ATUM22 | bespoke titanium bicycles

	Tefnut, God of rain and storms, this expedition Touring Bike fears no extreme. Weatherproof as an otter, strong as an ox, and versatile as a chameleon - this bike is built to take everything you throw at or on it, and come begging for more. They say there’s no place like home. With no fixed abode the Tefnut is always… at home. The Request … was really simple. But not at all. Our touring cyclist wanted the most comfortable, reliable, capable, and robust expedition tourer we could build. And he wanted it to be light. He wanted the parts that could break to be easily replaceable, and the parts that couldn’t be replaced easily… to be unbreakable. Simple, no? The Task We had to do just as the customer wanted- to make the frame, gears, and brake levers immensely robust whilst using easily replaced 26” tyres, 7 or 8-speed chain, and a serviceable v-brake system. The Solution Gearing up the frame; Ultra-reliable gear system? Look no further than the Rohloff speedhub [rohloff.de] - 14 undestructible gears with a 526% range, all sealed within a low-maintenance rear hub. Which makes for just one chainring up front, and yes- you got it- effectively a single-speed chain setup. In order to accommodate this system many frames use slider dropouts or an “eccentric bottom bracket shell”. The former is not up to a heavy touring task, and the latter is often not the best solution as the bottom bracket is lifted towards the saddle as the chain wears and the shell needs to be rotated. So we sourced a highly machined and engineered, ultrareliable yet remarkably light Bushnell eccentric bottom bracket [novacycles.com] which meant we could machine a solid BB shell from one large lump of titanium, for greater strength where it matters in touring. Above: A22 Eccentric BB Shell, complete withsuper-neat double-pass welds Below: Rohloff Speedhub and zero-resistance Reelights We then custom-designed some specific Atum22 rohloff rear dropouts, and added beefy mudguard and rack eyelets to the rear end. The Cockpit One of the traditional drawbacks to the Rohloff gearing has been that it is only flat-bar compatible. Not good enough for us. So we measured the customer’s hand and designed a pair of ergonomic drop-bar-ends onto which we fitted drop-bar brake levers for descending and a more aerodynamic position. These were geometrically compensated to allow for reach differences in road and mountain bike bar setups. On the flat section of the bars went the Rohloff grip shifter, but also a pair of auxiliary brake levers (with internal cable routing) and some wrist-saving Ergon grips. So the best of all worlds- mountain biking technical capability and relaxed posture allied with road drop bar aerodynamics and braking power, and finished in an all-day comfortable package. Brakes can break Not content with the traditional incompatibility of v-brakes with road levers, we decided to “upgrade” the braking performance by fitting boosters (cam devices) and by running the front brake behind the bespoke Atum22 forkset. This harnesses a phenomenon called brake deformation to produce an even stronger brake progression. At the rear we engaged our special reverse-curve seatstay design to a similar effect. The unbroken internal cable runs ensured a weatherproof system and v-brake pads are a readily available part worldwide. Frame and Forks Whew, you’d think that would be enough detail to put into one bike, wouldn’t you? But it was still not perfect. It was not yet an Atum22 bike. We oversized the compact mainframe, making it lighter but more rigid. The customer expressed a wish to sit on the toptube whilst map-reading so we killed two birds with one stone by using a slightly square section to this. A flat top would mean more comfort, whilst the square join between the toptube and the headtube increased weld surface and hence strength by about 1/3rd at this critical point. We ran a very low bottom bracket- this bike needed stability and cornering ability and would not be used to race on. In order to have a frame which could-when the going got rough- be shouldered, we internally routed the gear and rear brake cables, and with Atum22 attention to detail drilled a small drain hole to the rear of the sloping toptube. Not happy with the huge weight penalty of comfortable and reliable steel forks, we designed our own tapered, ovalised, and shockingly lightweight Atum22 double plated crown touring forks. At 576g with full touring kit and clearance for a 2.3inch tyre, these forks are as strong as they are comfortable, and were the only solution befitting of such a well-considered design. Go anywhere, anytime Anyone for a night ride? This rider could not afford to carry battery-driven devices so we needed to use “onboard power” to run a reliable light system. A Schmidt Original Nabendynamo hub of legendary longevity [nabendynamo.de] was laced to a Sun CR18 rim and a twin light system (one flood, one spotlight) of the simple, reliable and effective Busch and Muller D-Lumotec Oval senso plus (automatic) and Schmidt E6-Z (giving equivalent of 20Watts at 100feet) was fitted. So as not to leave our rider unprotected from passing vehicles, we sourced rear lights from the innovative dutch Reelight company [reelight.com]. This runs off spoke magnets on the rear wheel and produces a constant flashing light while moving, with virtually no drag! Finishing Kit To finish the package we used industry-standard oversize SKS chromoplastic mudguards, hard-as-nails Atum22 titanium seatcollar and seatpins, and durable but light “Brooks-style” Selle Italia Storika leather saddle. No less than four bottle-cage points, adorned with stainless steel “replace me when I break” cages were fitted, to allow for more extended wilderness travel. The Result Well, if you’ve read this far you’ll probably have realized that this bike was a highly considered and intricately designed piece of titanium hardware. So how does it ride? Very well. Very, very well indeed. The steering is very predictable yet alive, the position is comfortable yet the drop bars allow for a faster aerodynamic feel. Amazingly our braking tests showed that this bike can stop at least as fast as any standard geometry road bike! A weatherproof engineering marvel- a true cycling nomad. The Tefnut.

