Written by: Aaron Hersh
Race wheels are not the most cost-efficient way to improve your bike split, but they may be the sexiest. But those deep rims aren’t just for looks: The rim is the most critical component of an aerodynamic wheel. Triathlon race wheels reduce wind drag by converting a standard tire and rim into an aerodynamically efficient shape. Designing race wheels with deep rims is the most common way manufacturers reduce drag, but the rim’s shape is just as important as its depth. The first aero wheels utilized narrow V-shaped rims but aerodynamicists eventually figured out that certain wide and deep rims actually create less drag than narrower alternatives.
Zipp and Hed have dominated the race wheel market for many years because they shared a patent on the most aerodynamic rim shape—the toroidal rim. This bulged rim shape creates less drag than a deep-V rim even when the rider is in a gentle crosswind. The patent on this valuable rim shape just expired, leaving the race wheel market open to serious new competitors. No one has yet grabbed this opportunity but Zipp has already designed and patented a new shape that they assert is even more aerodynamic than a toroidal rim.
Zipp 404 Carbon Clincher
Ride quality: 130/140.6 It corners like a tubular but the carbon brake track isn’t as grippy as an aluminum rim.
Usability: 125/140.6. The clincher tires make changing a flat simple, but the wide rim requires a brake adjustment when going from a standard training wheel to these.
Value: 128/140.6 Cutting edge aero profile and carbon clincher rims make it a phenomenal piece of wheel technology, but it is still really pricey.
Aero profile: Truly the next generation.
Despite the name, the biggest difference between the Zipp 404 Carbon Clinchers and competitors’ race wheels is not the fact that they are carbon clinchers. Other manufacturers have, in fact, been successfully producing carbon clinchers for a couple of years. The 404 CCs are a milestone in race wheel design because of their evolutionary rim shape and unmatched combination of speed, weight and usability. Like the Hed Jet’s, the 404 CCs have an ultra-wide brake track to improve wheel aerodynamics, but Zipp has taken the toroidal rim shape another step forward with its new Firecrest rim profile.
The rim of the 404 CCs is not only incredibly aerodynamic, but the wide brake track also creates a silky ride experience that can only be matched by tubular tires and other wide clinchers. Widening the brake track increases the amount of air held in the tire and lets it absorb little bumps in the road that would normally skip the rider off the pavement. This buttery ride quality, combined with the incredibly light rims, make the 404 CCs a thrill on the road. Even with the carbon rim they are still heavier than comparable tubular wheels, but the 404 CCs are more nimble and eager to accelerate than any aero clincher wheel I’ve ever ridden.
Hed Jet 9 and Jet disc clincher
Ride quality: 120/140.6 Aluminum brake track grips perfectly, and the spoked disc corners better than any rival, but the deep front rim can feel twitchy in the wind and the Jet wheels’ relatively stout weight makes them slow to accelerate.
Usability: 130/140.6 Clincher tires. Aluminum brake track. Solid cornering characteristics. The only issue is spreading the brake calipers to accommodate the wide rim and handling the front wheel in a crosswind.
Value: 130/140.6 Best aero profile for the price in the industry, but the flexible fairings give the wheels a cheap feel.
Aero Profile: Hed Jet wheels are simply standard aluminum rim wheels covered with carbon fairings. The fairing is flexible and feels a bit chintzy. Despite their low production value, the Jet 9 and Jet disc are near the pinnacle of wheel aerodynamics. The key to their aerodynamic efficiency is the smooth integration between the rim and the tire. Its 23mm wide brake track, as opposed to a conventional 19mm wide track, turns the wheel and tire combination into one smooth toroidal unit.
Until just three years ago, even the most aerodynamic wheels in the world had an obvious design flaw. The rims themselves had an efficient toroidal profile but, with a tire on, the wheels became a figure eight because they had a narrow brake track that formed a waist between the wide tire and wide rim. Mad scientist Steve Hed was the first to solve this problem by building an aero wheel with a wide brake track that smoothly transitions from rim to tire and makes the entire system, rather than just the rim, fully toroidal.
Not only is the Jet disc aerodynamic, but it rides better than any other disc because of its construction. Foam core discs transmit more road vibration than spoked wheels. This make the ride feel harsh and compromises cornering because the wheel bounces off the pebbles that make up an asphalt road. The Jet disc rides like a spoked wheel because it is a spoked wheel. It has sheets of carbon covering the spokes to give it the aerodynamic properties of a disc.
Easton EC90 TT
Ride Quality: 135/140.6 Wide rim clinchers are great but nothing rides as well as a tubular tire. Light yet stiff rims accelerate and corner like a motorcycle. Deep from wiggles in crosswinds.
Usability: 100/140.6 Tubulars are a pain to install and expensive to replace.
Value: 115/140.6 They are light and stiff but lack the formerly patented aerodynamic toroidal rim that separates Zipp and Hed wheels from the rest.
Aero Profile: The EC90 TTs have a hurdle to overcome to compete against the incumbent industry-leading race wheels. Although the EC90s have a deep rim, the wheels are built with a rim shape that is inferior to the category-crushing options from Zipp and Hed. The rim of the EC90 TT is straight-walled rather than toroidal, but that doesn’t mean that the EC90 TTs aren’t great wheels. Easton’s mastery of carbon construction is evident when jamming these wheels into a high-speed corner or accelerating away from T1. The rim sidewalls are paper thin but the wheels are still stiffer than many of the bulkier race wheels on the market. The snappy and responsive ride distinguishes the EC90 TTs from many other tri race wheels.
SRAM S80 wheelset
Ride Quality: 90/140.6 The S80s weigh more than some training wheels and have a standard, narrow clincher rim so they so they aren’t a blast to ride.
Usability: 130/140.6 The narrow clincher rim makes swapping wheels and changing a flat easy. The deep front wheel catches air like any other 82mm deep rim.
Value: 120/140.6 Moderately priced with the rim shape that made the Zipp 808 an aerodynamic marvel.
Aero Profile: These SRAM wheels are built on Zipp-designed rims. They have the same shape as the previous generation
Zipp 808 clinchers that sold for more than $2,300. Lower grade hubs, cheaper spokes and no dimples are the differences between the 808s and the S80s, but they still have the all-important toroidal rim shape. The S80s are not light but once they are up to speed, they keep rolling because of the aero rim shape. They do not, however, have a wide brake track to take full advantage of the toroidal shape like the pricier wheels from Zipp and Hed. They provide most of the performance of the most expensive race wheels at a sensible, although certainly not cheap, price.