0223_Exclusive: Kuroshiro Reinvents the Tubeless Wheel with their Incredible ensō685 Carbon Fat Bike Rim

This is much more than just another carbon fatbike rim. The Enso385 represents impressive technological advancements that may have a serious impact on the way carbon rims are manufactured in the future. Lighter, stronger, and tubeless with fewer parts, Kuroshiro’s ensō685 fatbike rim is rewriting the rules for single wall carbon rims. Kuroshiro is a new company from owner of Raceware SRL, a 22 year old Italian distribution company. As a distributor Mauro has always been ahead of the curve helping to usher in the age of the 29er in Italy, and being the first to import fatbikes. Seeing an opportunity to offer a new product that was both extremely simple while revolutionary, Mauro formed Kuroshiro – Japanes for Black and White which Mauro says is based on Zen philosophy. Kuroshiro’s goal is to make simple, effective products but also to create things that have never been done before. Things like the ensō685 – ensō is circle, the 6 is for 26″ wheels, and the 85 signifies 85mm wide.

What makes the ensō685 so special? Make sure to read through to find out!

Exclusive: Kuroshiro Reinvents the Tubeless Wheel with their Incredible ensō685 Carbon Fat Bike Rim

Exclusive: Kuroshiro Reinvents the Tubeless Wheel with their Incredible ensō685 Carbon Fat Bike Rim

If the rim design looks familiar, that’s because we’ve posted Alchemist’s incredible design and engineering work before. With everything made 100% in Italy, the company is known for incredibly light parts that stand out due to their unique shapes. Looking at the cutouts of their mountain rims, you can get a sense for their incredible carbon manufacturing capabilities thanks to the varied wall thicknesses, and a really clean bead seat. The ensō685 will be created in partnership with Alchemist and sold through Kuroshiro and Raceware.

0223_8183 Exclusive: Kuroshiro Reinvents the Tubeless Wheel with their Incredible ensō685 Carbon Fat Bike Rim

Exclusive: Kuroshiro Reinvents the Tubeless Wheel with their Incredible ensō685 Carbon Fat Bike Rim

Like their other rims, the ensō685 uses carbon to reinforce the spoke holes, but in this case the design has a number of functions. Called SP-line, the patent pending technology is crucial to how the rim performs and ultimately how it got to be so light. How light? How does 399g sound? Yes, 399 grams*(see section on 40 Below) . For a tubeless, 85mm wide fatbike rim. We didn’t get a chance to weigh this particular version, but it felt extremely light.

So how do they get there? Built as a single wall design, the ensō685 gets its strength from a 14 layer carbon layup with 8 bi-axial and 6 mono directional layers and their patent pending SP-line technology. Compared to a standard single wall carbon rim, SP-line increases lateral stiffness by 18%. Not only is the SP-line technology efficient in terms of stiffening the wheel without adding extra weight, the added material serves to reinforce the spoke holes allowing for higher tension. While most wheels are tensioned to 100kgf up to 130kgf, testing on the ensō685 rim allowed for an astounding 382kgf tension without the nipple pulling through, and without nipple washers. The ability to run high tension means the wheels can use lighter weight, high tension spokes like the Sapim Super Spoke, which can save up to 70g per wheelset. So not only is the rim lighter, but the wheel components can be lighter as well.

Exclusive: Kuroshiro Reinvents the Tubeless Wheel with their Incredible ensō685 Carbon Fat Bike Rim

Are you ready for the really impressive part? ensō685 wheelsets will be built with Sapim Super Spokes and Sapim Polyax nipples, and are tubeless compatible without tape. Thanks to the conical shape of the nipple holes, the high tension of the Super Spokes, and the round head of the Polyax nipple, the pierced rim bead is still air tight with sealant. In testing the company noticed that without any sealant at all, the rim would hold air for over 7 minutes. Add the sealant, and you have a tubeless wheel.

Kuroshiro calls this their 40 Below technology due to the fact that the amount of Gorilla Tape needed to make a fatbike rim tubeless usually amounts to 40g per wheelset. That is where the 399g rim weight comes from. Technically, they are around 415g per rim, but since competitors have to use tubeless tape in the end, the 20g weight savings make for the equivalent somewhere around a 399g rim weight all things considered. Prototype wheelsets built with Tune 170mm fatbike hubs, Sapim Super Spokes and Polyax nipples, and the ensō685 rims have been measured below 1,600g. To put that in perspective, the Salsa Mukluk shown above lost about 7 pounds when the Rolling Darryl wheelset and 45NRTH tubed tires were swapped out for the ensō685.

