Easton’s EC90SL wheelset is the first no-compromise set of all-carbon clincher wheels that we've used. Before trying these, carbon clinchers seemed like a bad idea. Now we can see their potential.
Prior to our experience with the EC90SLs, all of the carbon clinchers we’d used had issues that stemmed from their inability to deal with the heat that builds up from braking friction. These ranged from excessive brake pad wear, poor brake modulation and performance, to catastrophic failures of the rims’ sidewall resulting in a blow-off of the tyre.
In our extensive testing, Easton’s new wheelset didn’t suffer from any of these problems. Why? Early on, Easton decided they wouldn’t put out a carbon clincher until they came up with an acceptable solution to deal with heat generated during braking. This led their product engineering team down a six-year path which started with hybrid carbon and aluminium wheels, and culminated with the development of this all-carbon clincher.
So, what's the secret? A specific carbon laminate and a heat dispersion coating called ThermaTec. In our experience the resulting rim has zero issues with heat, even during excessive braking in mountainous terrain. It appears that Easton aced their goal.
Testing: one, two
We conducted our field tests of the EC90SL clinchers during a four-month period, which spanned winter – December to March – in Colorado. Our main five-mile out-and-back test route is perfect for the evaluation of road bike components. It consists of a 2,100ft climb over the first five miles, before a summit turn-around for the 20-odd switchback descent, on which speeds vary from creeping around 180-degree corners to 40mph tucks.
Riding this route through the winter on a carbon clincher wheelset took some preliminary, and tentative, test riding, during which our confidence in Easton’s EC90SLs quickly skyrocketed. Those first rides went something like this: ride to the top and turn around, then on the descent run the brakes for 30 seconds, stop, evaluate the rim temperature, continue, brake for 45 seconds, evaluate.
This continued until the point where we were running the brakes for multiple minutes at a time, just to see how much the system could take. Even during this extreme scenario, we were unable to reach the temperatures we’ve felt on other carbon wheels, both clinchers and tubulars. In total, we’ve been up and down our test course over 20 times with Easton’s wheel without a single problem; that’s over 40,000ft of hard descending. This is ultimately what gave us confidence in Easton’s EC90SL.
Not only does the ThermaTec coating manage heat build-up, it also makes for one of the best braking carbon wheels we’ve ridden, especially in its ability to modulate power. In fact, Easton are now looking to implement the coating across the board ‘on anything carbon'. This performance is undoubtedly aided by SwissStop’s Yellow King brake pads, which Easton include with the wheels.
Braking power is still only average compared to alloy rims, though, and is lower, albeit adequate, in the wet, when the pads must skim water from the surface before the job can be done, which requires an adjustment to braking distances. The rims do seem to maintain the ability to modulate well when wet though.
Wheel stiffness seemed good, as evaluated by their predictable handling under hard, hairpin cornering and climbing efforts. Off the mountain, our best attempts to sprint with the wheels to force some sort of wiggle, wind-up or other lateral instability proved futile. They can be considered solid and stiff under lighter riders, who aren’t self-proclaimed sprinters. Vertical compliance was on the lower side, big hits felt big, though on dirt washboard the wheel seemed to soak up some of the vibration.
During testing we bent a spoke, which pulled the wheel out of true. The rim didn’t break and was easily trued. The biggest centered on the hubs. In cold temperatures (below 40 degrees Fahrenheit) the freehub becomes sluggish, due to the viscosity of the grease used. This caused infrequent chain derailments – due to the chain slackening, especially during backpedalling – which in warmer temperatures weren’t a problem.
Easton do offer lighter grease for those who frequently ride in cold temperatures. Freehub engagement was consistent and solid, though; its engagement speed can only be described as average. Also over the course of testing, both hubs loosened and required adjustment, once for the front and three times for the rear.
How did Easton solve the heat issue?
“When we were getting ready to launch our first hybrid carbon wheels we gave some to the team [Astana] and they were able to cause it to fail due to heat,” said Adam Marriott, Easton’s wheel product manager. “So we realised there were some issues, and didn’t launch it. It then took another year-and-a-half in development. In the meantime, we developed a test to simulate what the team riders were doing in a matter of weeks, but what mere mortals weren’t able to do.”
