[Toshi]

i built myself an electric bike. why, pray tell, given that i'm still sound of mind and body, at least by most accounts? the answer is power.

electric assist is the difference between a) cruising up a decent grade at 18 mph in street clothes and shoes with cargo, contributing moderate pedaling effort and b) busting one's butt in clipless pedals to ride a road bike up the same hill at 8-10 mph. top speed on the flat with me tucking like a goon and not pedaling is right around 25 mph.

it's really quite fun, and, with the racks and such, useful.

technical details:

Novara Transfer bike from REI with a Nexus 7 rear hub

Crystalyte 407 front hub motor in a 26" wheel

was 36V 35A immediate start controller (good for 48V as well), now a 72V 20A pedal first controller, mated to a Crystalyte twist throttle

Cycle Analyst - Direct Plugin model

48V 12Ah LiFePO4 battery with battery management system (BMS)

was Ortlieb Bike Shopper pannier, now REI Safari waterproof panniers to hold the battery

the electric bits were all sourced from http://ebikes.ca/ . they ran about $1600 including shipping, with the majority of the cost ($900) being that fancy lithium battery. lithium isn't cheap! true story. the bike itself ran $510 on sale (anniversary sale ends may 11th!) at REI, and came stock with the fenders, rack, and even a front wheel generator/light setup that i'm clearly not using, and sold for $100 on craigslist.

i don't anticipate this being a financial windfall - i have a bus pass already, and previously was commuting the vast majority of the time on my road bike, the bus, or some combination thereof. however, i do think this will allow me to reduce gasoline usage even more, and that's worth it to me. if you're hard core enough (or your city is flat enough!) to get by on a fixie, cross bike, or regular roadie without electricity, then bully for you.

update: i sold the 35A immediate-start controller as the Hall sensors in the motor died in the Seattle rain. without Hall sensors one needs to run a pedal-first controller -- i'm running a 20A model at the moment -- that relies on back-EMF instead of signals from the Hall sensors to tell what position the wheel is in. the downside is that you have to take a few pedal strokes before assist kicks in. this isn't fun on steep hills with a very heavy bike and tall gearing but it's doable, and worth it for the increased reliability imo.

 

[LordOpie]

Awesome!

Could you have used something other than lithium? That seems absurd for a battery?

 

[stevew]

cool deal.

 

[Toshi]

Awesome!

Could you have used something other than lithium? That seems absurd for a battery?

i wanted a comfortable 20 mile range, and LiFePO4 in that size already weighs a solid 18.1 lbs! NiMH in nominally-equivalent capacity (less capacity in reality) would have been 22 lbs and $625 with a shorter lifespan to boot. SLA, sealed lead acid, would have been unbelievably bulky and heavy. other lithium chemistries might have been lighter than LiFePO4, but they have the annoying problem with exploding sometimes... (think cell phone and laptop batteries.) LiFePO4 is thankfully stable.

as it turns out i'm not using that much power, between 10-20 Wh/mile so far. for reference, a 48V 12Ah battery has a theoretical capacity of 576 Wh if you multiply the volts and amp-hours together, and a realistic capacity of ~500 Wh. this means i should be able to easily go 20-25 miles.

 

[w00dy]

I'd been thinking of building one of those for the longest time. I'm surprised they aren't more popular.

Sandwich got me hooked on this idea a long time ago:
http://zeromotorcycles.com/

 

[LordOpie]

thanks for the details.

That rocks.

Can you hook lights into the battery system?

 

[Stray_cat]

other lithium chemistries might have been lighter than LiFePO4, but they have the annoying problem with exploding sometimes... (think cell phone and laptop batteries.) LiFePO4 is thankfully stable.

QUOTE]


Man I wish I could remember the name of the short lived electric bike company that sourced it's Li batteries from one place, and it's chargers from another. One guy burnt his garage, another l had one explode in his car as it heated up in the afternoon sun.

 

[LordOpie]

Sandwich got me hooked on this idea a long time ago:
http://zeromotorcycles.com/G]

That's cool, but is it much better than Toshi's build? His was <$2000, while that (albeit, very cool) starts at $7500.

 

[ire]

Thats awesome Toshi! I've been thinking about building up an electric bike, but I was hoping the cost would be a lot less. The cost makes me lean more towards getting a moped, but the nice about the electric bike is that you can use the bike paths!

 

[Toshi]

I'd been thinking of building one of those for the longest time. I'm surprised they aren't more popular.

