"True assist": is anyone else doing this?

[wayover13]

As far as not using the motor constantly while pedaling, why not just install an on/off switch up on the handlebar? You flip it on when you want to use it and off when you don't.

At the end of my two-year experimentation with the DD hub motor, this is exactly the sort of system I envisioned as likely most congenial for my needs. I decided at that point that what would be ideal for me would be a mid-drive motor that would match, via various types of gear reduction, my typical pedal RPM range (ca. 95 RPM's) to the motor's most efficient RPM range. The system would essentially have, as you suggest, a simple on/off switch; for safety reasons, such as I was envisioning it, some kind of spring-loaded paddle or button switch. When assist is wanted, the switch is pressed and helps the rider keep the desired RPM level. When assist is not wanted/needed, the switch is released. Simple but perfectly effective for my uses. It could be enhanced somewhat by causing the motor to do what I think they call "ramping," i.e., bringing the RPM's up gradually rather than instantaneously. Of course no such system as this exists, and I'm not competent enough electronically to implement it myself. So I'm looking at regular throttle-activiated mid-drives now.

 

[wayover13]

For me, an important realization is that once you get to the top speed of a motor, its not going to help you much beyond that.

Thanks for your input, chas58. I discovered this principle rather quickly during my initial experimentation with my DD hub motor. Its top speed was about 18 mph (16" wheel), and if I wanted to go any faster than that, it was going to be down solely to the power of my legs and respiratory system.

I don’t think there is a real easy solution, unless you want to get sophisticated by a torque sensing crank. The easiest thing to do is find a motor that has a no load speed similar to your typical cruising speed. If the motor does 15mph by itself, and has a no load speed of 18mph, really any speed you choose over 15mph is split between you and the motor. If you were cruising at say 17mph, you would be doing roughly half the work, and the motor doing the other half (and helping more on the hard parts).

How little is too little? There is not really a too little, as anything will help. But if your motor has a max speed of 10mph, and you are riding 15mph, the motor is doing nothing. Really, once you get beyond the “no load” speed of the motor, it isn’t giving you assist. It depends a lot on the person, but if you are doing lots of pedaling, you can do fine on a 36v5Ah battery (which is tiny). Yeah, to some degree it is a personal question. Most people using the small 250watt motors are using minimal assist, as that motor is about as strong as a rider in average shape (in my case, my legs are a lot stronger than the motor).

This seems to refer to hub motors, and I was initially doing the sorts of calculations you mention. But, since on subsequent reflection, I've begun to gravitate toward mid-drives, the equation will be calculated somewhat differently. I believe I should be able to get by with a 24 volt, 200 watt mid-drive kit for my minimal, true assist needs; but I'm still trying to confirm that.

Where is the info that “John Tetz” found?

google the name John Tetz. He's been doing a lot of interesting things with various types of assist for some years now. He's also got other cool bike projects: he's developed a full bike fairing, for example, using zotefoam. Interesting guy.

 

[wayover13]

Wayover13, I currently own and operate both throttle-only and torque-assist systems and find that I much prefer torque assist. I believe it is the best way to achieve "true assist". It feels so natural that no thought or particular skill/coordination is required to operate the bike. You will also have the option to dial in the amount of assistance that you want or to turn it off altogether.

I do believe that a torque-sensing, or torque assist, as you call it, system, if it can be properly tuned, should provide the most efficient sort of assist for my needs. Given what you mention about having "the option to dial in the amount of assistance that you want," though, the system could veer away from the true assist concept as I'm describing it. In other words, presumably it could be set such that it would be doing 90% or more of the work of propelling the bike, whereas what I'm aiming for would be something more along the lines of 50% or less--and that only on uphill grades. It's the convenience factor of torque sensing, though, just as much as the possibility of maximal efficiency, that appeals to me: I already have more than enough controls to fiddle with, and adding a throttle to the mix just makes one more. That said, as I've mentioned previously, I will be sticking with the throttle/brain method of regulation for now. Introducing torque sensing will come somewhere further down the line.

Mid-drive systems work well at low speeds, buy you will need to consider if the complexity of installation and potentially greater noise levels from a mid-drive system would be worth it.

