Trek 1.2 Lightweight High-power hybrid-unlimited pedal range

[grindz145]

So I've been doing this whole Electracycle thing for a while now, and it owns. I love my ebike. I love having 3kwh at my disposal. I love that I can load 60 lbs of gear without batting an eye, and I love real acceleration.

However, what I have with that bike (as most of us do) is a fast electric moped. You really wouldn't want to pedal it for much more than a block or two without power.

So that is the motivation for this build; to build a bike that it pedalable as a decent road-bike by itself, but with assist. I'm inspired by AJs commuter booster friction drive, and other lightweight builds. So I decided to do a build with a small geared hubmotor.



Specs:
-Trek 1.2 with Carbon fork
-Cute Q100 rear hubmotor (~4lbs)
-Lyen mini-monster 6FET sensorless controller
-20s 5ah nanotech lipo (in backpack)
-Surly Adventurer rear rim
-9 speed freewheel
-clipless pedals
-Old school cycle analyst
-cheap Chinese brakes
-Potentiometer "knob" throttle
-Brooks Saddle





Yes, that's the throttle...for now...


The main technical motivation for this bike was to build a bike which would current limit fairly low (maybe 10-15A), but will continue to provide assist up to 30mph. This way as the voltage goes up and the current stays limited, the effect will be linearly more power as the rider pedals faster.

So I had to use a potentiometer as the throttle to start off with, because the bars are too wide and I couldn't come up with a decent way to mount them on drop bars (suggestions appreciated). Right now I'm thinking about using some other type of pot, and an old road downtube road shift lever to adjust the throttle. Since it's going to be more or less binary, I don't have to worry about modulation too much, but I shouldn't have to hold the throttle down.

Performance:
I haven't set up current limit yet, so it really isn't set up the way I play to, but let me tell you, the Q100 is capable of about 1000w for short periods of time. The thing took off and accelerated hard up to 30mph. The nylon gears will not put up with this for very long I can't imagine...

Issues:
Right now the sensorless controller is giving me grief. If I try to accelerate (give it throttle) from 4mph to 12mph it looses sync and starts making some horrible noises. After 12mph (If I pedal up to 12mph first) and then accelerate, the controller has no problem. I suspect this is EMI getting on to the non-powered phase widings and confusing the controller. Anyone else had similar issues? I'm going to try winding the phase wires differently and see what happens.

Future Plans:
-Finely calibrate Cycle Analyst
-Limit current to 10A
-Fix the damn sensorless Sync issue
-Find better throttle setup
-Find the "sweet spot" where I can get 20 miles per charge or about 19wh/mile

All in all so far, the bike is quite pedalable on it's own. I wouldn't hesistate to ride it 20 miles, leaving the backpack and the batteries at home. I haven't weight it yet, but I imagine the bike itself is well under 30 lbs. The original bike was around 21. It feels a bit heavier in the rear, but surprisingly not terribly so.

 

[grindz145]

I guess pedal power doesn't get much love around here...

 

[GCinDC]

I guess pedal power doesn't get much love around here...

patience grasshopper. if you want instant responses, say it'll go > 75mph w/ 150mi range...

click on pics? ok, they work, but most times on ES they don't... lazy picture poster... :lol:

pot as throttle? wow, that sounds dangerous! why don't you just grind the tip into a point to make it safer in case you fall on it? how 'bout a thumb throttle and cruise control? how do you stop in a hurry?

The main technical motivation for this bike was to build a bike which would current limit fairly low (maybe 10-15A), but will continue to provide assist up to 30mph. This way as the voltage goes up and the current stays limited, the effect will be linearly more power as the rider pedals faster.

as the voltage goes up? what do you mean?

 

[grindz145]

I guess pedal power doesn't get much love around here...

patience grasshopper. if you want instant responses, say it'll go > 75mph w/ 150mi range...

click on pics? ok, they work, but most times on ES they don't... lazy picture poster... :lol:

pot as throttle? wow, that sounds dangerous! why don't you just grind the tip into a point to make it safer in case you fall on it? how 'bout a thumb throttle and cruise control? how do you stop in a hurry?

The main technical motivation for this bike was to build a bike which would current limit fairly low (maybe 10-15A), but will continue to provide assist up to 30mph. This way as the voltage goes up and the current stays limited, the effect will be linearly more power as the rider pedals faster.

as the voltage goes up? what do you mean?

Dude how do I get the damn pictures to show up? Is it just when they're below 70kb or something?

The voltage to the motor goes up proportionally with speed given a fixed current limit. This bike is designed not to come out of current limit... unless your going down a massive hill.

 

[dogman dan]

19wh/mi should be quite doable, but maybe not as fast as you'd like. My guess is about 18 mph. Likely you'll need to go sensored controller. The freewheeling tends to confuse a sensorless one.

