The HED Jet 180 is a radical rear wheel with a rim depth of 180mm

HED announced the Jet 180, a new 180mm deep rim rear wheel.

The Jet 180 was designed specifically for athletes competing at the Ironman World Championship in Kona, Hawaii. Full disc rear wheels are banned on Kona due to safety concerns in windy conditions.

The 180 mm deep rim has a maximum outer width of 32.5 mm and an inner width of 21 mm.

It is compatible with tubeless tires and is available in both rim and disc brake form. The declared weight of the wheel is 1229g in the version with a disc brake or 1258g in the version with a rim brake.

HED has yet to announce pricing, but has indicated availability is currently available within four to six weeks of ordering, with a limited number of wheels available at the 2022 Ironman World Championship in Kona.

How fast is the HED Jet 180?

The HED Jet 180 rear wheel uses the deepest rim we’ve ever seen.
HED

At the time of writing, HED has not released any performance claims or data comparing it to other more traditional aero wheels in its range such as the Jet 6 or Jet Disc.

That said, the purpose of the wheel seems to be to mimic the rim surface of the disc wheel as much as possible, within the limits imposed by the organizers of the Kona race.

The greatly increased surface area of ​​disc wheel rims and rims such as this one helps improve aerodynamic efficiency in two ways, depending on how the wind hits them.

The huge surface area of ​​the rims is designed to optimize aerodynamic efficiency.
HED

In headwind or crosswinds, a deep rim or solid disc surface helps keep the airflow on the wheel as long as possible. This reduces turbulent airflow and lowers drag.

In backwind or crosswind, the rim surface acts like a sail, helping to push the rider forward with greater efficiency.

Can this rim be used on the front wheel?

In the current situation, the HED Jet 180 is only available as a rear wheel.
HED

Theoretically yes, although for now HED only offers it as a rear wheel.

Neither the ITU (International Triathlon Union) nor the UCI (Union Cycliste Internationale, the world’s governing body for cycling) impose any particular restrictions on the depth of the front wheel rim in individual time trials.

The CTT, the UK time trial governing body, does, however, place restrictions on the depth of the front rim. Its rules say that the front wheel “must have at least 45 percent open area”, although it is unclear how this would be measured during a competition.

Solid disc rear wheels are commonplace in the time trial world, but can we see even deeper front rims soon?
Simon von Bromley / Direct media

However, aside from regulations, the main problem holding people back would probably be concerns about handling.

A very deep rim can theoretically be faster than a shallower rim (everything else is equal), but if this prevents you from confidently maintaining the optimal aero position on the bike because it is still catching the wind, you will likely be slower overall.

Today’s wider and more refined rim profiles, however, generally offer significantly better handling compared to rims of the past.

As a result, time trial and triathlon specialists routinely push the boundaries for incremental gains.

Super deep front rims like this unbranded Aerocoach AEOX Titan are increasingly found in WorldTour racing.
Simon von Bromley / Our media

The 100mm deep Aerocoach Titan front wheel has been used extensively in recent years by some of the world’s best time trial specialists such as Filippo Ganna, Geraint Thomas and Wout van Aert.

There were even rumors that at least one WorldTour team tested a front wheel with a time trial disc on the road and did not rule out the possibility of using it in a racing scenario.

So, if HED made this rim available for use as a front wheel, you can be sure it would attract interest among marginal profit seekers.

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