Just read your response to my post. Thank you for sharing additional insights and thoughts. Interesting and enjoyed. I have to agree that most of our riding with an electric assist CAN be done in its “sweet spot”. If 90% + of a rider’s routes are mostly level or just short hills done near the optimal speed for the hub motor’s powere and efficiency than the trade off against an EMD is minimal. I completely agree. And like you, I am VERY much attracted to the quieter nature of the slower turning hub motors. So your points are very well taken. And fact is my riding routes ARE 90% flat 90% of the time. A quality hub motor would do the job for me without a doubt.

There remain many performance advantages to the EMD as you agree. The lighter weight, the less stress on the motor when working hard, superior acceleration and hill climbing. But at the end of the day, most of us are just cruising, some faster, some slower, and the hubs do the job. AND, by nature I’m very much an easy does it cyclist. I like to go slow and “smell the roses” as I cycle. A gentle assist is all I’m looking for. Something to spare my legs and leave me feeling strong at the end of my “getting from A to B” rides. At 50 I don’t have endless reserves for all the riding I enjoy doing. I’m looking for the assist to give me the same speeds I do now, 8-10 mph, with half the effort. That ratio would keep me refreshed day to day.

Money no object, we’d all have several bikes. Each set-up for the particular type of riding we plan on doing that ride. Enjoyable pedal only bikes, an optibike or EMD for “adventurer” and high performance riding, and cargo rides for shopping and kids transport, smile. Your assisted cargo bike set up IS the do anything combo in one machine.

Again, thank you so much for taking the time and sharing your experienced cyclist, real world experiences with me and others. I intensely look forward to the day when my finances improve and I can finally choose with confidence the system that will work best for me. The insights you share are invaluable.

I will enjoy your every posting and further system reviews.

Regards,
Floyd

I have removed the EMD and moved onto testing a Nine Continent hub motor.

Honestly (and this is just personal preference), I like the hub motor better. There are people for whom the EMD will be perfectly suited, but that wasn’t the case for me.

My hills are such that I can maintain that “sweet spot” speed range that is perfect for a hub motor. Only a few hills around here are so steep that I get into the < 10mph inefficiency range, where the EMD would really shine.

But I've found that, for my regular cruising speeds (17-22 mph), the NineContinent is a bit more efficient, and definitely more quiet.

I agree with you and the designers that hub motors have a limited range of efficiency.

But I believe that for a motor like the nine continent, IF you're within that range (15-20 mph at 36V for the standard wound motor), then the efficiency is very high – as much as 85-90%.

My experience indicates that the EMD efficiency is never that high, though it maintains its efficiency over a broader range of speeds.

So for people who are grunting up long steep hills, the EMD will shine. Maybe if/when I move to the mountains, I'll get a chance to test it under those conditions.

But for rolling hills with occasional steeps (we do have some hills ~25% grade, but they only last for a few hundred yards), I'm pleased with the hub motor silence and efficiency.

Thanks again for your note!

(and ps – your idea of me testing the Optibike is a great one! We're going to start doing more in depth testing of some motors soon)

From a physics standpoint, I don’t see how a hub system without the “through the gears” advantage can be as efficient, let alone more efficient. Simply because the speed of rotation of the motor is the single largest variable for efficiency, all else being equal. Although a hub and EMD can theoretically be equally efficient, this would only be in the ride envelope where the motors were turning the same speed and producing the same power. In practice this is only happening at around the 12-17 mph area. An important area because most riding time should be spent there for aerodynamic resistance reasons. BUT, everywhere else, slower and faster, the efficiency stays pretty much the same for EMD while the hub efficiency drastically falls off. And on hills, if you aren’t in the optimum motor speed range with a hub motor you are REALLY inefficient while the EMD is again at optimal efficiency because with the through the gears transmission the motor speed can allows be kept in its optimal range.

Ecospeed explains this nicely with graphs on these pages:

http://ecospeed.com/emddet.html

http://ecospeed.com/motdet.html

So, as you suggest in your post, I think it would be GREAT if you can do some comparative testing for us. Ecospeed should be doing this but they don’t seem inclined which is understandable but in my opinion leaves a, valuable for them, demonstration of the superiority of their kit against hubs undemostrated. If someone would equip two identical bikes with identical loads, batteries, and rider inputs, where one is a hub motor of similar continuous and peak power rating and the other an EMD, we could at last see what is what in performance, usability, and efficiency. Showing real time data from their “Cycle Analysts” side by side they go up a moderate hill, side by side they go up a steep hill, flat riding at various speeds, and coasting efficiency i.e. what if any drag the systems produce when coasting, motor off.

From a physics standpoint the hub motor could approach the EMD in only one area of the performance envelope. That would be constant speed at the hub motor’s optimal motor speed for power and efficiency. Everywhere else the EMD should drastically outperform any hub of similar power rating in both performance and efficiency. On hills and at high speed and acceleration, the EMD should leave the hub systems far behind. And in comparison to any hub motor of sufficient power to match the EMD on the hills and at low and high speeds, that hub system would be drastically less efficient and suck the battery down at several times the rate of the EMD in those extreme areas of the riding envelope.

The EMD can do the entire envelope of required functioning without restriction. And this isn’t because hub motors are inferior, but simply because the EMD’s motor output is transferred to the wheel through variable gears. This requires extra expense, complexity and noise (for a lightweight motor). Those are the admitted trade-offs. But for the cyclist looking for a system that can do it all and do it with the highest efficiency, nothing other than the Optibike can match the ecospeed systems for performance, lightweight, and longevity (unreliable controllers aside, smile ). The other current through the gears systems simply don’t have the quality, and the stokemonkey by design does not allow for motor use with the rider not peddling. I.E. when the stokemonkey motor is on, the cranks are turning and the rider must peddle along if only to keep their feet on the pedals. This is a point that stokemonkey admits freely to their credit but didn’t come up in this post. The EMD can run with peddle only, motor and peddle, and motor only cranks stationary, as the rider prefers. Complete flexibility for the rider, no compromises. And the EMD’s motor is a lot lighter and smaller. Reliability, longevity, performance comparisons are unknown to me.

By the way, ecospeed’s new fully digital controller is now available. They claim unmatched efficiency, adjustability, and performance. Maybe you can get a hold of one of those to test. I’m not aware of ANY posted independent testing on that controller.

Stick with the EMD. You may get used to the noise and find that as the miles pile up the reliability, efficiency, range, and just plain do anything that rises before you bike strengths will win you over. If not, I’d be so grateful for the stories and insights. It’s a system I am very interested in and I appreciate and will appreciate all the testing and posting you can do. Your efforts towards educating us prospective electric riders is rare and very much appreciated by myself and I’m sure countless others.

If you can talk Optibike at optibike.com into a bike lend and review for us, that would be GREAT !!! smile. You could pull a trailer with a “tub” bolted on for the kids. It would be great to hear your reviews for trailers from: http://www.bikesatwork.com/ and http://www.tonystrailers.com/.

Thank you,
Floyd