Bontrager’s Aeolus 6.5 clincher wheels have a rim section that’s 65mm deep, this dimension being chosen because, according to the manufacturer, it is the optimum height to width ratio for a 22mm tyre. Many performance clinchers are, or course, either 20mm or 23mm in width but owners wanting optimum aerodynamic performance can choose from several 22mm offerings including Continental’s Attack model.
The shape of the rim cross-section owes much to the work of cycle aerodynamics guru Steve Hed, and has the familiar curved flanks bulging slightly outwards as they leave the braking surface before tapering to the centre. Similar to the shape of rims made by Zipp, the shape is designed to keep airflow attached to the sides of the rim as long as possible and is said to work especially well in cross winds, where the air “sticks” to the rim as it passes behind it.
Unlike most deep-section rims, those on the Aeolus comprise a conventional box-section rim, made using OCLV carbon technology, with a fairing or cladding attached to it, the spokes passing through holes on their way to the main structural part. This concept has a long history and has a couple of performance advantages over the usual construction method of moulding the aero sides as part of the rim structure. It saves a little weight over one-piece rim of a comparable shape, since the non-structural aero cladding can be made very thin.
Indeed, on the Aeolus it is so thin it can be flexed using light finger pressure. More importantly, the flexible cladding makes a minimal contribution to rim radial rigidity, which retains instead the “give” of the conventional box-section rim to which it is attached. Finally, the cladding flexes as the rim deflects while the wheel rolls, acting as a diaphragm that vibrates and creates sound vibrations; the wheels sound much like a disc rear wheel when under way.
There are 16 bladed DT steel spokes, finished in white, at the front and rear, the latter laced tangentially on both sides for effective power transfer. The aluminium hubs are by Bontrager as are the quick-release skewers, which have an internal cam for durability and a meaty, curved lever.
Both Shimano/SRAM and Campagnolo freehub bodies are available, the wheels are available individually (£749.99 front, £899.99 rear) and the price includes wheel bags, Bontrager Carbon Stop cork brake pads and aluminium alloy valve extenders. Claimed wheel weight is 1680g per pair.
Ride report soon.
Bontrager Aeolus 6.5 clincher £1,649.98 (pair)