Go Back  Bike Forums > Bike Forums > Electric Bikes
Reload this Page >

Under $250 brushless Ebike

Electric Bikes Here's a place to discuss ebikes, from home grown to high-tech.

Under $250 brushless Ebike

Old 11-13-08, 12:52 PM
  #51  
cerewa
put our Heads Together
 
cerewa's Avatar
 
Join Date: Jun 2003
Location: southeast pennsylvania
Posts: 3,155

Bikes: a mountain bike with a cargo box on the back and aero bars on the front. an old well-worn dahon folding bike

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
The motor is 24lb? Darn that is heavy.
My 1000w motor is less than one pound!
Point is the stuff out there is too heavy or too expensive and we have $200 6500w motors that weigh 6-7 pounds or so and the batteries to make it go.
To make a gearless 6500 watt motor that runs at only a few hundred rpm, you need it to be a big 24-pound chunk of metal.

The key is, "gearless". Gear reduction for a small RC motor will allow you to get 1000watts from a 1 pound motor and 6000 watts from a 6 pound motor, at reasonable rpms for a bicycle wheel.

but the gear reduction stuff is going to weight a couple pounds, at least.
cerewa is offline  
Old 11-13-08, 07:55 PM
  #52  
outrunner
Junior Member
Thread Starter
 
Join Date: Jan 2006
Posts: 24
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Originally Posted by cerewa View Post
To make a gearless 6500 watt motor that runs at only a few hundred rpm, you need it to be a big 24-pound chunk of metal.

The key is, "gearless". Gear reduction for a small RC motor will allow you to get 1000watts from a 1 pound motor and 6000 watts from a 6 pound motor, at reasonable rpms for a bicycle wheel.

but the gear reduction stuff is going to weight a couple pounds, at least.
Hey are you just guessing?
Check out fallbrooktech.com for light weight you get infinite gears! At infinite cost!

Apparently there is concern with bike chains and max rpms/length/tightness of turn chain takes-
anyone have an idea or is it guess that the rpm is too high?

Here is what I so far:
A piece of plywood with sprocket and motor on one side with chain drive.
The larger sprocket driven by the motor has a smaller one on it that drives another big one.

If we have a 1:30 ratio from the motor M:S1
and a 1:30 ratio from sprocket 1 to sprocket 2
and sprocket 2 has a small sprocket at center going into the chain.
What is the ratio?
outrunner is offline  
Old 11-13-08, 08:02 PM
  #53  
outrunner
Junior Member
Thread Starter
 
Join Date: Jan 2006
Posts: 24
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Originally Posted by cerewa View Post
attach one of these to your rear wheel:
http://www.google.com/products?q=%22...ocket+80+tooth

attach one of these to your motor:
http://www.google.com/products?q=%22...ket+%229+tooth

buy a #25 chain (a go kart type chain).

pick a motor that's around "480kv" and get 3-in-series LiFePO4 battery (about 9.5 volts)

... or about 360kv and 12 volt lifepo4 for the same speed.
Hey hey how about making it turn the chain instead of the wheel?
that will work! Even with partial reduction I do not mind pedaling up to 20 then letting it take me to 50

It is okay if there is a big giant gear in an odd spot.
It is okay to leave the bike in first gear and the pedals spin around.
The pedals can be taken off and at that point it is easier to add one more reduction to match output speed to comfortable pedal speed.
outrunner is offline  
Old 11-14-08, 08:13 AM
  #54  
cerewa
put our Heads Together
 
cerewa's Avatar
 
Join Date: Jun 2003
Location: southeast pennsylvania
Posts: 3,155

Bikes: a mountain bike with a cargo box on the back and aero bars on the front. an old well-worn dahon folding bike

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Hey are you just guessing?
you'll need several feet of chain at about 0.1 pounds per foot, and those large #25 sprockets are just big plates of metal.

The NuVinci hub is not lightweight either, although one bikeforums member tried it out on an e-bike and said it was great... but heavy. 11 pounds.
cerewa is offline  
Old 11-14-08, 01:06 PM
  #55  
outrunner
Junior Member
Thread Starter
 
Join Date: Jan 2006
Posts: 24
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Then we go back to smaller chains with gear reduction in a smaller area.
It sounds very simple using basic bike parts which is why I made the video to get attention and help simply configuring them and knowing where to order them online.
I am not asking anyone if they think this is possible I simply need the specs for a reduction gear.

I'm under the impression many of you know off the top of your head sites and sizes for sprockets and easy way to go to hardware store to get something together.

Questions asked to me would be how fast the motor will spin at medium rpm and how much rpm the final drive should be.
A reply with some tips for parts is all I need.

Thanks!

Last edited by outrunner; 11-14-08 at 01:10 PM.
outrunner is offline  
Old 11-15-08, 01:00 AM
  #56  
outrunner
Junior Member
Thread Starter
 
Join Date: Jan 2006
Posts: 24
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
You guys are unable to comprehend!
outrunner is offline  
Old 11-15-08, 07:53 AM
  #57  
cerewa
put our Heads Together
 
cerewa's Avatar
 
Join Date: Jun 2003
Location: southeast pennsylvania
Posts: 3,155

Bikes: a mountain bike with a cargo box on the back and aero bars on the front. an old well-worn dahon folding bike

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
30 miles per hour is 387rpm at the wheel, on a 26 inch wheel. so for 40 miles per hour multiply rpm by 1.33, for 20 miles per hour multiply by 0.67. to get rpm from miles per hour, you need inches per revolution (26 times pi = circumference); inches per revolution times revolutions per minute equals inches per minute. Then convert minutes to hours and inches to feet to miles, and you have miles per hour.

