SUPER LIGHTWEIGHT BANTAM El.BIKE PROJECT

Miles

Miles

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SUPER LIGHTWEIGHT BANTAM El.BIKE PROJECT
Proposed specification:


Maximum total weight: 16kg.
Wheel size: 16 inch (EUR.349) or greater.
Motor power: greater than 400Watts.
Batteries: minimum of 250 Wh?
Performance: ability to climb a 5% slope @ 25 Kph (eu speed limit for EAPC)

Anything else that should go in the spec.?
 
Miles said:
SUPER LIGHTWEIGHT BANTAM El.BIKE PROJECT

One motor available in UK for this project would be TARN motor.
I think it just hits 400W at 33V and that's about max voltage useable with the controller supplied.
http://cgi.ebay.co.uk/BLISS-BIKE-ELECTRIC-CYCLE-BICYCLE-BOAT-CARAVAN-MINIMOTO_W0QQitemZ150155631725QQihZ005QQcategoryZ33503QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

Just taking apart this bike and using wheels in a lighter/probably even bigger bike could together with a better battery do the trick.... be within the 16kg margin. May/may not. ! I'll need to buy a good digital scale now!
I have 2 of these bikes and can get them for 250 pounds complete with charger/battery.
Why I don't like them :
It is hard to pedal without the motor
400W is fine, but not that exciting.
weight of bliss is probably around 20kg.

And that is too much!
Why the bike is very hard to peddle without the help of motor I don't know.
I never had a small wheels (16 inch) so my experience is from 26 inch. And this is not the bike I want to pedal, believe me...can anybody explain why 16inch bikes are so hard to pedal? On dewalt at 33V it goes 26km/h, probably useable.

Tarn is 12:1 geared motor and i took it apart.
Here:
http://endless-sphere.com/forums/viewtopic.php?t=435&postdays=0&postorder=asc&highlight=tarn&start=15

From this post I've learned that it can run on 48V with a different controller.
That could be one of the ways to go for our aim.
The difficulty would be that the motor is wider than normal bikes forks.
Click to expand...
 
There shouldn't be a huge difference in rolling resistance because of the diameter, (on a reasonably smooth surface, of course). They're probably crap low pressure tyres. How much resistance is there in the freewheel mech. I wonder?

If you want to know more about bicycle physics, get hold of a copy of "Bicycling Science" 3rd Ed. David Gordon Wilson. Publ. MIT Press 2004.
 
I see these ways to get to our SUPER LIGHTWEIGHT BANTAM El.BIKE :

A:
a lightweight HUB motor with an internal gears
PUMA motor is probably too heavy(3.7kg), otherwise my favorite 230
TARN..2.5kg not much power there ? £150
RABBITTOOL MOTOR..not much data yet, regenerative,300W, 500W £100
special controller £85

http://www.rabbittool.com/frames/frorder.html

some other HUBs, rather expensive ...


OR:
B:

lightweight controller[/b] (150g RC planes?)£60
http://www.unitedhobbies.com/UNITEDHOBBIES/store/uh_viewItem.asp?idProduct=4691
and

lightweight outrunner motor (0.5-1.5kg)£100
http://www.unitedhobbies.com/UNITEDHOBBIES/store/uh_viewItem.asp?idProduct=5142
with external/internal gearbox 8:1-15:1
OR:

C:
smaller BLDC motor with a gearbox .....2.5kg(500W)
I like to look at the bikes from these guys (on some pages with music)
http://www.cyclone-tw.com/index.html


What is your favorite bike size?And what system would you choose.
Does anybody have cyclone bike/setup? Very interesting too..

I would love to put the setup onto a 26 inch (BMX) bike.
Lightest are around 10kg! but way too expensive...
We need to start with a bike with 10-11kg max!
Can't decide which way to go....
Can't spend fortune either.
 
A. Even with a geared hub motor it would be a struggle to meet the spec. , I think - unless you start with a very lightweight bike.

B. Seems the most promising route, to me. I'd favour belts over gears, though.

C. Not that keen on the Cyclone. It's noisy, and not that efficient. You do get the advantage of going through the existing gears, of course. The large Cyclone motor isn't that easy to accommodate. If I was going to do a Bottom Bracket or Shared Chain drive, I'd start from scratch. Certainly a possibility, though.
 
2 reasons for the slug like pedalling performance the biggest from my experience is the rear suspension as folders have a rear weight bias and pogo like crazy, and the second is the squishy round black things they pass off as tyres. IMO
I have 2 trikes one being 16" (349) all round and the other 16" front and 20" rear (FWD) neither would be classed as slow, or difficult to pedal.
I also have a couple of 16" folders around 12kg and on road especially with any kind of hill they feel like slugs and the softer the rear suspension the more slug like they become. On the flat and once upto speed where you can develop a nice smooth spin they improve markedly.

I will follow this project with interest as ultra light assist that does not greatly impact human powered use interests me greatly.
 
From my brief experience of riding a Bliss elec. folder, the rear suspension didn't do anything very much, apart from add weight......

My Brompton folder with 16" wheels is not at all sluggish but I always keep the tyres pretty hard. It has rear suspension and a Pantour suspension hub in the front.
 