Pics can be made smaller in ms paint, if you have nothing better to do it with.

 

[kafka-cloud]

For your bike,

If the 75mph 15mile range is not a requirement:

I too am looking in the next couple of year to make a pedalling performance bike with some power assist just to pass up all spandex club with their 5000$ bikes.

For more pedalling, I agree that you would need a geared motor I would also recommend 250-350 watt. The advantage of a geared hub is less interference when it is not powered. In other words, directdrive creates additional resistance when not running. Smaller/cheaper then 500W, stealthier.

A 20 Amp controller would be ideal. With the cycle analyst you can limit amp or speed until which you will have assistance. I would also recommend a kit which has a direct input for a cycle analyst. This will enable you to control Amp sent to motor.

Many kits have cruze control and I know on my nine continent/cycle analyst ebike the more you pedal at a given speed the less watt is consumed by the motor. I have limited a while my consumption of power to 10A on a 500 watt motor and yes you pedal a lot more then when at 20A.

A 48v (charged to around 54V) battery at 10Amp will provide approximatively 500W.

At 20 Amp the same setup gets me to around 960W

Suggested is brakle cutoff often provided in kit and either a pedelec system, a thumb thrttle or a twist throttle. I wouldn't go about inventing something new. All of these exist and are fairly cheap.


If you are looking for a bike that will let you pedal at 75mph, you will need a heck of a small cassette and a real big derailleur. Monster truck size. You may need to have a new bike configuration to accept a 24 inch derailleur to keep up with the motor. You may also want to have a bigger motor such as a 3kw and around 100V. I would probably buy a motorcycle frame for all the battery and motor and then weld a bottom bracket

 

[John in CR]

I was going to make a nice post, but now you get "Where's the beef?" I see an ebike that my cargo/school taxi will lap each and every lap. I guess the 75mph is down a big hill with a face white with terror. :lol:

Seriously though, it looks good. My only question is about the Cutie handling 20s. I'll be joining you soon, actually my son will. He needs to get more knee exercise, but it too much of a whimp to pedal our other bikes with the key off, so he wants a true electric assist.

John

 

[grindz145]

theres no reason why the cute won't handle 20s if the controller is set up properly. In the end it's the controller that has to deal with PWMing the motor low enough.

Dogman, I bet I can get a little over 18mph at that power consumption if I'm pedalling as well. That's the logic anyway, but time will tell and Ill let you know. I wouldn't be disapointed withe 20mph average with pedalling and 18wh/mile since I can only average about 15mph on my purely pedal road-bike.

OK Ill remove the bogus title: Greg made me do it

 

[mud2005]

looks good

how do you like the cute motor and where did you get it?

I'm doing a stealth build and want the smallest motor possible

 

[neptronix]

I guess pedal power doesn't get much love around here...

Sorry, i didn't see your post.

This is an admirable goal, and is similar to what i set out to do when i first got into ebikes.
I am a little concerned about your motorchoice. It's smaller and handles less power than the ebikekit / amped bikes small motor, which can be easily fried once you reach into the 1000w zone.

Cruising at 30mph is going to require wattage in the neighborhood of 1000w-1500w constant. When you hit hills that watt requirement will increase.

Another problem is staying within the efficiency band of the motor. If you let it bog down during hills by not pedaling like your ass is on fire, you will turn a lot of energy into heat running at 60% the unloaded speed or less. These tiny motors can't shed a lot of heat, so it could be a problem for you.

Otherwise this is a really cool build... i just think asking 30mph out of that motor may lead to settling on something larger like a bafang, bmc, or mac.

 

[adrian_sm]

Hey nice build. I love a light weight ebike. A small geared hub motor like this really tucks away nicely behind the gears.

I agree about the pot throttle with no return spring being a dangerous, but there is no real off the self solution for drop bars like yours. I went with a simple button throttle on my bike. With a low power system I don't find I need to adjust the power level much. On/Off is fine. For a controller like yours that has a hall or pot throttle input, you can just use a button acting as a simple voltage divider to send zero or full throttle signal. Here is a link but unfortunately the picture looks lost.
http://www.endless-sphere.com/forums/viewtopic.php?f=28&t=29846&hilit=button+throttle&start=90#p448986

The main technical motivation for this bike was to build a bike which would current limit fairly low (maybe 10-15A), but will continue to provide assist up to 30mph. This way as the voltage goes up and the current stays limited, the effect will be linearly more power as the rider pedals faster.

The Lyen Mini-monster controllers only really limits the battery side amps. So it will not behave in the way you described. For this you would have to be controlling the phase amps, to maintain constant torque. The Xiechang controllers limit the battery side amps which enforces a maximum power, so as speed goes up, torque drop off.

