Review: Gulo Composites' GMX-25 Carbon Spoked Wheelset

Over the years, his company has been defined by the evolution of what he calls experimental problem solving, rooted in an environment that focuses on small details and collaborations. At a composites conference a few years back he had the idea to develop a better bicycle spoke, so in 2017 ideas were put into motion, and Gulo Composites was born.

Gulo has a variety of road, mountain, and gravel wheelsets. For mountain wheelsets, there are three options, the XC Race GMX-25, Downcountry GMD-27, and Enduro GME-30. I've spent the last few months on the GMX-25, which weigh a scant 1,290 grams, with tape and valves, and sell for a whopping $2,525 USD.



Design

All of the wheels in Gulo's line use the same design, which is based around those aforementioned braided carbon spokes. The spoke is composed of carbon, adhesives, graphene, resins, and aviation-grade alloys, all developed in-house by Gulo. Each spoke weighs about 2.9 grams. Gulo is reasonably protective about their braiding system but, since I'll be visiting the factory in the near future to get a closer look at the manufacturing, we'll have a more comprehensive run-down of the process then.

On each wheel, 24 spokes tie into Gulo's specially drilled hub. The hubs have 6 pawls, which operate in 2 phases, meaning 3 are engaged at a time. This mates to a 27 tooth drive ring to give 6.6 degrees of engagement. The hub only works with Gulo's spokes and vice versa. The spokes leave the specially drilled hub and enter the specially drilled rim at a natural and direct angle to reduce stress.

The rims are also designed by Gulo, and have a 25mm internal and 30mm external width, with a claimed weight of 360g. Everything together builds out to be 1290g for the set, with an XD driver, according to my scale. This includes valves and rim tape.

The wheels carry a five year warranty on the spokes, no questions asked. Rims are also covered five years for manufacturing defects/normal wear and tear. They aren't covered for poor line selection or crashing but there is a crash replacement option for $350 which includes the price of a rebuild by Gulo. Hubs are covered by a two year limited warranty. If a rider develops what Gulo deems to be abmormal bearing wear or play in the first year of use they'll fix the hubs free of charge and if it's outside that window, they'll service them for free at the cost of materials. All of this applies to the original, registered owner only.


Performance

The wheels are quick to accelerate, as one would expect a sub-1,300g set of XC race wheel wheels to be, and they feel nimble and light through and over varied terrain with no hesitations when it comes to putting down power. Stiffness and responsiveness are excellent. The overall ride quality the wheels give is different from an alloy spoked wheel. It's more damped and smoother, remarkably similar to the ride feel of the BERD wheels I tested months back.

Durability is what everyone, including myself, has been curious about. After a couple of months of riding on the rough and rocky trails located a short pedal from my back door, I noticed the rear wheel had a big hop in it. On inspection, I noticed that some of the spokes had started to back out. Typically that's not a big deal, but with these wheels you can't just crank things down trailside. Instead, you have to pull the tire and rim tape off, hold the spoke with one tool and tighten the head with another, which is a little frustrating to say the least.

I contacted the Gulo team, and they told me they were aware of the issue and had switched up the way they prep spokes and build wheels a couple of times since I had received my set. "Without getting too far into the weeds, the issue with nipples coming loose is due to the stiff nature of our spoke combined with the stiff carbon rims. It is worse on the road wheels but still pops up from time to time on the MTB wheels. Our current spoke prep is a pre-applied solution similar to Nylok - that's the blue stuff on your rotor bolts."

After having the updated spoke prep applied to my test wheels, I've put in another few months of riding with zero issues. I've ridden in all conditions, wheelie hucked drops into rocks, and they've held strong. At this point, I can't find any quibbles outside of the issue with the spokes loosening up, which seems to have been completely resolved.

Price & Weight Comparisons

At 1,290g, the GMX-25 is a light wheelset, no doubt, albeit expensive at $2,525 USD and with a proprietary system, 220lb weight limit, and a five year warranty on spokes and rims, two years for hubs. There are a number of other wheelsets in the same realm of "really fancy and expensive and light with proprietary technology" that I've ridden lately. The most similar riding wheels are Atomik's BERD XC33 wheelset. The spokes are one of a kind yet several different and more common hubs can be adapted to work with them. The Atomik wheelset weighs in at 70g more (1,360g) and sells for $2,150, as I rode them with a DT Swiss 240 hub.

Bontrager's Kovee XXX sells for $2,399, also weighs 1,290g, and has a DT Swiss 240s hub system with no rider weight limit. These wheels also have a lifetime warranty. Another popular system wheel, Industry Nine's Ultralight 280c Carbon, weighs a bit more at 1,450g and also has a unique system spoke and hub and a 210lb rider weight limit. These wheels sell starting at $2,250 and have a lifetime warranty.







Pinkbike's Take:

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Reviews and Tech Reviews Wheels Gulo Composites Gulo Composites Gmx 25