Conversion to an electric recumbent bicycle Text and photos Erwin Villiger, from Future Bike, Switzerland
The Peregrin is a light carbon lowracer made by Birkenstock and constructed by Charles Henry, weghing around 11 kg, set up for touring about 12 kg. The Peregrin is an ideal vehicle for races as well as longer tours, the carbon seat designed in such a way that the angle of inclination can be adjusted. If riders of different sizes want to ride on it, you can also push the seat and it is not necessary to adjust the chain length. After several years of riding flats, passes and longer tours to North Holland (600 km) and South Africa (1000 km), I had the idea to electrify the recumbent. Reasons for this was partly my age (70) and also the topography in Switzerland, where you have to ride inclines of 15% and more. But which motor? Because both wheels are 20 inches it will not be easy to install a larger motor on the rear wheel, because the spokes then become extremely short creating angles in the rim unfavorable for centering. I came across a Maxon motor, which is built in Sachseln, Switzerland, and was designed for fast mountain bike rides. Small diameter, light weight and simple electronics. Battery: 48V 7.5 Ah and 360 Watt (today up to 500 Watt). There are 4 power levels that can be switched quickly. Steep terrain
quickly requires level three. Stage four is a booster stage that can be used on very steep sections but cannot be locked. However, this stage is not designed to drive whole passes at full speed. That would result in overheating. The installation went smoothly, I could go on tour and gain my first experiences with the electric drive. The total weight, equipped for the tour, now amounted to 22 kg without luggage, second battery and charger. The expectation was that I would get a lot further because of the lower air resistance of the recumbent compared to the MTB. It soon became clear to me that this calculation could not be made in this way. The decisive point is that your own performance also plays an important. If I drive down the Rhine towards Karlsruhe, I hardly need the motor and one battery charge could reach as far as Holland. But if I ride in hilly or alpine terrain I cannot do it without support, because with a total weight including driver of about 110 kg, you use electrical assistance even at smaller gradients of 2%. Also there’s the total ascent: being completed with one battery charge depends on your own performance. Your own power and the steepness of the terrain determine how much battery power is consumed. So it is not easy calculate if you can ride 1000 m or 1500 m before the battery has to be recharged, or replaced by a second one. If you don't want to make any effort on the flat, this configuration gives assistance for 70 to 80km.
The electronics show 5 lights the remaining capacity, but it is not linear. The last two lights are used up much faster than the first three, which has to be considered, especially in the mountains.
Personal conclusion The electrification of a recumbent is not necessary on level and only slightly hilly terrain unless you want the 45 km/h (licensed) variant. In hilly and alpine terrain, the electric assistance, which never caused any problems, is a good help, especially when it comes to daily trips to work. In a city with a lot of starting and braking, you will notice the extra weight of the engine and battery if you switch off this extra power and accelerate only with leg power. I have attached a table showing what is possible with the configuration and own power described above. Personal power can also mean barely pedalling along, because without it the engine does not kick in. <
A personal example Date Weather 8.8.2016 fair 12.9.2016 fair 18.9.2016 fair 19.9.2016 fair 27.9.2016 fair
Wind km/h 0–5 mix 0–5 mix 0–5 mix 5 mix 5–10 mix
Temperature 18–20° 23° 20–25° 17–19° 15–20°
Distance 33 km 10 km 85 km 65 km 60 km
Heights 650 m 450 m 400 m 300 m 1200 m
Steepness 5–12% 5–16% 5–8% 5–8% 5–18%
Battery units used 2 from 5 1 from 5 1 from 5 1 from 5 all 5 2019-2
57
