New! 105mm Carbon Rim from Kuroshiro called the ensō6105


With Eurobike kicking off today, Kuroshiro is introducing a new carbon fat-bike rim called the ensō6105. The 6 in the name is for 26″ rim and the 105 designates the width in millimeters.

You may recall the zig-zag design of the spoke reinforcement area from other Kuroshiro rims as they no make four sizes for the fat-bike and plus bike markets.

  • ensō685 – 26x85mm Fatbike rim to fit 170,177,190,197 rear spacing fatbikes
  • ensō950 – 29x50mm 29+ rim made also to fit several 29” frames with a tire up to 2.4
  • ensō747 – 27.5x45mm for 27.5+ made to fit also several 29” frames with tires up to 2.8
  • ensō6105 – 26x105mm Superwide Fatbike rim to fit 190 and 197 rear spacing fatbike





Check out the official Press Release below for more details. Expected European delivery is slated for October 2015 with an expected price of 899 € with US availability and pricing still to be announced.

Friedrichshafen (DE), August 26th 2015 – Kuroshiro, the Italian brand dedicated in extreme performance ‘Plus’ size and Fat-bike composite rims, is presenting its fourth product in the ensō range: Kuroshiro ensō6105. Ensō6105 is the extreme performance 26”, 105 mm wide fat bike rim designed to deliver the maximum floatation and control.

“Fatbiking is evolving at the speed of light” says Mauro Bertolotto, Raceware’s owner and manager, the Italian company owning Kuroshiro brand, ‘”The latest composite frames are very capable and can deploy performances that only two years ago was impossible even to imagine. All the Fatbike component industry is under pressure designing products addressing the need of bikers that want the highest performances from their fatbikes and our Ensō685 is giving us big results in this. In the last year we started developing a new project able to add 20 mm in width to our rim to deliver the ultimate floating and grip performances. Adding 20 mm to our ensō685 rim moved it to a 105mm width, that is the widest fatbike rim ever produced since the “wide” rim standard measurement is 100mm.

New Fat-bike designs are built for exceptional performances on soft ground and our “superwide” rim design builds off our current ensō685 model: offset of ensō6105 is the exact same of ensō685 and weight is 525 grams.

Evaluating weight for a product so unique is difficult. A way can be the ratio between weight and width. 525 grams for a 105 mm means this rim has a weight of 5 grams per mm of width. This is just a sign of the performance level reached by fatbike components nowadays.

We designed this rim for use on snow or very soft sand when weight and floatation are the focal points and for all conditions when extreme grip is a priority”.

Technical features

These models share a lot of technologies that have been developed for this line. ensō950 and ensō747 have a very special hybrid structure, unique in the industry, with a boxed chamber filled with a rigid cell polymer to grow stiffness reducing weight and ensō685 and ensō6105 exploits the ‘All Terra’ tecnology using a bead lock structure to enhance impact resistance.

Here there are the technologies developed for the ensō line.

1. Alpha-Ridge® (patented)
105 mm. rim width is today the widest fat-bike rim produced. Ensō6105 is designed to run on Fat-bikes with 190 or 197 mm rear spacing and can fit both 4 and 5 inches tires. The open rim shape (not based on a box section) has a structure similar to that used in wheels on cars, motorcycles and trucks since the start of last century. F1 racing cars started using non-box section composite rims decades ago with impressive advantages in weight and performance. Kuroshiro engineers realized that a spline connecting the high-stress points of the rim (the offset spoke holes) that is impressively efficient. This design is now patented and increases rim stiffness more than 18% with a negligible weight penalty compared to non-splined designs.

2. Allterra design
Some fat-bike rims eliminate the bead lock to save weight. In theory, this does not compromise performance and safety, but this is only true on soft ground. Kuroshiro engineers decided to keep the bead lock in place. Kuroshiro keeps the bead lock to guarantee the strength and impact resistance necessary to deal also with compact ground.

3. Reinforced spoke interface
ensō6105 has a very strong spoke interface. A special design is used to put more material where the spoke holes are placed, to distribute stress more efficiently. This design completely eliminates the need for reinforcement washers, allowing ensō6105 to support higher spoke tensions, while reducing weight and complexity. A set of wheels built with light fat-bike hubs, high tension spokes, alloy nipples and ensō6105 rims has a weight below 1,750 grams, which is on par with several racing 29-inch XC wheels.

4. Tapeless design
Tapeless design will probably be the most discussed feature of Kuroshiro ensō6105 unique design. The reinforced spoke area is so strong and precise that it’s possible to design a rim nipple interface that is ‘almost’ sealed. Under tests in various conditions ensō6105 with no sealant and no tape takes several minutes to deflate. Considering the low tire pressures involved, and the amazing efficiency of modern sealants, ensō6105 finally offers a Tubeless Tapeless design. The proprietary Alpha-Ridge® design, with spoke holes optimized to match the nipple shape, combined with high quality sealant creates a seal between the rim and the nipples. The typical ensō6105 weight is 525 grams. The tape used to seal a set of fat bike rims has a weight of 40 grams.

5. Interlaced Layer Structure
To grow strength reducing weight the carbon layering hand made process is Interlaced moving the conjunction of the layers in geometrically opposed positions. This is enhancing impact performances and durability even if production is more complex and requires higher quality control.

  • The Kuroshiro ensō6105 is 100% made in Italy.
  • Delivery for ensō6105 will start October 2015 through a selected distribution network.
  • Recommended retail price per rim is 899 €. US price TBD.
  • For questions a or extra specs Kuroshiro ensō line please write to:
  • For orders a list of distributors is available asking to:
About Greg Smith 1127 Articles
Greg Smith, known to many site visitors as Sven Hammer, founded in 2011 and the site quickly became the #1 online community for all things Fat. You can currently find Greg outfitting Everyday Cycles; a Milwaukee, WI retailer of gear for fatbikers, adventure cyclists and urban assault riders.


  1. I wonder what the weight limit restriction will be? The 85mm version has a limit of 200lbs (91kgs), which renders them useless for a majority of the grown male population geared up.

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