Shimano

Dura-Ace WH-7850-C24 Carbon Wheelset - Tubular

We hope the following association doesn't ruin your appreciation for the ultralight Shimano WH-7850-C24-TU wheelset. Michael Rasmussen rode them at the 2007 Tour. We think despite his reputation, this is worthy of note. Rasmussen was an absolute, dyed-in-Lycra, worship-the-digital-gram-scale-more-than-racing itself, weight weenie. The guy raced with one water bottle cage on his bike. He used a one-piece handlebar-stem combo. He shaved his head. He even was allowed to use discontinued Vittoria CX tubulars with the 100% cotton casing. Truthfully, he preferred the older, custom wheels with the internal nipples, but he also had a set of these, as did the rest of his Rabobank team. The internal wheel nipples were given the thumbs-down by team mechanics, which is why Shimano switched to external. But neither they nor you want to rip off a tubular to true a wheel.

Teammate and possibly the wiliest sprinter of the bunch, Oscar Freire pulled these out for the hillier stages and rolling races. Even when he knew there was a likelihood of a field sprint, these were on his bike. Freire is small and explosive and these help him jump around the peloton as he looks for the right attack or the wheel to latch onto.

This is not only a climbing wheel, but a wheel than can accelerate quickly. Jumping out of corners, getting away fast, is also where this wheel excels. We think this ultralight DA Carbon Fiber Tubular wheelset is where the Shimano wheel line starts to get really interesting. Rather than use the same carbon fiber front and rear rim, they use not only different heights, 28mm in front and 24mm in back, but have a unique asymmetric, or offset, design for greater strength. This is the first time we've seen this in carbon fiber. For those who are concerned with the durability of ultra-light rims, this is one to seriously consider. The target weight is 310g for the rims. These may be flyweight, but they're strong enough for a heavy weight.

The result is a great climbing wheel with fewer spokes than we've used to seeing on wheels designed to go uphill. The fewer spokes, the less resistance to the wind, which is a benefit going down and racing along the flats. And despite the light weight, the wheels still exceed the tough, European DIN-plus standard both for strength and longevity. The latter is the result of using angular contact bearings, something Shimano adamantly believes are better than sealed cartridges.

Shimano is also staking a claim at the hub. They stick to loose angular contact bearings rather than sealed cartridges for long life and easy rolling; this is the second place where Shimano exceeded the DIN-plus standard, by an order of five. They also have designed an oversize 15mm aluminum axle for strength and stiffness at the hub. Does this matter? It can help minimize flex if the fork is one that moves around under pressure. A better line when leaning hard into a turn and less effort to keep the bike going straight when thrashing out of the saddle are nothing to sneeze at if you're the kind of rider that can flex everything or has already found some unwanted flex. Further stiffening the wheel are wide hub flanges, 59mm wide in the back. The wider flanges mean greater lateral stiffness, so less energy loss from side flex.

Note: Shimano recommends their R55C cartridge brake pads for their carbon rims. The cartridge pads fit brake shoes on the Shimano BR-7800, BR-7700, BR-6600, BR-6500, BR-5600, BR-5501, BR-5500, BR-R600, and BR-R560 brakes. This doesn't mean that SwissStop or Kool Stop carbon-specific pads don't work, just that Shimano doesn't recommend them.

The Shimano Dura Ace Carbon Tubular wheelset has 28mm deep carbon fiber front rim and a 24mm offset carbon fiber rear. The front wheel has 16 radial spokes, the rear has 20 cross-two spokes, all straight-pull. The spokes are stainless steel, ion plated, double-butted and bladed. The gauge is 14g/16.5g/14g for the front and non-drive, 14/15/14 for the drive. The spokes are attached to the rims via aluminum nipples at the rim. The nipples are anodized red. The hubs have aluminum shells and axles and run on loose-ball bearings. The quick release skewers have aluminum shafts and parts. The cassette body is titanium and is compatible with 8/9/10 speed Shimano, Shimano-compatible and SRAM cassettes. It is available in 700c only. Shimano offers a three-year warranty with Dura-Ace wheels. Front wheel weight is 530g and rear wheel weight is 727g. Weight is 1257g for the set without quick releases.