Building my E-Bike

X

xarvox

100 mW
Joined
Dec 22, 2008
Messages
35
Hi all!
First time poster on this forum, but i started this idea on a rc forum but figured i should probably spend some time here instead :)

so ive cut/pasted some of my earlier posts on rcgroups (slightly edited for clarity :) ).

Ive been playing with this idea for months now and i simply cant shake it off..

The idea is to put roughly 1-1,5 kW of power, thru a electric brushless outrunner motor thru a gearbox.
The gearbox will be connected to the back wheel on the left side where the hub has mounting holes for brake disks, but will be fitted with a chain sprocket instead.
Top speed is 50 km/h on flat surface, but tourqe is more than welcome

I was hoping to use a simple servo tester as throttle (custom built), a 100A ESC and run it on 3-6cell series lipo (11-22v).
I will start by using my current batteries (2,5-3Ah 3s lipos).
a tad little prehaps but i would like to start with something cheap and readily available in case this project fails for some reason..
---------------------------

I have ordered a bunch of bike stuff, new back wheel among other things
this one has fittings for disk brake that will be used for the drivetrain instead.

The motor im buying is still unknown model (the seller havent still had time to look it up), but its a axi 41xx of some sort.

The current owner used the motor for a almost 3m wingspan depron/foam 3d acrobat on 3s 2Ah batteries in 2p, so my current packs seems to be a good starting option (3s 2,5Ah and 3s 3Ah) for paralell connection.


i have started a conversation with a swedish company selling belt wheels and belts (correct word??).
So as soon as i get an idea of what sizes to use, i will order the belt drive components and start building the gearbox house.



I also have a open question:
Is there a simple way that i could implement a on-the-go changeable gearing?
..3 gears would probably be enough, so i was concidering using a 3-5 gear planetary back wheel hub from a bike as a last gear reducer, but i wonder if its strong enough to handle the beating..?
and what gear ratios are thease hub gears normally?




and please apologize my butchering of the english language (3rd language) and please correct me where im wrong (life is a constant learning progress)
Click to expand...


A bit much in a single post prehaps, but i figure its easier to get you up to speed by cutting/pasting like a cheating highschool-student :)


Ive started sketching on the gearbox itself, as i will be fabricating this out of aluminium at work (4 axis cnc) but the sprockets and the rotary parts will be ordered when things clears for me.. :roll:

Any hints/suggestions are most welcome, aswell as links to other gold-mines of knowledge :)
 
Welcome aboard. That was a good introduction. It lets people know your level of experience, progress, desires and capabilities.

I started from scratch and spent at least six weeks searching the archives. My brain can only take in so much and there is more than enough in the archives to make my head spin endlessly.
You'll find expert advice there. Lurk and learn I always say. As it turned out I've only asked one question and those answers confirmed what I'd already suspected from weeks of reading.

Miles, for one, knows what you're talking about. I have a hub motor so can't help.

Anyway, happy gold mining! I think we've struck the mother lode here.
 
xarvox said:
""I also have a open question:
Is there a simple way that i could implement a on-the-go changeable gearing?
..3 gears would probably be enough, so i was concidering using a 3-5 gear planetary back wheel hub from a bike as a last gear reducer, but i wonder if its strong enough to handle the beating..?
and what gear ratios are thease hub gears normally?""
Click to expand...

oh, oh, oh! Here's one I can help with.

A handy page listing the gear ratios of various popular bicycle hubs is:
http://www.sheldonbrown.com/internal-gears.html

Neither myself nor any manufacturers' legal departments would condone driving one with more watts than a normal human produces though it's probably been done. bon chance.
 
I'm working on the custom servo tester. :wink:

I helped John Tetz a while back with an early RC drive bike. He found the current limiting in most speed controls is not really suitable for bike loads and snapped the shaft off at least one motor.
Don't forget the extra capacitors for the controller too.
 
xarvox said:
Hi all!

The idea is to put roughly 1-1,5 kW of power, thru a electric brushless outrunner motor thru a gearbox.