Yes, hub motors certainly do qualify much more as drop-in solutions. That's a very appealing aspect. But I've got decent mechanical sensibilities and believe I've come up with a viable mounting system for my bike's unusual design. And noise won't be as much of a factor for me since I intend to use the motor in limited scenarios, as mentioned.

I have been experimenting with a Chinese e-bike kit that integrates a rear, geared hub motor with a built-in torque sensor, a sine-wave controller (for quiet operation), and an LCD display. By pressing a button on the display you can, on-the-fly, choose from 6 levels of assistance from no assist to full power assist. The system I purchased has a top speed of 17-18 mph and operates at 350W continuous to 700W peaks. It is similar in concept to the BionX system except that it, being a geared hub, lacks regen. This kit is much less expensive than BionX - about $400 (w/o battery) including shipping to the USA. Add another $300 to $400 for a modest capacity battery. I found the kit very easy to install - it took me one afternoon to get it up and running. The motor is very quiet on the road - in fact a friend commented that it make less noise than a bike with knobby tires would.

You can view my build thread here: http://endless-sphere.com/forums/viewtopic.php?f=3&t=46608. Yes, I did burn out the motor and had to replace it, but I think I would have burned out any motor of similar size on the brutal hills that I have to navigate. The sales manager of Minshine Electronics, with whom I have frequent contact, tells me that his company is developing a temperature sensor to fit inside the motor and link to the display which will then reduce current before the motor gets too hot. When that feature becomes available, likely this summer, the Minshine kit will, as far as I know, be the most technologically advanced Chinese e-bike conversion kit available on the market. The kit is available in different no-load rpms for different wheel sizes down to 20 inch, so it should work with your tandem recumbent. If you are interested I can give you more info via PM.

Best of luck to you on your quest!

Thanks for pointing out that new kit. It's amazing these things can sell for such low prices--I guess we have the Chinese government's artificial manipulation of national currency to thank for that state of affairs. I do want to look into these kits further and may PM you for more information. I'm pretty firm in my resolve to go with a mid-drive, though.

 

[wayover13]

Then, if you wish, you can make it less dependent on user active throttle control by adding anything from a simple cruise control, a three speed switch and cruise control, or a crude pedelec sensor combined with a three speed switch.

For the first phase of this upgrade I plan, as mentioned previously, to stick with the tried and true method of brain/throttle modulation. Sometime later I may move to phase two and implement one of the forms of modulation you've mentioned or else go with torque sensing. But that's far enough down the line that I'm not seriously considering it yet.

Or if you really want a lot of sophistication, you could buy a newest model Cycleanalyst, and get a torque sensing crank to plug into it. That's likely what you really want. You keep talking about "true assist". But I think you really mean, "assist without having to think about it".

I do plan on getting a Cycleanalyst. But in the initial phases of this upgrade, its role will be mostly informational, i.e., helping me to track things like battery level and motor efficiency. Maybe later, in phase two, I'll start looking into a torque-sensing bottom bracket or some such. But for now, as I've said, I'll be sticking with the brain/throttle method of motor modulation. I have nothing against thinking about modulating the motor, and it's what I've been doing for the last couple of years with my current kit: if I move to torque sensing or something similar, it will be, not owing to the fact that I don't want to have to think about modulating the motor, but because a) my supposition that it is more efficient than the brain/throttle method proves out, and/or b) it means my hands will need to be occupied with--in addition to steering the bike--one less set of controls (this is primarily a safety concern).

But I will keep saying it over and over. TRUE ASSIST is just a matter of gaining control over your throttle hand. Nobody is forcing you to use more power than you want. It just takes most people some time to get used to using a throttle, particularly if they never spent years riding motorcycles. Learn to use a throttle correctly, and you have the most sophisticated infinitely variable true assist there can possibly be. It's controlled by a computer with a lot of capacity, your brain.

And I will keep repeating that this is what I've been doing with my current kit for the past couple of years, and that it's what I intend to continue doing for the foreseeable future. If and when phase two of the upgrade comes to pass, that may change. But, for the time being, since I've learned well the ins and outs of the brain/throttle method of motor modulation, I'm sticking with it.

