The Bontrager Aura 5 wheels made their debut at RCUK Towers at the same time we had the pleasure of hosting the Avanti Corsa DR4.
This aero machine was equipped with Shimano’s Dura Ace C50 wheels (for a detailed description of the Aura 5s, read our ‘first look’ article).
While, sadly, the C50s were early prototypes and unrideable, an occasional feature of demo bikes, such is our clamour to test the latest equipment, it did give us a chance to see the two rivals side by side.
At £300 cheaper than the C50s, the Aura 5 wheelset began to look like good value. While we cannot confirm the final production weights of Shimano’s offering, the prototypes were only a fraction lighter than the Aura 5s, and not by enough of a margin for us to consider it a factor.
So how did these aero hoops fare over the winter months? Pretty well, actually; indeed, considering the looks, I was expecting a jolly harsh ride, but in fact was content on the treks out into the countryside to be on a wheel with a noticeable aero advantage but without a bone-jarring ride. This comfort is no doubt due to the fact that the aero carbon profile is extremely flexible and provides no torsional stiffness whatsoever. Think of it as an aero topping to an alloy rim. This is unlike the rival offerings which use carbon and alloy in a composite fashion to increase stiffness. Heavier riders may find the wheel a little flexy under extreme power, but I think that it will suit the majority of riders; indeed, I rather admire the different approach taken by Bontrager’s engineers.
On flat sections of tarmac, and in a fairly aero body position (flat of back and hands resting with the outer edge of the palm grasping the hoods), the Test Rig seemed to cut through the air with extra efficiency and purpose. The increase in weight over its usual hoops no doubt contributed to the feeling of extra velocity on the downward sections of an undulating road. It would be fair to say that in all but the most blustery conditions, or on routes with a considerable amount of climbing, these are fast wheels
I’m not wholly convinced I would use them year-round. The ingress of water and muck into the carbon shroud was a little alarming; while much of it is likely to drain, some detritus (grit and road debris) will inevitably remain inside; so these are not, in spite of the alloy braking surface, the answer for fast winter rides.
The hubs rolled well throughout the test period, despite being subjected to some pretty horrible winter conditions. Removing the seals confirmed zero ingress of the aforementioned detritus into their inner workings. The three-pawl pick-up in the freehub proved adequate.
The DT Aerolite spokes required no tweaking during our test period, but we did have to rummage in the cupboard for some time to find tubes with a removable core so we could use the supplied valve extenders (finished in natty anodized red).
The quick releases are not entirely in harmony with the Aura’s aero intentions. They are chunky and clunky objects, which, despite their positive closing action, did little to enhance airflow around the bike. This is a minor flaw, perhaps, but one Bontrager’s designers may wish to note for future iterations.
On the whole, we liked the Aura 5s, which we consider solid, dependable, and, in the context of the market, good value. Greater praise, however, is limited by the strength of its competitors, against whom the performance of these offerings from Bontrager was satisfactory, rather than astounding.