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THE 3.7 PROJECT

THE DEVELOPMENT OF THE RECORD-SETTING ROAD BIKE

The lightest bike in the world shares the same genes as the Canyon F10 carbon frame.

We took on the challenge and would not accept any preconceived boundaries. At Eurobike in 2004, Canyon – together with Hans Christian Smolik – presented the lightest road bike in the world. Based on the Canyon F10 carbon frame and equipped with ultra-light parts, the complete bike – ready to ride – weighed a sensational 3784 grams. Our futuristic technology shows what can be achieved with this relevant development work. This technological showpiece has many specifically developed parts… and these patented components are destined for future production models. Weighing a mere 6.4kg the new Ultimate CF 9.0 SL – which shares the genes of the 3.7 Project bike – shows what is currently possible for production race bikes, while offering the best possible ride qualities and handling. Thanks to the Project 3.7 Record bike, the boundaries for the future’s lightest race bikes have been pushed aside.

As described by Hans Christian Smolik

Based on the F10 frame I have tried to build the lightest road bike possible for Canyon. The work can be seen as a study and a testing platform of the technical limits. In addition to the use of super-light standard components, the majority of the components had to be hand made. The choice of materials therefore was not weighed in economical terms or from the perspective of production, but more in terms of weight reduction and if the individual part could be modified by hand. As a design engineer, this type of project forces you to step out the box and look for new and exciting ways of doing things. Through this you gain knowledge, which can then flow back into the development of production bike parts. For this project the hubs, brakes and gearing were developed as if they were prototypes headed for production… in many places on this bike, I replaced 6061 aluminum with a magnesium-alloy that has a strength of 320 N/mm2.

The following lists how Hans-Christian Smolik approached the individual components of this record-setting bike and in turn, displays the revolutionary ideas that took shape during the bike’s development.

Frame (Canyon) 818g and Fork (Canyon) 260g
The F10 frame was developed in cooperation with a world-renowned composites design institute. This partnership spawned completely new techniques that were used for many of the frame’s details… an example being the squared tube shaping at the base of the seat tube that improves bottom bracket stiffness by over 20%.

Tour magazine – in recent years – identified low stiffness as a shortcoming in the traditional straight steerer tubes on carbon forks of current road bikes. This is the reason we developed a conical, tapered steerer tube which has a diameter of 38mm at the lower headset race area. Just as with the Motivation fork – also tapered, but to fit a 1 1/8” headset – the carbon fibers in this new fork run uninterrupted from the steerer to the fork crown and into the fork legs. Therefore these “slim” carbon legs allow for stability and comfort in “oversized” proportions.

For the Project bike the light 970gram 58cm production frame was given a coat of weight-saving paint. The dropouts were built from carbon with a magnesium insert for contact at the wheel axles. For the headset and bottom bracket alloy inserts were replaced with carbon. Using these methods the frame weight was reduced to 818 grams!

The fork was also given just a hint of clear-coat. Dropouts, steerer expander and the conical adapter for the headset were also made out of magnesium… this allowed us to slim down the weight of the production fork to 260 grams.

Headset (Canyon) 73g
For the headset we had to minimize the weight, because the naked angular sealed bearings already weighed 49g. What this means is just as on the production model, the lower race with a 52mm diameter, can better withstand rough road surfaces and provides increased lifespan. The remaining grams of weight can be accounted for by the alloy installation bolt, the upper race spacer and a carbon top cap.

Seat post clamp (Smolik) 8g
I used a handmade alloy clamp and a titanium bolt, with a combined weight of 8g. By reducing the material in the clamp it works like a tensioning band and therefore exerts an equal amount of pressure around the seatpost.

Cranks (Propeller Titanium) with bottom bracket 296g
At this weight – complete with a bottom bracket and weighing 330g – the Propeller cranks have no competition. I replaced the chainring spider with a carbon version and have done away with the bearing races. Next, I customized the carbon bottom bracket adapter within the frame, so that the pre-preg lay up could better withstand the loads experienced is this area, and to reduce the inside diameter to that of the 31mm bearings. The final weight is only 296grams.

Stem (Syntace) tuned 88g. Bars (Schmolke) 125g
For the bars (125g) and the stem (88g) we called upon the proven production models from Schmolke and Syntace. Thanks to my reinforcement – a ferrule which is bonded securely inside the steerer – I was able to machine down the stem at the clamp to slightly reduce the weight.

Brake Levers (Smolik) 94g
For the brake hoods and levers (together 94 grams) I took a carbon fiber sheet and wrapped a pre-fabricated core. It was then pressed tight using a textile band. When the carbon hardened the core was drilled out. At the clamp and pivot areas, the hoods were then reinforced with bonded alloy inserts. In addition, I made a carbon mount for a shift lever machined from magnesium and bonded it to the right hand hood.

Chainrings (Tune Carbon) tuned 72g
The minimum weight that can be achieved by filing down alloy chainrings is about 85g. Because other light bikes were already being built with carbon chainrings, we couldn’t explore this path. The 13grams saved by using carbon chainrings are sure to weigh heavily on the durability and resistance to wear. Hand modified, shortened chainring bolts remove another 8grams from the total.

