If you haven't heard of Gulo Composites, you're probably not alone. Based in Brevard, North Carolina, the brand is a new fish in the sea of mountain bike wheels, with a unique design that uses specially braided carbon spokes.
Why a carbon spoke? Gulo's team believes their house-made carbon spokes offer a beneficial blend of strength and durability, minimal weight, and stiffness. The spokes are triaxially braided, with a combination of different fibers, to give an impact resistance Gulo claim is better than that of any steel spoke on the market.
The owner of the company, David Keir Watkins, is well versed in carbon fibers and composites. Watkins has always been intrigued by the creativity found in manufacturing and started KEIR Manufacturing, Gulo's parent company, when he was fresh out of college.
GMX-25 Details• Size: 29"
• Intended Use: XC
• Hub: 24h; 6 pawls, 2 phase, 27 tooth drive ring, 6.6* engagement
• Driver options: SRAM XD, Microspline, HG
• 25mm Internal / 31mm external
• Weight: 1290 grams; 595f, 695r - with tape/valves (confirmed)
• 100kg / 220lb rider weight limit
• MSRP: $2,525 USD (as tested)
•
www.gulocomposites.com 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.
DesignAll 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.
The carbon spokes are bonded to aluminum ferrules on each end. Spokes must be trued using a combination of wrenches to prevent the spoke from twisting, its only claimed weakness.
PerformanceThe 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 ComparisonsAt 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.
Pros
+ Great ride quality
+ Lightweight
+ Stiff and responsive
Cons
- System wheels and very rare components
- Still not completely proven technology
- Extremely expensive
Pinkbike's Take:  | I had my doubts about carbon spoked wheels, but they've been largely abated during the period I had Gulo's GMX-25 wheels on test. They perform as advertised and are one of the lightest and stiffest wheelsets one could buy and, the ride quality is top-notch. I do hesitate to recommend them to anyone other than a weight connoisseur or someone with a spare wheelset since every component of the system is proprietary. Finding replacement parts, depending on locale, could be challenging should the need arise.
I think it's incredibly cool to see people from outside the bike industry bringing a fresh set of eyes and ideas to the table, and believe this kind of innovation can drive a lot of the products we see in the future.— Daniel Sapp |
125 Comments
Rules out half of pinkbikers.
Customer: "I'd like you to replace the carbon spokes that I broke"
Manufacturer: "Sure - but first I need to ask how fat are you? "
"Hi, I broke my wheel under warranty." - You
"Certainly sir. I just need to fill out the claim form. Do you mind me asking your weight?" - W
"Excuse me? Odd question. I don't really want to discuss my weight. I've been going through a difficult time during lockdown." - You
"I'm sorry sir. It's just that we have a rider weight limit on our frames." - W
"Let me go check." - You
......"...224lbs" - You
"ooohhh...so that exceeds our 220lb maximum rider weight limit sir" - W
"HOLD ON! I'll be right back." - You
"....219" - You
"Sir, you lost 5 lbs?" - W
"Took my work boots off" - You
"Oh....ok. Well that's great. let me just keep filling this out. Do you have a spare wheelset to ride in the meantime?" - W
"Yep. Out in the gear shed." - You
"Got any shiny new bits?" - W
"Nah, just my old stuff." - You
"You ride with a pack or are you strapping your stuff to your bike?" - W
"Pack." - You
"Oh...I'm sorry sir. You're still ineligible. Management just told me we go off your fully dressed weight. I'm going to need to see you in a helmet (Safety First) and riding kit standing on the scale" - W
"FOKKKK!! Be right back." - You
"......202 lbs" - You
"Oh...terribly sorry sir. We're going to have to deny the claim." - V
"FOKKKK!!! Stupid clipless shoes" - You
"Clips sir. They're called clips. Have a good day." - W
Yea that was the business when getting air in a crosswind!!! Lol
WON"T SOMEONE THINK OF THE GALVANIC CORROSION ? ! ! !
good point htough
extra plus: standard spokes
Lesson was they can be ugly with wear and still full strength. A few of the tests, I couldn't believe it passed. In terms of strength, heat is much worse than abrasion.
The customer ended up replacing them way more frequently then necessary just because they look so ratty (and on a ship, that's saying a lot)
The carbon concept is cool, but that's another $1000+ over a set of "string" wheels. And these appear to have a lot more limited an application...
That stated I'd personally welcome back a 29" tioga disc drive. ;o)
the myth that modern carbon fiber reinforced plastics are fragile should be done & dead. it's been almost ten years since that great vid from Santa Cruz of trying to break their carbon frames, and the composites have only gotten better since.
Did you use spell check for that? Props if you didn’t ????
pirope.net/produkte/mountainbike
Big brain time, if mtb keeps using riders as charged guinea pigs, riders are going to continue to be skeptical with every part of "innovation" that is marketed at us.
What happens if the best line choice option breaks my wheel, and I somehow manage to ride it out???
This may be of interest to folks trying to do other methods of fiber-spoke bonding methods. The rim end of the fiber spoke could be the stationary part, with the adjustment end being at the hub.
That's great, but is impact resistance really a large concern for spokes? Certainly some spoke breakages are from a stick or something hitting them, but it's probably not a significant but I would think consistent tensile strength and consistent elastic stretch are the major factors for a spoke.
What I can't figure out is why they went to alllll this trouble to get special light spokes but then picked heavy components for the rim and hub. Who is this aimed at? Not weight weenies thats for sure.
BTW this wheels recall me this:
www.spinergy.com/content/pbo-spoke-technology
$5 valves. ????