New Shimano GRX wheels finally go carbon fibre

Internal width really is becoming the buzzphrase of the day when the conversation turns to gravel wheels. Wider tyres ideally need a wider rim to support the sidewalls and resist the tyre rolling over in heavy cornering. As with many others, Shimano’s latest GRX wheels are wider than their predecessors, as in this case they’re also deeper and made of carbon. 

What's new?

The existing crop of GRX wheels took the form of an aluminium wheelset that is available in either 650b or 700c, with a 22mm rim height and a 21.6mm internal width. These aren’t archaic numbers by any stretch, but by the standards of the best gravel wheelsets of today, they are a little dated. 

In response, with the all-new GRX wheels, Shimano has produced a much more modern rim profile; 30mm deep, with a 25mm internal width. This should accommodate, according to Shimano, tyres between 32mm and 50mm. It will probably be possible to exceed this 50mm limit, but you’re likely to lose the optimised sidewall support.

The 30mm depth is a middle-of-the-road depth in comparison to the competition. Shimano states this depth was chosen to better perform in heavy winds. Not going for a deep profile also keeps the weight down to a respectable 1,461g (636g front, 822g rear).

Naturally, the rims are tubeless-ready, though it’s unclear as to whether the wheels will come set up tubeless at the point of sale or if that will be down to the customer. There is also no mention of rim size - a 700c option is a given, but as there is no mention of 650b, it appears that Shimano sees this as a diminishing standard in the sector, and not worth supporting.

Cup and cone hubs

While the rims may have received a modern overhaul the hubs remain something of a throwback. A 24-spoke count front and rear, with centre lock discs and thru-axles are all very contemporary, but the cup and cone bearings are certainly a choice worth mentioning.

The majority of high-end gravel wheelsets, particularly carbon ones, opt for sealed cartridge bearings. These GRX wheels keep the same cup and cone system from their alloy siblings, mirroring Shimano’s commitment to the system that is evident when you remember their high-end Ultegra and Dura-Ace wheels still roll on loose ball bearings.

How well they hold up against the best gravel wheels on the market will require some testing.

Pricing

If you're after a set, then you'll need to budget $1,399.99. UK pricing is yet to be announced, although given the US price matches that of the Ultegra road wheels, we predict they will cost the UK equivalent for those - around £1,259.99 - in the UK.