Electric bikes in education

Since I bought one (a Stöckli e.t.), this piece includes a somewhat expanded technical part. I do believe that e-bikes can be nice learning objects for a variety of purposes, but did not spend a lot of time searching for literature. - Daniel K. Schneider (talk) 14:53, 28 April 2013 (CEST).

Introduction

Electronic bikes (ebikes) most often refer to some kind pedal-assisted bicycles.

Ebikes offer interesting opportunities for education:

• Technical design and STEM principles: An ebike as learning object can be used to study mechanics, physics and electronics.
• Technical design (advanced): At least one of the better designs was made in collaboration with an engineering school
• Technical design and fabrication (DYI): E-bikes can be hand-crafted, i.e. be used as ambitious object in a design and fabrication class
• Teaching evaluation methodology: Evaluation of e-bikes is relatively easy, and could be conducted as a class project

Ebikes in education examples

The list below should be complete with both a literature analysis and by mining course materials. In principle, everything that can be research also can be education. Therefore we also listed a few items found in the literature. There are some interesting issues that refer to organizational and informal learning, i.e. users participating in design and policy making.

Collaboration with engineering schools

A good example is the Swiss Stromer developed in partnership with Bern University of Applied Sciences (Engineering and Information Technology), Lucerne University of Applied Sciences and arts and a Swedish Designer.

Ebikes in fabrication classes

This is related to fab labs and other digital design and fabrication initiatives. For starters, one can upgrade a normal bike to an ebike using one of the many commercial kits.

A good example is the annual e-Kart competition (in french), e.g. Vierzon International and Educational Meeting of Electrical Gokart e-Kart 2013 in France

Ebikes for STEM teaching

Understanding the electrical and electronics parts of an e-bike could be an interesting activity for a vocational school training electricians and related professions. We know, for example, one example of a french school who acquired a ebike for that purpose.

As you can see below, there is quite a large combination of features in current ebikes.

Technical evaluation of Ebikes

Since E-bikes are fairly simple "products" as compared others they are ideally suited for evaluation studies, marketing classes, etc.

A good example of a technical report is the report (in German/French) in the ATE/VCS VeloJournal made in collaboration with an engineering school.

Ebikes in management and policy studies

E-bikes also could be nice object for innovative management studies with the advantage that there is a literature on ways to design products (e.g. Arnold).

Informal learning in participative design

“Changes in production and consumption patterns are a crucial element of the sustainability agenda. Communication between product developers and users, and user integration in product development, can serve as a means for organizational as well as individual learning processes, resulting in sustainable product development. [...] Improved methods, such as INNOCOPE (innovating through consumer-integrated product development), tested in this study with a cycle manufacturer and resulting in a new product, a pedelec, are needed for effective communication, activating consumers and enabling them to promote sustainability goals. Through co-operative product development processes key factors facilitating and obstructing the adoption of sustainable innovations may be identified. Such processes can enhance the emergence and diffusion of sustainable product innovations and different forms and bodies of knowledge can be combined. Integrating users' contextual everyday knowledge of the product with the technical knowledge of companies may lead to mutual learning, technical innovations and changes in consumer behaviour.” (Hoffmann, 2007).

Designs

Types of designs

We could distinguish roughly types of e-bikes

• So-called Pedelecs, i.e. the motor only turns when the user pedals. In most systems (see legal restrictions below), the motor will fade out and cut assistance at 25km/h or 45km/h (s-pedelects).
• So-called Power-on demand. The user will turn a throttle and can either pedal or not. Such designs are illegal in most countries, although some models like the Ezee were modified to require the user to pedal and therefore become legal. Others will cut assistance at 20Km/s when not pedaling.

