Specialized 29″ers: Roval Wheels Tech And Interview

Editor’s Note: As part of our intensive look at Specialized’s 29″ers, we are also focusing in on some of their proprietary technical features found on some of the 29″ers. Here Grannygear takes a closer look at the Roval 29″er wheel set found on the Epic Marathon 29″er.

Roval Wheels Tech Article and Interview by Grannygear:

When I first saw the Epic Marathon 29er at Sea Otter last year, it had a set of Roval wheels on it. I did not think too much about that other than I was skeptical. To me, Roval was a road wheel with too few spokes in it. And when I rode the Epic again at Demo Days, both Guitar Ted and I looked askance at the radial laced, non-disc side front wheel, and lack of a through axle hub on the front fork. Both seemed like concessions to foo-foo-ness or the gods of weight weenies to me.

Later on, when I received the Epic Marathon 29er for long term testing I had the time to look at the bike in detail and as I was playing around with tire changes and converting to tubeless, I was becoming more of an admirer of the Roval wheels. Hours and hours of riding later, some of that on pretty rough and fast trails, the Roval Control EL XC front wheel with OS 28mm end caps and the Roval Control EL XC rear wheel with straight pull spokes have remained true and straight.

Then I read that the hubs were DT Swiss made and the front hub was convertible to 15mm QR or 20mm thru axle.

The rims are 26mm wide, right between the vaunted Stan’s Arches and Flows. As well, they are taped from the factory and supplied with tubeless valve stems. I have found I needed to use some kind of goop under the valve stem when first converting to tubeless or I had air leaking around the valve stem that the sealant could not deal with. Other than that, the combo of the 2-Bliss tires and the Roval rims was floor pump easy to air up. I also had excellent results with a WTB Wolverine, but WTB does not suggest the tire is tubeless ready.

They seemed like a pretty sweet set-up, so how come I had not heard of Roval wheels as a player in the 29er world? Maybe they were too new or maybe I was missing something.

So, it interested me to see what the Roval EL XCs were all about. I had some questions and doubts about the radial lacing of the front wheel. I also questioned the lack of any through axle option in a 29er market that is increasingly concerned with improving the front end stiffness of the big wheeled bikes. To get some of those answers, I went to Specialized engineer Jeremy Thompson, the wheel guy for all things Roval. First some details from the Specialized website on the Roval Control EL 29 Disc Wheelset :

We took our light and proven Control EL and made the best 29” wheel available to the masses.

TNI: So, Jeremy…can we start with who Roval is, how Specialized came to own the product line and such?

Jeremy Thompson: Roval was originally started by Claude Lehaneur, a French civil engineer that envisioned a way to make a better bicycle wheel by approaching it as if it were a bridge wrapped into a circle. He produced high-end wheels on a small scale until technology got away from him (he never moved past his freewheel design). He closed the doors on his operation in the late 1980s. Specialized approached him in 2004, and he was happy to help us take over production using his name and concepts. We started out making road wheels, but introduced our first MTB wheels in 2008 using many of the same concepts that Mr. Lehaneur designed into his original wheels: straight-pull spokes, DoubleDrive, radial lacing, etc.

TNI: When I hear DT Swiss hubs, I think understated quality. Hubs like the DT Swiss 240S are held in high regard by many, even though the hubs do not have the panache of an I9 or Chris King. The Roval hubs are DT Swiss made, yes? Are parts interchangeable from another DT Swiss product like a 240S? Bearings, drive system, etc?

Jeremy: Yes, all of the internal parts on the rear hub are completely interchangeable with DT 240s hubs. This makes it easy for customers to get service parts if they need them. Everything about the front hub is proprietary, so the parts are only available through Specialized.

TNI: I was very skeptical about two things on the EL 29er wheel set: The lack of a through axle arrangement and the odd choice of radial lacing on the non braking side of the front hub. Stiffness in the front ends of 29ers is very key and both of these factors seem to add up to noodley-ness. However, I can attest for feeling no lack of steering precision in the Epic Marathon and using the old ‘front wheel between the knees and twisting the bars’ test, it compares to a bike I have that is equipped with a Fox 15mmQR, tapered steerer, and stout wheel set. What is going on here?

