If you're serious about going fast, then you're probably serious about Zipp wheels. But, if you need to exploit every available advantage, the Zipp 303 Firecrest Tubular Disc Wheel takes the pronounced benefits of Firecrest technology and adds disc brakes into the equation. So, whether you're racing on the road or getting dirty on the 'cross course, you'll enjoy the enhanced braking power and modulation of the 303 Firecrest Disc wheel. The layup of the rim hasn't changed from Zipp's venerable 303 Firecrest tubular. That may come as a surprise, as disc brakes negate the need for a braking surface. However, Zipp's engineers found that the 303 Firecrest rim is already optimized in terms of strength and weight, so there wasn't an advantage to be had by changing the rim profile. However, there is one notable change from the rim brake version, and that's the brake track itself. The standard 303 Firecrest uses a high abrasion brake track, and the disc brake wheels receive no such treatment. As such, even though there is a vertical sidewall, the 303 Firecrest disc wheels are not compatible with rim brakes. It follows that the disc version of the 45mm deep 303 Firecrest provides the same advantages as its rim brake counterpart. The Firecrest shape refers to a wider rim profile. Extensive research has proven that this wider rim shape enhances the grip of your tires by increasing the size of the contact patch, and increasing the air volume of the tire. Not only does it improve grip, but because the increased air volume allows tires to deform more naturally over irregularities in the road, the wider rim profile enables these wheels to roll faster than comparable wheels using a narrower rim. Putting that extra rubber on the ground is especially noticeable on tubulars, where the stability gained lets you enter turns faster and carry better speed. In the spirit of quickness, the 303 Disc wheels retain the dimpled surface of the original. Like a golf ball, those dimples create...