One also can classify designs according to usage. E.g. the German site distinguishes between 11 types:

• Urban-easy: Light and easy to use, small range
• Urban-business: Fairly speedy and good range
• Urban-folding: Take it in your car or public transportation
• Comfort - City comfort: Confortable, includes full equipment (e.g. lights)
• Comfort - Classic: Like the above but comfortable position and highly reliable
• Comfort - Reha: For rehabilitation patients
• Leisure - Tour: High range, good climbing, full equipment, carry lots of stuff
• Leisure - Sport: Speed, power, off road capbable, and range
• Leisure - Wellness: As above, but easier to use
• Transport - Family: Strong (bring a kid along)
• Transport - Business: Carry lots of weight, e.g. Pizza boxes

We would add to this:

• Commuting: High speed, high range and full accessories, but still easy to use in city traffic.
• Trekking: Same as above, but even higher range and allowing for heavier bags. Not necessarily high speed and easy slalom driving needed.

Power system

Motors

Motors can be front or rear wheel hub motors or in the middle. All decent motors are brushless, i.e. there is not friction that would reduce its lifetime.

• Front wheel: cheapest solution since it doesn't need to interact with the gears, a bit dangerous when breaking on wet roads
• Rear wheel: Most possible raw power, some 500W motors do have overheating problems. Until recently, this design required crank shifts. The only exception is the Grace easy that has 3 gears.
• In the middle near the bottom bracket: The motor typically interacts with the bracket and then indirectly with the chain.

Main motor makers:

• for read drive motors: BionX, Panasonic (new), Ortlinghaus (GoSwissDrive), Alber (Xion, Greenmover).
• For middle motors: Panasonic, Bosch, Impulse (Derby), and smaller/newcomers like AEG, MPF, Yamaha, TranzX, Acron, TDR, MPF.

Many makers have their own motor, though often (most of time ?) it's just a custom version of some known brand. E.g. Stromer uses a special Bionix line. Stöckli uses its own (maybe a version of the GoSwissDrive ?).

Power output

• Pedelecs: 250-350W (in some countries only 200-250W are allowed and the output is electronically locked)
• S-Pedelecs: 350-500W
• Other: Up to anything ....

Horse power is not everything. Torque also counts. Loosely speaking, torque defines how much force is applied for turning the wheel. Typically, you get:

• 20Nm for Pedelects
• 30-40Nm for the faster S-Pedelecs

More torque means better acceleration. Typically, rear wheel motors have higher torque.

Choosing a motor/sensor combination

Available products (motors, senors, batteries, control systems. etc.) change fast since the e-bike market shows a strong growth. In principle, get a rear motor if you want a lot of raw power and acceleration (e.g. for a 500W motor). Middle motors are more energy efficient and less subject to problems (e.g. overheating). Middle motors usually are combined with integrated rear hub gears, and rear motors with derailleurs. Both have advantages and disadvantages. E.g. the former require less maintenance, are easy to use in go-and-stop traffic, but require taking off weight on pedals when shifting. Therefore the latter (derailleurs) are better for speedy overland and hills cycling.

But the whole is also influenced by the sensory systems which are very different from model to model. E.g. A typical 2013 Panasonic system requires pedalling for optimal support (55/minute?) and has both a pedalling frequency and a speed sensor. You don't get much assistance if you pedal very slowly or very fast. Typically, a rear motor has a force sensor, i.e. you get lots of support fast when you start pedalling in a low gear, i.e. it will "feel" your need for assistance.

Batteries and range

Battery position is most often somewhere in the middle. Some high-end models integrate the battery in the frame. Others on top of the rear wheel. Many models offer a choice of batteries, i.e. smaller/bigger and also with respect to quality. Currently, most batteries are either NiMH or the lighter Ion-lithium batteries.

• Capacity: Typically between 250Wh and 500Wh (energy), 8Ah and 20Ah (charge). The relationship between the two is not really clear to me, except that "more" is better. In principle Ah * V = Wh, but if you look at published data, you get somewhat different results.
• Voltage: typically 36V (e.g. Stöckli, Stromer), but also 48h. E.g. the Flyer Vollblut has a 8.8Ah/48 V battery, that means more Wh than a "normal" 36V comparable battery.