Sometimes I blow a lot of talk here, or maybe all the time. But it's backed up by more than 10,000 miles of riding with motors. My experience is not one days commuter repeated 1000 times either. I've done the race track, the commute, the dirt trails, and the 70 mile a day tours.

In terms of total mileage you've probably got me beat: I'd say we put 3-4k miles over the last two years on our DD hub motor bike. Maximum daily mileage for us was probably slightly above 80, though. No off-road riding, however, and I intend to keep it that way.

On the long distance days, I use a really sophisticated method. I jam my bar grip against the half throttle, so it sticks where I set it. Then I ride along for 20 miles or so, without thinking about a thing.

I've not gotten that sophisticated and am using a thumb throttle. But I do assume varying hand positions when my hand or fingers get tired.

 

[wayover13]

My touring pace is similar to yours, but riding solo (and being less fit) I need occasional assistance on the flat too. I find I use about 5 watt hours per km, plus 40 for every 100 metres of climbing. I have a 36v gear hub limited to 15 amps, and the peak wattage on my Cycleanalyst is actually a little under 500. That works very well for climbs where I can maintain 10 mph, but below that I'm very conscious that increased resistance is met by decreased assistance.

If you only use power for slow climbing then your requirements are easy to calculate: power is roughly proportional to speed. To climb at 7 mph instead of 5 you need 40% more power. Two fit people together can maintain maybe 350 watts on a long climb, so you need a motor that will produce 140 watts at the wheel.

Another way to look at it is that you want to reduce your effective weight by 40%. No matter how efficient your system is, no battery can lift more than 3kg 100 metres for one watt hour.

Thanks for offering this information. My aim, more so than going faster up grades, is to lessen exhaustion. I do most of the work of getting our weight, the weight of the bike, plus the weight of our gear, to the tops of those hills. Were my wife riding on a separate, non-electrically-assisted bike by herself, she would surely stop far short of the crest and walk her bike up the rest of the way.

As you might imagine, I am sometimes pushing myself to my absolute limit--which is probably unusually high for someone my age--by the time we crest some of those hills. I want to get to the tops of those hills with a heart rate of, say, 160 BPM or less, rather than the 180 BPM or more I'm often seeing. But adding assist is, after all--in addition to lowering my level of exhaustion--likely to increase, at least slightly, our speed on uphill grades. So I'm probably splitting hairs a bit here.

 

[Samd]

Oh I see now that you have had a DD motor for two years.

Am I the only one who feels like I am offering hard-earned advice to a friend of Chalo?

 

[dogman dan]

I'm just never going to really understand what you need.

One thing I definitely do understand, is that you absolutely for sure are using the wrong motor for your use needs. You will like a gearmotor better, but more importantly you have the wrong winding speed (rpm spec) motor for grinding up hills slow.

I had similar frustrations when I used the wrong motor for long tours. Designed for cruising 25 mph, the typical hubmotor kit sucks for climbing rocky mountain passes ten miles long. Slow motors that are happy going 10 mph is what you want to do that task.

 

[hekdude]

Where is the info that “John Tetz” found?

google the name John Tetz. He's been doing a lot of interesting things with various types of assist for some years now. He's also got other cool bike projects: he's developed a full bike fairing, for example, using zotefoam. Interesting guy.

Here is the link for the e-assist

http://www.recumbents.com/mars/tetz/E-Assist.htm

with his other projects at

http://www.recumbents.com/mars/pages/proj/tetz/projtetzmain.html

I have enjoyed reading about his projects.

 

[chas58]

Maybe I misunderstand you, but a simple thumb throttle gives you what you are looking for as I understand it. Ramping is of course determined by your thumb. A small hub motor for help hill climbing might be just what you need. the "hilltopper" kit actually does just that.

...The system would essentially have, as you suggest, a simple on/off switch; for safety reasons, such as I was envisioning it, some kind of spring-loaded paddle or button switch. When assist is wanted, the switch is pressed and helps the rider keep the desired RPM level. When assist is not wanted/needed, the switch is released. Simple but perfectly effective for my uses. It could be enhanced somewhat by causing the motor to do what I think they call "ramping," i.e., bringing the RPM's up gradually rather than instantaneously. Of course no such system as this exists, and I'm not competent enough electronically to implement it myself. So I'm looking at regular throttle-activiated mid-drives now.