Seven. Pounds. Less.

To set up the rim tubeless, simply pour some sealant into the center rim channel and rotate the rim. The channel guides the sealant around the nipples and makes sure they’re coated, then install the tire, add the remaining sealant through the valve, and inflate. And that’s how you make a rim with spoke holes that is tubeless without a rim strip or tape. The v7 prototype above was built with a different process than the final production version will use, which will result in a cleaner inside rim surface.

The last design feature of the ensō685 is their “Altera Design.” Mauro mentioned that while some companies have gotten rid of the bead lock for fatbike rims, they wanted to keep it for increased durability. Riding in soft snow doesn’t pose much threat to carbon rims, but the ensō685 is meant to be an all seasons, all terrain rim that needs to be able to withstand strikes from rocks, roots, curbs, whatever. Because of this, the wheels should have a firm grip on the tire at any pressure and prove to be quite durable.


Exclusive: Kuroshiro Reinvents the Tubeless Wheel with their Incredible ensō685 Carbon Fat Bike Rim

The two rims on the prototype wheels Mauro showed us had two very different graphics packages. I think the general consensus was that the rear was more appealing than the front, but they will likely change a bit when v8 sees production. About that production – this isn’t vapor ware. Mauro says that the final version of the rim will be in production on March 15, 2014. If you want a pair, you should probably get your order in early. In spite of the expensive 800€ per rim price tag (US price TBD), if demand is high they could get backed up pretty quick as we’re told they can only make two rims per day. You can’t rush perfection.



  1. Ripnshread on

    Love the design. Absolutely 100% hate the claim that they weigh 399g because

    “since competitors have to use tubeless tape in the end, the 20g weight savings make for the equivalent of a 399g rim all things considered.”

    That’s the biggest load of horse sh*t I’ve ever heard. Btw, 419g is still light. Lets not start reinventing the way we take measurements for the sake of marketing.

    Again, incredible design, horribly dishonest marketing.

  2. Isaac on

    Tubeless 4 inch tires are awesome. The tube alone weight loss is 1 pound apiece and the ride is unreal. I’m glad they made this rim for year round riding, now someone just needs to build these into a $10,000 Borealis with XX1 that only weighs 18 pounds. I’m calling you out Fairwheel bikes.

  3. talkinSmack on

    Holy balls, that’s awesome. Can’t wait to see the production units and hear back on durability. More and more impressed with carbon innovation all the time.

  4. Herp-a-derp on

    Wow. That’s a terrible carbon layup, the wrinkles are visible in the close up pic. Those aren’t supposed to be there, lol.

    Subtracting 16g from the rim weight because they don’t “require” rim tape is bs. They also subtracted 16g, and then mentioned that it was 20g. Too early for basic math?
    I wouldn’t be surprised if most rims can hold air for a few minutes without rim tape or sealant. That’s not a big deal, nor useful.

    How about that spoke tension comparison? Comparing recommended spoke tensions for wheel building with what seems to be a spoke pull-through test number? Apples /= oranges.

  5. Bobby McGoo on

    Gorgeous rim. Unbelievable marketing BS… WTH, Italy? Ripnshread got it right.

    And is Alchemist actually shipping product now? That’s awesome. I love their designs, but it seemed like they were just vaporware for the longest time.

  6. Mauro on

    Hello, my name is Mauro Bertolotto and I have been part of the designing team that created our enso685 rim.
    I want to answer to Rip about his note on the way we declared our rim weight.
    Sorry for my english, I’m italian and I hope to be clear enough explaining our point on this topic.
    Sometimes is difficult to convey the REAL efforts to have a better product when marketing is in the middle. What really counts are not figures of an item but the value of the full package.
    Marketers are playing with this. A lot.

