PowerTap

GS ENVE SES 6.7 Powermeter Tubular Wheelset

We cyclists of advanced years can remember a time in the not-so-distant past when training wheels were equipped with box section alloy rims and powermeters while racing wheels were tubular carbon rims laced to DT Swiss 240 hubs. No exceptions. This is because powermeters were too heavy for racing and carbon was too fickle to handle everyday abuse. Today, kit like the PowerTap GS ENVE SES 6.7 Powermeter Tubular Wheelset has become a common sight during base miles and at the starting line, and advances in carbon construction (largely thanks to ENVE) and reductions in powermeter weight (mostly PowerTap's fault) are to blame. This kind of race-able versatility is no longer the exception; it's the rule.

The 6.7 rims included here are the same cruise-missiles featured in the standard ENVE SES line, which means they aren't subjected to static, arbitrary NACA widths and shapes. Instead, the engineers let each wheel's depth requirements dictate the ideal dimensions in order to reduce lateral forces and increase aerodynamic benefits across a wide range of yaw angles. This is evident in everything from the rim's rounded inner face to the position-specific dimensions for the wheels, which takes the shallower, more stable front rim and deeper, more aerodynamic rear rim philosophies to their logical extreme.

The result is that the 6.7 handles crosswinds and gusts with the confident stability of a wheelset with half its depth by building up a side-force equal to the changing angle of the wind. While this sounds like so much marketing palaver, it's verified by a Stability Index, an externally developed testing protocol borrowed from the Formula One industry. ENVE remains the only cycling manufacturer with the confidence to measure its wheels by such a demanding metric. To rate a wheelset on this index, the front wheel is subjected to quick changes in wind degree at set yaw angles, and the steering torque of user-correction is then measured. This helped ENVE dial the wheels to handle with intuitive predictability, even in gusty conditions or frequently changing wind angles.

Of course, we also recognize that aerodynamics and handling are absolutely meaningless if a wheelset crumbles at the first sign of less-than-optimal road conditions, so we expect ENVE's obsessive engineering to carry over into the wheels' materials and layup. ENVE routes the fibers around each hole in a 100% intact design — no cutting, machining, or drilling required. By continuously wrapping the fibers, ENVE adds strength, boosts rigidity, and allows for less material and a lighter rim. The use of a removable bladder also keeps weight down compared to other wheels, so the SES series boasts the highest claimed strength-to-weight ratio on the market.

All of that aerodynamic rim strength stuff is great, but the hubs are the wheelset's real star. PowerTap partnered with DT Swiss to create its GS line of hubs. The "S" in the title stands for "straight-pull" and as you would expect, the spokes on the hub are indeed straight-pull. The electronics are identical to the G3 hub and the caps are interchangeable, but the body itself looks completely different because it's essentially DT Swiss' 240 hub — complete with the brand's signature star ratchet engagement system and stainless bearings.

Like the G3, the GS's electronics are built into the end cap, so if you have wheel-based power reading problems, you're able to send just the cap back rather than your whole wheel. Additionally, it is powered by a single CR2032 battery, which is easier to source than the two 357 batteries in older hubs. Each battery lasts for about 300 hours of riding, and the hub communicates power data with an ANT+ transmitter so most head units are already able to read and display the metrics. The hub's eight strain gauges yield power measurements within +/- 1.5% accuracy — on par with the industry standard because PowerTap pretty much is the industry standard.