I think maybe to achieve the same (high) torque he would want, a the smaller the gear on the motor shaft, the larger the wheel gear would need to be to get that same (or more torquey) ratio, so a bigger bearing would be needed to accommodate for that extra size?
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He probably means that with a very small drive gear, there is a lot of load on the motor bearings and shaft.
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Smaller the motor gear, the more rpm for the same speed. More rpmâs = more motor wear and tear which = less motor life.
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The larger the wheel gear= less ground clearance⌠also the smaller the pinion means more undercut on the gear for the meshing to be good. More undercut means a weaker gear
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A smaller pinion would mean less load on the motor for the same external load, so no.
@DEEIF Motor RPM depends solely on input voltage and KV. If someone was using a 1:10 ratio with huge wheels, their motor would be none the wiser. I think MTB people would gladly trade top speed for more torque stillâŚ
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Whatâs the size of the casing, would the AT drives also be compatible with bergs? Even tho theyâre a comparatively small pneumatic.
Gear casing is 98mm. Bergs will be compatible even though theyâre hard to find these days.
This means a nominally 6" tire will have 27mm of clearance.
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Thatâs not enough clearance right?
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I am unfamiliar of other gear drive clearances so I am not sure how that compares?
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6" tire smol, not for off road.
8+" tire has enough clearance for off road then
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Is doing a 83/17 an option?
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I ride some times with a friend which has a MTB with 8" tires, while I only have Ali 6" tires. Nonetheless I have more traction than him and can be quicker in general.
Perhaps having a kicktail helps?
I wouldnât say 6" is not for offroad though.
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A small pinion will cause more load on the shaft. You cannot think through external load, since you cannot control it. What you can control is motor torque (and conveniently, itâs about constant for constant motor amps!). Think about it this way. If the pinion is huge, with a given shaft torque, the tooth pressure will be quite small. Therefore the bearings on the shaft donât need to support the shaft that much to bring the system to equilibrium. So vice versa, if the pinion is tiny, the tooth pressure will be very high, and the motor bearings have a lot of load as well.
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This ^
Besides random shocks such as a crash, the gear teeth experience a very predictable load
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Is that straight cut or helical?
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Huh, that seems very counter-intuitive to me. I would have thought that the motor bearings, always being the same size (i.e. same distance away from the shaft center), would feel no difference in pinion choice⌠But I suppose factors like free-roll decreasing due to the motor not wanting to make such huge RPM changes quickly would become an issue in âshocksâ as Kevin mentioned. Youâre probably right; sorry!
straight
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Since we canât get bergs maybe make some adapters for the obtainable 6x2âs and some wheel gears. Just sayin
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@Boardnamics how fast would you spin these bad boys before youâd start to consider your life choices?
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10K RPM+ on the motor pinion would start to make me concerned.