Sandwich got me hooked on this idea a long time ago:
http://zeromotorcycles.com/

please post that in this thread instead: http://www.ridemonkey.com/forums/showthread.php?p=2925761

L'opie, it's possible to run lights off the main battery with a step-down converter (48V to 12V or whatever the lights expect), but i thought i'd keep the wiring simple given that this is my first foray into electrics since my R/C car/boat days waaaaay back when.

 

[I Are Baboon]

Sweet! It needs an RM sticker...

 

[Toshi]

Thats awesome Toshi! I've been thinking about building up an electric bike, but I was hoping the cost would be a lot less. The cost makes me lean more towards getting a moped, but the nice about the electric bike is that you can use the bike paths!

advantages:

- use bike paths, yes
- can throw the bike on bus bike racks (explicitly allowed in seattle: http://transit.metrokc.gov/tops/bike/loadbike.html )
- can park legally wherever a bike can, on the sidewalk, in bike racks, etc.
- much, much, much lower pollution than a moped. i cannot stress this enough. going electric is cleaner than a car, but even a car has 95+&#37; less smog-forming pollutants than motorcycles and mopeds

it is possible to build electric bikes for much less, mind you. you get what you pay for, however.

walmart sells electric bikes for $350, for instance...

their electric bike range: http://www.walmart.com/search/browse-ng.do?ic=48_0&ref=125871.415453&catNavId=133073
the model you'd probably be interested in in particular: http://www.walmart.com/catalog/product.do?product_id=8467096

 

[Toshi]

it is possible to build electric bikes for much less, mind you. you get what you pay for, however.

walmart sells electric bikes for $350, for instance...

their electric bike range: http://www.walmart.com/search/browse-ng.do?ic=48_0&ref=125871.415453&catNavId=133073
the model you'd probably be interested in in particular: http://www.walmart.com/catalog/product.do?product_id=8467096

mine ($2100 + my time and labor) vs. walmart ($350 prebuilt):

48V 12Ah (576 Wh, 500 Wh realistically) LiFePO4 vs. 24V 10Ah SLA (180 Wh realistically)
1300W peak vs. "450W" peak, more like 250W in reality
Nexus hub vs. Acera derailleur
Aluminum with normal bike ergonomics vs. hi-tensile steel with dept store ergonomics
~70 lbs. vs. 81+ lbs.

basically my bike is lighter, has about 3x the effective battery capacity, and MUCH more power.

 

[moff_quigley]

The front hub is the motor? How does that work? Pics of the "drive" arrangement please.

 

[jimmydean]

That's what I had envisioned for your battery pack in a saddle bag configuration. I need to run the numbers to see what cost/size of a home made pack would be though.

 

[Toshi]

The front hub is the motor? How does that work? Pics of the "drive" arrangement please.

stock pic from ebikes.ca:

it's basically a really big diameter brushless electric motor. the axle is 12mm and threaded with 10mm flats, so it fits tightly in the dropouts (it clearly doesn't spin). the rest of the wheel spins about the axle. cabling exits through the left end of the axle, runs up the fork thanks to the magic of zip ties, and then joins the thicket of wiring in the velcro cable guides around the top tube.

if you're thinking "wow, so it puts all its torque against the short lever arm of the dropouts -- that's a recipe for disaster!" then you're on the money. thus i have a crescent wrench on the axle lashed to the fork with hose clamps to lengthen the lever arm and thus lower the torque. you can see the top of it on the far side of the bike above the front hub.

 

[urbaindk]

the bike itself ran $510 on sale (anniversary sale ends may 11th!) at REI, and came stock with the fenders, rack, and even a front wheel generator/light setup that i'm clearly not using, and will be selling to offset costs a bit.

You should just figure a way to mount the generator to the rear wheel to charge the battery. It would be like a perpetual motion machine. How cool would that be?

 

[Toshi]

You should just figure a way to mount the generator to the rear wheel to charge the battery. It would be like a perpetual motion machine. How cool would that be?

/ / /

 

[xy9ine]

You should just figure a way to mount the generator to the rear wheel to charge the battery. It would be like a perpetual motion machine. How cool would that be?

regenerative braking would be neat. think something along the lines of those vintage generators that were driven off the tire, except it'd be coupled to the v-brakes & only engaged when braking. brilliant!