More output means more weight and more money. A high-end Lithium-Ion battery costs at lot. E.g. For the Stöckli E.T. (4/2013 in a Swiss shop) you get the following specs and prices:

• 11 Ah/396 Wh (990 CHF)
• 14.5 Ah/522 Wh ( 1390 CHF)
• 17.6 Ah/634 Wh ( 1390 CHF)
• 23.2 Ah/835 Wh ( 1790 CHF).

Th 32.2 Ah model has a huge capacity compared to what most other makers offer. But 500W also do eat up a lot more energy than let's say a 350W middle motor model that is almost as good for pedalling in a mostly flat topography. I.e. on a different bike you can get away with smaller batteries and still get range.

In principle, you would use about 100W (your own energy) for moderate pedalling at 22km/h. If you select 300% assistance (high), that will add another 300W and you can pedal almost twice as fast, i.e. about 27km/h (you will encounter increasing resistance from wind). Therefore, if you got a 400Wh battery, you got a range of about 37km at 37km/h. If go more slowly and use less support (200%), then you can drive further, e.g. 60km with a 400Wh battery. (Read more in die Die Schnellen im Vergleich)

Main makers: Panasonic, Bosch, Samsung

Electronics and motor control:

All pedal-assisted ebikes offer to control the degree of assistance (from none to high), usually about 3-5 levels. Support ranges from 30% extra power to 300%. For example:

• Little = 30 to 50% (little support, e.g. for exercising, slow driving and large range)
• Normal = 100% (good support)
• High = 200 to 250% (very little effort on your part)
• Boost = 300% (in this mode you can easily climb steep roads)

The motors can be controlled in various ways

According to Wikipedia (March 2013):

For switching or control of the motor, there are several possibilities:

• Measuring the force or torque on the signal of a force sensors on the pedals, the pedal crank, the chain or at the wheel
• Measurement of treading on the signal from a revolution counter or threshold switchs on the crank, or at another suitable location
• Measurement of both force and the speed
• Measurement of acceleration or drawbar force at the push trailer
• Measuring electrical values in the serial hybrid (pedal generator)

In addition, the speed of the vehicle are measured on the wheel, in particular, for example, to drive the motor from 25 km/h off. The measurement can be further processed mechanically or electronically and is used to control the motor on and off or to regulate a control function based on continuously.

The fed power is based on the sensor data (force sensor, crank speed, ground speed) is calculated based on the chosen level of support from the motor controller. The so-called support levels, that is, how much the motor supported in addition to the driver's performance lie in horizontal drive 5-400 percent.

Examples:

• Stöckli E.T. Urban: Force and speed sensor
• TDS Impuls Trekking XT: Force, Speed, Pedal rotation frequency, inclination
• Flyer R-Series: Force, Speed, Pedal rotation frequency
• Stromer: Force and speed sensor
• Dolphin Express: Pedal rotation frequency

It is very important that sensors work well and that they are integrated/tuned for good usability. Although ebikes do need some initial mental adjustment from riders, some model do much better then others, e.g. most testers seem to prefer the TDS Impluse over the Stöckli E.T. over the Stromer (which model?) with respect to reactivity. Of course, usability is subjective and some people may prefer one behavior over an other. However, cheap bikes may be just plain bad and this is why test driving is important.

Different control design (various combinations of sensors and software) require different behavior from riders for an optimal experience. E.g. on some bikes like the KTM Amparo, you would have to pedal fast (effortlessly though) in order to get more support.

Controllers:

A decent controller should offer at the least the following

• Energy display: charge level
• Speedometer
• Selection of output: Should offer at least 4 degrees of assistance (none to high)

Optional:

• Boost mode and push assistance
• Regenerative breaking, current consumption, kms to go, etc.
• Trip data

Bicycle part

Frame

Frames are usually made from aluminum since both the motor and the battery will add weight.

