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Posted: Sat Nov 01, 2008 1:09 am
by Lentamentalisk
well, from my experience with attaching the motor to the wheel like that, you will have to buy new tires very very very often. I would suggest directly gearing the motor to the chain, with some sort of ratchet mech like the back wheel has. That way you can get varying torque, as well as speed, by just shifting gears.

Posted: Sat Nov 01, 2008 7:35 am
by VH_man
Lentamentalisk wrote:well, from my experience with attaching the motor to the wheel like that, you will have to buy new tires very very very often. I would suggest directly gearing the motor to the chain, with some sort of ratchet mech like the back wheel has. That way you can get varying torque, as well as speed, by just shifting gears.
I tried that, and getting the right gear ratio off of the motor would take farrrrr more money and engineering than i would like. as long as the wheel doesnt slip it doesnt cause much wear.

Posted: Sat Nov 01, 2008 8:53 am
by THUNDERLORD
Great job making a working prototype VH_man!
Looks like a good idea to have everything mounted on the seat post because with a removable seat post, the assembly can be transported, stored or switched to a different bike easily.
BTW, I would've replied before, but I'm still out of town with very limited internet times. But I'll be moving today and getting that straightened out ASAP in my new place (As well as some new projects hopefully) :) . Sorry the wheel sprocket I suggested didn't work out. Do you plan on using it for something else or...? 8)

Posted: Sat Nov 01, 2008 9:16 am
by VH_man
If i ever get some spare cash and access to machining facilites (which i will sometime soon) i will attach a Gearbox and an Electromagnetic Clutch (from a car AC Unit) directly to the wheel with the large sprocket i have. Untill then, this is what i will stick with. It works quite well, and is actually quite small. I am suprised.....

Only further modification i will make to this will be some uprights running off the frame to help maintain a good level of friction between the wheel and roller.

Posted: Sun Nov 02, 2008 10:36 am
by VH_man
Bump

Video has been posted on First page.

Posted: Sun Nov 02, 2008 11:22 am
by psycix
Awesome!
Could you post detailed specs of the motor: how much amps does it draw and whats the power output?

Have you already tried different sizes of rollers? Maybe you may increase the power of it when picking another torque conversion factor.

Anyways, its a lovely help-motor to aid lazy people biking.
judgment_arms wrote:and the other for all the duck tape!
Well, it does not matter whether it is duct or electrical tape, it is surely not DUCK tape....

Posted: Sun Nov 02, 2008 12:26 pm
by VH_man
Specs:

Nominal v: 12v
No Load RPM: 5280
Stall Current: 115A
Kt: 3 oz-in/A
Kv: 440 rpm/V
Efficiency: 74%

I just added side braces to aid in nulling the "motor falls off the wheel" problem. Works even better now, i dont loose traction when i go over bumps.

And, i will eventually buy a larger sprocket for the roller drive, as i too feel it could still use a little gearing down......... If i can find a 120 tooth one, i could even re-try my attemps at driving it directly from the wheel.....

Posted: Sun Nov 02, 2008 2:29 pm
by john bunsenburner
1. wer did u get the motor
2. i got a small question which is some what off topic: i have a shake table made from a piece of woad mounte on two copper tubes that fit into each other not i want this manual shake table to be electric could you help me seeing that you are working with motors(yes this is a school project!)

Posted: Sun Nov 02, 2008 3:23 pm
by VH_man
The motor is a CIM motor. its a 25 dollar motor that is relatively hard to come by at this time of year (FIRST season) but its relatively easy to find one on some robotics sites. just type in CIM motor. Youll find it. I got my motor for free... :-D

2. I dont know what your talking about.... Rephrase it?

Posted: Sun Nov 02, 2008 3:30 pm
by littlebro05
Rofl awesome bike!!!

Didn't sound like it was having any trouble but i'd assume like you said before it will probably overheat after a couple of minutes.

You know what you could do! Buy a one gear BMX bike, then get a longer chain for your motor and stick it on the back wheel of your bike where the other chain is. I'd imagine that the rubber wouldn't wear out at all XD.

Posted: Sun Nov 02, 2008 3:37 pm
by VH_man
Actually, I did some testing, and the "hotness" i was getting was just because its like 30 degrees out here now. the change in temperature from warm motor to cooolld air was.... a large difference.

Its really more a problem of the battery dies hella fast now. If i pedal with the motor up hills, it can actually hit its top speed and not have any problems. I just have to give it a little "boost" every once and a while.

Posted: Sun Nov 02, 2008 3:57 pm
by littlebro05
Hmm you know what, I feel like going to a hobby store and find a decent sized motor or some sort of store to make my own easy pedal thing XD. I'd assume it's not water proof though :(?

Posted: Sun Nov 02, 2008 4:08 pm
by starman
Just saw the video...looks solid enough. It would be nice if you could get a little more speed though. That's a really creeping pace for road travel.

I like your idea of retoothing your gears for a little more speed.

Posted: Sun Nov 02, 2008 4:10 pm
by VH_man
Id need a new motor, which is a possibility. I have a 200 watt Hub motor on my Christmas list........

Posted: Wed Nov 05, 2008 7:02 pm
by SEAKING9006
I wish my school did FIRST. Our team competes in BEST, so we are fairly limited in our ability to build, based mainly on the stuff they give us, as well as size restrictions.

I feel that my school would completely SWEEP FIRST, because we have a full machine shop, and DAMN smart people. (Not to mention they know me by name at Fastenal.)