Enve's latest wheel, the SES 4.5 AR Disc, is aerodynamically optimized, the company claims, for 28- to 30c road tires. This wheel is designed for the increased clearance of disc-brake road bikes, and seeks to capitalize on the growing interest in wider road tires.
According to Enve’s press release, the 4.5 AR (All-Road) Disc was born out of a 2015 wheel test with Enve-sponsored Team MTN-Qhubeka (now Team Dimension Data) on some of Paris-Roubaix’s famed cobblestone sectors.
Paris-Roubaix covers over 250 kilometers total; only about 50km is cobblestoned. But those kilometers often play an outsized role in who wins and loses, which is why equipment is specially selected (like 30c tubular tires), and prepared with the cobbles in mind.
Still, the riders have about 200km of racing on smoother roads.
“On these open roads, those same 30c tires cause costly losses in aerodynamic efficiency, stability, and rolling resistance because they are mounted to rims developed for 23- to 25c tires,” says Kevin Nelson, Enve’s chief engineer. Effectively, he says, a 30c tire on a rim developed for 25c tires “kills aerodynamics.”
Disc-brake road (and road-ish) frames are becoming more popular, and offer greater tire clearance than race bikes with rim brakes. These bikes build on the momentum towards wider tires overall, and Enve saw an opportunity to design a disc-specific wheel aerodynamically optimized (company representatives claim) for wider tires.
Aerodynamicist Simon Smart (he’s the first ’S’ in SES) claims the 4.5 AR Disc allows riders to use higher-volume tires, without the traditional aero trade off. “It’s not necessary to compromise aerodynamics given that the aerodynamic drag reduction and stability are on a par with narrower mid-depth wheel sets,” he says.
If you believe Enve’s data, the results are pretty stunning. The chart above shows the 4.5 AR, with disc rotors, tested against Enve non-disc wheels. “With a big tire and a rim designed around that size tire, we can virtually match the efficiency of our rim brake 4.5 with 25mm tire—and beyond 10 degrees, the 4.5 AR performs much better than the 4.5 rim brake wheel with a 28c tire,” says Enve’s director of marketing, Jake Pantone.
Though still an aerodynamic road wheel developed for racing, according to Enve’s presentation, this wheel is for more than just pavement. The ideal 4.5 AR rider would, Enve representatives say, “[ride] roads that can be defined as rough, broken, chip-sealed, or dirt," and, “[be] enticed by mixed-surface road events like the Belgian Waffle Ride, Flanders Sportive, or Paris-Roubaix Challenge." However, nothing mentions gravel riding or cyclocross, so I asked Pantone if the 4.5 AR is approved for those uses: “Yeah, I mean it certainly fits the bill dimensionally and structurally speaking," he says. "However, this is really designed to be a road wheel. It is super aerodynamic, reasonably lightweight, and rolls like a dream. Or better put, if you own a road-disc bike that this wheel fits in, you won’t find a cooler, more dynamic or versatile wheel.” Of the SES wheels, he adds, the 4.5 AR is the toughest wheel, with the best strength-to-weight ratio.
The 4.5 AR, like the rest of Enve’s SES series, uses different rim dimensions front and rear. The front measures 49mm deep by 31mm wide; the rear is 55mm by 30.5mm.
But the real stunner is the clincher’s internal width: 25mm, or the same as Enve’s M70 mountain bike rim. I installed 28c Schwalbe Pro One HS tires and, at about 50psi, the tires measured just under 32mm.
Like Enve’s other SES Disc wheels, these are not rim-brake rims with disc hubs, but rims specifically designed for disc brakes. Eliminating the rim-brake track lets Enve cut weight (about 30 to 60 grams, versus the same rim for rim brakes, Enve claims), and tweak the aerodynamics.
