Smaller Pulley = less heat + same range?

How-Tos & Esk8 mechanics
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#1

Hello,

if a belt driven setup uses a 16t pulley and 72t on the wheels what effects will switching to a 12T pulley have?

  • the top speed decreases ofc
  • acceleration increases ofc

BUT (assuming you ride the same route with both the 16t and 12t setup at identical speeds)

  • will the motors run cooler or hotter?
  • will the range get smaller or bigger?
#2

For esk8 motors usually a higher gear ratio (smaller motor pulley) will lead to slight efficiency improvements, meaning a cooler motor and more range.

The biggest difference will be that your top speed will decrease, so you will ride slower, and have less wind resistance :laughing:

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#3

Ignoring that 12t will have major belt slip.

If you only accelerated once and road the entire time on a level surface, the 12t will get hotter and have lower range. The more times you start and stop (ignoring battery regen) the more it will move in the other direction (16t hotter and lower range). The more hills and steeper they are, the more the 12t starts to win out as well.

Now if your motors and drive train were 100% efficient there would be no difference.

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#4

Yup. Basically, motors don’t like to spin fast, but an easier time getting up to speed helps a lot.

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#5

Can be mitigated with an idler.

#6

No way lol 12t is still way too small for 5M belt

I’ve had a skip on 15 to 40 setup even with idler

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#7

wtf really :exploding_head:

I’m currently running 15 to 62 just fine with one idler. :smiley: Maybe your belts are a bit on the loose side?

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#8

With all the pulley posts, I’m confused. If the gearing ratio is the same, does it matter what pulley sizes you use to get there?

#9

Yes because tooth engagement matters.

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#10

Not loose, my motor settings are very strong. Also, 15:40 vs 15:62 is different tooth engagement

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#11

Centre to centre distance can also make a big difference

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#12

So in general, is it better to go with the largest pulleys you can when attaining the gear ratio you want?

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#13

Thats how i do it :man_shrugging:

#14

True, maybe mine is longer than @ShutterShock 's

Whats strong for you here? I’m running 80A I think.

Yes, 62T is bigger, therefore potentially even less tooth engangement. That’s why I’m confused that your belts are skipping.

1 Like
#15

Eddy currents are produced exponentially. If the motor gets to the speed where they start to go way up (roughly 8500rpm with a common 40-50mm motor) it can become a bigger source of heat than the current in the wire, but up to that point the speed can be transformed to torque and a benefit. The more magnets or bigger the motor the lower the speed it will occur.

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#16

I have tried 12/72 with an idler and it was a no go.

14/72 was fine…

12 I think is asking for trouble.

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#17

100 motor -100
50 batt -15

Per side

Idk, I haven’t had belt slip on other ratios except the 15:40 either, I might try a longer belt sometime soon, my idler is at its almost max open position

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#18

I think thats the culprit here.

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#19

Probably yeah, gotta try maybe 330 or 335mm belt

#20

I started a similar thread a few days ago.

Nobody here can tell you for sure what 12t vs 16t will be like. There are good reasons not to go to 12t though. You will get belt skip.

If you try it, let us know how it goes!

1 Like