The gearbox will be connected to the back wheel on the left side where the hub has mounting holes for brake disks, but will be fitted with a chain sprocket instead.

Top speed is 50 km/h on flat surface, but torque is more than welcome

I was hoping to use a simple servo tester as throttle (custom built), a 100A ESC and run it on 3-6cell series lipo (11-22v).
---------------------------
I have ordered a bunch of bike stuff, new back wheel among other things
this one has fittings for disk brake that will be used for the drivetrain instead.

i have started a conversation with a swedish company selling belt wheels and belts (correct word??).
So as soon as i get an idea of what sizes to use, i will order the belt drive components and start building the gearbox house.

I also have a open question:
Is there a simple way that i could implement a on-the-go changeable gearing?
..3 gears would probably be enough, so i was concidering using a 3-5 gear planetary back wheel hub from a bike as a last gear reducer, but i wonder if its strong enough to handle the beating..?
and what gear ratios are these hub gears normally?

and please apologize my butchering of the english language (3rd language) and please correct me where im wrong (life is a constant learning progress)
Click to expand...

A bit much in a single post perhaps, but i figure its easier to get you up to speed by cutting/pasting like a cheating high-school-student :)

Ive started sketching on the gearbox itself, as i will be fabricating this out of aluminum at work (4 axis cnc) but the sprockets and the rotary parts will be ordered when things clears for me.. :roll:

Any hints/suggestions are most welcome, as well as links to other gold-mines of knowledge :)
Click to expand...

Hi,

I recommend looking at the following:
http://endless-sphere.com/forums/viewtopic.php?f=6&t=3904#p57685

If you are interested in purchasing a reduction drive or getting some ideas look here:
http://www.endless-sphere.com/forums/viewtopic.php?f=28&t=7180&start=0&st=0&sk=t&sd=a
http://www.wisil.recumbents.com/wisil/shumaker/edrive.htm

A nexus 3 speed hub would work well for gearing but you would need to drive through the right side:
http://endless-sphere.com/forums/viewtopic.php?f=6&t=5297&p=79741#p79741
I'm sure the Nexus hubs can handle the power. There's a guy with a bike shop down in San Diego (Rusty Spokes, in Pacific Beach...) who custom builds chopper-style motor bikes, using Etek and Mars motors. He uses these same Nexus 3-speed hubs with these beasts, and they have worked flawlessly, even pumping 15 hp through them. Instead of chain, hoever, his bikes are belt driven, using regular toothless v-belts. There's a little bit of "slippage" when starting out, which is like a clutch. Works great, he says, and these things can hit close to 60 in just 2nd gear. Anyway, he's never had a single problem with any of the Nexus hubs.
Click to expand...

The easiest way to do that is via the crank something like this:
Rahmen%2003.jpg


For further discussion:
http://www.endless-sphere.com/forums/viewtopic.php?f=28&t=7641

Nexus Hub Gear Ratios (and more) here:
http://www.sheldonbrown.com/harris/shimano-nexus.html
 
Thanx for the input guys :D

The recumbent project linked above is actually the first site i found when i started on this quest for motion :)
Many of my ideas are "stolen" from that project :)


regarding the 3speed hub and the drivetrain in general:
I will not use right side propulsion because i want to keep the power trains separate.
regardless of this projects status i still have to bike to work every day on the test platform :)

the hub would rotate the wrong way if i would just flip it around with the sprocket on left side, but i could easily use the custom fitted (fixed) sprocket to be the left one while the geared input-sprocket is on the correct side. :)


Fetcher, thanx for the advice :)
Im planning on using a friction clutch that releases in case of overload (ajustable) to sort it out.
Eather this or a v-shaped belt drive to the rear wheel.

also, there are electronic speed controllers (ESC) that has soft-start, for geared motors and helicopters.

But still, i would like to be able to control max amps on the throttle level but i doubt i will be able to construct my own ESC with that function..


