For over fours years now I have been testing different E-bikes of various drives and designs, and I had the opportunity to test an electric bike that uses the new Bosch electric drive system, recently introduced in Europe. My curiosity was piqued, especially given Bosch’s storied reputation for getting things right the first time after researching the pros and cons of competitive systems and reviewing user feedback.
I set out to test the new Bosch drive system thoroughly, and chose as my proving ground a bike route as beautiful as any that exists here in Italy, about 70km long. This route has a little bit of everything, stretches of compacted gravel alternating with pavement, lots of dips and rises over rolling terrain, and a seemingly infinite number of bridges. A final climb takes you into the the the center of Clusone, where I encountered many short ramps and an occasional stiff headwind. In short, this was a test route chosen to ferret out any weaknesses that might reveal themselves under these challenging conditions.
There were two Cannondale E-series bikes in the test, the men’s and women’s versions, with the women’s bike having the usual step-through frame but otherwise identical in their front forks, rear chassis, and equipment components. Available sizes are 50-55-60cm (mens) and 45-50-55cm (womens); those tested were two 55cm.
These are classic aluminum frame city bikes with a 1110mm wheelbase. Features include Headshock SI, aluminum fenders, Trelock headlight, AXA security lock, and integrated luggage racks by Bell. Both were equipped with Headschok Fatty LD50 lockable front suspension forks. Other equipment included Selle Royal Freccia gel-saddle, Shimano SLX Deore 9-speed shifters, Schwalbe Marathon Supreme 700x35c tires, Shimano hubs, cranks and FSA crankset, and Magura MT2 hydraulic disc brakes.
The first impression in lifting the bikes from my car carrier was how surprisingly ass-heavy and unbalanced they were, even without the battery packs mounted. This could be a problem for anyone needing to physically lift the bikes frequently, whether up a flight of stairs or onto a car or camper rack. Total bike weight is 22.8 kg with battery inserted; the battery pack itself weighs 2.5 kg. Surprisingly, at the end of the day this uneven weight distribution did not seem to affect the bike riding, except perhaps for a very light steering response.
The Bosch motor assembly weighs 4kg, and includes gear reductions to transmit a rated continuous torque of 40Nm at the bottom bracket, with a maximum of 50 Nm. Motor power is 250W. The battery mount is integrated into the rear of the E-bike by multiple points on the frame. The battery pack is 36V 288-WH lithium-ion with a warranty of 500 full recharge cycles or 1000 cycles from a partially depleted pack.
The controller is integrated with the console and communicates data at speeds of 200 times per second. The system has three sensors: Cadence, Torque, and Speed. Efficiency is reported to be about 80% from 65 to 110 RPM.
My first impression on climbing aboard the bike was how well everything was positioned on the handlebars, with comfortable, ergonomically designed full-width hand brake levers and an on-board computer display on the left, with the rear shifter on the right. (The bike has no front derailleur.) The computer display is removeable and will temporarily disable the bike to discourage theft or tampering. This E-bike’s on/off switch is mounted directly on the battery pack casing, along with a 5-light LED display to indicate the battery’s state of charge in increments of 20%.
The LCD console up front presents various data and displays the selected program type you’ve chosen from among the four offered: Eco, Tour, Sport, or Speed. Within each of these programs the rider can choose from among three levels of assistance with a simple touch of the up-down buttons on the console. You can also switch on the lights, reset the data and call up a current battery SOC display that mirrors the LED lights on the battery pack itself. Finally, you can view your ride efficiency rate en route and predict your ultimate range based on the same.
Summary table of methods of care of the engine
Summary table modes of consumption in the motor assist
Note: Maximum battery life and range depend on several factors, including the chosen level of support, road surfaces, rider weight, tire pressure, wind, ambient temperature, etc.
