If Zipp's 303 Firecrest is built, as the brand asserts, to go the distance, faster, then the tubeless 303 650b Firecrest Carbon Disc Brake Road Wheel is built to go the distance in comfort. And then keep going when the distance gone extends beyond paved roads and onto gravel, graded dirt, and even singletrack. The 650b 303 is a bikepacker's carbon dream: tubeless 650b for unrivaled plush traction, disc brakes for uncompromising stopping power on mucky dirt with a full load of camping gear, and carbon rims because, well, why the hell not?
Despite its mammoth tire capacity and wide footprint, the rim is still decorated with Zipp's Aerodynamic Boundary Layer Control (ABLC) dimpling. When compared to smooth-sided rims, Zipp credits those dimples with reducing drag across all yaw angles; however, the largest gains occur between 10 and 20 degrees, a range that Zipp claims encompasses 50% of the time we spend on the bike. We're not sure how the huge rim and tire affects those claims, but surely aerodynamic gains are aerodynamic gains, regardless of a little extra girth.
Focusing on aerodynamics with this wheelset feels a bit, well, sheepish, because the wheel really shines when you're pedaling up mountain paths used by actual bighorn sheep or across soft, pine-needle-carpeted forest beds. 650b donuts represent the plushest, grippiest ride you can get on a road bike. Though they were largely just tradeshow novelty acts when Zipp committed to the platform, road-plus bikes are becoming more and more common as bikepackers hit the ceiling of tire width allowed by 700c framesets. Unconstrained tire sizes means unconstrained adventures across terrain that occasionally features no trail at all.
Each wheel ships with standard quick-release skewers, 12x100mm and 15x100mm thru-axle adapters for the front, and 12x142mm drop-out adapters for the rear. We should note that, though they clearly want to go bikepacking with fully loaded panniers, the wheels do still carry Zipp's universal recommended weight limit of 250lb for rider, bike, and whatever gear you manage to strap to your frame.
- A road-plus wheel for all-terrain bikepacking adventures
- 584mm bead diameter clears real estate for huge tires
- Aerodynamic features reduce drag and increase stability
- Disc brakes stop in all conditions with full bikepacking loads
- Zipp proves time and again to be the iconoclast of carbon wheel construction