RC motors tolerate a wide variation in RPM without any gear changes.
The ideal RPM for the motors is about 80% of the no-load speed.
The no-load speed is KV * volts
so a 480kv motor at 9 volts is 4320 rpm at no load speed, 3460rpm at 80% of no load speed.
3460rpm run through 9 / 80 gearing is 390rpm, or about 30 mph.

I picked 480kv because it's a cheap lightweight motor you can find on ebay. its torque is probably only enough to get you to 30mph if you pedal a lot.
cerewa is offline  
Old 08-12-09, 07:20 AM
  #58  
gbrignardello
Newbie
 
Join Date: Aug 2009
Posts: 2
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Exclamation pedal turn

How do you resolve the pedal problem? i supose that the pedal turns whit the motor movement...
thanks
gbrignardello is offline  
Old 08-12-09, 07:22 AM
  #59  
gbrignardello
Newbie
 
Join Date: Aug 2009
Posts: 2
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Exclamation pedal problem

Originally Posted by Kraeuterbutter View Post





mounted left


mounted right


with good power and great handling because of weight-balance


so.. i like this idea here (maybe even more than a hub-motor):
http://www.bike-elektro-antrieb.ch/

the wheels keep light, and you can use the gears on your rear-wheel, so
--> high speeds when going onroad
--> low speeds when going up steep hills

here some very good pics:
http://www.bike-elektro-antrieb.ch/Produkt1.htm

i would like to use an Outrunner
on the pics i could see that the gearing with the chain is about 1:4,5 ?!?
would you agree ?

so the paddels need to go with about 80-90U/min
with 1:4,5 ---> so the motor-output should spin 400rpm/min

when i look for Rc-plane-Motors:
for example this Orbit 30-14:
http://www.plettenberg-motoren.com/D...Orbit30_14.pdf

peaks of 2500Watt are possible (just to show what the motor is cabable)
and it weights only 305g
(but even if it was 600g it would be unimportant when you think that you and your bike are over 100000g )

this motor would spin - i prefer higher volts over higher amps because of better efficience -
at 27Volt with about 12000rpm - 13000rpm
(i have used Outrunners with only 7000rpm in my heli.. and its running way not that powerfull and efficient like a outrunner with double rpm and higher gear-reduction)

so: to get the 400rpm we would need a 30:1 Gear-Reduktion

hmm - that should be possible to be achieved by a two-stage belt-drive
so: 7:1 first stage with smaller belt and 4:1 at second stage bit bigger, stronger belt

that should be relative quiet as well, i bet ?
to protect everything you can laminate a case from Carbon (would also look cool)
and seal everything as well (to protect from dirt)

when you drive a bike with full suspension, the electric driveline-parts would beguarded by the suspension, wheels would be still as light as normally for good performance and handling offroad

for the batts:
i would not take LIpos..
Lipos are too fraquile, and - when treated wrong way - can burn..

i would go with A123-Systems FePO4 cells, the new technologie..

benefits of the cells:
can handle up to 50C currents
can be charged with 4C (= 15min charging time)
or - if you except a lifetime of the cells of "only" 200-300 cycles - even with 10C (full to 95% within 5min !!!)

the cells have a hard-case like NiMh,
the are absolut safe (will not burn unlike LIpos)

and have a shelf-lifetime of 10 years (lipos only 2-4years)
and a cycle-life in such a bike-application of FAR over 1000cycles (more like 2000-3000cycles)

compared to NiMh (100-200cycles in reality) or Lead-acid (500cycles)
a HUGE benefit !!

you can get that cells cheap when buying DeWalt 36Volt-battery-packs from ebay..
(they are used in power-tools)

3 packs would cost 300Euro
and delivere 36Volt (under load about 27volt) and about 7000mAh
the cells have the same high voltage from start until end of discharge, so unlike NiMh, LiPos or lead-acid, you will not notice any power-loose until its there...

and: a 7000mAh-Pack can easily handle 200A continously and 300A peak..
(that would mean: 10cells, 2,5Volt, 300A --> 7500Watt Peaks *lol* - not needed, just shows that you can not stress this cells to death in a bike like you can with lead-acid !)

weight of such a 36V-7000mAh-Pack: about 2200g
How do you resolve the pedal problem? i supose that the pedal turns whit the motor movement
gbrignardello is offline  
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
Oakparkcycler
Advocacy & Safety
5
07-29-15 09:18 AM
Chris516
Advocacy & Safety
54
11-14-11 05:21 PM
geoluv
Bicycle Mechanics
9
08-30-11 07:13 PM
Kamala
Pacific Northwest
0
05-22-09 09:47 AM
slagjumper
BMX
11
02-24-06 07:05 AM

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off


Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

Copyright 2018 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.