Summary Table of Programs
|Effective support for maximum efficiency with maximum convenience / Ideal for long distances|
|Uniform support for long-haul travel / acceleration / fresh Ideal for commuters|
|Immediate support and powerful sports off-road as well as start / stop city traffic / Dynamic Help / maximum range of climbs|
|Top performance, the most powerful support for up to maximum cadence is ambitious, sporty driving / Sharp increase in support / For those who prefer a sporty drive|
Summary Table of Error Codes
|Internal error in the control computer|
|One or more buttons on the control computer are blocked||Check the ignition keys, check the connections and clean the contacts|
|Connection of the control computer problems||Check the links and connections|
|Internal failure of the drive|
|Problem of connection of the drive unit||Check the links and connections|
|Error rate sensor||Check connections and the connections and the integrity of the sensor|
|Connection problem of illumination||Check the links and connections|
|Connection problem of the control computer||Check the links and connections|
|The temperature of the drive unit is too high (40 ° C)||Continue to cool the unit, continue the journey without any engine support|
|Internal electronic failure of the battery|
|The battery temperature is too high (40 ° C)||Continue to cool the battery to continue the journey without any engine support|
It starts Read or write without knowing delivery with the previous selection stored by computer use, the selection is Speed, Level-1. Not having had time to read the instructions proceed in “on demand”, using it you will understand. The first start feeling more than ready, but to proceed in stages, and I take off immediately to zero, ie without any assistance, just to test the smoothness of the bike and the possible influence of the gears of the motor mechanism. We are in urban path with false flats both uphill and downhill, the bike is maneggevolissima, as written the steering is very responsive, the E-bike very smooth, the tires will make the task easier and still absorb the bumps well supported the shock front, but also in the rear seat or in the rough did not perceive much although there is a rear shock.
First taste of motor.
Since there were several detours for ongoing work on the bike path as well as your everyday obstacles including asphalt, porphyries, sidewalks, bicycle parts, etc., with continuous ups and downs, I activated the motor at speed level 1. At this level the motor is very quiet, and makes its presence felt by bringing me over the top with a slight effort on my part. The operation of the motor is automatic, and kicks on and off with your pedaling. This integration was seamless and the best I’ve experienced so far in an E-bike. The E-assist is never jerky or intrusive; instead it gently and gradually complements and follows to the letter the effort I put into the pedals.
The Bosch E-drive system uses computer-coordinated current sensors that continuously monitor pedal effort and cadence, as well as overall bike speed. By using sophisticated algorithms programmed by experienced engineers, Bosch’s E-drive system is IMO the most “stitched” to mirror the human body’s efforts. This may seem banal, but this one detail makes the all the difference in making the E-riding experience feel smooth and completely natural. Managing to get a well functioning and optimized system that intuits from moment to moment whatever the rider is expressing on the pedals could not have been an easy task, and I tip my hat to Bosch for this achievement.
Consider that we have 4 different programs with 3 levels of effort within each–already 12 possible variants–then add all the other dynamic factors (rotation of the pedals, pedal effort/torque and overall bike speed), and one realizes that the computer must have a much greater range of programs stored in it to address all of these variables. For instance, if you are using one of the four programs and one of the levels of care, all is not solved in a trivial X provision of assistance, but is modulated and massaged according to the three fundamental parameters such as speed, cadence, and pedaling effort. The harder you push the pedals, the more power the E-assist provides up to a maximum speed of around 24-km/h, which initiates an on/off variable frequency up to complete motor shutdown at speed of 25km/h or above.
E-assist power delivery is almost transparent in normal riding, but the Bosch system interprets abrupt strong pedal pressure from the rider as a call for maximum power and will respond accordingly; otherwise in normal usage the E-assist is gradual and discreet. This is further apparent with the various programs selected, where you will experience more or less assistance, depending on your own pedaling efforts.
