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Mid-Drives for Bikes and Trikes - Are they the correct solution?

In a recent talk at Recumbent Cycle Con, Our President Rakesh Dhawan laid out a case why Mid-drives are a really bad solution for the bikes and trikes. 

Here is the summary of the talk.

Electric Bike Technology Comparisons

The Talk was Titled "Electric Bike Technology Comparisons"

Electric Bike Tech Comparison based on Torque, Speed and Throttle Sensor Operation and Customization Availability

The talk compared electric bike technologies on the following four factors:

  1. Torque Sensor Operation;
  2. Speed Sensor Operation;
  3. Throttle Operation;
  4. Ability to Customize.

Mid-drives such as Bosch, Brose, Shimano operate solely on the principle of torque sensor. The torque sensor operation concept was developed by BionX and Accell group in and around 1998 and thereafter adopted by other European companies. Torque sensor operation was exclusively applied to direct drives initially. The most significant advantage of a torque sensor is its ability to increase the battery range massively. Such is not possible with any other sensors in a bike or trike. Also, torque sensors allow for the most intuitive feel of all the available sensors in the market. Different companies have developed different torque sensor technologies over the last two decades. 

Bafang mid-drives available in the market don't have the torque sensor capabilities. They are purely driven by a built-in speed sensor. Speed sensors hog batteries just like throttles do. There is no mixing of human power into a speed sensor operation. 

Falco electric hub is the only eBike technology which allows for simultaneous and individual operation of torque and speed sensors. There has been cases where the rider is completely disabled and has no ability to apply any pressure on the pedals. In such a case, the speed sensor is a good option.

Throttle operation in mid-drives is dangerous. It is so because of the fact that the pedals also move when you push the throttle. That can lead to severe accidents. 

Falco electric hub is the only eBike technology which offers customization. No other available technology offers this level of customization. Falco hub can be customized to a very fit athlete as well as to a very disabled person. This range and level of customization is simply extraordinary in the industry. 

The chart above shows how limiting the mid-drives technologies of Bosch, Brose, Shimano and Bafang are. Falco scores high on all four areas of Torque Sensor, Speed Sensor, Throttle and customization. 

Hill Climbing, Speed, Price and Range comparison between the mid-drives and Falco direct drives

The next comparison among the technologies considers the following four factors:

  1. Hill Climbing;
  2. Speed;
  3. Range;
  4. Price.

Torque sensor based mid-drives are expensive. They also have much lower speed capabilities and range because of their poor efficiency. The only advantage they offer is hill climbing. That too is a trade-off because of the fact that they can be unreliable and prone to frequent failures. 

Stability, Speed, Portability and Comfort comparison of mid-drives vs. Falco direct drive

The next four factors we consider are:

  1. Stability;
  2. Speed;
  3. Portability;
  4. Comfort.

Mid-drives are best for mountain bikes because they offer lower center of gravity and lower unsprung mass. This given rise to spectacular electric mountain bike industry. It has also done wonders to the awareness of the electric bike technologies. 

Are mid-drives stable for tadpole trikes?

The stability argument does not apply to the tadpole trikes.

With a direct drive such as Falco, the stability, comfort and portability are enhanced tremendously. Let us review the below statement from Wikipedia regarding unsprung mass.

"A beneficial effect of unsprung mass is that high frequency road irregularities, such as the gravel in an asphalt or concrete road surface, are isolated from the body more completely because the tires and springs act as separate filter stages, with the unsprung mass tending to uncouple them. Likewise, sound and vibration isolation is improved (at the expense of handling), in production automobiles, by the use of rubber bushings between the frame and suspension, by any flexibility in the frame or body work, and by the flexibility of the seats."

So for a bike or a trike, it makes a whole lot more sense to have the direct drive like Falco than a mid-drive. Is it not? We are riding on gravel, or asphalt or concrete roads and we are not going 50 mph. Are we?

Now, coming to the speed, mid-drives can not match the high speed efficiency of a Falco hub. They are inherently highly in-efficient and prone to failures.

Mid-Drive Technology - Blind leading the Blind

It begs the question, why mid-drives are popular? Well, bigger companies can afford to act blind for a long, long, long time. Take the case of Boeing, hiding the evidence about 737 Max under the rug. Why? They did not understand it. They meaning the powers to be. The leadership and top management often ignore critical evidence to deny reality until a lot of people get hurt. Let us educate the end consumers about the pitfalls of mid-drive technology which is killing the beautiful science of cycling.

Mid-Drive Issues: Expensive, Highly Complex, High Maintenance Cost, Unreliable and Limited lifetime.

Mid-drives are expensive, highly complex, unreliable, with limited lifetime and very high maintenance cost. Mid-drives should never be used in a bike or a trike.

The battle of Falco direct drive vs Mid-drives, David vs. Goliath

The big companies are locked into the mid-drive solutions. One big company jumped in and then all the other big companies jumped in. When one big company brain washed a number of bike companies ( and most bike companies are tiny compared to this big company), the solution is set in. It becomes the holy grail.

Don't worry. Falco will continue to fight for the right solution. The battle is on and we do have a secret weapon to decimate the mid-drives. Mid-drives are unlikely to win in the long run.

History of Mid-drives. Why mid-drives became a solution

Let us circle back the clock slightly and see what happened before the advent of the mid-drive commitment by the bike companies. Prior to 2011, mid-drives produced around 25-30 Nm (Newton Meter) of torque. Flyer used to be a big brand in Switzerland with the Panasonic drive. Bosch introduced its mid-drive solution with a 40Nm system. It was the system which was fully recalled by Bosch in Europe. It was utterly noisy and had many quality and reliability issues. Nevertheless, the "Big Brother" convinced the bike manufacturers to adopt them as they could provide service with their deep pockets all over Europe. 