 

[dogman dan]

Might have helped some, if along the way he tried a half twist throttle. Far more comfortable to hold at half throttle or less for 30-40 miles. Even better with a three speed switch.

 

[wayover13]

I'm just never going to really understand what you need.

Yeah, I have to admit there's a fair amount of subjectivity involved in the equation. As I said, John Tetz is so far the only individual I've found who's had almost exactly the same aim. I do believe there will be others out there who will understand and aim for such ends, though. Or maybe some that are in the early stages of investigating electric assist and who will read about my aims and think to themselves "that makes a lot of sense--I want to try that, too." One can hope, at least.

One thing I definitely do understand, is that you absolutely for sure are using the wrong motor for your use needs. You will like a gearmotor better, but more importantly you have the wrong winding speed (rpm spec) motor for grinding up hills slow.

You refer here to the DD hub motor I've been using for the last couple of years? If so, yes, I've learned through my lengthy trial period that this really is the wrong motor for my needs. Which is why I'm intending to upgrade from it. The two upgrade paths I've considered thus far are the geared hub motor and the mid-drive (the one that drives the crankset). It's proving a tough decision, but whichever I chose, it will end up making the DD hub motor I've been using a thing of the past.

I had similar frustrations when I used the wrong motor for long tours. Designed for cruising 25 mph, the typical hubmotor kit sucks for climbing rocky mountain passes ten miles long. Slow motors that are happy going 10 mph is what you want to do that task.

Yeah, that's the conclusion I've come to. The nice thing about the mid-drive kits I'm looking at is that, ideally, you use your bike's drivetrain to govern speed: the motor just keeps the cranks turning at ca. 90 PRM, and the bike's gearing is what determines what that comes out to in actual road speed.

Might have helped some, if along the way he tried a half twist throttle. Far more comfortable to hold at half throttle or less for 30-40 miles. Even better with a three speed switch.

Since I already had grip shifters on the bike, the thumb throttle was actually a necessity in my earlier testing. But I'll be switching to bar-end shift levers, so the possibility of using the twist throttle will be more realistic--though underseat steering, which I have on one of my bikes and which I'm planning to add to the other, is also not very compatible with a twist throttle (the handlebars are essentially mounted backwards in the underseat steering configuration).

 

[wayover13]

Maybe I misunderstand you, but a simple thumb throttle gives you what you are looking for as I understand it. Ramping is of course determined by your thumb. A small hub motor for help hill climbing might be just what you need. the "hilltopper" kit actually does just that.

I did look at the hilltopper. Seems a bit overpriced, and it's a bit too much of a "canned solution" for my tastes (I'm into at least a bit of tinkering with the system). But, yes, as the name implies, it is a kit very much along the lines of what I'm after. So there's another indication that there are others out there interested in the sort of approach to electric assist that I'm taking.

It's true that a thumb throttle or twist throttle will give much the same result with respect to ramping. I should point out that my idea of an on/off switch was just a sort of projection of what the ideal system for my purposes might be, and part of the impetus was to further simplify things (the KISS approach). But it's nothing I intend to do in the initial phases of this upgrade I'm doing--just an idea about how an ideal system might work. It's pretty much filed away for future reference at the moment.

 

[GCinDC]

[youtube]NHV86kwfdx8[/youtube]
older vid, but explains assist modes.
[youtube]pd1jheM_Cqo[/youtube]
my wife has been riding her bike w/ the bionx 250pl every day for close to 4 years. i've gone through many power builds for myself, but she's still happy with hers..

she hated the GM 48V kit i first gave her cause it was all too heavy.

this is far more expensive than i was at first willing to consider, but after all this, i think it's worth it..

you probably have to try it to see if you like it.

 

[el_walto]

You really should just pick up a small geared hub motor, 36v battery, and Cycle Analyst V3 with torque sensor, or a bionx system. Give that a go.

