Gulo Composites GRX-SL Wheels: Getting Rolling – by MG
Folks who know me will tell you I’m a wheel guy. They’re one of my absolute favorite parts of a bike, and they’ve been a bit of an obsession since I laced my first wheel almost 30 years ago. So to say I’m so stoked to be testing the new GRX-SL wheels from Gulo Composites would be an understatement.
Who is Gulo Composites?
Based in Brevard, North Carolina, Gulo Composites is an independent brand of Keir Manufacturing, a manufacturer of industrial ceramics and technical composites. The Gulo Composites wheels are Kier’s first consumer product offering. Keir saw the opportunity to leverage its expertise in composite manufacturing to build better wheels.
The company hired engineer and cyclist, Richie Trent, to develop its technology into a full line of wheelsets for mountain, road and gravel bikes, each using Gulo Composites’ unique composite spokes. The multi-year development and testing process culminated this year with the launch of five new wheelsets: two for road; two for MTB and one for gravel.
The GRX-SL Wheelset
Gulo’s G1 composite spokes are the core of the company’s wheels. The spokes are designed, engineered and manufactured in-house using a triaxial braided composite structure. The composite spoke body is molded, then bonded to alloy threaded ends with aerospace adhesive. The resulting spoke weighs 40 percent less and significantly increases fatigue and impact resistance compared to traditional spokes, the company says.
The spokes thread directly into the straight-pull flanges of the Gulo ETI (Easy Thread Interface) hubs. The hub design features matched-ERD spoke hole angles, so the spokes leave the hub at the precise angle needed to reach the appropriate hole of the rim.
At the rim, the G1 spokes pass through holes that are carefully drilled to be at the exact angle to ensure they stay completely straight. This focus on correct angles reduces the likelihood of stress or fatigue failures. Gulo’s G1 Hidden Nipples feature a smooth, rounded contact surface that mates perfectly with the rims. The wheels can be trued, however, to do so requires removal of the tire and rim strip.
Gulo’s carbon rims use a hook-type bead, so they can accommodate both tubed and tubeless setups safely. The 22mm internal, 29mm external width is a good match for gravel tires in the 32-45c range.
The GRX-SL rims have a 28mm profile. Constructed of Toray T700 carbon, they have a 2mm spoke offset. This evens out spoke tension from side-to-side and improves the bracing angle of the drive-side spokes. The result is a stronger, more balanced wheel system.
Gulo uses subtle, tasteful rim graphics that are permanently cured in place. This eliminates peeling or cracking, and contributes to a refined, high-end look and feel.
The ETI rear hub is equipped with a Shimano 10/11s compatible freehub body. The patented “anti-bite” design prevents the steel cogs from damaging the softer alloy cassette body. The cassette body uses 6 pawl drivers in a staggered arrangement to deliver 7.5-degree engagement. SRAM XDr and Campagnolo cassette bodies are also available.
Both hubs use cartridge bearings – two in the front and four in the rear. The hubs can easily be configured for thru-axle or quick release equipped frames with available end cap kits. The standard configuration is 12x100mm thru-axle front, 12x142mm thru-axle rear, which was a perfect fit for our test bike.
The GRX-SL wheelset weighed 1,296g on our scale, with tubeless tape and valves installed. MSRP for the GRX-SL wheelset is $2,625.
Setup and Initial Ride Impressions
Out of the box, the GRX-SL wheels were impressive in appearance and in weight, or rather, lack of weight. The build was impeccable as well. In the stand, the wheels were as true and round as any I’ve seen, and spoke tension was very even on both wheels.
Tubeless tape and valve stems came pre-installed, so all I had to do was mount the tires, cassette and disc rotors, and I was ready to roll.
Tubeless setup was easy using my Silca Super Pista Ultimate floor pump, however I did need to sort out leaks in the valve stem gaskets on both wheels. It seems the curved inner wall of the rim and the rubber valve stem seal aren’t a perfect match.
While it was possible to eliminate the leaking by tightening the stem nut, to do so required the use of pliers. Since I don’t always carry pliers on my rides, I used a dab of Shoe Goo on each valve, letting it cure overnight before installing the tire. This allows me to keep the stem nut finger tight, and the bond of the Shoe Goo is easy to break free if I flat and need to install a tube.
With that minor issue sorted, I mounted up our recently-reviewed Continental Terra Trail and Terra Speed tires using Bontrager TLR sealant. Since I just finished testing the tires on another set of carbon wheels, they are a good point of reference for the GRX-SL wheels.
On the road, the Gulo wheels made an immediate difference in both the acceleration and ride quality of our test bike. They feel stiff in corners and out of the saddle, but they have a calm, composed ride in rough gravel. Perhaps there really is something to those G1 composite spokes? And while I was initially skeptical of the aerodynamics of the large, round spokes, the wheels feel very fast in a variety of wind conditions.
We’ll need to ride the wheels quite a bit more before we can comment on their long-term durability, but so far, so good. I’m also planning to ride the Gulo wheels back-to-back with other wheels in my quiver, so I can better understand the performance and ride quality of the GRX-SL wheels. Look for the results of that testing to come in my ‘Checkpoint’ review.
Learn more about the GRX-SL wheels and the technology behind them at GuloComposites.com.
NOTE- Gulo Composites sent over the GRX-SL wheels for test and review to Riding Gravel at no charge. We are not being paid nor bribed for this review and we will give our honest thoughts and opinions throughout.