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!
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.
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.
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.
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.