 

[Warren]

I grew up in Wisconsin, but spent the last 39 years in Virginia. My wife and I rode our RANS Screamer tandem for a decade, in the mountains of Virginia. After several knee surgeries, and a knee replacement, she has decided to quit riding. If you have a tandem with a 20" front wheel, and only want to use assist for climbing, there is no point in getting a mid-drive. You are making this way too complicated.

http://em3ev.com/store/index.php?route=product/product&path=40&product_id=52

Get the 12T, in a 20" wheel for an ~15 mph top speed on 52 volts. Get this pack.

http://em3ev.com/store/index.php?route=product/product&path=35&product_id=106

Get this controller.

http://em3ev.com/store/index.php?route=product/product&path=38&product_id=80

I think you said you have bar end shifters, so this throttle will work great.

http://em3ev.com/store/index.php?route=product/product&path=41&product_id=91

With this setup you will never have a problem climbing the steepest, longest climbs. You will never be tempted to use it for anything other than climbing, and perhaps starting from a dead stop. With the built-in freewheel in this motor, on a tandem, you won't even know the motor and battery are there, until you use it. Get a CA so you know what is going on, and keep it at 750 watts or less mostly.

http://em3ev.com/store/index.php?route=product/product&path=43&product_id=103

Or get something similar from GrinTech.

9073 miles as of yesterday, Warren

http://www.evalbum.com/4525

 

[Warren]

After looking at some simulations, I think even a 20" wheel is not small enough for hauling all that weight up really steep grades.

 

[Diamondback]

im using what i consider a "true assist" setup on my trike.

im running an ezee geared hub motor on 12s lipo (50.4v fresh of the charger), with a CA V3 and Thun BB.

i can easily get less than 3wh per km on most solo rides, and even when loaded up touring, i can get 6wh/km.
more often than not, i get home having provided more watts than the electric system has. it's usually close to 50/50 human vs electric.
most often it's more l like 65/35 human / electrons.

for one example, i recently did a 186km weekend tour and used only 19.1ah to do the distance, and that was loaded up with 14% hills in the mountain passes.

i am about to leave (tomorrow morning actually) for a 1200km 19 day tour.

Jason.

 

[-dg]

I grew up in Wisconsin, but spent the last 39 years in Virginia. My wife and I rode our RANS Screamer tandem for a decade, in the mountains of Virginia. After several knee surgeries, and a knee replacement, she has decided to quit riding. If you have a tandem with a 20" front wheel, and only want to use assist for climbing, there is no point in getting a mid-drive. You are making this way too complicated.
...
Get the 12T, in a 20" wheel for an ~15 mph top speed on 52 volts. Get this pack.
...
With this setup you will never have a problem climbing the steepest, longest climbs. You will never be tempted to use it for anything other than climbing, and perhaps starting from a dead stop. With the built-in freewheel in this motor, on a tandem, you won't even know the motor and battery are there, until you use it.

The above is really good advice for OP's request. I have a very similar cycling background and age etc to the OP. Generally I am interested in making assisted bikes rather than electric motorbikes. I don't have a tandem but am planning a cargo bike so the question "how do I get my older-weaker self and 150 lbs of compost up the hill to my house without horking up a lung?" has been something I've thought a lot about.

I also own a torque sensing mid-drive factory made bike (the Aerovironment Charger) which really should meet these goals but doesn't. This is a well engineered drive system, much better than the common kits, no bed-rail and u-bolt brackets or under-spec belt engagement or anything problematicly like that. However, it is excessively noisy and requires more maintenance (belt tension, intermediate chain tension and wear etc) than a bike should. I've had it a long time and have fixed some of the issues (replaced SLA with lithium batteries, upgraded components etc) but don't really trust it or enjoy riding it. It will be replaced with a hubmotor in a bike that I already like. I admire the design principle of mid-drive, it seems like a good idea, but all the actual examples I've seen are crappy or annoying or both.

A similar but lower budget, somewhat quieter, alternative to the suggestion from Diamondback that is even slower because it uses lower voltage would be: a 36 or 48V Bafang BPM front motor in a 20" wheel, a 25 amp controller and a 20+Ah battery in the neighborhood of 30-ish volts. You want a no-load speed of around 12-13 mph.