 

[Toshi]

regenerative braking would be neat. think something along the lines of those vintage generators that were driven off the tire, except it'd be coupled to the v-brakes & only engaged when braking. brilliant!

it is a good idea, and even my setup will regenerate if i'm coasting at more than 35 mph down a hill (that's the freewheeling speed of the motor).

however, the gains are minimal as compared to with hybrid cars/regenerative braking. this is because there's a lot more wind resistance as opposed to kinetic energy in a bike/rider system moving 25 mph as compared to a car/driver system moving 25 mph. wind resistance is lost energy regardless of regen.

 

[xy9ine]

it is a good idea, and even my setup will regenerate if i'm coasting at more than 35 mph down a hill (that's the freewheeling speed of the motor).

however, the gains are minimal as compared to with hybrid cars/regenerative braking. this is because there's a lot more wind resistance as opposed to kinetic energy in a bike/rider system moving 25 mph as compared to a car/driver system moving 25 mph. wind resistance is lost energy regardless of regen.

did i mention the accessory helmet mounted windmill?

 

[splat]

SInce a Fork is designed for forces toward the rider , is there any concern about the long term pulling force on the fork ? , and why Not use Lead Acid batteries , yes they are heavier , but much easier to obtain , cheaper and easier to charge.

 

[LordOpie]

did i mention the accessory helmet mounted windmill?

 

[Stray_cat]

SInce a Fork is designed for forces toward the rider , is there any concern about the long term pulling force on the fork ? , and why Not use Lead Acid batteries , yes they are heavier , but much easier to obtain , cheaper and easier to charge.

I've seen some companies reccomend a cro-mo fork. Lead Acid degrades faster over time, and doesn't play nice when it comes to disposing of.

 

[Toshi]

SInce a Fork is designed for forces toward the rider , is there any concern about the long term pulling force on the fork ? , and why Not use Lead Acid batteries , yes they are heavier , but much easier to obtain , cheaper and easier to charge.

i did rig up a torque arm. see last paragraph of post #16 in this thread.

SLA batteries were never an option. they deliver much less than their stated capacity when at high discharge rates (such as in my 48V 35A setup, google Peukert effect iirc), are really, really heavy, have a short cycle life, and are in a very unwieldy form factor.

 

[Toshi]

I've seen some companies reccomend a cro-mo fork. Lead Acid degrades faster over time, and doesn't play nice when it comes to disposing of.

good point. LiFePO4 is a stable chemistry, and recyclable!

 

[LordOpie]

You should get some solid rubber tires.

How's the Nexus working out for you? Does it shift well? If you take the wheel off, is it a pain to disconnect?

 

[Toshi]

You should get some solid rubber tires.

How's the Nexus working out for you? Does it shift well? If you take the wheel off, is it a pain to disconnect?

it rides rough enough already with fancy late-19th-century tech pneumatic tires

the Nexus is pretty good so far. it hesitates to downshift if you're under load much like a regular drivetrain, but it's quiet, the chainline is clean, and i'm happy. right now the people-power-calibrated gearing is too short, but i'm swapping out the chainring and the sprocket, no big deal and pretty e-bike specific. i haven't taken the wheel off yet, but i guess i'll have to for the sprocket. wish me luck!

 

[buildyourown]

Lead Acid degrades faster over time, and doesn't play nice when it comes to disposing of.

While I agree that Lead acid is a horrible choice for an electric/hpv hybrid, for cars, they make sense. They are cheaper. They can be recycled easily, and they can be serviced. A "worn out" lead acid battery can be revitalized quite cheaply.
Considering the price difference for a car is 5 figures, it makes a lot of sense.

 

[SuspectDevice]

I just started doing some electric bike consulting again... They are fun to work on, but really, starting from the ground up to integrate the drive system and batteries makes the whole thing so much more fun.

that Ran's is the last conversion I did, back in '06. Even with '06 battery and controller tech, that thing, even without the fairing had a 50mile range cruising on flat roads at 30+ mph.

Of course, to get the nice low frontal area and stable steering it had a 57" wheelbase. But when the bike is that fast, and with that much range, it's pretty viable for rural commuting, which is what it was intended for.
A setup like that Rans would end up being more like $5000.

The client we have at the moment that has commissioned the design work thinks they might be able to bring a ground-up 'bent to market for less than $3k. That'd be pretty neat, but I don't know how possible the economies of scale are going to be. It's great to just be getting checks and sending files, but I kind of miss arcing myself too.

 

[SuspectDevice]

Btw, my favorite hub-motor by far right now is the SRAM sparc-dualdrive. The complete system is 5.2kg, it's a rear hub w/internal 5speed

nice small battery box too. Of course it's just 200watts. But the lightweight makes it practical to primarily pedal, and just use the assist to keep your work clothes sweat free. The real downside is the 16.8v battery. I haven't tried wiring it to a different voltage, but not having the ability to siebel-machen a kit with more AH's is a PITA.

