Zipp 404 Firecrest Tubular Track Rear Wheel

This is the 404 Firecrest Track Tubular, the shallower depth rim and lighter overall weight of the two.

The shallower depth means it's easier to handle when turning.

It also puts less mass at the rim, making it easier to accelerate. Overall weight is 1655g for the set, 795g for the front, 860g for the rear. The 404 rim is 58mm deep, features a blunt end and a max width of 26.53mm, to make this firmly a wide-body rim.

The width works both for aerodynamics, where the curve of the rim comes close to matching the curve of the tire, making the leading and trailing edges nearly identical, better controlling airflow around the rim, particularly in crosswinds. The width also works for reducing rolling resistance, as the wider contact patch is shallower and the tire turns better with a shape that's closer to a U than a bulb. It is also faster than the NACA-inspired V rim profiles of old.

Yes, 19mm tires are still used on the track. No, you don't want to use those tires with this rim. And the wheel will roll faster, both with better aerodynamics and lower rolling resistance with a 22-25mm wide tire.

Cool note: The exposed spoke nipples, which are liked because you can true the wheel without special tools and with the tire still glued on, are totally hidden from the wind when the tire is the leading edge. Those spokes are the fastest available, Sapim CX-Ray, which are thin blades capable of holding high spoke tension. 28 radial spokes in front and 28 two-cross in back.

The spokes are J-bends are laced to Zipp's 333 track hub. The name is for a classic track length. The shells are made of 7075 aluminum alloy and feature solid flanges for stiffness and strength.

Axles are 15mm in diameter and made from stainless steel. The axles run on sealed cartridge bearings, which are easy to service thanks to the wide wrench flats. Likewise, the axle nuts are tightened by a 6mm Allen key The rear hub has a larger drive-side flange.

This allows Zipp to achieve equal tension on both the drive- and non-drive-side spokes, making the wheel stronger and stiffer. Weights are low, with the front weighing in at 215g and the rear 270g. The wheel is delivered with a Zipp valve extender designed to thread into valve stems that are at least 37mm long and feature a removable valve core.

The Zipp 404 makes any bike faster. It can be paired with another 404, or with a shallower wheel in the front or a deeper wheel in the back, depending on your strengths, how you ride, and the conditions you ride in. There's a slight chance that the 404 rear won't fit between narrowed chain stays, like on some super-aero pursuit bikes.

Check first. The Zipp 404 Firecrest Track Tubular is like having climbing wheels that outperform discs.