Gears

Gears are either in rear hub (typically for models with a motor in the middle) or derailleurs (for models with a rear hub motor). Nearly all models require manual shifting, but some models exist that will select a gear to match your cadence, e.g. the NuVinci Harmony.

• Hub gears usually have something like the 7 gears Shimano Nexus or the 8 gears Shimano Alfine. Just 3 are not enough for hilly places, even if you can compensate with high assistance.
• Derailleurs: Usually between 10 and 30 gears. Most better models use a Shimano SLX or XT.

Brakes:

Ebikes should have strong brakes, either disc brakes (preferably hydraulic) or hydraulic rim-brakes (e.g. a Magura HS 11). Some models offer regenerative braking, i.e. an interface with the motor and the battery to generate energy when you break.

Suspension

Some argue, that an ebike should have some kind of front suspension, i.e. be able to cope with potholes at higher speed or off-road conditions. However, in countries with flat roads (e.g. Switzerland, Germany or Holland) you don't need that extra weight for extra price if you stay on roads and/or drive slowly in difficult terrain. Some makes (like the Stromer) let you choose.

Price

• Lowest: Around 500 Euros in mass retailers, E.g. the German hardiscounter Aldi sells a 700 Euro 27kg city bike. Probably a good quality/price relation, although makers of pricier bikes claim that these are dangerous. They are not more dangerous than the models these guys sold only a few years ago ...
• Lower mid-end: 1000-1500 Euros (best buy for city usage if your budget is low)
• Higher mid-end (best buy for city usage): 2500 to 3500 Euros
• High end (best buy for commuting and trekking): 3500 to 5000 Euros. E.g. a simple Stromer ST with the larger Battery plus accessories (light, fenders and luggage) would cost about 4000 Euros in Germany.
• Very high end: Up to anything, i.e. custom bikes

Of course, you always can get nice bargains for older "last year's" models.

In general, more expensive bikes are better. However, this is just a trend. E.g. the "Kassensturz" Consumer program from our state TV found in a 2012 study confined to an engineering school, that "Supermarket" bikes, e.g. the 1400 CHF (1200 Euro) "Leopard" bike from COOP did very well. Evaluation is "good" (almost the same as the three times more expensive 25km/h Stromer). They also pointed out a very bad model from a discounter. In other words, you can find good cheap models, but read the tests first.

Legal restrictions

Most countries put restrictions on specifications of e-bikes:

• Switzerland defines two categories of so-called Pedelecs: 25km/h (16mph) and 45km/h. Both require that the user pedals. Limited non-pedaling assistance is allow for the second category (S-Pedelecs) that is assimilated with mopeds and require a vehicle permit and wearing a helmet. Germany has a similar solution.
• France, Australia and the UK only allow 25km/h bikes.
• In the USA, each state has a different regulation. For faster models, a driving licence, helmet, etc. can be required.

EU Standards:

• EU: EN15194 (EPAC – Electrically Power Assisted Cycles) defines the use pedal-assisted less than 25k/h bikes: "Cycles with pedal assistance which are equipped with an auxiliary electric motor having a maximum continuous rated power of 0.25 kW, of which the output is progressively reduced and finally cut off as the vehicle reaches a speed of 25 km/h or if the cyclist stops pedaling.”
• However, each country is free to allow faster s-pedelecs if they go through collective or individual type approval. Typically, an S-Pedelec can be associated with "mofas" or "mopeds" or "light scooters". Germany has such a solution: S-pedelecs have max. 500W motors, max 45km/h, max 300% support, can drive up to 20Km/h without pedalling, plus other constraints regarding security, and are associated with Mopeds. In the City you can't use bicycles paths, but you can in the country side.

