Electric bike power

[BrianG]

Originally Posted by Patrick

Do you mean this one? http://www.rc-monster.com/tempforum/...read.php?t=487 It was in the temp forum.
Wonder if Brian ever started it.

No, I never did. The lack of disc-golf partners kinda withered my interest in the game, and I had (and still have) other things on my plate. It's all I can do to fund my R/C projects let alone dump cash into experimental projects. It's still something I'd like to do though.

However, I've been eyeing my Mazda 3 thinking that a BL system driving the rear tires may give those turbo'd MazdaSpeed 3's and STi's a little run for their money, especially in the 1/4 mile. Keeping gas powering the front and adding "only" around 30HP (but tons of torque) to the rear would be fun! Since BL has max torque at 0 rpm, it would help get me off the line where the gas engine is the weakest. A hybrid, but for a different reason. But, 200v/150A ESCs are hard (and expensive) to come by...

[johnrobholmes]

You could cut a lot of cost off if you have a farm implement/ yard tractor place around you. Gears for combines and brush hogs can be bought there, as well as many chain sizes.


Seems like a good setup. Just make sure you have enough room for the 54t sproket on the bike, the gearbox to house it will be bigger than your motor most likely. You have the skills to pull it off pretty clean, I would love to see it.

[MTBikerTim]

This may be a silly idea but if gearing down enough is an issue why not just use 2 chains. It has been done on some mountain bikes. So have a chain coming off the motor going to another chain which goes to the back wheel. It would make changing gear ratios easier and cheaper.

[johnrobholmes]

Originally Posted by MTBikerTim

This may be a silly idea but if gearing down enough is an issue why not just use 2 chains. It has been done on some mountain bikes. So have a chain coming off the motor going to another chain which goes to the back wheel. It would make changing gear ratios easier and cheaper.

That is what MetalMan and myself are doing. My first reduction stage will be a pocket bike tranny.

[MetalMan]

Originally Posted by johnrobholmes

You could cut a lot of cost off if you have a farm implement/ yard tractor place around you. Gears for combines and brush hogs can be bought there, as well as many chain sizes.


Seems like a good setup. Just make sure you have enough room for the 54t sproket on the bike, the gearbox to house it will be bigger than your motor most likely. You have the skills to pull it off pretty clean, I would love to see it.

Thanks for the idea, I'll see if I can find a place like that.

The 54t gear actually won't be too big, only about 6.5" in diameter. The motor will mount directly to the gearbox, so this unit won't take up too much space.

[MTBikerTim]

Originally Posted by johnrobholmes

That is what MetalMan and myself are doing. My first reduction stage will be a pocket bike tranny.

Ididn't understand but it sounds good. When I first read this I thought you were talking about an RC motor bike. This should be good to see. I'll be interested to see if you can make something that can beat good old human power.

You may want to take just a regular bike (the pedaling kind) and try putting a BL system in that. You already have the gears and for me to be going 25-30mph on the flats I know that I need to put out about 350-400 watts. Thats not very much, you could get over 50 on a system that would put out 2000 watts continuous.

[MetalMan]

Uh-oh, what have I gotten myself into... One of these is now on its way to me:
http://www.hobbycity.com/hobbycity/s...idProduct=5142
$150 + $43 for EMS Express shipping! I opted to pay the extra $12 on shipping over the Air Parcel option. Supposedly the shipping time is 3-5 days, I'm getting anxious!

Now it's time to start collecting some of those specialty sprockets and chains for the reduction unit (JRH, I know, I could save a lot if I just look around, so I will). However, if I don't find anything soon I will just order the ones I posted from SDP-SI since they aren't normally stocked and will require me to wait for them to be made.

[johnrobholmes]

I have been trying direct tire scrubbing drive over the past few days. I think I will need a wind for 36v to work proper, the 11.1v wind of the scorpion 3032 doesn't work as it overheats. The startup with a MM is also much too hard, as the tire scrubbing force is pretty great. I am seeing if I can get a proto with a knurled case. In the mean time I may try an epoxy/ sand coating. The can face speed is 15mph, which is right where I want it.

I haven't started my gearbox drive bike yet. I want pedal assist so the rear hub will be the tricky part.

[BrianG]

Originally Posted by MetalMan

Uh-oh, what have I gotten myself into... One of these is now on its way to me:
http://www.hobbycity.com/hobbycity/s...idProduct=5142
$150 + $43 for EMS Express shipping! I opted to pay the extra $12 on shipping over the Air Parcel option. Supposedly the shipping time is 3-5 days, I'm getting anxious!

lol, you think that 7 ft-lbs of torque will be enough? And that's just the motor (@130A) without any gear reduction.

[MetalMan]

Originally Posted by BrianG

lol, you think that 7 ft-lbs of torque will be enough? And that's just the motor (@130A) without any gear reduction.

I hope so . And to think, that's before an ~14.5:1 gear reduction!
Initially the motor will probably run at 24v, and if I have enough balls, then I might try 48v .
Who wants to make a bet on how fast it will push me? (it will still have a rear dérailleur, and I weigh 165lbs).

[BrianG]

In that case, you need two of those running at the full 48v. 14.5:1 gearing will give you 101 ft-lbs of torque. For two motors, that's 202 ft-lbs, but only 17.4HP (130A X 48v X 2 motors).

[Serum]

No sir, I've got no idea what it was.. I heard no motor, only squeaking tires..

[johnrobholmes]

I just got version one working. 6s a123, mamba max, 4035 outrunner. The OEM RC ESC wouldn't stay synched on the hills, but I think it might have been a bad cell in the battery pack. I will retest it tomorrow and see what is up.

Final speed about 10mph last I tested. Runtime is about a mile on 2 amp hours so far, but with a new cell that will probably improve. It has a ton of torque, the motor is rated 4hp continuous and 5000w peak.


I have to be careful, it likes to wheelie with the seat so far back.

[johnrobholmes]

Here she is



I ruined a mamba max during today's test. I also tried out the OEM RC ESC and it wouldn't keep sync under load. Still worked well if I didn't goose it too fast. The mamba max wasn't even hot, kinda strange that it bit the dust although not a complete surprise.