Tefnut, God of rain and storms, this expedition Touring Bike fears no extreme. Weatherproof as an otter, strong as an ox, and versatile as a chameleon - this bike is built to take everything you throw at or on it, and come begging for more. They say there’s no place like home. With no fixed abode the Tefnut is always… at home.

The Request
… was really simple. But not at all.
Our touring cyclist wanted the most comfortable, reliable, capable, and robust expedition tourer we could build. And he wanted it to be light.
He wanted the parts that could break to be easily replaceable, and the parts that couldn’t be replaced easily… to be unbreakable.
Simple, no?

The Task
We had to do just as the customer wanted- to make the frame, gears, and brake levers immensely robust whilst using easily replaced 26” tyres, 7 or 8-speed chain, and a serviceable v-brake system.

The Solution
Gearing up the frame;
Ultra-reliable gear system? Look no further than the Rohloff speedhub [rohloff.de] - 14 undestructible gears with a 526% range, all sealed within a low-maintenance rear hub. Which makes for just one chainring up front, and yes- you got it- effectively a single-speed chain setup. In order to accommodate this system many frames use slider dropouts or an “eccentric bottom bracket shell”. The former is not up to a heavy touring task, and the latter is often not the best solution as the bottom bracket is lifted towards the saddle as the chain wears and the shell needs to be rotated. So we sourced a highly machined and engineered, ultrareliable yet remarkably light Bushnell eccentric bottom bracket [novacycles.com] which meant we could machine a solid BB shell from one large lump of titanium, for greater strength where it matters in touring.

Above: A22 Eccentric BB Shell, complete withsuper-neat double-pass welds
Below: Rohloff Speedhub and zero-resistance Reelights

We then custom-designed some specific Atum22 rohloff rear dropouts, and added beefy mudguard and rack eyelets to the rear end.

The Cockpit
One of the traditional drawbacks to the Rohloff gearing has been that it is only flat-bar compatible. Not good enough for us.

So we measured the customer’s hand and designed a pair of ergonomic drop-bar-ends onto which we fitted drop-bar brake levers for descending and a more aerodynamic position. These were geometrically compensated to allow for reach differences in road and mountain bike bar setups.

On the flat section of the bars went the Rohloff grip shifter, but also a pair of auxiliary brake levers (with internal cable routing) and some wrist-saving Ergon grips. So the best of all worlds- mountain biking technical capability and relaxed posture allied with road drop bar aerodynamics and braking power, and finished in an all-day comfortable package.

Brakes can break
Not content with the traditional incompatibility of v-brakes with road levers, we decided to “upgrade” the braking performance by fitting boosters (cam devices) and by running the front brake behind the bespoke Atum22 forkset.

This harnesses a phenomenon called brake deformation to produce an even stronger brake progression. At the rear we engaged our special reverse-curve seatstay design to a similar effect. The unbroken internal cable runs ensured a weatherproof system and v-brake pads are a readily available part worldwide.

Frame and Forks
Whew, you’d think that would be enough detail to put into one bike, wouldn’t you? But it was still not perfect. It was not yet an Atum22 bike.
We oversized the compact mainframe, making it lighter but more rigid. The customer expressed a wish to sit on the toptube whilst map-reading so we killed two birds with one stone by using a slightly square section to this. A flat top would mean more comfort, whilst the square join between the toptube and the headtube increased weld surface and hence strength by about 1/3rd at this critical point. We ran a very low bottom bracket- this bike needed stability and cornering ability and would not be used to race on.

In order to have a frame which could-when the going got rough- be shouldered, we internally routed the gear and rear brake cables, and with Atum22 attention to detail drilled a small drain hole to the rear of the sloping toptube.

Not happy with the huge weight penalty of comfortable and reliable steel forks, we designed our own tapered, ovalised, and shockingly lightweight Atum22 double plated crown touring forks. At 576g with full touring kit and clearance for a 2.3inch tyre, these forks are as strong as they are comfortable, and were the only solution befitting of such a well-considered design.

Go anywhere, anytime
Anyone for a night ride? This rider could not afford to carry battery-driven devices so we needed to use “onboard power” to run a reliable light system. A Schmidt Original Nabendynamo hub of legendary longevity [nabendynamo.de] was laced to a Sun CR18 rim and a twin light system (one flood, one spotlight) of the simple, reliable and effective Busch and Muller D-Lumotec Oval senso plus (automatic) and Schmidt E6-Z (giving equivalent of 20Watts at 100feet) was fitted.
So as not to leave our rider unprotected from passing vehicles, we sourced rear lights from the innovative dutch Reelight company [reelight.com]. This runs off spoke magnets on the rear wheel and produces a constant flashing light while moving, with virtually no drag!

Finishing Kit
To finish the package we used industry-standard oversize SKS chromoplastic mudguards, hard-as-nails Atum22 titanium seatcollar and seatpins, and durable but light “Brooks-style” Selle Italia Storika leather saddle. No less than four bottle-cage points, adorned with stainless steel “replace me when I break” cages were fitted, to allow for more extended wilderness travel.

The Result
Well, if you’ve read this far you’ll probably have realized that this bike was a highly considered and intricately designed piece of titanium hardware. So how does it ride?

Very well. Very, very well indeed.
The steering is very predictable yet alive, the position is comfortable yet the drop bars allow for a faster aerodynamic feel. Amazingly our braking tests showed that this bike can stop at least as fast as any standard geometry road bike!

A weatherproof engineering marvel- a true cycling nomad. The Tefnut.