45mm deep the 45mm deep 303 firecrest delivers unmatched aero performance when used with the wide tires that todayrsquos riding demands zipp have achieved this with a wide disc specific rim design featuring ablc dimples extending all the way to the outer edge of the rim in addition to achieving aerobalancetrade the industry leading crosswind stability and low aerodynamic drag that defines all firecrest wheels the new 303 firecrest delivers lower drag than the outgoing version when used w