The 4.5 AR Disc will be offered in two versions:
• Clincher. This wheel is tubeless ready (valves and tape are included) and uses hookless beads. Hookless beads are used in several companies' mountain bike wheels, but this is one of the first road wheels with hookless beads. According to Pantone, hookless is a superior design for tubeless because it “allows for a more precise bead-seat diameter, helps prevent burping, and improves tire-to-rim interface and consequently aerodynamics.”
The clincher rim uses a hookless bead like a mountain bike rim
Hookless sounds scary, but we’ve been hammering mountain bike wheels with hookless beads for years with no issues.
According to Enve’s product data sheet, the wheels are aerodynamically optimized for 28c tires. The product data sheet also states, “We recommend the use of tubeless-type road tires only. If using a tube-type tire, there is a max pressure rating of 80 psi.”
Claimed weights for clincher rims are 440 grams (front) and 450g (rear). Wheel weights are 1,507g with DT-Swiss 240 Disc hubs for Centerlock and 1,582g with Chris King R45 Disc hubs for Centerlock.
The 4.5 AR Disc is also offered in for tubular tires
• Tubular: Other than the tire-mounting format, the tubular version of the 4.5 AR differs in that it’s optimized around a 30c tubular tire (the clincher is optimized for 28c). This currently presents a bit of practical problem, as 30c tubulars are exceedingly rare. Current choices are the Challenge Strada Bianca, and the Schwalbe S-One. Both have suggested retail prices of over $100 each.
Claimed weights for tubular rims are 388g (front) and 396g (rear). Wheel weights are 1,382g with DT-Swiss 240 Disc hubs for Centerlock and 1,420g with Chris King R45 Disc hubs for Centerlock.
Enve’s press release states the 4.5 AR Disc is shipping now.
I received a set of 4.5 AR Disc clinchers built with King R45 hubs previous to this announcement, and was able to squeeze in a few rides. On my scale the wheelset weighed 1,550g, or less than the claimed weight.
Installation of the Schwalbe tubeless tires was a struggle of nearly epic proportions. It might have been an unlucky tolerance stack, or this particular tire/rim combination, but be prepared for a high-effort install. Removing the tires was tough also, but doable with the aid of a tubeless-approved (wide, with soft contours) tire lever.
When I informed Pantone of my struggles, he offered this advice: “It is important on the install of tires to make sure the beads are seated as deep in the center channel as possible, and then start opposite the valve stem. Work towards the valve stem so that it’s the last area of bead to install. [This] should be doable with no levers in my experience.”
This was my first look at King’s R45 Disc hub for Centerlock. It’s beautiful, but installation of the rear rotor requires removing the axle's end and preload-adjust mechanism. It’s not a massive undertaking, but it’s more involved than other Centerlock hubs.
On the roads—both paved and dirt—the 4.5 AR Disc is (like most deep carbon wheels) loud, and sounds like it rides stiffly. And while I've previously found many of Enve's road wheels a bit numb and stiff riding, these wheels ride very well. They're livelier than their weight would telegraph, with excellent smoothness. How much of the smoothness comes from the wheels, and how much of it was the 32mm (effective) Schwalbe tubeless tires I was riding at pressures in the low 40s/high 30s psi, though, I couldn't tell in my initial rides.
The lateral stiffness of the wheel is very good, though there's no escaping some squirm when riding wide tires at low pressure.
My big takeaway was how quick and lively the bike felt and how precisely it handled with the deep-section carbon wheels, and big tires at low pressure. That might not sound revelatory, but then you also consider the comfort and control offered by the wide, low-pressure tires.
I was able to just plow over small potholes I’d dodged before; I could stay seated and pedal through bumps that were bouncing my riding companions on narrow, high-pressure tires off line. And then there’s the improved cornering and braking traction, which was most welcome as I got caught out in the rain on one of my rides.
With these wheels, there’s nothing slow-feeling, heavy, or vague about wide, low-pressure tires. What you get is comfort, control, and traction, in a fast package.
The Enve 4.5 AR Disc Wheelsets are available here.
Link to Original Article Here.