Geebee said:
2 reasons for the slug like pedalling performance the biggest from my experience is the rear suspension as folders have a rear weight bias and pogo like crazy, and the second is the squishy round black things they pass off as tyres. IMO
I have 2 trikes one being 16" (349) all round and the other 16" front and 20" rear (FWD) neither would be classed as slow, or difficult to pedal.
I also have a couple of 16" folders around 12kg and on road especially with any kind of hill they feel like slugs and the softer the rear suspension the more slug like they become. On the flat and once upto speed where you can develop a nice smooth spin they improve markedly.

I will follow this project with interest as ultra light assist that does not greatly impact human powered use interests me greatly.
Click to expand...

this guy was probably first one to try outrunner on bike and posting it on youtube, to get the idea how B option will sound:
http://www.youtube.com/watch?v=Qxh_cMrIyVI
 
nemo said:
to get the idea how B option will sound:
http://www.youtube.com/watch?v=Qxh_cMrIyVI
Click to expand...

Not that bad... half the sound is the friction-drive.

Keeping an outrunner cool could be a challenge.

:D
 
Geebee said:
I will follow this project with interest as ultra light assist that does not greatly impact human powered use interests me greatly.
Click to expand...

I think I've found a suitable motor for the project.
To sum up:
regenerative braking, motor 500W,hub, small , geared, HQ, not expensive and lighweight!

motor 500W $200,
regenerative controller $175
throtle $49 with regen.

total:$424..not bad!

dewalt 33V 9.2Ah....$400

mounted onto( for eample):
dahon helios 20 inch folder bike...
or dahon D5 20 inch folder $450 11-12kg

OR full size 26 inch alu folders
dahon matrix, rabbit, cadenza all from 12-13kg

GRAND TOTAL $1200 for ultimate 16kg bike !!!!!


Not much info on the weight of the motor, but it must be VERY lightweight.
What I've found....
95%eff
NdFeB
alloy gear reduced 11:1
Regeneratively braked
"The motor is a gear-reduced brushless AC design with a continuous rating of 300W."
.....now they have 500W...
they say"This E-Kit can be bolted to the rear dropout of almost any mountain bike, most road bikes, many recumbents and some folding bikes; however, the 500W Series hub motors are too wide to bolt onto any known stock bicycle front forks......."

here is the secret:
http://www.rabbittool.com/frames/frorder.html

What do you think?
Shall somebody write for the availability and possibility of shipping them to UK...I'm interested!
 
Rabbit Tool have always been something of an enigma.......

This page has been there for years: http://www.rabbittool.com/

They licensed their motor design to Sanyo, who produced it. I haven't seen an actual review of it anywhere.. The "reviews" on their site are simply re-quotes of their own PR...

Send them an email, but don't hold your breath.....

In any case, the 500W will not be a continuous rating...

Sorry to bring you down to earth, nemo... :wink:

Anybody else know any more about them?
 
Miles said:
Rabbit Tool have always been something of an enigma.......
...

Anybody else know any more about them?
Click to expand...

I remember somebody from either this forum or the Old V unsuccessfully trying to order the large NiMH cells they advertise.

http://www.rabbittool.com/frames/NiMH2.html
singbatts.jpg
 
Miles said:
Rabbit Tool have always been something of an enigma.......

Send them an email, but don't hold your breath.....

In any case, the 500W will not be a continuous rating...
Click to expand...
I did email them.
I think that with a hub motor of this size with 11:1 gearbox it may be possible to get with 95% eff. 500W cont.

But 95% seems to be rather high (unrealistic). The best motor I've seen that has 97-98% eff. and output 3000W weights 15kg with a wheel assembly.
It's not even for sale and is used for solar car races!
90%..I would believe it...95%...may well be possible but hard to believe for $200.

Well, I thought I had something interesting. :?
 
Miles said:
nemo said:
But 95% seems to be rather high (unrealistic). The best motor I've seen that has 97-98% eff. and output 3000W weights 15kg with a wheel assembly.
It's not even for sale and is used for solar car races!
Click to expand...

Didn't you see these? :)
Click to expand...
I got the info from here.
http://www.ctip.csiro.au/Machines/success/sc.html
What a beauty.
So I assumed that 95% is rather high. Maybe it can be 95-97% but not through wide range of RPM.
Can anybody throw some light at these numbers?
 
Anything else that should go in the spec

Cost?
Otherwise, my Christmas wishlist:

Airnimal Joey: 12.0 kg http://www.airnimalfoldingbikes.com/M_JoeyCommute.php
Nano hub motor 2.3 kg
7 Ah Lipo 2.7 kg
http://www.nano-motor.co.uk/nanomotor.php

Damn, that's a kilo over your 16 kg target. But if you replaced the Nexus hub gear with the Nano hub motor and a fixed gear setup you could probably get the weight pretty close to 16 kg.
I think I'd take the weight penalty though, and use the hub motor as a bottom bracket drive. That way you still have a bike that's light enough to pedal without assist, but when you do want to use the motor you can use it through the gears to give optimum hill-climbing ability.
 
Impressive. These lightweight, high rpm motors sound great, but I still think there'll be problem with heat dissipation unless you can run them at peak efficiency most of the time. That means either forced air cooling or running the motor through the gears. Do any of the RC experts here have any thoughts?
 
Don't forget MCL. You can overvolt all you want with a small motor if you compensate with MCL. (motor current limiting) The small motor category is a lot of fun... :)

It's BCL that actually kills the motor not the voltage...
 
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