German brand Lightweight has long claimed the lightest and stiffest (and most expensive!) aero-inspired road bike wheels. However, it may soon be an Australian-made wheel that takes that crown, with materials engineering firm Partington looking ready to up the ante.
Said to weigh just 1,150g for a disc brake, tubeless-ready and aero wheelset that can hold a 110kg rider, the new Partington 39R and 44R could well become the new gold standard for performance wheels (by contrast, Lightweight’s Meilenstein C 24D wheelset weighs a claimed 1,380g). Partington’s offering might even be the first in a new wave of disc-brake specific wheel designs.
Australian tech editor Dave Rome got the lowdown on these yet-to-be-released wheels while at the Australian Handmade Bicycle Show.
Who is Partington?
Before moving to Australia, Jon Partington had a rich background in mechanical design and engineering in the UK’s automotive and motorsport industries. Since then, he’s become a PhD scholar for advanced composites at Deakin University, and of course, the founder of Partington Advanced Engineering – a composite-centric, multi-materials engineering firm.
Partington is located in the future economy precinct of Deakin University in Geelong, close to Deakin’s globally renowned Carbon Nexus research facility. They’re also neighbours to CarbonRevolution, the premium automotive and aviation carbon fibre wheel specialists whose rims come standard on the Ferrari 488 Pista, among other supercars. Not bad company to have.
Bicycle wheels are said to be the core and passion of the business, but financing such an endeavour has meant opening the doors to other projects. At this moment, Partington also services customers in medical, civil, leisure and materials-handling industries.
“We are an end-to-end engineering firm, all under the one roof,” Jon Partington explained. “From concept ideation, detailed design, analysis, materials characterisation, tooling design, tooling manufacture, component manufacture, testing etc. all conducted in-house.
“Ultimately this means we have full awareness and complete freedom over the design architecture and manufacturing processes we use.”
It has taken four distinct iterations across five years of development and testing to get the Partington wheels ready for market. If these wheels look vaguely familiar, that’s because an earlier iteration was briefly launched in 2015 under the name 36T. The wheels teased by 36T never made it to market, and Jon Partington has spent the past few years refining and redesigning them.
Some wheel specs
Much like Lightweight’s wheels, the Partington wheels are produced as a single unit. A unique carbon fibre spoke design is bonded under tension to two points of the rim, wrapping itself around the in-house-made aluminium hubshell in the process. It takes 20 spokes, or ten pieces, to create the wheel.
“The design is foremost sympathetic to the preferred loading of carbon fibre composites, such that we eliminate many of the poor loading occurrences encountered in ‘conventional’ carbon wheels,” Partington said. “Secondly, we’ve developed a number of proprietary manufacturing processes that yield exceptionally high-quality parts.”
That unique spoke design is an integral part of the Partington design, and the spoke’s carbon modulus will be adjusted to produce three different stiffness options of the otherwise same wheel. According to Partington’s test and development engineer, Ned Volk, the stiffness variance is about adding a level of customisation to this premium product and is aimed at providing a consistent experience for riders of different weights.
The highest-stiffness option is said to be stiffer than a Lightweight Meilenstein, with the medium option being a little less stiff, and then the least-stiff option designed specifically for more slender riders.
“We can’t disclose how we’re attaching the spoke to the rim, but it gives us a greater range to rim shapes and reducing stress risers,” said Volk of the intriguing design.
Partington will launch with a single mid-depth wheelset, the 39R and 44R. Those numbers refer to front- and rear-specific 39mm front depth, and 44mm at rear, said to weigh 520g and 630g respectively as complete wheels.
The shorter front rim features a blunter, more rounded profile that’s said to offer better handling in crosswinds. While the deeper rear rim features a slightly more triangular profile, chosen for the increased strength and stiffness the shape offers.
According to Volk, the rim shapes are closely based on popular aero wheels. The shapes were designed and tested through computational fluid dynamics (CFD), but they’ll come to market without having spent time in a wind tunnel. Given this, the focus on being a class leader in stiffness-to-weight makes sense – these aren’t being sold as an aero-specific wheel, even if they do tick that box to some degree.
A look inside a cut cross-section of the rim reveals a high density “PMI” (polymethacrylimide) foam core. “For this application, the foam supports the very thin carbon wall,” Volk said. “We found that rather than adding more carbon onto the rim this is a more effective method for lightweighting, strength and stiffness.” It likely assists greatly in the initial moulding process, too.
Both front and rear wheels offer a 21mm internal rim width and 26.5mm external profile. Partington took the gamble and designed the rim to meet Mavic’s UST Road Tubeless “standard”. Partington has been using Schwalbe tubeless tyres as its baseline, and says even the crummiest of hand pumps can bead the tyres with its rim profile. Of course, like all tubeless wheels, you can use clincher tyres and tubes, too.