Help with math

[atom1025]

Trying to figure out how many teeth the new sprocket should have.

Currently running 14s 10amp Lipo through this combo. http://www.thesuperkids.com/10wabmc36vor.html

On a 26" mtb.

I can tell you that I currently top out at 30 mph on the flats. Currently geared with a 19t pinion and 54t on the wheel. How do I do the math to figure out motor rpm more importantly the kv.

I am setting up to run six 5s 5000 in a 15s2p configuration.

I was hoping to keep the 30 mph top speed but lower the amps and get some more torque for hard starts and hills. Heck I was even happy when it was 25mph so I am willing to gear it down more.

I can make any tooth count so I am not stuck with stock options.

So what I really need to know is :

What sprocket will get me 30mph

What sprocket will get me 25mph

Adam

 

[Hillhater]

Keeping it simple..
you plan to increase voltage by ....15/14 = 107%
so to keep the same speed you need to reduce your gearing by the same amount ..107% x 54 = 58T ..( in round numbers)
.. and if you want to reduce that speed by 5 mph, thats a 5/30 = 17% reduction ....17% x 58 = 10T change = 68 T .. (rounded)

however...
something seems odd that you can run that motor with single reduction of 19:54 ??
Are you using it with some other reduction box like the Currie drive ?

 

[atom1025]

Oh yeah totally forgot to mention the planetary reduction. http://www.thesuperkids.com/plge19tofrsp.html not sure what the ratio is on these. Not sure how to count the ring and planets but it appears to be a 4-1 turning by hand.

Thanks for the help will likely go with a 60t.