Specialized-Roval-Traverse-SL-Fattie-Wheel-(1)Photo credit: Specialized / Dan Barham

Just like apple pie, when it comes to wheels, bigger is definitely better. This time though, the big industry push isn’t towards larger hoops, but rather wider internal rim diameters.

It’s not a novel concept, but one that has only recently gained traction, and is strongly backed by on the trail performance, and lab testing.

Specialized Roval Traverse Fattie Tire Deflection GraphFor the team at Specialized, the come-to-jesus moment of realization was due (strangely enough) to fat bikes. Though sometimes pejoratively referred to as snow bikes, the clown soled fatties can be quite fun on the trails because of the traction provided by their gargantuan tires and rims.  During the development of the Specialized Fatboy, Sr Design Engineer Jason Chamberlain discovered just that, and an idea was born.

To prove the concept, the engineering team used an angled grip table to simulate leaning a bike over in a corner. This helped them visualize what happens to tires at load, and proved the wider is better concept wasn’t just a placebo.

Studying the graph, you can see that the tire on the wider rim moves less under the same amount of force, which translates to better support and handling on the trail.

Specialized-Roval-Traverse-SL-Fattie-Wheel-(2)Photo credit: Specialized / Dan Barham

While wider is better, the downside is having to add extra material, which means more weight. Early mountain bikers ran into this same issue. During the first days of klunking, the Araya 7x had a 25mm inner diameter and were the defacto rim of choice, but the pursuit of lower rotational weight led innovators like Keith Bontrager to start trimming down road rims to klunker scale.

From the original 22m ID of the Roval rims to the 30mm ID of these Fatties, the improvement in traction is massive, but Specialized found anything wider offered only diminishing returns.

Specialized Traverse SL Fattie Hub (2)Photo credit: Specialized / Dan Barham

The wheels are available in 27.5″ and 29″ sizes only, at two different price points. The carbon model retails for $1,400 USD, while the aluminum models are priced at a more attainable $600.

Weight for the carbon 29″ wheelset is 1,570g, while the 650B models hits the scales at 1,530. The aluminum 29″ wheelset is 1,770 g, and the 650B version is 1,690 (weights do not include valve stem, rim strips, or decals).

Specialized Traverse SL Fattie Hub (1)Photo credit: Specialized / Dan Barham

The front hub is convertible between 15/20mm with different end caps, while the rear hub has 135mm, 142/142+, and XX1 compatibility.

Both wheelsets make use of DT Swiss Revolution spokes and hub internals, although the Carbon model utilizes a higher 56 T point engagement.   specialized Roval Plastic Caps TubelessWheels will be shipped with traditional rim strips, but the carbon model will also include these Roval plugs. Lighter than a traditional tape setup, these Delrin plugs seal the spoke holes and can be run either with a tube or tubeless.

Specialized-Roval-Traverse-SL-Fattie-Wheel-DecalsPhoto credit: Specialized / Dan Barham

The rims will also be available with three different colored Vinyl decals, for optimum color optimization.

For more info, visit Specialized


  1. The fact that the front hub can be converted to 20mm is kinda a big deal… lots of wheelsets leaving that standard out these days because it keeps rowdy DHers from breaking their wheelsets and asking for warranty replacement.

  2. I am hoping that ‘fat’ and ‘fattie’ will mean 65mm or wider rims to you guys at some point… perhaps after the Pugsley’s 10th anniversary in a couple years? How about ‘wide’, or list the dimension instead? Mmmkay… thanks.

  3. I mostly let the persistent writing errors and typos on BikeRumor go, but it’s starting to get to the point that its difficult to concentrate on the subject. These wheels seem really cool, but I can’t get the phrase “come-to-jesus moment of realization” out of my head. First, “Jesus” is always capitalized because it’s a proper noun. Second, the cliche “come-to-Jesus moment” is always going to describe a moment of realization. So not only is the phrase cliched and silly in this context to begin with, it is also redundant.

    You don’t have to attempt complex writing. There are other places you can do that in a supportive environment. We’re just here for the facts.

    Always have to leave on a positive note, so I will say that this writer, Saris, uses passive voice far less often than some of the other writers on the site. (I’m also assuming that “optimum color optimization” at the end is a joke, in which case, that’s pretty funny).

    Finally, those wheels do look cool, I’d be interested to see a review.

  4. +1 with Skeeter.
    Why call these rims fat ones ? Fat bike for me it’s another story. Ok do I want some extra weight on my already cumbersome Stumpy FSR 29 ? No thanks. Unfortunately the market will eventually do,so the 2016 Stumpy FSR will have these things OEM period. Boring. Or am I just getting old ?

  5. Jeebus, didn’t you guys get the memo? Roval is NOT a Specialized product! Even though they are owned, operated and designed by Specialized, they are a TOTALLY separate and independent wheel brand… [/sarcasm]

  6. I have the rovals on my 2009 S works FSR. I have literally never even had to tru them. And at $1400 for carbon, seems like an amazing deal.

  7. @Superstantial

    Considering I wrote this article before 6 AM this morning, I’m surprised that’s all the criticism you could levy. I’m going to call this a win!

  8. Somehow I doubt the gains in traction are “massive” just as I doubt that “diminishing returns” fail to justify widths over 30mm. Also, no mention of the tire size in the graph?

    Sorry, but this language is useless marketing-speak. It’s nice to see a graph that demonstrates something that we already intuitively know but there’s no reason to believe that 30mm is the dimension that we want. It’s simply the size Specialized has chosen to sell. I have great confidence that there will be another true innovation down the line when the width goes up another increment. Just won’t happen until there’s a proven market.

  9. @Superstantial. jESUS, mix yourself a drink and relax. ITS not worth blowing a gasket over.

    $1400 seems like a fair price for what it is.

  10. Hi all,

    I would like to add this useless, meaningless post and add it to the rest of the useless, meaningless posts on this article.

  11. That graph shows the inexperience of the Specialized “engineers”. Unless the marketing guys got ahold of the data and switched it, it is hard to believe that a real engineer would not know how to graph something properly. Maybe a co-op student?

    Also, the width of a rim is not an inside diameter or and outside diameter. It is an inside width or outside width. Race Face actually has “inside diameter” written all over their website. Embarrassing!

  12. @dr. sartorious. here is another unrelated post for you – oh wait, i couldn’t think of a “cooler” post than you.

  13. @Dr.Sartorious: Garbage in, garbage out right? The useless, meaningless posts fit well with the useless, meaningless articles that Bike Rumor seems to be churning out these days…

  14. @Saris – the way you write it seems like you’re at least trying to be a better writer. This isn’t like a typo, this is a conscious choice you made that didn’t work out. Maybe my earlier post came off as aggrieved, but hopefully you learned something.

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