    We need to explain people we consider the wheel as something as a whole and not just a rim, just a spoke or just a hub.
    Is a producer declaring the truth saying the rim has a definite weight without telling that it needs 32 steel washers to be assembled?
    Is a manufacturer honest when he declares the weight of the pedals without noting how much weights the custom cleats?
    People is ‘naturally driven’ to forgot that what counts is not the single weight because it’s easy to move the weight on something you can discard from your press release.
    Our goal was to explain that our rim can run without tape.
    Cheating was not a purpose, sorry if someone misunderstood us. We are anyway VERY light, we do not need to cheat.
    Our intention was to explain this system have been refined and optimized on a very high level and that our rim runs with the same exact weight as a 399 grams rim that still have to use the tape. IN fact we declared we reached this goal with a design that is not requiring tape.
    We tried to explain this is the a result of an engineering rethinking process. 415-20 = 399.
    This have been declared as a ‘technology’, one of the four that permitted us to produce this rim, named ’40 below’.
    We pointed it out as a technology to be very clear about the nature of our way to reach our goal, we gave a name to the technology as much clear as possible to avoid possible misunderstandings.
    No needed washers, no needed tape. Just a new approach.
    Thanks for your comprehension and sorry for the misunderstanding.

  7. EpicThroatBeard on

    i like that “i’m upset with marketing claims” line of thought. being shoveled on a product that is not even available

  8. Ripnshread on

    Actually, now that I think about it (well past my coffee now), the design of the rim with the reinforcing near the spoke holes in neat. But the claims that it will hold air will not in my well-educated-and-experienced-in-the-manufacture-of-high-end-wheel-systems mind will not…er…hold air. Even with incredibly high spoke tension (which is useless as far as stiffness goes past a certain point and will only lead to premature rim failure) only used to keep the air in, a spoke nipple in this configuration will “burp” on compression. Now with 4″ tires at low pressure on snow or sand you may never get to this point, but the spokes at the point of impact (compression) on a wheel naturally loose tension while the ones adjacent increase in tension. Anyone can test this for themselves by leaning on a wheel putting pressure directly down and feeling the loose lower spokes. So, in practice if you hit a hard bump…your spokes would break the seal on the “goo” and burp and then hiss until the (frozen?) sealant can refill a hole. Love to know who is making the sealant for snow bikes that contains some type of anti-freeze yet is formulated to seal carbon and aluminum as well.

    Again, I do like the direction they are taking with the use of carbon to make great rim shapes.

  9. Mindless on

    Skipping tape is stupid. Broken spoke anyone? At least you can cover spoke holes with a tape patches, it will be like 4g per wheel. But than they can not promote (deleted) weight anymore, I guess.

  10. Collin on

    My road bike weighs negative 27lbs because if I would have decided to run chrome 22’s off my escalade it would have been nearly 40lbs.

    But in all seriousness, Mindless brings up a good point. Even with quality spokes, stuff does happen (stick/derailuer/nasty crash) and a broken spoke happens. Now instead of having an out of true wheel that you can normally limp home on, now you have a flat tire. An external threaded nipple and rotatable straight pull spoke (like Mavics) would be an answer to this dilemma.

  11. Michael Braun on

    Like it or not, I applaud the invention and initiative. I think we users benefit because we have more options. For now we had only HED and Carbondale, now there’s some more competition, which will ultimately make products better and cheaper. Congratulazione Mauro!

  12. Bobby McGoo on

    Mauro, admitting you’re lying and saying it’s ok because everyone else does it isn’t helping. People want to know what a specific part weighs. Not what the “system goals and functions” are. If you’re selling a complete wheel, just show the wheel weight, no big deal. But you’re selling an individual item, and no one likes how you’re manipulating your data.

    Also, some good points about the need for spoke tape. I’ve popped spokes on a ride, and if it wasn’t for the tape, I would have been boned.

  13. Mauro on

    Hi Bobby
    This rim does not need tape but it’s always possible to use it for long races. There is a lot to learn about this story. We just tried to reach a target weight eliminating the only non-structural part. Globally this idea can work but you are right: focusing on a single component this point is only confusing. The best we can do is offer complete wheels and we are working on this. It’s complex because axle lengths looks growing overnight (look the Ice Cream Truck) and there are very few manufacturers in this moment.

  14. Andrea on

    Wow, so much temper is raised for a rim! :-O
    People calling out “liars” some manufacturers without even having bought something from them. That’s hilarious.

    That guy has made an official statement, apologizing for his bad English in the very first place; still, a few wild ones won’t get it and try to hold their pointless position.
    FYI, in the real world, the vast majority of carbon products would have weight discrepancy of 5% or more. How many manufacturers do tell you this? Not many, and maybe they are not even obliged to this, unless they are selling a product clearly stating a guaranteed weight.
    What’s the point of making such a fuss about those 20gr., then?

    I’d say is wise to think twice and take one or two chill pills before boasting this so-called-knowledge-that-comes-from-reading-forums against some guys that are actually working hard.
    It’s just fair.


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