To develop the test, Easton engineers took a 150lb test rider, added 50lb in a backpack and sent him down a mile-long hill at a constant 15mph with the front brake applied. This forced the rider to pedal as hard as he could to keep the speed up, causing the same failure experienced by the pros. Once this failure was recreated, the engineers added thermo couplers and infrared sensors to the bike to measure the temperatures and gather information. “From there we created a lab test, so we have a machine that does this now," said Marriot,
“Now we know, we’ve tested the competition, we’ve tested our wheels and we’ve tested aluminium wheels. We’ve analysed what’s good and what’s bad, and due to that we have a hybrid wheel that’s been in the marketplace for four years with no issues. We knew with carbon clinchers the biggest problem is heat, so we designed a laminate that would pull the heat through the system, but we're also working with ThermoTec, which is the coating that’s moulded on that helps to manage the heat. There’s only been one other brand that’s ever rideable after the test; most aren’t.”
The best, but still a choice
Even with a solution to the problems that plague other carbon fibre clicher wheels, prospective buyers must weigh the pros and cons of the EC90SLs. Firstly, weight is a big issue. The 38mm-tall EC90SL clincher set weighs 1,506g on our scales (front 659g, rear 847g), which isn't all that light compared to tubular equivalents – Easton’s EC90SL tub weighs 1,224g (actual weight). “We haven’t gotten to a point where we can make it the same weight as the tubulars because the structure needs to be able to support it and handle the heat,” said Marriot.
For a clincher comparison, Easton’s EA90SLX aluminium wheelset, with a 21mm front and 24mm rear rim, weighs 1,398g (claimed weight, £629.99/US$999) and the EA90Aero aluminium set weighs 1,603g (actual, £549.99/$850) with 28mm and 32mm front and rear rim profiles. Without wind tunnel testing – or even with it – it’s pretty tough to give a definitive answer as to how much faster the 38mm rim is compared to the alloy offerings in Easton’s line. Easton’s skewers add another 120g (actual) to all of these wheelset weights.
Keep in mind price, too, which is the next biggest factor when considering the EC90SL clincher. At £1,449.99 ($1,799), the carbon clincher wheelset is considerably more expensive than the two comparable alloy sets. Durability, on the other hand, falls into the ‘pros’ category. The carbon rim is beefy, even overbuilt when compared to the tubular version, and should wear accordingly.
Carbon rims don’t have the memory that metal rims have, meaning they’re either perfect or broken; there’s no in-between, as there can be with a bent alloy rim. If you break or bend a spoke on a carbon wheelset but don’t crack the rim, then it should be possible to replace the spoke and true the wheel to its original state. The same applies for ‘denting’ the rim. In Easton’s testing the carbon rim holds up to a ‘hit’ that’s magnitudes higher than what their alloy rims can take.
The EC90SL uses external nipples, which aren’t as aerodynamic but are much more user-friendly should you bend or break a spoke. This is a point of contention, as Easton use internal nipples on their tubular wheels. We’d much rather see the designs reversed, as it's much easier to pull off a clincher to maintain the wheel than a tub.
Easton say internal versus external is more a function of the rim construction, as the tubular rims would need to be beefed up to support external nipples, so they made the choice to use a lighter rim and internal nipples. The EC90SL wheelset features Easton’s top-of-the-line R4SL hubs, with oversized 7050 aluminium axles, Grade 3 ceramic bearings and Easton’s option of four cassette body styles: 8/9/10-speed, 10-speed Shimano, SRAM Red and Campagnolo.
Hands down, Easton’s EC90SL is the best carbon clincher we’ve had a chance to test. Is this the best clincher wheelset, though? That’s an entirely different question. We reckon that to be the best it needs to lose 100g or more and go tubeless, while maintaining its current attributes. Adding these two merits would leave no option, but to give it five stars. Right now, we’ll leave you with this: the EC90SL is a wheelset we're confident in and for the rider who covets a carbon clincher it is the best, if not only, option out there that doesn’t force a performance compromise.