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by Dave Rome
June 21, 2019
Photography by Hunt
Hunt says its new Limitless 48 Aero Disc wheels are the “world’s most aerodynamic disc road wheel[s] below 50mm depth”. I know, I know. Every company with an aero wheel claims that. But Hunt, the British consumer-direct wheel company has done something new — dare I say, innovative — in order to make such a tired claim. And whether it remains true across all conditions or not, it’s undoubtedly clever.
The trick? The rim is wide, really wide. Widening rims is nothing new. HED and Zipp were perhaps the pioneers of the wider-is-faster movement, and many others have followed since. But Hunt has taken it’s 48mm-deep U-shape rim to a whole new level, boasting a 34.3mm external width while keeping the internal width a more commonly acceptable and compatible (but still wide) 22.5mm.
Doing so would typically result in a bunch of excess material and weight where you want it least, but as a disc-specific design, Hunt didn’t need to worry about a braking track. Instead, the rim features a low-density foam molded with the carbon fibre to produce the desired external width while keeping wheelset weight at a competitive 1,582g. The foam is said to add approximately 50g per rim.
Shown is a 3D render of the final rim shape. The areas formed from carbon fibre are in grey, while the low density expanded polymer (foam) is shown in black.
I won’t bore you with too many aerodynamic specifics — Hunt covers that in its white paper. But the short of the story is that in 2017 Hunt hired Luisa Grappone, an aerodynamics expert and former senior R&D engineer at Campagnolo and Fulcrum. Since then, Grappone, along with Hunt’s owners and brothers, Peter and Tom Marchment, have been refining the now-patented concept. I first saw an almost-final prototype at last year’s Eurobike, and it’s been a year since then.
Tyres play a vital role in a wheel’s aerodynamics, and the Limitless 48 Aero Disc was designed with 25c and 28c rubber in mind. Hunt’s white paper aims to show the company’s testing transparency in this regard. Hunt tested its wheels against a number of market-leading options, each fitted with both Schwalbe Pro Ones and Continental’s new GP5000 TL, and in 25c and 28c.
Hunt’s 48mm-deep rim offers a U-shaped profile. Much of the aero trickery is down to the extreme external width profile used.
Some of the competing wheels, such as the Enve SES 4.5 AR or Zipp NSW 303, come extremely close to or even best Hunt’s Limitless wheel in certain configurations, but on average Hunt pulls ahead. That average was taken at 45kph, across a wide range of yaw angles, and weighted using the ‘ponderation law’ proposed by Mavic.
There are no standardised aerodynamic tests in our industry, but this averaging method is somewhat common and sees Hunt’s new design save as much as three watts compared to other popular 50mm wheelsets. All wheels were fitted to a Canyon Aeroad Disc and used on rollers during the wind tunnel testing.
The wheels were designed to meet the new road tubeless ETRTO “standard”. Like all tubeless wheels with a hooked bead, regular clinchers and tubes can be fitted, too.
CeramicSpeed bearings are fitted as stock and carry a six-year warranty (service conditions apply).
Other than variances in freehub body selection, all the wheel options are the same. They’re built with Hunt’s Sprint straight-pull hubs, featuring CeramicSpeed bearings and 48 points (7.5°) of engagement from the pawl-system. The wheels are laced two-cross with Pillar Wing 20 spokes – 20 front, 24 rear.
Coming from a consumer-direct company, they’re impressively well priced, too. Hunt’s website currently lists the Limitless 48 Aero Disc wheelset at US$1,459 / AU$2,109 / £1,184, including free worldwide shipping, CeramicSpeed bearings, tubeless valves, spare spokes, axle adapters and a pair of six-bolt rotor adapters.
However, some big questions remain. For example, will the 34mm-wide rim create fitment issues with the current crop of disc-equipped race bikes? And how will they feel in gusty conditions? We’ve requested a test sample to answer this and more. In the meantime, it’s exciting to see disc-brakes spurring a new design path.
The rim is designed for use with tubeless or clincher tyres. It meets the new road tubeless ETRTO sizing, and Schwalbe had direct input on the shaping and tyre interface used.
The U-shaped rim profile is becoming increasingly popular on modern aero wheels.
The wheels are shipped with all of these little pieces.