12 to 13 Tooth Front Sprocket - Nothing to Write Home About

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Gregski
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12 to 13 Tooth Front Sprocket - Nothing to Write Home About

Replaced the 12 tooth front sprocket with a 13 tooth one on my 1989 Suzuki Katana GSX600F yesterday. The rear is the original stock 47 tooth one. I didn't have to add any links to the chain after adding 3 or 4 initially for the conversion as the motor sits further away than the engine/transmission had.

I think I may be getting 2 MPH more on the top speed maybe a little more somewhere around high 30's, ie 38 MPH. The good news is the bike is not any slower off the line. So I question all the people who told me electric bikes need to run a 5:1 gear ratio, that or I misunderstood their advice.

Bike Specs:

  • Mars ME0709 motor (heavy)
  • 48 Volt Alltrax 300 amp controller (soon to be upgraded to 72 volts)
  • four 55 Ah sealed lead acid batteries (soon to be six)
  • 48 volt Elcon 20 amp on board charger (awesome)
  • Magura Twist Grip Throttle (kinda cheap and plasticky)

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LeftieBiker
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Re: 12 to 13 Tooth Front Sprocket - Nothing to Write Home About

Let's see, going from 12 to 13 teeth is a 1/12th increase. If you were getting 35mph before, and now get 38, that's...about a 1/12th increase. I think we were all expecting a bit more speed because we are still thinking in terms of final drive rations for geared transmissions. IOW you would have gotten more speed at the top if you had a multi-speed transmission with something like an overdrive gear. As it is, with direct drive, you apparently are running the motor flat-out, so the speed increase is directly proportional. The good news is it sounds like you could go with an even higher ration, this time most likely by dropping a few teeth from the rear sprocket. Not literally, of course. ;-)

Older vehicle conversions often kept the transmission from the ICE setup. Usually only two gears got used at most, so it was considered a waste of weight. I'm beginning to think that maybe it's not...

Gregski
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Re: 12 to 13 Tooth Front Sprocket - Nothing to Write Home About

Let's see, going from 12 to 13 teeth is a 1/12th increase. If you were getting 35mph before, and now get 38, that's...about a 1/12th increase.

That is the type of gold nugget I keep coming back to this forum for, thank you very much. See my simple mind does not work that way, I blame it on ball sports and women, lol reasons I did so bad in school.

So using your logic/formula now I am able to forecast a little and I like that. So a 14 tooth sprocket would give me almost 41 MPH very cool. So let's see, let's see all I would need is a 34 tooth front sprocket to go 100 MPH, where did I put that rat tail file, LOL

jdh2550_1
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Re: 12 to 13 Tooth Front Sprocket - Nothing to Write Home About

So using your logic/formula now I am able to forecast a little and I like that. So a 14 tooth sprocket would give me almost 41 MPH very cool. So let's see, let's see all I would need is a 34 tooth front sprocket to go 100 MPH, where did I put that rat tail file, LOL

Now you're getting it. Also bear this in mind: To get 14 teeth you'll have to make 'em smaller, right? Well, keep making them smaller and smaller and pretty soon you have a completely smooth front sprocket which is the same as infinite small teeth.

So, simply make a smooth front sprocket and you'll have infinite speed!!!

Pretty cool, eh?

John H. Founder of Current Motor Company - opinions on this site belong to me; not to my employer
Remember: " 'lectric for local. diesel for distance" - JTH, Amp Bros || "No Gas.

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