Assuming 440 lbs gross weight, and 250 watts pedaling input total, this combination will climb a 12% grade at 5 mph and is most efficient on a 5% to 6% grade (very common highway slope) around 9 to 10 mph. By 12 or 13 mph the motor is doing nothing which is what you are asking for. For example, with this setup you can climb Rabbit Ears pass (which I still remember from my cross country, 7%, 3000 ft gain) at 8 mph. It would still be a hard climb, but practical, not torture. All these combinations work without overheating the motor according to the simulator.

Get the motor first and measure the speed with a known voltage and then order the battery with the right voltage to get the no load speed around 12-13 mph. A Ping would be a good fit for this as he can make custom sizes, eg 33 volts last I checked. Since it's a tandem you can afford the space and weight. But anything 20+ah around 30-ish volts will work. This application is not going to demand much from the battery as long as it is big enough to be useful.

I think the control issue in this case is pretty simple. Thumb throttle with auto-cruise control, or almost even just an on/off button. Given that you only want it when you have a hill to climb, that the power is limited by the low current, and that it won't go very fast anyway, you are almost always going to want most or all of it. I'm assuming you can accept climbing 7% at 9 mph at full throttle instead of 7 mph at part throttle or 3.5 mph on your own.

Try out the ebikes.ca simulator, it is great for this sort of design exploration. For your criteria I used a 30 V 20 Ah battery, the 25 A controller, 20" wheel and the Bafang BPM motor (this is the 36 V motor, the 48 would be slower yet, you can scale the battery voltage to see some of the effect)

 

[dogman dan]

BING!

20" wheel, 12t mac, and some kind of watt or speed selection switch, so most of the time you will never be given much more than 150w. . Pedelec if you wish, and a simple bar mounted on off switch to the controller. Perhaps even a doorbell like button, hold down to get assist.

Don't just pick any small gearmotor, if it's the wrong winding it will work every bit as poorly as your previous dd did, for that kind of ride. 12t mac or any other similarly slow winding will grind up those hills fine.

What you need is different from me by a lot. I got sick and had to all but give up pedaling altogether. I hate it, but compensated by making my longtail cargo bike very powerful when I need the power. The price is lugging around a monster heavy motor even though I mostly ride around with my two speed switch set to low wattage. I sure miss being able to put out even a mere 100w for very long.

Anyway, what I'm trying to say is get something able to put out 1200w, but use only 200 of it. Trade low speed efficiency for speed with the slow motor. You won't often need the 1200w, but the key thing is to not have too fast a motor, which will eat 500w, but turn 400 of it into heat at 10 mph. What you want is 400w when going up the steepest hills, but only 50w of it making heat.

Your old motor was only happy going 15 mph or more, so it performed like shit unless you rode it wide open throttle at 20 mph or more. You're right, that's not "assist" .

FWIW, one reason the bionx works good as designed is that they selected a slow ish motor for it. Not super slow like my favorite motors, but I bet it's 4-5 mph slower than your current dd motor.
That helps it work well at the lower wattages, and slower speeds. It doesn't choke so much below 15 mph.

 

[Warren]

Yes. My suggestion looked good, even at 440 pounds all up on a recumbent tandem, and a 10% grade. But at 15% it went all to hell.

If all your touring is in the Midwest you would be fine. Finding a 15% grade that it will take longer than a minute to climb isn't happening.

Also, the simulator doesn't account for your input.

Figure 85 pounds for the bike, plus 160 pounds, and 9% body fat for you, 140 pounds for you ex-ballerina wife, plus 55 pounds of camping gear and cloths.

 

[-dg]

Finding a 15% grade that it will take longer than a minute to climb isn't happening.

Also, the simulator doesn't account for your input.

15% for any distance is pretty rare almost anywhere.

The simulator does account for your input. Click on the graph to move the vertical "speed" line to a higher speed then examine the numbers in the boxes in the lower left below the graph labeled "motor power" and "load". The difference between "load" and "motor power" is the rider input required at that speed. So just adjust the speed until your difference matches what you can put in.

For example the BPM configuration I was suggesting earlier will climb 15% at 4 mph with total "load" at 536 w and motor power of 277 w leaving 536-277 = 259 watts required from the riders. This is using the BPM36V500 in the simulator with battery voltage set at 25 V. I'm trying to model the 48V BPM which would be a slower winding and something like a 10s LifePo4 (33 volts) battery, but the slower BPM is not in the simulator.