Bosch had to spend millions to rectify these mistakes with two recalls. However, fundamentally wrong solution can not be made right. 

Mid-drives offered superior hill climbing than the drives available at those times. Electric mountain bikes were advertised as the new eBike life style. There was a race to redesign the mid-drives to deliver 90Nm torque, which is really not difficult to do if you could look at the science of bicycling. 2011 to 2018, there was a mad rush by major electric bike companies to launch electric mountain bikes. All other companies in the bike industry went on to re-engineer all the components because "Big Brother" commanded it. Commitment to the wrong solution continued. Mid-drives continue to be expensive, wasteful and unreliable. Smaller companies believe in the "Big Brother". and Big Brother's leadership is busy burying the evidence under the rug. It is a perfect storm. 

In 2018, GoSwiss and BionX disappeared. They were two major direct drive brands. As bike companies ditched direct drives and adopted mid-drives, such brands did not stand a chance. Bike companies don't know any better. They don't know or understand electric bike technologies. They want to go with what they feel is safest for their brand. Big Brother offers the pretense of that safety. 

There is hope. Falco is fighting vigorously for the right solution. Falco has the secret solution to decimate the Goliath just as David did. 

Internals of Brose mid-drive

Let us look at the internals of some of the mid-drives. Brose as shown above has two gear stages. First gear stage is made of plastics and second gear stage is made of a belt. No matter how strong or sturdy the plastic gears or belts are, they are bound to fail eventually. Would you invest in a solution where an eventual failure is guaranteed? and the Big Brother is sitting right there to collect a HUGE maintenance fee.

Internals of Bosch mid-drive

Above is the mid-drive from Bosch. That is even more spectacular. Two gear stages made of plastic. Any amount of engineering can not prevent eventual failures and issues with plastic gears. That is a guarantee. Why not ask Bosch to provide a lifetime warranty. I am sure Falco would match Bosch's life time warranty happily. Today Bosch offers a mere two year warranty. That is Big Brother warranty. Falco offers 5-year warranty on its motors. 

Probability of failure of mid-drives. issues of reliability with mid-drives

Next is the look at the probability of failure from some of the data gathered at the websites of electricbikereview.com and pedelecmonitor.com. What we estimate is that by 4000 miles of riding, probability of failure is almost 50% and by 11,000 miles, probability of failure of mid-drives is almost 100%. However, it would be great if the Big Brothers would reveal this data to the public. They must be loving all the "maintenance fees" being collected by the dealers and the big brother. Bike dealers make more money through the maintenance of bikes than thru the sales of new bikes. Is that not ironic? So this solution fits well into the whole economic system well. You scratch my back I scratch yours. 

Bicycle gear efficiencies at 80, 150 and 200W

Regular bicycle gears are not 100% efficient. Shimano gears lose efficiency as output power is increased. Nevertheless, we can see that bicycle gear efficiencies range from 90 to 95% and the efficiency does deteriorate over time simply because like all bike parts, these gears require maintenance and must be taken to the bike shop frequently.

Bicycle gear efficiencies at 80, 150 and 200W

Another study puts the bicycle gear efficiencies between 88 to 95% at different power levels. Efficiency does improve with higher power but then you are losing a lot more of your power in the chains and gear systems. Imagine what happens to the mid-drives. They have to use the chains and gears to transmit their power as well. Good Luck Mid-Drives!

Bicycle Science - Calculating chain tension and force produced on the wheel

Now, let us look at some of the math behind bicycle science. We can easily compute chain tension based on the force on the pedals. We can also compute the force on the tire based on the diameter of the wheel and the gear ratio. 

Power Transmission Analysis of Mid Drive Motors

Based on these analysis, we can easily conclude that a mid-drive motor can increase the chain tension by as much as 10 times the previous tension. What happens to chains and derailleurs under these circumstances. 

Power Transmission Efficient of Mid-Drive Motors

We can easily calculate the overall system efficiency with a mid-drive. Starting from the battery to the motor to the gears, derailleur and the wheel, lowest efficiency is 42%, less than half. Under ideal conditions, you could go up to 73% but unlikely to go beyond 73%. That is a massive loss of energy - human and electric before. Big brothers need to smell the coffee.

Power transmission efficiency of a Falco direct drive motor

Compared to a Falco direct drive motor, magically, three stages are eliminated. And efficiency jumps upto 85%. Lowest efficiency is 68%. However, during hill climbing, direct drives do have a poor efficiency as compared to mid-drives. Nevertheless, Falco hub efficiency does not deteriorate over time as compared to the mid-drives because of the plastic gears involved. 

Power transmission efficiency of geared direct drive hub motor

Power transmission efficiency of a geared direct drive hub motor is even better than a mid-drive motor. Nevertheless, its efficiency deteriorates over time because of the plastic gears used inside these motors.

Torque transmission through a mid-drive motor

Even if you don't use the mid-drive but change your front chain ring to a small size, you could increase your torque producing capability by three times. You won't need the mid-drive at all. However, if we would use a 90 Nm mid-drive, you could possibly get a 270 Nm torque on the wheel. I say in that case, we might as well quit cycling and get motor cycles. 

Here is the video of the talk covering the above points

Do write to us with questions or comments at info @ falcoemotors.com or call us toll free 1-877-278-6323.