Unless you've been living between the walls of a Mavic MA40 rim, you've probably noticed that rims have gotten wider over the last five years or so. Raymond Scruggs and his company, Derby Rims, claim some credit of this wider-is-better movement, and we're currently testing a set of his carbon rims built up for gravel and cyclocross use.
From Forums to a Carbon Foray
Scruggs of Derby Rims has a long history with mountain bikes, riding the trails and dirt roads of Northern California in the 70s and 80s as "mountain bikes" were starting to appear and take form.
However, his exposure to the motorized two-wheel scene has had an oversized influence on his current work.
"I did like to go to moto bike races with friends since the early '80s," Scruggs recalls. "Sometime after 2010 I noticed bead seat retention ridges on some moto bike race rims and thought [they] would be helpful to cure the early bicycle tubeless rim's air burp problems as the tire beads would slide inward while cornering on the first generation tubeless-ready narrow and flat bead seats. The retention ridges add safety to prevent a flat tire from falling off a rim." At the time, only Mavic's UST designs offered similar bead retention profiles.
Scruggs also appreciated the benefits of wide rims, common on motorcycles. Although mountain bikes were originally built on wide rims and "balloon tires," the wide rims went the way of the dodo once enterprising and weight-conscious racers and then manufacturers cut down narrow 700c road rims like the Mavic MA40 and Matrix Iso C to create light 26" rims.
Scruggs lamented this change as his tires squirmed and folded in hard cornering, and could not find wide, lightweight and durable rims. The opinionated rider didn't keep his opinions secret. As a longtime member of mtbr.com under the handle of Derby, Scruggs advocated for the use of wider rims and retention ridges for off-road biking. However, spinning his wheels by complaining on online forums didn't solve his problem, and he decided to do something about it. He reached out to manufacturers, built some prototypes and, and got things rolling.
Before he knew it, he had started Derby Rims.
Although he now focuses on cycling, Scruggs’ motorcycle days are still with him. He adopted motorcycle wheel design concepts for his rims and claims credit for developing the hookless bicycle rim with retention ridges.
What’s behind the name? Scruggs is a fan of “bike derby,” a simple game of riding around with others and trying to get them to dab (no, not that type of dab) before you do. Derby was Scruggs' mtbr.com screen name, and bike derby is understandably hard on equipment, making the name a natural choice for the rims Scruggs designs to survive hard riding.
The fat bike and plus bike crowd were his early adopters, as Derby was the first company to offer carbon rims wider than 30mm, but Scruggs has expanded his offerings to a narrower, drop bar-oriented offering as well.
We've got a set of his latest cyclocross and gravel-oriented rims in for a review, and we're taking an early look at what we're rolling on.
Derby CX 23i Rim
Derby provided Cyclocross Magazine with a set of review wheels built using Derby CX 23i carbon tubeless rims and White Industries XMR 6-bolt disc hubs that would retail for $1,470. The rims retail for $445 each.
While Derby offers rims as wide as 50mm, its drop bar offerings are middle-of-the-road in terms of internal width. Scruggs believes that's partly because his competitors have followed his lead.
Derby’s internal rim profile is Scruggs’ own design and proprietary to the brand. The hookless, tubeless-ready CX 23i rim is 32mm deep and has 29mm external and 23mm internal widths. The profile was first introduced in 2013 and features a deep center channel with ridges on the bead seat to secure the tire at low pressures and prevent it from rolling off the rim.
The profile is similar to other current tubeless rims, although Derby claims it is the first brand outside of Mavic (and its UST design) to release this profile and other manufacturers have since copied it. American Classic introduced Bead Barbs around the same time, but Derby's profile was one of the earlier versions on the market.
Derby uses 12mm Stan’s tubeless tape on its rims. Scruggs said he considered using his own tape with his rims, but chose Stan’s tape because it is readily available. The 12mm tape only covers the rim’s center channel, leaving part of the rim exposed. Scruggs chose this design because he believes tires seal better against the bare rim than tubeless tape. He also said the bare rim interface helps keep tire and rim tolerances from becoming too tight and prevents the tape from peeling back or tearing when changing tires. It's a creative, simple solution to a problem that has inspired other companies to seal off their rims.
The wide rims are attractive for cyclocross and gravel because they accept a range of tire widths. Scruggs said dealers and customers report using tubeless tires between 25 and 45mm wide and running tubeless pressures up to 95 psi for 25mm road tires.
The pressure rating above only applies to tubeless tires. Scruggs told Cyclocross Magazine many traditional clinchers stretch under high pressures and will blow off Derby hookless rims at 100 to 115 psi.
Scruggs has also incorporated a small but thoughtful feature in his rims: a drain hole on the sidewall near the valve to allow trapped water to drain from the rim.