By scaling battery voltage down by the difference in the motors, ie 36/48 = 0.75 so 33 V * 0.75 = 25 V it is possible to get the simulated speed sort of right. This is not quite correct as it does not account for the increased torque constant of the slower motor, but that should be kind of ok since the real motor should perform better than the simulator in this case. An alternate approach is to scale the wheel size down by the difference in the motors KV. Ie simulate for a 15" wheel instead of 20". This is probably more accurate and produces even more favorable results.

The

 

[Warren]

dg,

" An alternate approach is to scale the wheel size down by the difference in the motors KV. Ie simulate for a 15" wheel instead of 20"."

Actually, I don't believe different winds/different KV is the same as changing wheel size. Changing wheel size is exactly like changing gears on a mid-drive. But per The Man Himself:

"Is there a tradeoff between speed and torque?

No, there is a frequent misconception that the hub motor windings are similar to gears in a conventional drive chain, and that as you go to a lower speed you get more torque or visa versa. This is generally untrue."

 

[Warren]

dg,

Thanks for the tip on rider impute in the simulator. I have been wishing for that for some time.

 

[hekdude]

I thing you can get a pedalac sensor which senses if you are pedaling (not a torque sensor) so you can get assist level based on pedaling speed. It does avoid having to hold the thumb throttle for long distances. My thumb can get tired for 10 miles.

 

[Kepler]

As to the Kepler thread, please do not take this wrongly, but that build is actually quite the opposite of the "true assist" concept as I'm envisioning it. The first indication of that is the stealth factor that seems to be so important to the build: why would someone who is aiming to somewhat lessen their physical exertion in challenging terrain be concerned with disguising the fact that they're using a motor to accomplish that end? This would be, I think, a non-factor in the true assist scheme.

I also note the speeds Kepler maintains on this bike: on the second build (he replaced the friction drive with a hub motor) he claims to be doing 35 kph (22 mph) on flats and 25 kph (15 mph) on hills. I suspect, based on those figures, that his system is supplying more than the minimal assist I'm hoping to investigate. Furthermore, why use electric assist at all on flat stretches of road: in a true assist scenario such as I'm envisioning it, the electric assist would be disengaged in such terrain.

Finally, the true colors of this project come out in Kepler's recounting of the instance when he "latched on a nice quick Lycra this morning" (page 8 ). He seems to relish the fact that the lycra fellow seems not to have realized, owing to Kepler's stealthy implementation of electric assist, that he was riding alongside an electric-assist bike. The culmination of the story is when Kepler, after he and the lycra fellow had chatted a bit at a stop, "switched to 750W mode and silently sped off to a 45kph cruise speed. That was the last I saw of him. Mission accomplished." Uh, no; cute as this story might seem to some, this is quite far from the true assist scenario I'm envisioning. So, though for someone who is knowledgeable, information that will be relevant to true assist can be gleaned from that thread, its main drift is quite off-target. This sort of discussion amounts to a bit of a red herring for purposes I'm discussing.

Take this wrongly? Why would I? Sounded like a bunch of complements to me. :lol:

Seriously though, I get where you are coming from but I can asure you the purpose of my build was not to be some sort Lycra hunting pretender. Its purpose is to blend in as a normal bike on bike paths while at the same time having the performance to mix it with the quick bikes without me busting a gut. With the Torque PAS setup on this bike, I can see in real time what my human Wattage input to the ride actually is. I like to average around 150W with the bike putting in around 300W most of the time. This gets me to work nice and quickly with a reasonable amount of exercise but without the need to take a shower when I get there. At the same time I complete the ride without upsetting anyone. Actual assist is just a ratio. In my case its 2:1

In truth, on my non assisted carbon road bike, I can mix it with most riders out there. At 52 years of age I go to the gym 5 days a week, run 30km a week, and free ride at least 100km a week with the point being fitness is not a problem. However I choose to ride a high performance assisted commuter as a healthy form of transport rather then driving my car. Considering The pedalling effort I put in is electrically rewarded at a 2:1 ratio I believe this does make this a true assisted bike.