Retired electrical engineer Jean-Pierre Schiltknecht (from Zurich Switzerland), has developed an electric bike that weighs only 7.66 kg (16.9 lbs). This is one-quarter the weight of most commercial E-bikes available in Europe. He calls it the ” Montanara Volta.”
(Article originally written in German by Martin Platter for the “Neue Zurcher Zeitung” [New Zurich Newspaper] @ http://www.nzz.ch/ )
I rubbed my eyes in astonishment as an elderly man shot up a steep path at high speed in the forests of Kusnachtertobels, just east of Lake Zurichsee. A faint high-frequency hum revealed that he was accelerating with more than just his own muscles. Once he came to a stop, he smiled mischievously at the faces of stunned bystanders. The man on this carbon-fiber E-bike is Jean-Pierre Schiltknecht, a 74 year-old avid mountain cyclist. The wily senior assured me he has been active with mountain cycling “Since the inception of the sport!”
“Guiness Book” record-holder
Schiltknechts life has been a living example of inspiring excellence. In his profession as an electrical engineer, he developed a philosophy that he passed along into his hobbies of running marathons, high-performance DIY model gliders, and mountain biking. A philosophy of adding new technology to his life that improves efficiency.
Every fiber of his extremely fit body betrays his life motto; Weight reduction is vital to peak performance. But…what if your strength and endurance gradually decreases with age? Should you just stay home, leaving your favorite hobbies as a distant memory?
Schiltknecht answered this question in a pragmatic way, like the restless tinkerer that he is. Others have quickly embraced half-measures and settled for the easy compromises, but that has never been his style.
His early hobby was designing and building model aircraft, while paying careful attention to every gram of weight. His own custom design of electrically-powered motor-glider won four electric flight world championships in Europe (1986-1992), and six titles in the United States. In 1991, he designed and built an 800-gram solar-powered model aircraft with a wingspan of almost 2-meters…and it set a world record flight of 10 hours, 43 minutes, and 51 seconds, which was officially recorded in the Guinness Book of World records.
Using that same meticulousness, he built a mountain bike out of titanium in 1995, and it is the lightest in the world. It weighs only 5.855 kg (12.9 lbs), and it became his second “ Guinness Book” entry. His latest entry into the record-books came in 1998: only 9.74 kg (21.4 lbs) for the lightest electric bike, of course using his custom titanium frame. The power was from an electric friction-drive similar to the Solex moped, powering the rear tire, but…that drive system would prove to be unacceptable for an off-road mountain bike.
This was a problem that Schiltknect pondered constantly and tinkered with. Electric hub-motors are becoming widely used, but he considered them out of the question because…as a professional electrical engineer, he knew that the lower RPMs of the hubs were not the most efficient way to power any machine, and they were also noticeably heavy. For an E-mountain bike, he knew he wanted high efficiency and minimum weight.
He felt his goals could be best met by adding power to the bike at the bottom-bracket, allowing the motor to use the most efficient gear that it needed, while seamlessly allowing the rider to add pedal-power.
He put in countless hours of work designing the drive system, motor, and controller. One challenge was addressing how the high motor torque would affect the ultra-light frame he chose, a Scott Scale made from carbon-fiber which was outfitted with the lightest components available on the market. Schiltnecht named his creation the Montanara Volta (Volted Mountaineer), and it weighed in at an incredibly light 7.66 kilograms…including a 240 watt-hour battery.
The electric motor is located just above the bottom-bracket, and it assists him with a range of power from 250-watts up to 400-watts, applied directly to the outer chainring. The power is not activated by pedaling through a pedelec sensor like many commercial E-bikes available in Europe. Instead, he chose to use a thumb throttle, which he has hidden under a classic bicycle bell.
Built into the bell cap are tiny LEDs that warn him about his level of energy consumption, and also how much battery power remains. The former marathon runner states “My aim has always been to use this bike 100% for off-road only” since E-bikes are legally restricted to a mere 250-watts maximum in most of the European Union countries that he enjoys visiting.
Lifts easily over obstacles
When he was choosing what battery pack to buy from vendors in Asia, he decided to build a custom pack that he would solder together himself from Lithium-Ion cells. When he chooses to ride with his larger battery pack that provides 800 watt-hours, the total weight of the bike increases from 7.66 kg up to 9.90 kg (21.8 lbs). With the impressive marathoner adding some athletic pedaling, the larger battery allows day tours of a distance up to 180-kilometers (120 miles), and climbing over 4000-meters (13,000 feet) in elevation. Says Schiltknecht, “In 2010, I even managed a one-day tour in Valais through the Diablerets [mountains]”.
The light weight of this bike makes it very easy to lift across cow guards in the road, and also over the fences and fallen boulders that are frequently found blocking the mountain paths, without any problem. ”Thanks to the electric assist, my weekend rides have almost no limits, and I can now enjoy them very much”.