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Discussions Question and Answer Forums Electric Scooter, Bike, and Go Kart Built From Scratch Forum

Building a BAR STOOL RACER

I'm building a bar stool racer and I'm new to the electric motor world. I would like the racer to at least run 20 mph and have enough power to pull my weight. I'm guessing me plus the bar racer will weigh around 275 lbs. The wheel size will be 10" in diameter. I would like a twist throttle that fits 7/8" bars. I have some used parts from racing go karts that i plan to use for gears. 35 pitch chain is what i would like to stick with if i can. I have rear sprockets ranging from 53 to 60 tooth. Can i get your help on putting together a kit?

For a 20 mph top speed a Unite brand 36 or 48 Volt 1000 Watt motor would be the best choice. Our 1000 Watt Unite brand motors have 11 tooth sprockets for 8mm chain and unfortunately sprockets are not available for them for #35 chain, so a sprocket for 8mm chain would need to be used on the axle.


I ran a gear ratio calculation and found that with a 36 or 48 Volt 1000 Watt motor and a 54 tooth axle sprocket the top speed would be 18.24 mph, and with a 44 tooth axle sprocket the top speed would be 22.39 mph. The 3000 rpm motor speed is the speed that the motor runs under a full rated load so these are the top speeds to expect from the motor. Here are the calculations.


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There is no difference in motor power between the 36 and 48 Volt 1000 Watt motor, so it is usually best to go with the 36 Volt motor because then only three batteries are needed instead of four. However if four batteries will fit onto the bar stool racer better than three batteries would then a 48 Volt motor would be the better choice.


The next thing we should figure out before I put together the kit is how many minutes you would like the bar stool racer to run for on a single battery charge. Do you have any thoughts on how many minutes or hours you would like for it to be able to run continuously for?

48V sounds like the way to go. I have room for 4 batteries. I would like to ride it around for more then an hour at different speeds. I have 4, 12v 9ah batteries that are left over from my race karts. Would those work?
Four 12V 9Ah batteries which are in good condition should power a bar stool racer with a 1000 Watt motor for around 20-30 minutes at full speed and a little longer if not at full speed all of the time. For a ride time of over one hour at various different speeds I recommend four 12 Volt 15Ah or 22Ah batteries. It is usually better to overestimate with battery capacity to allow for the batteries to age and still offer the capacity that you want so if you have the room then I would go with four 22Ah batteries.


I just remembered that a few of our customers have purchased our SPR-3510A 10 tooth sprocket for #35 chain and bored it out to 12mm to fit our 1000 Watt motors. If you want to stick with a #35 chain sprocket on the axle then this might be the way to go. The sprocket could be bored out to 12mm by a machine shop or at home using a drill press and jig.

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