Why do we use a front wheel motor?

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Why do we use a front wheel motor?

My first answer was and always will be after 15 years of bicycle construction: there is no alternative for cargo bikes. Our location is only a few kilometers away from the Bosch development center and we are often asked about there mid-mounted engines. One thing in advance, this text is not intended to say that hub motors are fundamentally better, it is only intended to balance the debate a bit and name the advantages of front wheel motors, that we are currently missing in many the public discussion.

So let us start with the advantages of front wheel motors, which should help you decide on the right cargo bike or engine concept:

  1. Independent drive
    This point is often overlooked, but the most important characteristic of an electric auxiliary drive is its reliability. This becomes particularly clear when "standing still" with a full cargobike and without electricity / motor support. Whether the chain is broken, the front derailleur is jammed or the gears are frozen, the front motor works independently and can drive you home even if the manual drive fails. With a mid-engine the whole system fails and in the best case you can still push your bike back home. This leads directly to the second point:
     
  2. Less stress on the wearing parts
    A hub motor in the front wheel takes away the extra power from the manual drive train. A mid-mounted engine does the opposite. Of course, for courier riders who drive 25,000 kilometres a year, changing the chain and chainring every 4 weeks is particularly annoying and noticeable, but for the private user it is also a high and expensive wear. In addition, gearshift systems are designed for human power and now have to withstand a significantly higher torque and a continuous load up to four times as high.
     
  3. Freedom in gear set choice
    One of the biggest innovations in the bicycle industry in recent years is internal hub gears. Rohloff with a total gear ratio of 519% or the infinitely variable Enviolo shifting system have revolutionized shifting not only because of the low maintenance intervals. By using a front motor, almost any shifting system can be installed in the rear drive chain. The separation of human and electric drive not only protects the hub with a lower starting torque but also significantly increases the overall lifespan of both parts.
     
  4. Manual controle
    For a mid-engine to work well, the rider has to shift a lot and correctly, even if he or she accelerates or slows down. To do this properly and with low wear, the engine power must be removed at the right moment. There are shift sensors, but even then the force will have to be significantly reduced. It is particularly annoying if you have forgotten to shift with a mid-engine, for example on a mountain, and then you want to start again. Our hub motor also accelerates the bike effortlessly thanks to its strong starting help (gas).
     
  5. Top performance, low wear
    The top performance of the mid-engine is limited by the chain or at least the higher performance has to be paid for with extremely high wear. A hub motor with a properly fitted torque arm has no such limitation.
     
  6. More controle with slower speeds
    In our experience, the lifetime of the motors is about 4 times longer than that of a mid-engine. Some hub motors, which are designed with direct rotors, have the problem that they get hotter and hotter with heavy loads or when driving very slowly. Newer controls then reduce the motor power, but this then leads to even slower speed, which can lead to a defect due to overheating. By using a 5:1 planetary gear, our front wheel can turn 5 times slower than a direct drive, giving you the maximum control when driving slower speeds. In addition also peak currents are reduced, giving you a longer battery lifetime.
     
  7. Turning radius
    A wheel hub motor creates an almost unbeatable turning circle in our cargo tricycle Musketier. With the help of the manual gas, it is possible to turn almost on the spot with the handlebars completely turned inwards. A mid-engine or rear engine simply cannot do this.
     
  8. More road power
    But the last, for me the most important, point is the advantage to drive a small front wheel. The 20" engine in the Rapid gets, compared to a rear wheel engine in 26" with the same engine torque, significantly more power on the road. This means that even a fully loaded Rapid can overtake a normal pedelec.

    M=F*r (M= torque in Nm, r= lever arm in meters = half wheel diameter, F= force in Newton)

We hope that this short text gives more information about why we are so satisfied with our front wheel motor. For further and detailed questions please contact us at 07473-5020777.


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