And finally, the ethics regarding putting more power than humanly possible into the bike.. :)
Ive wanted a trial motorcycle since i was a kid, and if this actually works, i can have it in the appearance of a mountainbike :D
Since i always found it more intresting with tourqe over speed, the goal is a fast accelerating, but speed-limited bike (aprox 50km/h tops)

And it doesnt really bother me if i would have to register the bike as a motorcycle/moped at that stage, since i would need to custom build it alot making it VERY hard to pass as stock anyway.

But i dont belive in over-complicating stuff, my motto is K.I.S.S, Keep It Simple Stupid!
better to take babysteps and get it done than to try to chew of a too big of a piece.. :)



Now im waitig for the gear casette for my new rear wheel and some initial gearing desitions i will be on my way :D


Since i have a 4 axis cnc lathe/mill at work i was actually thinking about cutting myself a belt sprocket out of nylon to fit on the rear wheel.
If i could find a piece large enough i could actually use direct drive to the motor sprocket.
Does anyone have suggestions where to get a roughly 40cm diameter cylindrical nylon disk (10 cm high) online? :)
another option is aluminium, but its expencive.. :/

Any extra weight placed on the swinging rear "fork" will result in less effective power transmission (since the wheel will hop and bounce off anything it rides over so i need to keep it light.

Now im off celebrate xmas (read consuming) so i wont be back for a few days..

marry Xmas and a happy new year everyone!
 
Welcome aboard!

I am glad to see you tackling this.

The AXI motor is a good option for the price. They are very efficient.

If we can help with anything, please ask. We are all interested in helping out on this forum.

Matt
 
xarvox,

I'm not keen on the idea of fixing things to spokes but, if you want a quick and easy way to get a test-rig, you might consider using one of the Golden Eagle rim pulleys:
http://www.bikeengines.com/orderpage2.htm
http://www.motoredbikes.com/showthread.php?t=5938
 
First off, merry X-mas everyone! :)


ive been thinking alot about the gearbox and have come up with some ideas..

levels of gearing:
1= motor
2= 3/5 gear hub
3= rear wheel


1-2 will be roughly 5:1 with a belt drive
2-3 is unclear at the moment, but i figure i should go with a chain drive from bike/moped on this last stage.
I dont know how much difference the gear hub will do, so i will leave it out at the moment, unless i just happen to stumble uppon one for free :)

the rear sprocket casette have arrived and are fitted, so now im waiting on the motor and the rest of the transmission....
:)
I will start buying the transmission parts after new years eve, but im unshure if it requires a closed gearbox.
I will probably make a simple box housing for it instad, with open sides and letting the gears stick out (just for support, not for covering it up).


but i do have a question.. :)

does anyone have suggestions where i should look for very large chain sprockets?
..im not looking for webshops (since im in europe, sweden) but rather tips of where such stuff are used.
For example, rear sprocket for gocarts are supposed to be fairly large and relatively easily accessible. :)


i still havent found a retailer that sells plain and simple sprockets, so i might have to insert aditional gearing levels and use bike sprockets.
 
Ive ordered myself the battery now, a 4,4Ah 5s lipo (4,2v/cell when fully charged) that will power this motor just great :)

The drivetrain will have to wait for the motor and battery to arrive (to measure it and so on) but i think i need to start concentrating on the throttle device.


Ive asked around on a swedish electronics forum and got quoted some 3 000€ pricetag for a throttle with max A/temp cutoff..


So now i ask here instead.. :)

What im after is to be able to set max output thru the battery connection and limit the throttle responce accordingly.
Meaning, if i try to start too quickly, it will work as a electronic friction clutch.

The same feature for overheating in any of the main components (motor, esc, battery), the drivetrain reduces throttle input.

im not shure about the technical descriptions, but i hope you understand what im after here :)



Since im rather clumsy with fine electronic soldering, im asking if anyone is up for the task, to co-develop such device with me?
i will indeed pay for it, but as its a personal project i simply cannot afford the swedish forum quotes.. :)
 
xarvox said:
does anyone have suggestions where i should look for very large chain sprockets?
..im not looking for webshops (since im in europe, sweden) but rather tips of where such stuff are used.
For example, rear sprocket for gocarts are supposed to be fairly large and relatively easily accessible. :)
i still havent found a retailer that sells plain and simple sprockets, so i might have to insert aditional gearing levels and use bike sprockets.
Click to expand...

