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Campagnolo updates its Bora wheels

9 Apr 2018
Verdict:

The new WTO version of the top tier wheels comes in 60mm and 77mm rim depths

The news of Campagnolo’s new Bora wheels may be overshadowed somewhat by the launch of the Italian company’s 12-speed groupset, but there is still plentyto get excited about.

Bora (which Campagnolo claims has won more races than any other wheel) now comes with an additional ‘WTO’ moniker, which stands for ‘wind-tunnel optimised’. Apparently the company dragged a small army of scientists and engineers into a wind-tunnel and wouldn’t let them out until its wheels were significantly improved in three areas: aerodynamics, rolling resistance and weight.

The result is a ground-up redesign of the Bora wheel, which now comes in two rim depths in the WTO guise: 60mm and 77mm. The deep 77mm wheel comes as a front wheel option only, as it is intended to be paired with a disc wheel for time-trials.

Campagnolo claims that the new rim design makes its Bora WTO more efficient aerodynamically than its rivals in ‘real world conditions’, which means a range of wind angles that are commonly experienced by riders.

Of course, it’s hard to verify comparative data, as every company selects the stats that show its products in the best light, but it’s fair to say that the new rims should offer significant gains in aerodynamics over previous models, especially at wider yaw angles.

Indeed, Campagnolo claims that at just the right angle and wind speed, the Bora WTO will confer negative drag – that is, it will act a bit like a sail and pull the wheel along.

As part of the new aero design, the rims are now slightly wider, with a 19mm internal width to best complement 25mm or 28mm tyres. The wider rim (previous internal width is nearer 17mm) allows the tyre to form less of a ‘lightbulb’ shape, and instead creates a smoother transition from tyre to rim, making the whole system more aerodynamic.

The search for slipperiness has also extended to the hubs and spokes. The new hubs are gently curved, narrowing at the centre compared to the cylindrical shape of the previous hubs. This makes them more aerodynamic, says Campagnolo, but does mean that they have had to be machined from aluminium rather than fabricated from carbon.

The spokes are not flat, as before, but now diamond shaped, which makes them more aerodynamically efficient in a range of different wind angles.

To improve the rolling resistance of the Boras, as well as using ceramic bearings in the hubs (USB bearings for the 60mm and pricier CULT for the 77mm), Campagnolo did numerous tests different types of tyres.

Its findings were quite surprising. Despite the reputation of tubular tyres for having excellent rolling efficiency, they turned out to have the highest rolling resistance of the tyres in Campagnolo’s tests.

Better performing was the good, old clincher tyre, and best of all was the tubeless option. As a result, the Bora WTO wheels come as clinchers, with a conversion kit supplied to turn them into tubeless-ready.

Finally, the issue of weight has been addressed through cunning use of carbon fibre layup, and even with the aluminium hubs the Bora 60 WTO wheelset comes in at a very respectable 1,540g. The Bora 77 WTO front wheel weighs just 745g.

In other aspects the WTO wheels maintain many of the attributes of their Bora predecessors, including the ‘Rim Dynamic Balance’ (where a counterweight balances out the mass of the tube valve) and the AC3 braking surface that helps with efficient braking in the wet.

Campagnolo is adamant that the new WTO incorporates all the best bits of the well-loved Bora wheels, and maintains its reliable and robust construction, while improving all-round efficiency.

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