No more uphill struggles

Written by: Proto Labs Ltd | Published:

If you're designing and making components for racing bicycles, weight is critical. As materials and manufacturing processes have advanced and improved, bike designers have embraced new opportunities to build lighter, stronger and faster machines. With the help of Protomold®, it's possible that the days of the derailleur gear system may be numbered.

For decades, the derailleur has been the best, tried-and-tested method for shifting gears. However, the derailleur's exposed position and fragile design makes it vulnerable and easily damaged, especially on mountain and cyclo-cross bikes. Even city couriers prefer one, reliable, low-maintenance single-speed.

Keen cyclists Christopher Lermen and Michael Schmitz used to work in transmission development for a Stuttgart-based luxury car builder, until they founded Pinion, in Denkendorf, Germany. Tired of chain-suck and unclogging and straitening recalcitrant derailleurs, in 2012, the two, intrepid engineers began production of their brainchild, the P1.18: a spur gear, consisting of two transmission structures connected in series to give 18 evenly graded ratios. Compact, light, durable and virtually maintenance-free it is protected by a sealed enclosure and securely and centrally integrated into the bicycle frame.

Without the services of Proto Labs®, however, the road to production could easily have been a rocky one.

In the summer of 2010, extreme mountain biker Felix Fröhlich crossed the Himalaya mountain range on a bike equipped with the prototype P1.18. Over 1,500Km, Fröhlich pushed the design to the limits of its endurance, climbing no less than 24,000 vertical meters in the process, without a single mechanical failure.

Inspired by their success, Lermen and Schmitz exhibited the gear design at Euro Bike 2010. Pinion development engineer Dominik Bernard recalls the reaction: "We had an incredible rush at the booth," he says, "from manufacturers, the press and from cyclists. From that moment on, we knew that we needed a production version as soon as possible."

In order to offer a complete bike with the Pinion gear system, manufacturers would have to create a specially designed bicycle frame, with a relocated centre-of-gravity. The pressure was on Pinion to deliver a fully resolved, series production model, so manufacturers could begin the work to create the frames and produce the bikes ready for customers.

"The team at Proto Labs helped find the right material," he says. "The choice for the handle was TPE, which is soft and pliable to the touch, has an interesting appearance and is tough and durable over time. This is an ideal combination for the critical interface between man-and-machine.

"As a substitute for the aluminium base support, which was too expensive for series production, we decided to use polypropylene (PP). We designed the part to be made from 2 component injection-moulding process. So, we had to make sure the materials we chose were compatible."

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