Osiris SL
The Lord of Divine law and Nature, the Osiris is our showcase of Road-Riding nirvana. In Egyptian mythology, Osiris symbolized the creative forces of nature and the imperishability of life, and so does this bike. Cyclosportive, fast audax, or longer road races are where the Osiris will shine. And shine. And shine.

The Request
Our Cyclosportive fanatic wanted a frame which didn’t fatigue him more than the task at hand. A frame which would perform with reliability and comfort to the fore. Which would take him through sweeping alpine descents with confidence in braking and fast cornering ability, and which would save every ounce over the thousands of meters of climbing he would be doing. Finally, and at 6ft2, he wanted to be able to better tuck in in pack riding, saving those vital reserves over the distance, yet without hurting his back in a crouched position.

The Task
In order to satisfy these demands, we would need to lower the rider without risking his grounding a pedal. We would need to push his centre of gravity back to allow him to brake later. This could not, however, affect his weight distribution in the corners nor his optimal physiological position over the pedals for maximum efficiency. By lowering him a touch, opening his hip angle to de-stress his back, and shifting him into an optimal pedaling position we could hide him from the wind a little more whilst putting him in a more comfortable and sustainable power position.

The Solution
So this we did. We convinced the rider to go to a 90mm stem for precision of steering, which allowed us to “push the front wheel out” and improve front-end braking. Having suffered from knee problems, it did not take us long to convince him to switch to speedplay pedals, whose lower stack height would allow us to lower the BB height by a crucial 8mm to get him out of the wind whilst drafting. We calculated that this would save over 25watts in the pack!
As the centre of gravity shifts back and down, the rider is less likely to lift the rear end under hard braking. So to enhance rear end comfort and at the same time further encourage the rear end to stay down, we reverse-curved the seatstays to deform when braking in a manner which pushes the rear wheel more firmly to the ground!
We custom-built DT RR1.1 rims onto Tune road hubs with aerodynamic bladed spokes which at 1380g would be one of the toughest, lightest, most aerodynamic wheels for this purpose.
The front end received the ergonomic ITM K-sword handlebars and 4-ever stem combination whilst for the forks we used the radically light yet stiff Easton SLX.
Dura-ace drivetrain was complimented by a KMC lightweight chain and titanium hardwared TRP brakeset. Garnished with the usual Atum22 logos, pink Chris King headset, and an engraved emblem personal to the customer, the bike was destined not just to function well, but also to be beautiful.

The Result
Just as planned, the Osiris SL justifies its “SL” rating. For an equivalent 58cm frame this fully built bike weighs in at a stifling 7.3kg! Only 400grammes over the legal weight limit, but with the comfort and reliability of most 9+kg bikes.
The steering is at first scarily direct, yet riding hands-free the bike is as stable as it comes. This directness is soon welcomed as the shorter wheelbase and stem do their trick in allowing you to put the bike where you want, when you want. The comfortable front end and optimized riding position allows the rider to save every watt available for the final climb of the day.
Osiris was one of the original children of the greek god atum, and so had heavenly rights… in this case the Osiris delivers none other than a heavenly ride.