The Extron composite #219 chain sprockets are good for our purpose:
http://www.radne.se/Store/Product/ProductList.aspx?CategoryId=51
 
Ive looked at the link above, radnet, and came up with the following:


yamaha motor sprocket, 12t on output last step (1140 rpm)
EXTRON 92 plastic rear sprocket input wheel (150rpm)

i assume 92 means 92 teeth, making the ratio between them roughly 7,6.

And by the following math: 5s lipo for the axi motor= roughly 12k rpm.
last ratio 7,6, meaning 12k/7,6=1578
and i want the tire to rotate at max 150 rpm: 1578/150= 10,52.

so the second gear-ratio must be at least 10,52

Is my math sound?

that sounds like pretty big number to me, meaning i should opt for 3 levels of gearing.. ?
 
300 rpm seems more reasonable :) (Is it a radius/diameter thing?)

So, assuming 12,000rpm is the no load figure, you'll need a total reduction of about 33:1

Which means your first reduction needs to be about 4.4:1
 
this means that step one should be a 14 to 60-72 tooth belt drive.

i was thinking of using a 3 or 5 speed hub gear from a normal type bike to use as an axle between the sprockets in step 2.
This way i should get freely rotating wheel when motor is stop, aswell as getting a slight gear spread, just in case the math is off..


how does this sound?

does anyone have generic gearing ratios for such hubs? i have no clue.. :)


im still looking for a electronic overload-eliminator, that drops the throttle when it runs to heavy (to fast start)..
any suggestions?
 
as i can understand it, its 1,33, 1,0 and 0,75 ratio, so i think this will be a good step 2 axle :)
i do belive ive read something similar in a recumbent e-bike thread.. :)
 
xarvox said:
yamaha motor sprocket, 12t on output last step (1140 rpm)
EXTRON 92 plastic rear sprocket input wheel (150rpm)

i assume 92 means 92 teeth, making the ratio between them roughly 7,6.

And by the following math: 5s lipo for the axi motor= roughly 12k rpm.
last ratio 7,6, meaning 12k/7,6=1578
and i want the tire to rotate at max 150 rpm: 1578/150= 10,52.

so the second gear-ratio must be at least 10,52

Is my math sound?

that sounds like pretty big number to me, meaning i should opt for 3 levels of gearing.. ?
Click to expand...

Hi,

5s lipo is about 20v?

You might want to consider getting a motor with a lower kv, something like this:
http://www.unitedhobbies.com/UNITED...HXT_63-74_200kv_Brushless_Outrunner_(Eq:5240)
HXT 63-74 200kv Brushless Outrunner (Eq:5240)

Model: HXT63-74
Input Voltage : 10~36V (3~8S Li-po)
Kv : 200 rpm/V within 10%
Dimensions: 63mm X 74mm

Price: $65.98
Click to expand...

This would lower the Max rpm from 12k to 4k. You would recoup some of the $66 spent on the motor, on parts for gear reduction, not to mention greatly reducing the complexity and labor required for your project.

BTW that is the motor Scott used:
Brief description here:
http://endless-sphere.com/forums/viewtopic.php?f=3&t=5156
OK so I've hit 52mph - who does this for real!!!!
Click to expand...

Build thread here:
http://endless-sphere.com/forums/viewtopic.php?f=6&t=5168
Scotts 5th - uh 6th build! now with a video - sorta!
Click to expand...

If you follow the build thread to near the end he mentions that even though the top speed is excellent the low speed acceleration is terrible and he didn't have the space to gear it down further for better low end. I think with a Nexus 3 Speed he could have had both.
 