Switzerland (not member of the EU) has a similar, somewhat simpler solution. From the official announcement (in German):

• Leicht-Motorfahrräder": “Solche E-Bikes dürfen neu über eine Motorleistung von maximal 500 statt wie bisher 250 Watt verfügen und mit reiner Motorkraft - ohne Pedalbetätigung - maximal 20 km/h schnell sein ("bauartbedingte Höchstgeschwindigkeit"). Mit Tretunterstützung beträgt die Höchstgeschwindigkeit weiterhin 25 km/h.”
• Übrige "Motorfahrräder": “E-Bikes mit einer Leistung zwischen 500 und 1000 Watt oder einer bauartbedingten Höchstgeschwindigkeit von 20 bis 30 km/h oder einer Tretunterstützung, die auch bei einem Tempo von 25 – 45 km/h wirkt, gelten als Motorfahrräder und benötigen ein entsprechendes Kontrollschild.”. You can use any bicyle path and also hiking roads forbidden to motorbikes if you drive slowly.

Caution

You are not allowed to drive S-Pedelecs in France even if they are registered legally in your country (e.g. Germany or Switzerland). In other words, if you plan to take your 45h bike that is legal in your country on vacation in another where it is not, you may violate traffic law. Remove the license plate or don't do it. People who commute between countries, are known to hack removable plates with magnets ...

Hacking

Electronic speed limitations

Most 25km/h bikes can be easily hacked to go a bit faster. If you use the bike for commuting and you got a model with good brakes, there is no reason for going at 25km/h if you can get it going a bit faster.

• Unlocking the electronics can be very easy, e.g. it takes a few seconds for the Panasonic middle motor. Just move the speed sensor on the rear wheel (of course, then you won't know how fast you go anymore)
• It seems that for Bosch motors, you may have to open the motor and bridge the chip that drastically reduces power above 25km/h. On YouTube, you can find videos that teach you how. Else, search the forums.

Some 25km/h bikes (pedelecs) can be made to go a lot faster. In particular, the ones that have 350W motors can support up to 45km/h. In order to reduce production costs, the same motor can be used both for pedelec and s-pedelec versions of the same model. However, the s-pedelec version may have better brakes, a different frame, etc.

• For example, the 250W/25kmh Stöckli can be software upgraded to go up to 40km/h. Same for the BH Emotion 350W bikes if I heard right.

I do not recommend hacking a bike into s-pedelec, i.e. make a 25km/h bike go at 45 or faster. If you have an accident you will be in trouble. Just get a legal version. In addition you will have good insurance. Of course, in countries like France or the UK that so far do not know S-Pedelecs, you will have to make a difficult moral choice.... At least, make sure that your rig is safe...

Other

In some countries mixed systems, i.e. pedaling and/or using a throttle is legal. In EU countries and Switzerland this is not the case. I.e. you can buy an electric scooter, but this is not considered to be an e-bike in the moped / light scooter category. That kind of hack is probably more difficult, unless the original design has been modified to fit with (s)Pedelec specs. E.g. The Ezee models are of that kind and modifications to revert to the original does not seem to be too difficult...

Some interesting designs

(As of spring 2013, i.e. it maybe be totally outdated sometimes in the near future)

High-end commuter bikes

Below a list of good well-looking designs for 45km/h bikes that are suitable for both city traffic and commuting and that are legal in some countries in specific versions. Most of these bikes do have version with powerful 500W motors and offer a choice of batteries. Most weight around 25kg, but that is somewhat compensated by the strong motors.