My test ride had many stops and gos, with multiple street crossings, traffic-slowing chicanes, etc., sometimes at the bottom of a climb where I was forced to restart from a dead stop; in all of these instances the Bosch system worked beautifully and without any special effort on my part. At one point I wanted to test a worst case scenario in terms of demanding maximum climbing assistance using the lowest power mode available, namely #1 level assist program within Eco mode on a slope in the center of Clusone. In first gear the motor without hesitation addressed the start and made the climb without a problem. Consider you have available another 11 steps with much greater assist and it goes without saying that you can hardly find a situation this e-bike can’t handle.
The geared drive train is clearly key to this superb performance, and learning how to shift for maximum efficiency is not much different than learning how to ride a motorcycle or drive a stick shift car. It is not always necessary to start in first gear, the motor can compensate for this, but it is a good idea when you slow down to downshift one or two gears (or four or five gears if you stop), and even better to stay in first gear when you are climbing.
Close to the pine forests of Clusone with the road going up a slope that continues for a few kms, I put myself in a pack of cyclists and entered Sports mode, level 1. As I pushed on the pedals, my speed gradually rose to around 22-23 km/h, and the cyclists who had been queued behind me began “drafting” my rear wheel. After a few hundred meters I could see in the mirror the trailing cyclists were beginning to crack, running short of breath until they eventually came off my wheel, not being able to keep pace with my legs in conjunction with the motor, even though I probably had a bike 12kg heavier. Moreover, climbing a hill at close to 25 km/h is no joke if you’re not a professional with a good light bike, and light yourself. Hard to hold down the rhythm at that speed without the constant assist of an electric motor.
This motor feels as I wrote, “stitched” to the legs, pushing back just a little if that’s all your legs want, pushing a lot if that’s what your legs are calling for, at least up to the cutoff speed limit of 25 km/h as dictated by law. It’s almost like riding a tandem where if I increase the pressure on my partner it makes him equally motivated to do the same. Except in this case it’s like having a synergy between man and machine on a system where the E-assist is hardly even noticed because the transition is soft and seamless, and automatically tunes itself to your efforts.
I tried the super sporty driving mode Speed - Level 3 setting in the city. Came to traffic lights and climbed into the first green pigiavo on the pedals as if I were in a race. The E-bike shot off like a cannon, the gears pitted in an amen, second-third-fourth to ninth gear, and in a second I found myself at 28 km/h acceleration. From a dead start it is not uncommon to hear the wheel spin, and at the top end it’s clear the bike is no longer inexorably tied to that 25 km/h; the momentum is such that it goes without engine, without notice, provided that you have the legs to help. Ultimately to say I was disappointed with this new Bosch E-drive would be an absurdity; on the contrary I was pleasantly surprised and amused at the pure pleasure of riding such a well designed electric bike.
This E-bike would be the ideal partner in stop and go city riding, as well as in the mountains (though mtb frame would be better there). Overall range on my test ride came in at 70km (see the profile of the route) during which I frequently changed riding modes and assist levels.
Downsides? My riding partner had excessive battery pack play on his bike, so much so that I had to intervene by inserting a strip of foam. The same battery also has two plastic guides that are very weak, one of which had come away.
I’m assuming all these kinks will be worked out over time once the bikes have seen more field testing.
All in all, this Bosch/Cannondale E-bike and drive system is definitely suited to a wide audience and will satisfy many users, especially those looking for a “transparent” e-bike that intuitively blends e-assist with human pedaling.
The Canonndale E-series
Notice: This is an electricbike.com translation from Italian author contributor. This translation is not 100% from original text, but readapted for English language and our interpretation. For original text go to Cadore Designer here:
For more information, here is the english version of the Cannondale E-series owners manual in PDF format. http://cdn.cannondale.com/manuals/2011_webOMS_01_english/2011_webOMS_127534_E-Series_EN.pdf
And here is a you-tube video of the bike: http://www.youtube.com/watch?v=eF2eCXYlTzY
Here a breakdown of the motor and gearbox: http://www.youtube.com/watch?v=Q_tFgwRdUfw&feature=related