Best strong and lightweight hub motor

Hi guys, today i broke the axle of my bafang 500w motor again... it's the 2nd time and finally i realized its not the right motor for the purpose, and that's sucks because this motor is super torquey, fast, and super lightweight, the problem is that the axle is only 12mm and hollow on the wires side....
so basiclly i'm looking for the best lightweight motor for the purpose.
i use this motor on a Rocky mountain flatline park (downhill bike), alot of offroad jumpings and rough trails. i use a 48v battery and 34a peak controller, the motor isn't getting warm and i'm getting to 50+ kph, so i'm looking for a motor which can do this stuff.
basiclly i need a motor that can handle this power and more (i wan't to move to 72v later on), with strong structure that wont break, and as lightweight as possible (bafang motor weighs nothing since it's geared).
any ideas?

Have you considered having a replacement axle made from proper steel? The design of the standard axles isn't terrible, but they are notoriously soft and weak. Have a search for posts by the user "Tench" for some inspiration

Be very interested to know exactly what it takes to bust one of these.

If you want strength, a mid drive might be the best option.

Punx0r said:

Have you considered having a replacement axle made from proper steel? The design of the standard axles isn't terrible, but they are notoriously soft and weak. Have a search for posts by the user "Tench" for some inspiration

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acutally i have a spare axle, if you know of a way to make it stronger please tell me
it's already made of tempered steel, i think the only way is to make a new one from scratch from better materials, but that would probably cost like a new motor

friendly1uk said:

Be very interested to know exactly what it takes to bust one of these.

If you want strength, a mid drive might be the best option.

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actually i busted two of these, thats the 2nd time, and basiclly i had a problem of the axle spinning in place until i got the torque arms i have today, so it was a bit "shaved" in some parts.
and lots of jumps.
actually i would love a mid motor, but there's no way of getting them here (in Israel), only brushed ones which are garbage, or 250w ones, which are not powerfull enough for what i do..

Simply use your Bafang as your mid drive motor. If you have some fabrication capacity, you can free the tiny motor inside of its heat limitations and torque limits of the plastics gears and clutch to run it at significantly higher power.

You can harden the axle by heating it cherry red in a crucible furnace or with a decent sized Oxy-Ace torch (rosebud tip is best) and dipping it in mineral oil (even motor oil) several times. The process is called "Heat-Treating". The rapid cooling from the outside-in sucks the oil into the pores of the cheap pig-iron burning the oil to a hard carbon. Repeat the process about 3-4 times at most. It can get too brittle if you overheat it or do it too many times.

Some words of warning:

1) Normally the part is tempered after hardening to reduce the hardness and prevent brittle failure. Although, see 2)

2) If the axle is low carbon (like mild steel) then you won't be able to harden it much

3) Heating and quenching will result in distortion of the axle

4) Hardened shit, weak steel is still shit, weak steel.

It may well help though, so give it a go if you're happy to potentially sacrifice the axle if it doesn't work out.

John in CR said:

Simply use your Bafang as your mid drive motor. If you have some fabrication capacity, you can free the tiny motor inside of its heat limitations and torque limits of the plastics gears and clutch to run it at significantly higher power.

Click to expand...

That's not so simple as you say, but it has many benefits, I should see what it takes and then decide

And about hardening the axle - I sent a message about this to 8fun and they say since my motor was made (2010) they improved the axle and it's been made now especially for jumps and off-road use, I asked if the new axle fits my old motor, we'll see what they say

Just got a reply from bafang - the new 2014 axle won't fit my 2010 motor, i can buy a new motor but thats expensive, but i'll keep that in mind, for now i will change the axle and hope it'll hold, maybe it will since the new axle won't be rubbed at some points like the one that snapped. if it won't hold i'll start thinking about replacing the motor again, BUT i'll still keep in mind the idea of making this motor a mid-drive, thats a good option and after i did the measurments i've seen it is possible and not too complicated, maybe i'll do that sometime instead of buying another motor. also i think that if this motor would me mid-mounted, the geard will keep the motor cool and i could move to 60v with no problem

I would consider getting a custom axle made with stronger materials. Like someone posted earlier. Tench makes them if you simply send him a sample. His prices seemed very good.

http://endless-sphere.com/forums/viewtopic.php?f=31&t=58509

Offroader said:

I would consider getting a custom axle made with stronger materials. Like someone posted earlier. Tench makes them if you simply send him a sample. His prices seemed very good.

http://endless-sphere.com/forums/viewtopic.php?f=31&t=58509

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and as i commented, it will cost like a new motor

How much are those geared motors?

And the next question is if you did buy a new motor, wouldn't you have the same problem with the axle?

Offroader said:

How much are those geared motors?

And the next question is if you did buy a new motor, wouldn't you have the same problem with the axle?

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Here in Israel this motor cost me 1500 NIS which is about 390$, everything is evpensive here
and by buying a new motor i meant the new version of this motor, as i said - i contacted bafang and they said the 2014 motor axle has been improved since they had this problem with the old motors (mine is from 2010)

I think a new axle will run you about $130 shipped based on what he said in the thread.

If the new model will be strong enough and offers some other improvements than you have to take that into account for $390.

I'd drop that replacement axle you own right now in the broken motor and sell it, then just buy the new version.