Kuroshiro, the Italian brand dedicated in extreme performance ‘Plus’ size and Fat bike
composite rims, is presenting its fourth product in the ensōrange: 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 last 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 Fatbikes designs are built for exceptional performances on soft ground and our ‘superwide’ design keep a lot of our previous ensō685
model: offset of ensō6105 is the exact same of ensō685 and weight is contained in
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’.
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 fatbike rim produced. Ensō6105 is designed to
run on Fatbikes 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
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
ensō6105has 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
ensō6105to 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
ensō6105rims 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
The reinforced spoke area is so strong and precise that it’s possible to design a rimnipple interface that is ‘almost’ sealed.
Under tests in various conditions ensō6105with no sealant and no tape takes several
minutes to deflate. Considering the low tire pressures involved, and the amazing efficiency of modern sealants, ensō6105finally 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.
Kuroshiro ensō6105is 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.