Jeremy: We’ve put a lot of thought into these wheels. Everything was done for a reason. Even though the perception is generally otherwise, radial spokes are a little shorter (and therefore lighter) and actually increase the lateral stiffness of a wheel. With this wheel, the 3x spoke pattern on the disc side provides enough torsional rigidity to handle all of the braking forces without transferring them to the other side of the hub. This allows us to take advantage of the stiffer radial lacing on the opposite side. The OS28 end caps on the front hub act like stabilizers for the front hub. If you think of the interface between the dropout and the hub as a traffic cone sitting on the ground, OS28 is the stable, wide side of the cone, and the standard is the narrow side of the cone. You can get the cone to stand up on the narrow side, but it works much better if you stand it up on the wide side. ( Editor’s Note: See below for a fact sheet on stiffness VS. weight of the OS28 system.)

Specialized Fork and Wheel Integration-Overview
As an extension of Total Suspension Integration (our holistic approach to developing bikes, where the frame, fork, and suspension are all designed together for each riding experience), we’ve created a system that integrates our forks and Roval wheels. By doing this, we can increase stiffness in the front of the bike to give the rider more control and confidence in technical situations, as well as out of the saddle pedaling efforts. The goal of the fork/hub interface is to add stiffness without increasing weight.

Concept
• Through axle hubs are bigger than standard quick release (QR) hubs, increasing surface area engagement with the dropouts and improving stiffness. Unfortunately, the larger axle and enclosed dropout add weight to the system.
• Specialized over sized (OS) end caps combine the stiffness of a through axle with the weight savings of a quick release skewer.
• OS end caps use a standard quick release skewer in conjunction with proprietary end caps, which increase surface area between the hub and fork, thereby increasing stiffness without adding weight.
• Specialized OS 28 end caps can be used on Roval wheels in conjunction with Specialized forks and RockShox forks. We also offer a modified version, the OS 24, for FOX forks.

Testing
· The hub and fork are attached to a fixture that holds them in place.

· The steerer tube of the fork is passed through another fixture to act as the head tube of a frame.

· Weight is applied at the stem at a 90? angle, and the resulting deflection is measured.

· In the Torsional Stiffness chart, a taller bar represents a stiffer fork/hub interface.

Results:

· The Specialized S140TA fork is 5.3% stiffer than a 15mm axle fork, yet 8.9% (158 grams) lighter.

· The Specialized S140TA fork is 28.6% stiffer than a standard QR, yet 6.5% (112 grams) lighter.

· The 15mm axle fork is 22.2% stiffer than a standard QR, yet 2.7% (46 grams) heavier. (Note: Click tables to see full size)

Now on with the interview!

TNI: The OS 28 set-up does not fit all of the dropouts on all forks in play. What does it and what does it not fit? Any plans to work around that?

Jeremy: OS28 fits on all proprietary Specialized forks, plus RockShox lowers. As far as we know, that’s it. FOX and other forks will fit up to 24mm, so we plan to release caps to fit these forks sometime this year. They won’t be as stiff as the OS28 caps, but will definitely be better than standard 19mm caps.

TNI:The Roval front hub on the EL wheel set appears to easily convert from 5mm QR to 15mm and 20mm thru axle. I pulled the end caps off by hand just to see how it works. Any plans for adding 9mm DT Swiss compatibility? Where can a person buy the 15mm and 20mm adapters?

Jeremy: Any Specialized dealer can order these as service parts. Just go to your local Specialized shop and request them. As of now, we have no plans to offer 9mm through-bolt compatibility.

TNI: I applaud the way the rims come pre-taped with blue rim tape and come packaged with tubeless valve stems. Combined with the easy to mount Specialized 2 Bliss tires, the combo looks like a dead simple tubeless conversion. It seems like Specialized is pretty committed to tubeless use. Some wheel and tire makers are not there yet. Thoughts?

Jeremy: We love everything about tubeless. It’s lighter, faster, and you can run lower pressure so it offers better traction. If the wheel/tire combination is designed correctly, it’s super easy to set up. Our goal was to design the wheel and tire so that it could be set up tubeless with a floor pump. With realistic manufacturing tolerances, this won’t work 100% of the time, but in my experience, it almost always works.

TNI: Along the tubeless line of thought, any plans to have your own brand of sealant like Bontrager does? Or, in lieu of that, is there a particular brand or type of sealant that Specialized suggests for use with the rims or tires? Some sealants are ammonia free, etc

From Chris Wyatt, Tire Engineer at Specialized: We are constantly testing different sealants with our tires to see how they perform, and along with this, we are looking at creating a better sealant out of what we are learning from these tests. We aren’t happy with the prototype sealants we have come up with at this point, and we don’t want to release until we are 110% happy with the performance. We are definitely looking at an ammonia-free option.

