is a perfect example: impressively light, and it still has steel spokes rather than carbon.

The smaller wheel is not only lighter but also nimbler, accelerates faster because the rotational weight is closer to the hub, and can feel more responsive. Sure, it doesn’t roll over large obstacles as efficiently as a 32in, but that’s only one aspect of off-road riding.

Manoeuverability is arguably more important on technical terrain. Perhaps most crucially, as is frequently pointed out, 32in is simply too big for small frames, resulting in unmanageable toe overlap or too-long steering geometry. The 650b is a much better option for smaller riders.

Those are the arguments: in conclusion, it looks as though the 650b is alive, kicking, better than ever, and here to stay.