e-bike, only 7.66 kg including battery !

[Lebowski]

http://www.nzz.ch/lebensart/auto-mobil/ein-fliegengewicht-von-einem-e-bike-1.17318558

 

[Ypedal]

Damn.. weight weenie....

 

[Chalo]

...resulting in neither a good bike nor a good e-bike. But very light!

 

[spinningmagnets]

I paraphrased the Google translation from the original German for electricbike.com: http://www.electricbike.com/the-lightest-electric-bike-ever/

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.

(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 elederly 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 Guiness 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 “Guiness 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…it 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 incredible 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.

Lifts easily over obstacles
When he was choosing what battery pack to buy from vendors in China, 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 to from 7.66 kg up to 9.90 kg (21.8 lbs). With some athletic pedaling added, 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 enjoy them very much”.

 

[HAROX]

(From spinningmagnets fine translation)

I paraphrased the Google translation from the original German for electricbike.com: http://www.electricbike.com/the-lightest-electric-bike-ever/
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 enjoy them very much”.

...and folks, that's EXACTLY the sort of comment I would expect from Leonardo DaVinci. Thanks spinningmagnets.

 

[HypnoToad]

Damn that's light, my battery weighs almost that much!

 

[kfong]

Thanks for the translation, very inspiring read.

 

[JennyB]

560 watt hours extra capacity for 2.26 kg. What cells are those? :?

 

[2moto]

...resulting in neither a good bike nor a good e-bike...

How do figure that? Seems like the perfect e-bike to me.

 

[Chalo]

...resulting in neither a good bike nor a good e-bike...

How do figure that? Seems like the perfect e-bike to me.

Not enough structure to be adequately stiff for normal riding.
Way too little structure to be durable or fault tolerant.
No toughness at all; no way to absorb energy in an overload.
Not enough motor mass to sink significant heat, or to generate satisfying amounts of power.
Not enough battery mass to provide significant range, or probably power either.
No creature comforts-- inadequate saddle, hard grips.

It's the sort of thing that seems like a great idea in principle, but in practice there are very good reasons that even expensive, high quality bikes are not that light. In the business, we refer to such bikes as "stupid light", because they overreach for lightness at the expense of more usable virtues.

To put it in simpler terms, that's a one-crash bike that probably cost at least $20,000. Are you a gambling man? How large a bet would you like to make?

Chalo

 

[John in CR]

My ebikes are one-crash bikes, but not because of too little weight or strength. Crashing is simply not an acceptable option.

 

[Chalo]

My ebikes are one-crash bikes, but not because of too little weight or strength. Crashing is simply not an acceptable option.

And yet you ride a homebrew bicycle at automotive speeds on Third World roads, in a country well known for capricious traffic behavior. Hmmm.

 

[John in CR]

My ebikes are one-crash bikes, but not because of too little weight or strength. Crashing is simply not an acceptable option.

And yet you ride a homebrew bicycle at automotive speeds on Third World roads, in a country well known for capricious traffic behavior. Hmmm.

I stick almost exclusively to good roads that I know very well. As far as traffic goes, the drivers here pay far more attention (they have to), and are accustomed to all manner of slow moving objects in the road, so they're much more polite about sharing the space available. Without any doubt, I'm magnitudes safer than those at pedal speeds except for those in the Netherlands, and far safer than you guys even on dedicated bike ways. Just because my bikes will all do well above 50mph doesn't mean I ride that fast. 35-40 is probably my average at cruise. I use speed and acceleration to give myself space, and lane position to be more visible. Mixing with all that heavy moving steel there's no room for mistakes, and it requires absolute focus to predict and avoid the mistakes of others. Relaxed riding is for deserted beaches at low tide, the only time I can let my guard down, but that's essentially a dead smooth lane to myself 100 feet wide with any obstacles visible for 100 yards or more. Beach riding is so peaceful and relaxing that I literally almost fall asleep. Around town my ebikes are basic transportation, getting me from point A to B in the most efficient fun and practical manner existing on this planet. I used to dread getting out in the car, but now I look for excuses to run errands.

John

 

[adrian_sm]

I like the bike.

Would be interested to know what sort of reduction he is using from motor to cranks.

 

[2moto]

...resulting in neither a good bike nor a good e-bike...

How do figure that? Seems like the perfect e-bike to me.

Not enough structure to be adequately stiff for normal riding.
Way too little structure to be durable or fault tolerant.
No toughness at all; no way to absorb energy in an overload.
Not enough motor mass to sink significant heat, or to generate satisfying amounts of power.
Not enough battery mass to provide significant range, or probably power either.
No creature comforts-- inadequate saddle, hard grips.

It's the sort of thing that seems like a great idea in principle, but in practice there are very good reasons that even expensive, high quality bikes are not that light. In the business, we refer to such bikes as "stupid light", because they overreach for lightness at the expense of more usable virtues.

To put it in simpler terms, that's a one-crash bike that probably cost at least $20,000. Are you a gambling man? How large a bet would you like to make?

