Long in need of an update, the Dura-Ace wheels have been (mostly) overhauled to keep with current trends. The C35, C50, and C75 will be replaced and simplified by the C40 (40mm depth) and C60 (60mm depth). Four variants will exist in each depth, most featuring an external rim width of 28mm and a hybrid-toroidal-like shape (U-shape).
Shimano makes big aero claims for its designs, and hints that this is its biggest investment into aerodynamically designed wheels to date. The chart we were shown claimed that the new C40 and C60 tubulars saved two and 16 watts, respectively, when compared to the current 9000-series C50. This was with a 25mm-wide tyre, at a 7.5-degree yaw angle in a sprint on a flat road (speed not mentioned).
Shimano have refined the range of wheels on offer, now depths come in just 40 mm and 60 mm. The C24 will also be available but is mostly unchanged.
Weights are down, too. For example, the C40 tubular is claimed at 1,343g and the C60 version at 1,400g. For reference, the outgoing C50 tubular weighs 1,442g for the pair.
Wheel stiffness is said to have increased through wider hub flange spacing (which improves the spoke bracing angles) and the wider/asymmetric rim design. The asymmetric rim design will feature on full carbon rear wheels only.
Only the clincher rim brake version of the C40 and C60 wheels will feature an alloy braking surface (left). The continuing C24 rim does too
Both the C40 and C60 ranges are split in disc and rim-brake options. Two variants exist for each brake type based on tyre choice. These new aero models will feature full carbon rims with exception to the rim-brake clincher versions of the C40 and C60; these two options will feature a carbon rim with alloy braking surface that make use of the existing C35 and C50 rims respectively.
Update 29/03/2017: In the case of the rim brake clincher C40 and C60s, these will use the same rims as found on the former C35 and C50 wheels.
Hubs also get the faded black to silver treatment.
Rim-brake versions will stick with standard quick-release hubs, while disc brake wheels will only be available to suit 100×12 and 142x12mm thru-axles. All wheels stick with Shimano’s 11-speed titanium freehub body, which means backwards compatibility with 10-speed drivetrains.
Looking to the shallower C40, the disc-brake choices consist of a tubular (TU) version and a tubeless (TL) that also doubles as a clincher, these are claimed to weigh 1,380 and 1,540grams respectively.
Rim brake versions of the C40 will include a tubular version at a claimed 1,343g and the alloy/carbon hybrid clincher version (using the older C35 rim) at a relatively weighty 1,620g.
Going deeper, the C60 are offered as equivalent variants to the C40. This includes the disc-brake tubular at 1,460g and the tubeless/clincher version at 1,690g. The rim-brake options include tubular at 1,420g and a hybrid alloy/carbon clincher at 1,750g.
Not interested in aero gains? The long standing C24 is mostly unchanged for the next generation, with a marginal improvement in drive rigidity through wider hub flange spacing. This wheelset remains as rim brake only (alloy braking surface) and is claimed to weigh 1390g in a clincher version.