Zipp 454 NSW wheels
£3,200, sram.com
Bizarrely, Zipp says it has improved its 454 NSW racing wheelset by making it less aerodynamically efficient. The company even provides numerical data showing the wheels are 1 watt aerodynamically slower at 40kmh. Come again?
‘Wheel design has reached a point where getting further drag reductions comes at an expense elsewhere that may actually result in being slower overall,’ says Zipp’s Daniel Lategan. ‘Therefore we are focussing on becoming faster, not more aero.’
Zipp has hinged the update on its concept of ‘Total System Efficiency’, where speed is defined by four barriers – wind resistance, gravity, rolling resistance and vibrational losses – that vary in importance depending on riding application.
Zipp’s recently modified 353 NSW and 303 Firecrest wheels were changed according to the same philosophy, so the updates to the deeper 454 NSW (and 404 Firecrest) wheels are broadly similar. They adopt a hookless (straight-sided) rim bead design that Zipp says creates a host of benefits. In performance terms, that means increased width – they are now 23mm internally – and lighter weight. The wheelset is now claimed to weigh 1,385g, dropping 450g over the previous generation, and the wider rim dimensions better support tubeless 25mm tyres run at lower pressures. They are also easier to manufacture, which Zipp claims makes their production greener as well as cheaper. Not that cheap, however. The new 454 NSW wheelset still costs £3,200, although it is £370 less than before. So while pure drag reduction may have fallen ever so slightly, Zipp says that by better catering for the other three barriers to speed, the new wheels save10 watts over the previous version.