Nut, Goddess of heavens and sky, barrier between chaos and order, she is our ultra-responsive Hardtail Mountainbike

The Request
Our mountainbike enthusiast wanted us to build him the last frame he’d ever need. A frame comfortable and fun on an all-day epic, yet readily capable of the occasional XC race. In particular he wanted a frame which was easy to jump, could handle the bigger hit descents but which gave him confidence that he was not about to go over the bars. He was not too bothered about grounding the pedals on tree-stumps or rocks, but wanted a frame which gave him the precise control level needed to choose the perfect singletrack line. A powerful guy, he also wanted a rigid power transfer yet a low back friendly and compliant rear-end ride without the weight penalty of full suspension. He wanted it to feel solid yet not cumbersome.

The Task
Whew! Quite a wish-list!...
To jump the frame we’d need a shorter rear end and a shorter stem. To handle descents we’d need to correct for a longer travel fork. To race we’d need a shorter travel fork and aerodynamic position. To be comfortable all day we’d need a more upright and laid-back position. How could all this be possible?!

The Solution
The Frame & Forks
We designed the frame around an adjustable pair of Rock Shox Reba Team forks, with on-the-fly 85-115mm travel adjustment, and handlebar-mounted remote lockout. By correcting the frame geometries this fork would metamorphose the bike from aerodynamic racing steed to laid-back all-day 100mm travel bike to all-mountain descent capable 115mm travel cruiser.

In order to overcome the customer’s fear of going over the bars, we would need to move his centre of gravity back and down relative to the front axle. We did this by lengthening the toptube, dropping the bottom bracket a fraction, and correcting the steering geometry to account for this. This facilitated our next task of “jumpability”. With his centre of gravity nearer the back wheel (running shorter chainstays) we also ran a shorter stem- meaning that both the front and rear ends could be lifted faster when required. The shorter stem allowed a more direct steering action, and by simply lengthening the fork the handling could become more stable and relaxed. The shorter chainstays in turn produced more direct power transfer, yet effectively made the rear less compliant, which was not what we wanted.

To counter this we employed our custom Atum22 Shockwave design. Laterally rigid but vertically compliant, we designed this unit to absorb high-frequency shock which would be particularly common on epic days out on harder summer terrain.

The mainframe was triangularised through the toptube for cable routing and torsional rigidity before being sloped aggressively for improved rigidity and decreased weight. To further meet the customer’s need for efficient power transfer we fitted a pair of custom Atum22 bottom bracket fillets to resist BB warp under intense out-of-saddle efforts. Three bottle cage mounts were installed plus one crud-catcher mount for those more epic rides.

The Kit
An immensely capable but light duo of hope mono mini rear and mono m4 front hydraulic brakes were routed through the bespoke cable-guides to produce a hair-raising stopping effect, made “safer” by the lower and rearward centre of gravity.
The trusty range of XT drivetrain componentry and SRAM chain were fitted to Mavic Crossmax wheels for mileage-proven performance.

Up front the customer’s request for a solid front end was fulfilled with bespoke Atum22 ski-barends, bars, and stem- all in harder-than-nails titanium 3AL-2.5V. For further comfort a pair of wrist-saving Ergon grips were fitted.

The bike was suitably finished with Atum22 titanium seatpost and seatcollar, Selle Italia SLR XC saddle, and a pair of durable titanium Atum22 waterbottle cages. For knee-saving purposes we fitted a pair of crankbrothers ti eggbeater pedals. This build was subtly garnished with the signature Atum22 pink Chris King headset.

The Result
At 10.9kg (24lbs), this equivalent 19inch frame isn’t quite the lightest… but it is the most capable! Stable when high, responsive when low, fast on the flat, fearless on the descents, and precise on the singletrack;

When you say jump, the Nut indeed says “how high?”