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[Tmentz]

Im a new ev moto convertor and nearly done with my bike.  I'm on to the sprockets now but I'm not sure what size, how many teeth, size of chain etc. . . Any help would be totally awesome.  

Motor = 48v ME 0708

[Bogan]

Depends on what top speed you want. I'm using the same motor but only at 36V and get 50-60kmhr with 14/68 sprockets.

[Gregski]

I'm trying to complete my conversion as well, also dealing with gearing.  A gasoline powered bike has a gear ratio of somewhere around 3:1 for an electric I am hearing you want to be close to 5:1

12, 13, 14 tooth front sprockets are a good start, I am going to start with a 12 front and my stock 47 rear for a ratio of almost 4:1 though I am sure I will have to get a larger rear sprocket, I don't know much about the rear sprockets other than 70 tooth may be as big as you can go before clearance issues with the swing arm

of course all this depends on what bike you are converting, I am working with a Suzuki Katana 600 so a mid sized bike

I just found out about SurplusCenter.com you can buy front sprockets there for cheap so order two or three so you can play with it

530 is a common motorcycle chain for metric (Japanese) bikes however luckily that converts exactly to the American #50 chain, but if you just buy a regular American #50 chain it most likely won't be what they call an O-ring chain, so it's better to buy a real motorcycle O-ring chain which just means it has tiny rubber O-ring wedget along the links to help keep it lubricated and last longer, however knowing that a 530 chain is the same as a #50 really helped me out when sprocket shopping as most motor sprockets are for #50 chains, tomato tomato, lol

good luck,
Greg

[frodus]

Rear sprockets from:
Sprocketspecialists.com

front motor sprockets:
www.surpluscenter.com if it's 7/8" or 3/4"

If it's a 19mm Agni, I hear people have gone to Zero for those, but I'm not sure.

#50 is a good start for motor mount sprockets, since they're used in the industry, which, as Gregski mentioned, is the same as motorcycle 530 chain. This helps a TON. Everything fits perfect.


Give us an idea of bike weight and type, and what the top speed needs to be as well as your battery pack voltage.

[Tmentz]

WOW! I never expected to get this much help, you guys are awesome.  Thanks!

The bike is a 1991 Kawasaki ninja 500ex.  It has a bit of room for a larger rear sprocket but not a whole lot.  The front sprocket is really my first main concern and you've all been a ton of help.  Speed isn't really the goal of this bike, it's mostly going to be used to commute a few miles through city streets to work. . . and to show off of course.

Thanks again everyone.

[frodus]

use at least a 5:1 ratio for a mars and commuting.

Don't go below 11tooth on the front (so you'll need at least 55 on the rear), or you'll have chain wear issues because of the tight radius, and possibly binding issues. I'd suggest 12tooth.

I got a 60 tooth on my rear, #50/530 size, ordered from SprocketSpecialists, perfect fit. Get titan tough coating, it'l resist scratches. I have a few front sprockets, so I can do anything from 5.45:1 on down, but probably not more than 16tooth, but I have an AC20 setup, so a little more power. For a smaller motor/lower power, you should have a higher ratio, so something between 5:1 and 6:1 works great for most people I've seen.

[Gregski]

please teach me about gearing and give me some advice
 


is a ratio a ratio, or does it make a difference for example

12 tooth front x 60 tooth rear is 5:1

13 tooth front x 65 tooth rear is 5:1 also

if those are the same why would you want to carry the extra weight of the larger sprockets and or require extra clearance and a heavier larger chain




right now I am running a 12 tooth front and a 46 tooth (OEM stock) rear for a ratio 3.8:1 call it 4:1

my top speed is barely 45 MPH, so I am torn with a decision, everything I read states that electric motors are happy at higher RPMs, so initially I was planning on replacing the rear sprocket with a 50 tooth one to give me that covetted 5:1 ratio, but then I am being told to go faster I need to lower the ratio and replace the front sprocket with a 13 tooth one while keeping the existing stock rear, which would give me a 3.5:1 ratio


are my goals of a higher speed and optimal motor performance mutually exclusive, or is there a happy medium?

[Bogan]

Large sprockets are slightly more efficient because the chain doesn't have to bend as much, they also put less tension on the chain, but in electric vehicle with far less torque than ICE puts out, we don't need to worry about that.

It's a balancing act to get the right speed, I set mine at a bit over 50kmhr (which is in town limit) so it is good for commuting.

With lead acid you are unlikely to get large range, so if you commute is on low speed roads you might be better to do the same?

If you plan on maintaining a higher speed, be aware it will be significantly harder on the batteries.

And of course, higher top speed, equals less acceleration.

[frodus]

mostly wear. Chain wears less, the sprocket has more contact area and wears less. 60-65 won't show a huge difference, but I'd keep that front as large as you can, people have gone to a 10 tooth and had binding issues.

[Gregski]

Well I just learned something that is sort of related and my help.  Your motor the ME0708 runs at higher RPM than my ME0709 which explains why I am able to run a 12 tooth front and the stock 47 tooth rear and am actually considering going to a 13 tooth front.  I am sharing this because everything I read talked about going to a 5:1 ratio on these conversions and I was like shoot I wish my bike had more gitty up in her, and tonight I read an interesting post that sorta put things in perspective here:

http://www.diyelectriccar.com/forums/showthread.php/me0708-vs-me0709-35771.html