Currently, I am thinking of getting one of these. So far, I only tested the Stöckli and it does feel "good" right from the start. - Daniel K. Schneider (talk) 01:08, 27 April 2013 (CEST)

• BH Neo Nitro, made in Spain: rear wheel motor, Samsung battery. There is a 500W motor version at 24.6kg
• Stöckli E.T. Urban Confort, made in Switzerland. It has SwissGoDrive motors and Samsung batteries. There is a 500W/17.6Ah combo that seems to be ideal for commuters, i.e. it has a 50km range using full assistance. In the USA, a similar product is available as Currie eFlow e3 Nitro (different motor and electronics). This model doesn't have a front wheel suspension, but comes with "balloon" tires that somewhat absorb shocks. Options are available through types: "simple"/Urban/CROSS and man/confort models. E.g. the Cross model has a front suspension, a 500W motor and no equipment like lights, fenders, etc. However, paying extra, you can compose your own configuration. If you commute using bumpy roads, then get a front suspension.
• Stromer ST1, made in Switzerland: rear wheel Bionix motor (or derivative ?), Samsung Li-Ion battery (11.5 or 14.5 AH). There is a 500W motor version. All models have small 26 MBT wheels and front suspension and saddle suspension are options. The Stromer ST1's very modular design includes other options (e.g. saddle, brakes, handle bar, grips)
• Cube EPO 45 Nature FE is A German bike that has a similar design as the Stöckli, i.e. rear motor and battery in the seat tube. 21.2 kg, 350W motor (?).

Both the Stromer and the Stoeckli are very nice looking designs and easy to handle. Reliability for both does not seem to be up to Swiss standards, e.g. some of the 2012 Stöcklis seem to have bad contacts. However, as of 2013, most of these problems should be fixed. The Cube got criticized for its battery/saddle system, but this has probably been fixed in more recent edition and it has less "punch" then the other's since the motor is smaller (324W?). I don't know about the BH Neo Nitro. Given the relatively low price of the BH Nitro, it may be the best buy in this category if you plan to cover smaller distances (the battery is limited to 9Ah, and Spain's industry does need some help ;) Anyhow, all of these models come with a variety of motors and country-specific modifications. E.g. in France, the BH Nitro comes with a 350W motor and is electronically limited to 25km/h, whereas in Switzerland you either can get a 500W - 45 km/h version or a 250W? - 25km/h version.

I bought a Stöckli E.T. in May 2013 and so far am very happy with it. Uphill performance is quite spectacular. Handling is easy and so far I didn't have any technical problems. My only regret is that I didn't get an (optional) front suspension. It would be useful since I do encounter dirt roads on the way to my work and I may change it later.

More traditional

• Flyer Vollblut. A new rear motor bike from one of the most reliable E-bike makers. This model doesn't look as "heavy" as most other Flyer models. The Vollblut 500 has the 500W new Panasonic rear motor, front fork suspension, 28 inch wheels. It is in the same price range as the Stöckli and the Stromer. Flyer is known for top service and reliability, but it's a new model with a new motor ....
• Kalkhoff Endeavour BS10, made in Germany: Has a new Bosch 400Wh/11.1Ah battery and a Bosch 350W motor
• Triton 45. This bike won some German tests in this category. Same motor and battery as above ?, 22.6kg.
• Bulls Green Mover E-45, 735 Wh/20.4 Ah large battery, full accessories, 29.3kg

Both the Kalkhoff and the Stevens may be more reliable and a bit easier to use than the more sexy Stromer/Stöckli/BH emotion designs. But they got less power and less "punch". Best bet for a more traditional design is probably the "Vollblut", but it's more expensive.

Good city bikes

There are dozens of good 25Km/h pedelecs. Our advice is to go the nearest good e-bike store and get it from there, because e-bikes may need good support. Only if you like servicing a bike yourself is buying from the Internet a good option. As of Spring 2013, a good benchmark to compare with is the Austrian KTM Amparo also called KTM Severo 8M or the German Kalkhoff Impuls or Agattu series. It has a reliable Panasonic middle motor and a good battery. If you want a more sexy design, try the SMART from the urban car maker of the same name.