Chalo

Sorry to disagree with much of that. As he rides is around Swiss mountains, I'd guess there is probably sufficient stiffness and structure for normal riding. And, the range seems to be adequate as well, being able to do a whole days of riding. It seems that this guys' definition of an e-bike differs from yours. Your ideal e-bike may not require any pedaling and go 55 mph while being able to survive multiple crashes and cost $500. Not my ideal, I am afraid. We are still talking about what is legally termed a bicycle, aren't we?

 

[kfong]

Going from titanium to carbon fiber and still meeting his definition of an ebike is a success in my eyes. I would like to see more of his bottom bracket design as well. I'm sure it is much more durable than you think, Chalo. Carbon fiber is amazingly strong if professionally put together. This engineer has shown the ability to master this.

 

[spinningmagnets]

I would like to see more of his bottom bracket design as well

It "looks like" the vertical part is the battery/ESC?

 

[kfong]

That's intriguing! Looks like a small RC motor with low KV used to drive the crank arm. That really would save a lot of weight compared to all other drive setups. I like it. Looking at his bike, it does look structurally strong. Even beefy at places were it needs to be. Must be a dream to ride, even without power.

 

[HAROX]

.

 

[Chalo]

I'm sure it is much more durable than you think, Chalo. Carbon fiber is amazingly strong if professionally put together. This engineer has shown the ability to master this.

Carbon fiber is strong, yes, but that's all. It's not ductile, tough, notch tolerant, energy absorbent, or any of the other things we take for granted on our bikes. Bottle glass is strong too, but it would make a sorry bike.

Also, metal is about equally strong in any direction (anisotropic). Carbon is only strong in the direction the fibers are laid, meaning you're really riding an epoxy bike when it encounters any force it was not designed to withstand. Lack of off-axis strength and lack of ductility are why carbon bikes do this when they fail, and metal bikes don't:

There are tons more photos at Busted Carbon, even though the blog is no longer being updated because it was just too easy and common.

If you browse there, remember that those are normal 16-22 pound unpowered carbon fiber bikes, not the stoopid-lite stuff that the old German guy is hyping. Remember: tens of thousands of dollars/euros, all for nothing after the first crash.

Remember also: Just because it is possible does not make it a good idea.

Chalo

 

[grindz145]

I think the lightweight ebike is the future. Small battery + Fast charging makes an amazing bicycle which is pedal worhty and ride-worthy. Traditional bike speeds only though. Hardly any rotating mass with the motor, but I think practically a small geared hub would be better.

 

[kfong]

Unfortunately carbon does break in a spectacular fashion. The layup has a lot to do with the quality of the product. I use carbon fiber masts for my windsurfing and have mistreated them and the still perform like new. Can't imagine using anything else. Even my cf ski poles have outlasted all my other poles and taken the abuse of luggage handling. If done correctly, I don't see why CF bike would not be a good choice to go with. I've been contemplating on making my own CF frame. If you have the ability to do your own layup, the cost is very reasonable. I would focus on strength rather than weight. Thick walled CF is rather bombproof.

 

[Chalo]

Unfortunately carbon does break in a spectacular fashion. The layup has a lot to do with the quality of the product. I use carbon fiber masts for my windsurfing and have mistreated them and the still perform like new. Can't imagine using anything else. Even my cf ski poles have outlasted all my other poles and taken the abuse of luggage handling. If done correctly, I don't see why CF bike would not be a good choice to go with. I've been contemplating on making my own CF frame. If you have the ability to do your own layup, the cost is very reasonable. I would focus on strength rather than weight. Thick walled CF is rather bombproof.

This isn't thick walled anything we're talking about. Carbon fiber composite has an intrinsically catastrophic failure mode, but it's fanatical weight reduction that makes failure likely/inevitable. Like your windsurfing masts and ski poles-- if it were heavy enough, it wouldn't be a problem that the bike is made from CFRP. But it's not built heavy enough to resist damage, and unlike steel it is unable to tolerate minor damage.

Any 12 pound bike-- and that's what we are talking about here, essentially-- is going to have a really bad case of the stupid-light problem. If well designed and constructed, it will be able to withstand normal riding loads, barely. But then you hand it an abnormal load or a tiny ding in the frame, and it ruptures.

Chalo

 

[kfong]

The weight is really in the epoxy, It can still be thick walled and relatively light. CF being a rather expensive product, manufactures will tend to use the least amount they can get away with. I'm guessing this engineer did hid own layup work and I'm sure he is confident that it will hold up. Being also a sailplane hobbiest, his experience in the material is probably quite good. I agree going too light isn't something I wouldn't want for my trail riding. But I would have no hesitation using any CF product with a proven track record, even if it was stupid light. I'm amazed at what they have done with CF golf clubs these days. Talk about shock and stress.

 

[Miles]

I'm guessing this engineer did hid own layup work and I'm sure he is confident that it will hold up.

It's a "thin-walled Scott Scale Carbon frame"...