As for posting pics just resize the pictures, I can't remember the size allowed but if you make the longest side less than 600 pixels it should be fine.

Oh and I managed to fit the same amount of batteries you have in a Topeak AeroWedge XL saddle bag, incase you want to ditch the backpack. Pic1, Pic2, Pic3

Anyway. Great bike.

- Adrian

 

[AussieJester]

RE: pic posting, if your uploading them to ES server they have to be no larger than 800x800 or they
will show as they are above as a clickable link...

Best of luck with the build i hope i does everything you hope it will

KiM

 

[grindz145]

I guess pedal power doesn't get much love around here...

Sorry, i didn't see your post.

This is an admirable goal, and is similar to what i set out to do when i first got into ebikes.
I am a little concerned about your motorchoice. It's smaller and handles less power than the ebikekit / amped bikes small motor, which can be easily fried once you reach into the 1000w zone.

Cruising at 30mph is going to require wattage in the neighborhood of 1000w-1500w constant. When you hit hills that watt requirement will increase.

Another problem is staying within the efficiency band of the motor. If you let it bog down during hills by not pedaling like your ass is on fire, you will turn a lot of energy into heat running at 60% the unloaded speed or less. These tiny motors can't shed a lot of heat, so it could be a problem for you.

Otherwise this is a really cool build... i just think asking 30mph out of that motor may lead to settling on something larger like a bafang, bmc, or mac.

I agree completely, I tested it out without and current limit on the controller and easily go to 30, but I don't intend to keep it that way. However, I have to say, with this type of setup, it's very efficient at 30. Wasn't even pulling 1000w (was only like 650) but I need to calibrate everything still so Ill reserve my data. That is part of what I want to learn about this is, what does a human/electric hybrid really have potentially. I would love to average 20-25 mph with heavy pedalling.

But rest assured I don't plan to push it to 30mph on it's own power for very long. That was just the first "out of the box" test before I tune it in and limit the controller. Like I said, I doubt Ill even be able to get it out of current limit, and thats the idea.

 

[grindz145]

Hey nice build. I love a light weight ebike. A small geared hub motor like this really tucks away nicely behind the gears.

I agree about the pot throttle with no return spring being a dangerous, but there is no real off the self solution for drop bars like yours. I went with a simple button throttle on my bike. With a low power system I don't find I need to adjust the power level much. On/Off is fine. For a controller like yours that has a hall or pot throttle input, you can just use a button acting as a simple voltage divider to send zero or full throttle signal. Here is a link but unfortunately the picture looks lost.
http://www.endless-sphere.com/forums/viewtopic.php?f=28&t=29846&hilit=button+throttle&start=90#p448986

The main technical motivation for this bike was to build a bike which would current limit fairly low (maybe 10-15A), but will continue to provide assist up to 30mph. This way as the voltage goes up and the current stays limited, the effect will be linearly more power as the rider pedals faster.

The Lyen Mini-monster controllers only really limits the battery side amps. So it will not behave in the way you described. For this you would have to be controlling the phase amps, to maintain constant torque. The Xiechang controllers limit the battery side amps which enforces a maximum power, so as speed goes up, torque drop off.

As for posting pics just resize the pictures, I can't remember the size allowed but if you make the longest side less than 600 pixels it should be fine.

Oh and I managed to fit the same amount of batteries you have in a Topeak AeroWedge XL saddle bag, incase you want to ditch the backpack. Pic1, Pic2, Pic3

Anyway. Great bike.

- Adrian

Agreed, throttle is super dangerous...

Obviously not intended to be permanent. If I could figure out some kind of brake switch I would be happy. I have the kill switch of being able to yank the battery connector off at any point right now so it's not that bad. But as all ebikes... its a WIP.

That's a very good point about the battery currrent limiting and not the phase. It's not a perfect scenario, specifically at lower speeds, but operating close to syncronous speed, and limiting very low (like 10A) should get you in the ballpark. That's the theory anyway. Ill definately post data as I get it.

I may very well want to ditch the backpack, but I generally ride with one anyway, so we'll have to see how annoying it will get, but Ill definately keep it in mind. Thanks!

 

[grindz145]

looks good

how do you like the cute motor and where did you get it?

I'm doing a stealth build and want the smallest motor possible

got it from BMSBattery.com Ill reserve my judgement, but first impressions are good.

 

[grindz145]

RE: pic posting, if your uploading them to ES server they have to be no larger than 800x800 or they
will show as they are above as a clickable link...

Best of luck with the build i hope i does everything you hope it will

KiM

Interesting, it looks like if I hold my phone vertically, the pictures will post, but horizontally no go...must be the resolution after google resizes them for me. Thanks KiM.