High end sports and minimalistic bikes

• The BH Neo, Stromer and the Stöckli (see above) have configurations without accessories (fenders, light, luggage carrier, etc.)
• Grace easy, made in Germany: 350W rear wheel Bionix motor, rear wheel motor, 3 (only) hub gears, carbon drive (no chain), 19kg without equipment. You can add fenders, luggage carriers, lights and suspension fork. Both pedelec and s-pedelec version.
• Specialized Turbo, similar design as the Stromer, 21.5kg without any equipment. Very expensive ($6000, 7000 CHF). Don't know if standard accessories exist, but probably they do.
• Coboc produces very light-weight (14kg) bikes with a rear wheel motor.
• A similar design is the Strassenfeger by Electrolyte (2 gears, 16kg).

Near future

Even bigger players now move in, e.g. the BWM Cruise is a very traditional build. SMART has a more original model. Others just go for cool prototypes, e.g. Audio and Toyota. In the future you may get one of these for reduced price if you get a new car ...

Do it yourself

(needs to be written ....)

Links

Overviews

• Electric bicycle (Wikipedia, as of 4/2013 needs some updating)
• Pedelec (Wikipedia)

User communities and websites

All in German (sorry, but Germany is the Pedelec country together with Switzerland)

• ExtraEnergy, includes tests and free mags.
• ebike.de, includes models, makers and Q/A (i.e. a brokering site)
• elektrobike-online. Many tests, stories and rumors
• newride.ch
• e-Bike Test
• Pedelecs & E-Bikes. Good blog with lots of news.
• e-Rad Hafen Blog. Good technical information, overviews and comparisons.

In English

• electricbike.com (US) Nice stories, tests and "top 10" articles.
• Electric Bike Report (US)
• Best Electric Bike Websites Awards (UK list of sites).

Technical information

• Bosch, Panasonic und Impulse
• Aktuelle Infos zum AEG Scheibenmotor
• Heckmotoren BionX, Alber (Xion, GreenMover), Panasonic und GOSwiss Drive im Vergleich

Some tests

(2012/13)

• ÖKO-TEST März 2013 (view per pay !)
• TCS - Schnelle E - Bikes auf dem TCS-Prüfstand
• Velojournal 2012 (view per pay!)

Do it yourself

• How to Build Yourself (electricbike.com).

Other

• 2009 Press articles selection for the Stromer.

Bibliography

• Arnold, M., & Barth, V. (2009). Klima-und umweltbezogene Lernprozesse in partizipativen Produktentwicklungsverfahren: Möglichkeiten und Grenzen. JSSE-Journal of Social Science Education, 8(3).

• Arnold, M. (2010). Stakeholder dialogues for sustaining cultural change. International Studies of Management and Organization, 40(3), 61-77.

• Chapko, A., Werth, D., Feodoroff, B., Schmitt, A., Walter, H., Stützinger, V., ... & Koch, M. (2012). MENTORbike-Das intelligente Pedelec. Proceedings of Technik für ein selbstbestimmtes Leben. Abstract (Access restricted)

• Hoffmann, E. (2007). Consumer integration in sustainable product development. Business Strategy and the Environment, 16(5), 322-338.

• Hoffmann, E. (2012). SUSTAINABILITY• RESPONSIBILITY• ACCOUNTABILITY. PDF

• Honsberg, M. (2011). Strategic review of a cleantech startup company (EMPO-NI). GRIN Verlag.

• Kaiser, O. S., Meyer, S., & Schippl, J. (2011). Elektromobilität. ITA-Kurzstudie. VDI Technologie-zentrum, Düsseldorf. PDF

• Reiter, K., Abramsky, K., Chioncel, N., Karner, S., Tritthart, W., Loorbach, D., ... & Wächter, C., Technologie & Politik. Soziale Technik (Technologie & Politik PDF)

• Schönberger, P. (2013). Municipalities as key actors of German renewable energy governance: An analysis of opportunities, obstacles, and multi-level influences (No. 186). Wuppertal Papers. Abstract/PDF

• Teo, K. M., & Odoni, A. R. A Systems Perspective of Cycling and Bike-sharing Systems in Urban Mobility. Mi.I.T (Draft paper ?). PDF