Scruggs says the patent-pending "weep holes" prevent galvanic corrosion that is common in mixed material setups and double wall rims. Water will drain out during riding or when stored at the right orientation, protecting the alloy nipples from corroding.
Derby’s primary business is selling rims, and supplies consumers and wheel builders with carbon hoops for custom builds. The company does offer complete wheels with Industry Nine, Project 321 and Onyx hubs starting at $1,735. Derby designs rims for cyclocross, road and mountain and offers several hub and spoke choices for its complete builds, so consumers have a variety of options for customized builds.
Our test wheel set has Derby’s CX 23i rims, which are 32mm deep and have an external width of 29mm. Sapim Race butted spokes and alloy nipples lace the rims to White Industries XMR hubs. The 6-bolt, disc compatible hubs have a Shimano-compatible 11-speed freehub body, and our test set came with 12mm thru-axle. Customers can order custom wheels for different axle configurations, but as of the date of this article, our exact setup is not available through Derby.
Derby says it gives actual weights (+/- 10 grams) for its rims. The CX 23i rims weigh a reported 430g, which will probably not wow weight weenies. However, Derby designed them with off-road riding in mind, and so they are competitive with other off-road options such as the FSE EVO 35CD wheels we recently reviewed.
Our complete wheels, with two layers of Stan’s tape and tubeless valves, weigh 780g front and 940g rear or 1,720g for the set. Figuring 18g for each valve, and a layer of tubeless tape adds 5g per wheel, we estimate the naked weight of the wheels around 1,664 grams.
Not impressed by their rotating weight-saving potential? It's worth noting some of the wheel’s weight comes from the White Industry XMR hubs. At 175g front and 298g rear, they are not the lightest available but feature a titanium freehub over more easily-gouged alloy offerings. Derby offers several hub options for complete wheel builds; Industry Nine hubs, for example, save 128g versus the White Industry XMR option. Using a lighter hub brings the weight of the complete wheel build closer to other wheelsets such as the Bontrager Aeolus 3 and Williams System 45.
Set Up and Initial Impressions
With a relatively deep center channel, and wide channel shoulders, tire installation was relatively easy. With a compressor pump, tire beads (of Kenda, Panaracer and Islabikes tires) popped into place with an audible snap, and remained in place overnight with or without sealant.
With a generous 23mm width, the CX 23i rims add some extra volume and width to the average cyclocross tire. The 32mm Islabikes Gréim Pro tubeless tires inflated to nearly 35mm, while the 35mm Panaracer Regacross measured out at 38mm. Any tubeless cyclocross and gravel cyclist without tire or mud clearance issues should appreciate the extra volume and compliance.
We're impressed after our initial rides. We haven't burped a tire at any rideable pressure, and despite flatting in a high-profile Nevada-based Masters race and unavoidably riding a bit of the course on the rim, the rim and build look and perform as if they're still new. The wheels have remained round and true, and seem to spin up faster than wheels of similar weight but with lighter hubs.
Most importantly, the ride quality, with a larger tire footprint, is what we've enjoyed the most so far. At 23mm wide (internal), the rims do not feature an eye-opening width, but still offer a noticeable bump in volume compared to the new normal of 17-18mm. Cyclocross tires inflate to be about 2mm bigger, which allows lower pressures and more bump absorption.
Scruggs perhaps is most proud of his rims' reliability, touting his overall less-than-1.5% damage stat (which includes downhill options), and maintains that this is an order of magnitude lower than his competition and that the CX 23i is at 0%. We don't have the data to verify his claim, but based on our initial rides and a few direct impacts of the rim while riding a flat, our experience with the rim and this particular build indicate these wheels should prove robust and durable, even if they won't inspire weight weenie dreams.
Stay tuned as we put the Derby CX 23i rims to a long-term test.
Bike derby anyone?
Specifications: Derby CX 23i Carbon Tubeless Clincher Rims With White Industries XMR Hubs
Price: Rims: $445 each; Wheelset, as built: $1,470
Weight: Rims: 430g each; Wheelset, as built with tape and valves: 780g front, 940g rear, 1,720g set, 1644g without tape and valves (estimated)
Rim: Width: 29mm external, 23mm internal; Depth: 32mm
Max pressure: 125 psi with inner tubes, 95 psi tubeless
Spokes: Sapim Race butted spokes (2.0-1.8)
Nipples: Sapim alloy
Hubset: White Industries XMR, 6-bolt disc, 24 spokes, front and rear
Cassette Body: Shimano/SRAM 11-speed
Axles: 12mm thru-axles; quick release and 15mm TA available
More info: derbyrims.com
Andrew Yee and Brandon Grant contributed to this piece.