Since im buying the axi motor for almost 80€ i kinda save money on buying the bigger, lower rpm motor :D

the big problem is the eu taxes and stuff.. but still, the price difference would be minimal :)



This means i need to rethink my drive train..

So we start again :)

the motor:
http://www.unitedhobbies.com/UNITEDHOBBIES/store/uh_viewItem.asp?idProduct=3890&Product_Name=HXT_63-74_200kv_Brushless_Outrunner_(Eq:5240)

(thanks for the suggestion!! :D)
battery: 5s 4,4Ah lipo battery (18,5v almost empty, 21v full w/o load)

resulting data:
Motor no load: 4200 rpm


So if i still use the 3speed gear hub as stage 2, i could use much lower ratio on both sides :)
3:1 ratio between motor and hub means 7:1 between hub and rear wheel to get max 200 at rear wheel.
Im using 26" rear wheel (559mm) and im really much more into low speed torque rather than high speed :)

i will be using this bike to/from work (assistance uphill) as well as a off the trail mountain bike in the woods behind my house.
So high speed isn't really that interesting, 30km/h tops is plenty enough for me :)
keep in mind, my bike is geared to top aprox 40 with me pedaling, so if i want i can kick the extra 10 myself on flat roads :)


To summarize; to start from the rear wheel:
EXTRON xx plastic rear sprocket input wheel (200rpm)
the fitted size sprocket on the 3gear bike hub still unknown :)

3gear hub with default sprocket on one side

Motor/hub connection is again up for debate, since i dont need such high ratio here :)
I was considering v-shaped belt drive, similar as on cars to power the generator/fan/water-pump.
This would slip if overloaded, while still giving me pretty decent power output.

But still, a chain drive would probably be the easiest and cheapest here.. :)

the motor has a 10mm axle, so there will be no problem for me machining a suitable adapter to fit a sprocket, and i will probably mill of a face on the axle to make sure the sprocket wont slip.

To keep this as cheap and easy to construct as possible; motorcycle chain in step 1, bike chain to rear wheel (without master link :) )
I was thinking of mounting the sprocket between the spoke holes on the gear hub, and strengthening he hub by bolting some bolts thru the spoke holes and through the sprocket.
i could probably machine a decent looking nylon distancer that would also strengthen the hub itself a bit as i´ve understood that these can be a bit flimsy when mistreated this way :)



Sorry if im trying to over-clarify here, im merely trying to understand it myself and document it as i develop :)
 
i think i just had an idea :)

can i place a fuse between the battery and esc in order to blow it if the current gets to high?
 
HW100AOp Turnigy/HWing Pentium 100 A OPTO

i have a few of thease, non opto tho, and a programming card for them.
my other are smaller tho, 60, 40 and 30A. none have been problematic, so it should work ok :)
 
recumpence said:
You can. However, most ESCs do not like a sudden drop at high amperage. You can blow the FETs that way.

Matt
Click to expand...


i was thinking of this when i ordered the esc, the esc has auto shutof in case of lost signal (rc link), meaning if it lost signal with servo tester, the thing would shut down.

This in turn means that i could implement a overload cutoff, that every time it draws over DNE amps (do never exeed), it cuts servo feed, thus killing the throttle. :)

i would rather have a limiter that electronicly limits the motor to say max 80A or something like that, but i´ll settle for a cutoff if its reasonably simple to implement.
 
You must log in or register to reply here.

Similar threads

J
Plan for MTB to E-Dirt Bike 8kW Dual Motor Conversion - looking for advice.
Replies
12
Views
567
JoltJockey
J
T
    • Like
Flying Merkel inspired e-bike & sidecar build
2
Replies
37
Views
6,717
nicobie
nicobie
P
Minimal 250W RC chain drive for road bike
Replies
2
Views
1,668
Norunec
N
upplastics
Electric Honda Ruckus
Replies
2
Views
12,824
IrishDrengr
I
E-HP
    • Like
    • Cheers
My econo-e-bike
15 16 17 18 19
Replies
450
Views
86,020
E-HP
E-HP
Back
Top