TNI: Where do you place the overall stiffness and strength of the EL 29er wheelset? The 26mm width is right between the well thought of Stan’s Arch and Flow. This wheel set is on a pretty racy bike. Do Clydesdales apply here? For instance, is this an appropriate wheel set for an FSR Stumpjumper 29er?

Jeremy: As far as 29er wheels go, this is a very stiff wheel set. Stiffness is probably the hardest part about designing 29er wheels. The combination of big rims and disc brakes is disastrous to wheel stiffness. And yes, this is a great wheel for a Stumpjumper FSR 29er. We don’t have a bike in our line that this wheel would fit on as an appropriate spec, but it would be a fantastic upgrade.

TNI: Do you have the numbers on a bare rim weight?

Jeremy:Our rims are only sold as part of wheel sets and were designed as part of a system. The rim weight is not important, but instead the set weight and overall performance of the wheel should be considered.

TNI: Think we may see a wider rim version down the road?

Jeremy: Right now, wider than 30mm rims are getting pretty popular for paring up with the bigger tires that are coming along, but I am not sure they mix with the high end wheel set market. We’re extremely weight-conscious, but we’re also not afraid to add a little weight when it’s necessary. When we developed the Control EL 29, we considered a narrower rim, but decided on 26mm as a happy medium between weight, stiffness, and tire shape. If the right opportunity arises, we won’t hesitate to make a wheel with a 28 or 30mm rim. The real question to us is, “Does it make the product better suited for its intended use?” If we believe it does, you can bet we’re at least going to experiment with it.

TNI: How easy is it to get spokes for this product and where would that be done? One good thing about non-proprietary spokes is easy replacement in most well equipped bike shops.

Jeremy: Since the spokes are straight-pull, you won’t be able to find them in inventory at most spoke suppliers. However, just like the end caps, spokes are available as service parts through your local Specialized dealer.

TNI: This wheel set is expensive, on par with a high end, hand made build from any number of small wheel builders around the country. Why should a consumer consider this as an option to a hand built, custom build?

Jeremy: Our wheels are all hand built to very precise tolerances, but we don’t offer any custom options. For people who know that they want, a specific hub laced to a specific rim, there’s little we can offer to make them change their mind other than to say, “Try our wheels.” I believe that they will notice a difference and like what they feel. For somebody who isn’t sure what they want, we offer a simple solution in a great product that is engineered to be strong, stiff, and relatively light. It would be difficult to match the combination of these three things in a custom-built wheel at the same price. In addition, the customer doesn’t need to make decisions about what spoke configuration, etc. to run, and therefore won’t try to second-guess their own decisions. You also get the reliability and confidence of a wheel system that is designed to be tubeless and works perfectly with Specialized 2Bliss-Ready tires.

TNI: Let’s talk single speed wheels. Often an SS build is down and dirty and kept inexpensive….but nice wheels are important to SS riders. They seem to be looking for wider rims…28-30+mm for a wider tire footprint and stable sidewalls, a free hub with quick engagement (like the newer DT Swiss conversion), and a wide flange spacing for a strong wheel and room for cog alignment. That and easy tubeless conversions are a good combo that, quite frankly, is not that easy to walk into a bike shop and find on the shelf. I know we talked about this in person, so I am hitting you one more time in public!

Jeremy: This is a similar question to the previous one. Hardcore single-speeders will most likely know exactly what they want. To try and out-guess them isn’t possible, and it’s not what the sport is about. They want to make choices and to customize their product so they end up with something that is unique or at least very well-suited to their riding style. In our opinion, offering a pre-built, single speed wheel would be the equivalent of telling the rider that we know more than they do. That’s not our intention. If and when the single speed market expands to the point where we believe people are looking for pre-built wheels, you can rest assured that we will bring a great product to the table.

TNI: Anything more for the readers that we did not discuss?

Jeremy: We’re always looking to push limits and expand our product range. Keep your eyes open to what some of our sponsored riders are running this year…especially around Sea Otter time. You might see some interesting stuff!

I wanted to put a tangible feel to the OS-28 end caps, so I snapped some pics of the three hubs I had at hand that used a 5mm standard QR: A Hope Pro II, a White Industries M6 hub, and the Roval from the Marathon. In each pic I took a shot of the bare end cap (the edges called out by the pretty arrows) and then took a penny, which is pretty much 19mm in diameter, and centered on the end caps to show the scale of the OS28’s size. The Hope hub is a 19mm, the White Ind. is around 21mm-22mm and the OS28 at 28mm.