The carbon fiber clincher is a problem child. It shows flashes of brilliance, can be faster than a power outage and melts down under high stress or when taken out of its preferred environment. The reality is that for most riders in the U.S. they work fine under most circumstances.
But if you live on the west side of Los Angeles, or anywhere near the Santa Monica Mountains, then you know at least two riders who have melted a set of carbon clinchers. The problem has to do with the crazy, winding nature of the roads that tumble down the canyons to the ocean. They’ve got all the ordered predictability of a schizophrenic’s one-sided conversation. And they are steep as Ferrari prices. That’s not necessarily a bad combination, but what it means is when descending those roads you brake frequently and forcefully. Heat buildup is a given.
And there a bunch of cooks scattering from this kitchen.
I won’t go into whose wheels I’ve destroyed, but I can say I’ve personally seen wheels from Reynolds, Enve, Bontrager and—gasp—Lightweight, all delaminated on descents. Typically, what I see is the brake track melt at one point and air pressure push that portion of the brake track out. I’ve never seen a Zipp wheel fail there, nor have I seen a set of Easton carbon clinchers fail in that way. The issue here is entirely heat buildup. Easton’s approach is a bit different from its competitors. Based on what I’ve learned from engineers I’ve spoken to, Reynolds, Enve and Bontrager all use resins (possibly the very same one) that cures in the 300 to 325-degree range (Fahrenheit). Lighweight is using a resin that cures at a temperature slightly above 350 degrees F. Easton has gone an entirely different route. The brake track on the Easton carbon clinchers (no matter which model you talk about) receives a ThermaTec coating which insulates the brake track from heat. I’m told it insulates the rim up to temperatures of 500 degrees.
Let’s back up a second. I’ve mentioned six wheels by name. I know there are more carbon clinchers on the market than that, but these are the six I generally see on the road and, more important, the ones I’ve been able to learn something about. To their credit, I’ve heard that both Reynolds and Enve have been really terrific about warrantying their product.
Easton’s approach with the ThermaTec coating is a novel approach in the bike biz. I haven’t run across another wheel taking quite this approach. Practically speaking, the braking experience is a bit different. The surface is banana peel slick. The first time I hit the brakes on my way downhill I immediately noticed slightly reduced braking power. It’s something I got used to pretty quickly though. The other thing you notice when riding these wheels is that the pulsing feel you get under braking with most carbon fiber wheels because one section of the brake track is just a little grabby, like the one sticky spot on a counter as you wipe it off, well that feeling doesn’t happen with the EC90 SLs. These wheels offer the most consistent brake response of any carbon wheels I’ve ridden, but they do require just a bit more braking force than with an aluminum rim.
I’ve taken these wheels down the two most notorious descents in the Santa Monicas, Tuna and Las Flores. Not a single issue. That said, because this is a coating and not a different resin used throughout the wheel, I suspect it is very important that you make sure the brake pads contact only the ThermaTec surface. An improperly adjusted brake pad might result in an expensive headache.
The EC90 SLs feature a 38mm-deep rim. This is the shallowest carbon rim Easton currently offers. It’s enough to offer some aerodynamic advantage once your speed is above about 28 mph, but it is still shallow enough that it doesn’t get pushed around a lot in crosswinds. The rim width is 20.5mm, the same as many other existing Easton rims. I’ve become enamored of some of the winder rims out there that give tires a bigger footprint and would be willing to accept a slight weight penalty to get that. Speaking of weight, Easton says these run 1530g. My scale agreed—1528g. To get there they use 18 spokes front and 24 spokes rear. The front are laced radially while the rear are 2-cross on the drive side and radial on the non-drive side. All the nipples are alloy.
I’m told that impact resistance was one of Easton’s big issues in building these wheels, that they wanted unassailable impact resistance. I’m told these carbon rims are more impact resistant than their aluminum rims. These are no wilting lilies. The rear wheel is available with either a Campagnolo or Shimano freehub body. And if, like me, you have a bit of everything, changing out the freehub body from one type to another, the operation is easier than pumping gas.
In my previous review of the EA90 SLX wheels, several readers wrote in to report their troubles with the bearings in Easton wheels. My EC90 SLs came with ceramic bearings; I’ve not had a bit of trouble with them and these, in theory, should be a bit more finicky than the steel bearings found in my previous wheels. They’ve been flawless in operation and they turn as fast as tables at a McDonald’s.
One thing you’ll notice in Easton’s product description is the phrase “acoustically tuned.” What that means in bike speak is that Easton trues their wheels with the aid of transducers. A transducer is a kind of microphone. The wheel builder—yes, all of Easton’s carbon wheels are built by hand—will pluck each spoke as he tensions and trues the wheel. Think guitar string. Once plucked, the tension on the spoke will determine what pitch the spoke vibrates. If all the spokes have equal tension, a true rim will run straight.
Easton sells the wheels alone or in pairs. The front goes for $850—the cost of many high-zoot wheelsets, while the rear goes for $1250. Given what some of their competitors’ wheels go for, this seems reasonable. I won’t call it a great deal, but I believe the value is there because of the level of confidence I have that I’ll get home with both wheels intact following a big descent. Riding home with your rear brake opened up to keep the pads from rubbing the bulging brake track and worrying with each bump that the bead will blow off the rim makes for a really stressful 20-mile return trip. “Blows” would be the technical term.
My general feeling has been that if you can’t ride a product anywhere you would ride your traditional equipment, it’s not ready for prime time. I’m not talking putting a 100g road stem on a downhill bike. I mean that a product intended for the road should work anywhere road bikes are expected to be ridden. Some of the companies offering carbon fiber clincher wheels (and honestly, this applies to some of the tubular wheels as well) are playing fast and loose with people’s safety in my opinion. It’s not many people as I expect there are only a thousand or so cyclists who regularly ride in the Santa Monica Mountains. But everyone I know who owns a set of carbon clinchers has a story of melting one or more wheels. On the other side, I’ve got a buddy, a big guy who likes German technology, who has stopped as many as three times on the way down a descent just to make sure he didn’t kill his wheels. I have to ask, what’s the point?
I can’t help but wonder what circumstances could bring riders problems elsewhere. There are some twisty, steep descents in New England. And I’ve raced some short, tight crit courses that required lots of braking. If there’s a chance that a wheel won’t survive under reasonable use, should it really be on the market?
We’ve got a ways to go, I think. Easton, at least, has given this some thought and devoted some of its considerable technology to addressing the problem. These are terrific wheels.