 

[gogo]

Another problem is staying within the efficiency band of the motor. If you let it bog down during hills by not pedaling like your ass is on fire, you will turn a lot of energy into heat running at 60% the unloaded speed or less.

Don't forget that grindz145 is intending to have a 10A current limit. If we assume he is addicted to WOT and assume a 2.5X current multiplier in the controller's software algorithm, the controller is going to cap the voltage at 19.2V, which will cause his effective no-load speed to be 12 MPH until he can contribute enough torque from his pedaling to keep the battery amps under 10A. Once he reaches 12 MPH, the motor can only contribute a continually decreasing amount of maximum torque. This will move the "efficiency band" considerably lower. So the "danger zone" is from 0 MPH - 7.2 MPH, there is a lesser danger plateau from 7.2 MPH - 12 MPH, and from there the danger decreases steadily between 12-18 MPH.

If grindz145 can tame his wrist, or thumb, (or a push button would work ok at these power levels), he can stay in his motor's efficiency most of the time. If you add in whatever the controller's super-low PWM ramp is, he can probably go WOT and be in the motor's efficiency band almost all of the time.

 

[dogman dan]

Nothing wrong with pedaling briskly, adding say 150 w to your wattage for awhile. But me at least, I call my sustainable for 30 miles effort to be about 100w, and even less to keep it up for 60 miles.

Any way you slice it, your goal of pedaling up some power to add to range loses it's luster the faster you go. The minimum watts needed to go fast are set in stone, unless you go recumbent or something. Meanwhile the watts you contribute get to be less and less percentage of the total. By 30 mph, you end up with nearly the same wh/mi, pedaling or not pedaling.

But the idea behind your build is still good. You'll get fantastic wh/mi by pedaling at 100w, and using 200-300w from the battery. Watching a Ca while you ride, you can really start making those batteries squeal by coasting down and pedaling hard up the grades. Some unbelievable wh/mi numbers have been done by really hypermiling it.

 

[GCinDC]

re images, AJ's right: max horiz OR vertical dimension is 800 pixels. (i'd always thought they were 640... so that's what i shrank them to):
View attachment 2

 

[neptronix]

Wow. That's the ultimate stealth bike...

 

[Gregor]

The drop bars that allow a tucked position will help alot in the speeds between 20-30mph. "Add on" aero bars that allow you to rest your weight on your forearms also help with hand fatigue. The high pressure tires sould help with the hypermiles--a range between 15 to 20 wh/mile sould be possible. I have a 58 tooth chainring that is made by Vuelta that I bought on ebay about a year ago, and that helps you still contribute your 150 watts when your in the 25mph plus range. I've used the Wilderness Energy sensorless controller with a cute motor and 14s lipo and it has a bit of trouble syncing up at 2 to 5mph, but after that it goes pretty smooth. I have mine on a 20 inch folder bike so I don't get a chance to make the motor heat up much, but seeing your build has inspired me to try a build like yours this winter. Cheers, Greg

 

[Warren]

http://www.jensonusa.com/store/product/SL307A06-Hubbub+Twist+Shifter+Drop+Bar+Adapter.aspx

http://www.flickr.com/photos/12887128@N00/2422551242/

http://www.ecovelo.info/2008/11/12/alfine-shifter-with-drop-bars/

 

[grindz145]

Warren thanks for the ideas! I may have to look down that route. I like it more than my lever shifter.

It's amazing how many more people check it out when you reside the images

I dont have time for that ish... Thanks Greg.

 

[grindz145]

The drop bars that allow a tucked position will help alot in the speeds between 20-30mph. "Add on" aero bars that allow you to rest your weight on your forearms also help with hand fatigue. The high pressure tires sould help with the hypermiles--a range between 15 to 20 wh/mile sould be possible. I have a 58 tooth chainring that is made by Vuelta that I bought on ebay about a year ago, and that helps you still contribute your 150 watts when your in the 25mph plus range. I've used the Wilderness Energy sensorless controller with a cute motor and 14s lipo and it has a bit of trouble syncing up at 2 to 5mph, but after that it goes pretty smooth. I have mine on a 20 inch folder bike so I don't get a chance to make the motor heat up much, but seeing your build has inspired me to try a build like yours this winter. Cheers, Greg

That's interesing Gregor, It seems like I've shifted that range from 2-5mph to 5-13mph with 20s. I might just have to try 10s to see what happens. I still suspect EMI is the issue, and I'm going to try various shielding/RF Choke solutions. Big chainring is also probably in order too

Again, I don't really need 30mph out of this. The main accomplishment so far is that I can pedal this for a long time without ever turning the motor on. That's an interesting and liberating prospect for me in many ways.

 

[grindz145]

Just weighed the beast this morning. The bike itself (without the lipo battery pack) weighs ~29 lbs. It doesn't feel nearly that heavy when riding it either.