 

[Toshi]

that SRAM sparc-dualdrive looks like a geared motor. any idea on what the actual motor inside is? a MY1017?

what sort of motor, controller, battery did you run on that 'bent? how many Wh/mile were you seeing? i'm hovering around 16 Wh/mile in my 35 miles of riding so far.

also, have you seen the "Ecumbent"? matt shumaker. VERY impressive. http://www.recumbents.com/WISIL/shumaker/default.htm skip to the bottom.

i'm going to try to build a battery holder within the front triangle today. having 18 lbs of lithium up high/out back makes for unpleasant handling when off the bike/parking it. it's actually ok when riding, but it sure wants to flip when carrying it up stairs... i already relocated the controller to the side of the rear rack to make room, and now it's bolted down, uglified, and pseudo-waterproofed for theft prevention.

i drew 1400W off the batteries on a steep < 10 mph hill yesterday. it's nice that the batteries can keep up with that (they're rated for 40A at 48V so are still comfortable), but the lame thing is that my hub motor is right around 40% efficiency at that speed. that means i'm getting maybe 600W to the ground, and dissipating everything else as heat.

 

[sanjuro]

That's great. I have thought about an electric motor, not for my regular rides, but those late nite jaunts across town.

 

[SuspectDevice]

that SRAM sparc-dualdrive looks like a geared motor. any idea on what the actual motor inside is? a MY1017?

what sort of motor, controller, battery did you run on that 'bent? how many Wh/mile were you seeing? i'm hovering around 16 Wh/mile in my 35 miles of riding so far.

IIRC it was perm PMG080 pancake motor, 2x12v 40A valence LIion gel cells (integrated BMU prevented self-immolation), all running through a custom controller we built. We modified a Magura throttle for cruise control. Front-freewheel cranks were necessary to use the center motor drive. We ran an adjustable gear reduction system from the motor to the drive cog to optimize the RPM range on the motor. We even rigged up an inertial automatic 3 speed system for the reduction, but it couldn't handle the torque.

at 24v deep in the amp's our DrainBrain telemetry was showing about 3000 watts peak. That's what that Paragon Machine 72 tooth chainring is on there! With the fairing and a flying start I got it up to 65 on the flats a few times. I was adding an easy 1000 watts myself. That adds up to total of about 5 horsepower for a total 220 pound package.

Things got even more rediculous with the tricycles...

And the Chopper...

The race trike runs a briggs and strattion ETEK, 48v on 12vx40a SLA's and an AXE controller. It goes really fast, and the pedals are COMPLETELY superflous. But man, it goes fast. Like 0-40mph in 4 seconds fast...

 

[Toshi]

wow.

 

[stinkyboy]

You're getting married?

Have I taught nothing here?!

 

[Toshi]

You're getting married?

Have I taught nothing here?!

in other news, over 57 miles (21.5 of them today alone!) i'm averaging just under 14 Wh/mile. what does this mean? it means i've used about 0.78 kWh to recharge the battery. keep in mind that i recharged it at the hospital, too, stealing their electricity... it's not a big deal, however, since the total amount of electricity is about 5 cents here in the pac nw.

that'd make cost per mile about $0.0009.*

(* if you conveniently ignore up front costs and battery replacement down the line. )

i also ditched the trunk rack and put the battery in a pannier, after several intermediate versions that didn't work all that well. this current setup rides quite nicely. the pannier bag's material dampens shocks to the battery making the ride as a whole noticeably more quiet and smooth.

 

[Reactor]

I see someone works with UNIX.

 

[Toshi]

bump with teh new picturas

yesterday and today have been absolutely beautiful here in seattle. it's also "bike to work day", so the burke-gilman multi-use trail was packed with all manner of lollygaggers. nevertheless, i cruised down it on the e-bike to take advantage of the sun and whip out the trusty 20D, which has seen all too little use over this stressful residency match season.

without further ado:

gasworks park e-bike glamour shots - april 16, 2008

that's the Space Needle and Queen Anne hill in the background across Lake Union

"Custom" U-lock mount made from four strategically placed zipties

Torque arm: 10mm crescent wrench, two hose clamps, and a ziptie

Center stand, like a motorcycle

Waterproofing and anti-theft/uglifying job on the motor controller

 

[Sherpa]

Did you not get a 50/125cc scooter because you didn't wanna buy gas at all?