Pedals (Speedplay) 75g
The mounted Aerolight pedals – which have a round plastic tube which runs on bushings over a titanium axle – have no competition at their weight. The slightly larger shoe mounted adapter takes care of the pedal’s engagement system.

Chain (Connex) 232g
We decided on a Connex chain with drilled-out titanium pins. At around 232 grams it is approximately 50 grams lighter than a Campagnolo 10 speed chain.

Tires (Tufo) 229g
18 mm Tufo tires weigh 109 and 110 grams.

Cassette (TA 12 – 18) tuned to 78g
The original TA alloy cassette has a thickness of 3.4mm around the cassette body and therefore could be machined towards the top of the 1.8mm wide sprockets. In this case the still functioning cassette weighs 78g including the shortened lock-ring.

Front derailleur (Shimano Dura-Ace) tuned to 65g
Because of its excellent function, I decided to use a Dura-Ace front derailleur, which through filing and tuning with titanium bolts, was able to reduce in weight to 65 grams.

Wheels (Carbon rims / Smolik hubs) 823g
The wheels (total 823 grams) are built with Reynolds carbon tubular rims weighing 212 and 224 grams. For these I made a prototype 18 hole front hub (54 grams) by hand. To be used with radial lacing, the hub has a 6mm flange extension above the spoke holes to provide security against the hub flanges being ripped out. Equipped with four bearings it will also be able to withstand constantly high loads. The bearing caps are made of magnesium.

The 24 hole rear hub (130 grams) is also a prototype. It has a modified Hügi ratchet mechanism and a carbon axle. The axle is made from uni-directionally laid carbon and has greater stiffness than an alloy axle with the same dimensions. The circumference of the axle is maintained through the use of magnesium end plugs and a thin alloy casing at the bearing contact points. The cassette body is trimmed down to 29mm and is magnesium lined for the outer bearing seat.

The skewers (together 15 grams) are machined from 5mm of aerospace alloy. A magnesium locknut is securely bonded to the axle, and the other locknut provides the tension for the axle with a 5mm Allen key.

The front wheel is laced with 18 chromed (no longer available) Prym spokes from my own collection. They have a diameter of 1.8mm that tapers to 1.4mm in the center. For the non-drive side of the rear wheel – where straight pull spokes are required – I preferred the somewhat heavier Sapim Laser spokes.

From the beginning, the spokes in the carbon rims were problematic. The barely 7.8mm wide holes in the rim bed only allow a spoke nipple washer of the same size. With high spoke tensions these pressed slightly against the carbon rim. For this reason – following the bike presentation in Friedrichshafen – I bored out the spoke holes to 10mm and added larger washers bowed circumferentially – with a special tool – to better follow the rim side-walls.

Brakes (Smolik) 96g
Current dual pivot brakes with a lever ratio of 1.3 to 1.5 weigh around 160gram. Obviously we needed to find something lighter. The guidelines were to replace alloy with magnesium, using more material at the critical points while squeezing the most possible braking power from the smallest amount of material. This thinking led to the stretched out form of the “X-Brake” with a concealed spring which has been made larger than average at the point of the greatest deflection.

Gears (Smolik) 56g
The gearing was also planned as a prototype. To avoid working against a spring, I thought about using a twin cable derailleur. The gears would be operated from a wheel on the brake hoods – in order to avoid patent disputes with Shimano and Campagnolo – even though it was me who first invented gears operated from the brake hoods. The derailleur swing arm and body were rebuilt from magnesium. I built the parallel parts and the rocker arms from carbon and including the mini installation screws, the weight came to a total of 56grams.

When fitted, I found that the shift indexing was useless, as the cable outers caused huge losses in tension. When the cables were pulled very tight, these loses were gone, but so to was the light shifting action. The gear shift wheel could barely be moved by hand. Therefore the gear wheel would have to be replaced with a small gear lever, and the indexing was forgotten. In fact the gearing does work, however the principle will not be pursued by Canyon.

THE 3.7 PROJECT

THE INDIVIDUAL PARTS:

Rahmen: Canyon 818g
Gabel: Canyon 260g
Steuersatz: Canyon 73g
Sattelschelle: Smolik 8g
Kurbel: Propeller Titan mit Innenlager 296g
Vorbau: Syntace 88g (getunt)
Lenker: Schmolke 125g
Bremsgriffe: Smolik 94g
Züge: Smolik 35g
Sattel+Stütze: Smolik 138g
Kettenblätter: Tune Carbon 72g (getunt)
Kettenblätterschrauben: Smolik 8g
Pedale: Speedplay 75g
Kette: Connex 232g
Schnellspanner: Smolik 15g
Reifen: Tufo 229g
Ritzel: TA 12-18 78g (getunt)
Umwerfer: Shimano-Dura Ace 65g (getunt)
Schalthebel: Smolik 6g
Laufräder: Carbon-Felgen/Smolik-Naben 823g
Bremsen: Smolik 96g
Schaltung: Smolik 56g
Spacer: Smolik 22g
Kleber/Luft/Lenkerband: 35g
Aufkleber+Führung:   4g
Das sensationelle Ergebnis:   3751g