Building a fat bike for the woods.

Greg47

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Some years back, I built a bike on a full suspension mongoose MTB with a small 250W front hub motor. Love the thing, but it’s just underpowered in the woods.
I’m getting ready to build a fat ebike, & need a little advice.
I found a fairly light aluminum frame FB on Amazon that’s enroute. Bought for the frame.
I’m trying to decide about motor etc.
would like it to be quiet, street legal (750W?) And somewhat waterproof as I ride in wet areas in FL & GA. Mostly flat terrain.
Definitely going rear drive. Mid motor? Rear hub? Need low end torque. Top speed not important.
Geared or direct? Seems one is better low end and the other is quieter.
Appreciate any input here from the experts.
Thanks,
Greg
 

Hoggdoc

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I think you're only option is a mid drive setup. This will allow you to use the gearing provided by the rear derailleur on the bike to multiply the torque of the motor that is already double that of a similarly sized hub motor.

I would suggest a Bangfung 750W kit, they are very affordable and their is a lot of after sale support for these motors unlike other brands. Check with LUNA Cycles in SOCAL they sell and support these systems.

As for the battery, a critical part of the system, make sure you buy from a company with good track record for support. Also only buy a battery pack made up with Samsung, Panasonic or maybe LG cells. If possible get 21700 cells, they are the latest on the market. Also check the specs of the BMS (battery management system) in the pack to make sure the maximum amps output is where you want it. I would say at least 30 Amps. At 48v that would provide 1440 watts to the motor.
 

Greg47

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I think you're only option is a mid drive setup. This will allow you to use the gearing provided by the rear derailleur on the bike to multiply the torque of the motor that is already double that of a similarly sized hub motor.

I would suggest a Bangfung 750W kit, they are very affordable and their is a lot of after sale support for these motors unlike other brands. Check with LUNA Cycles in SOCAL they sell and support these systems.

As for the battery, a critical part of the system, make sure you buy from a company with good track record for support. Also only buy a battery pack made up with Samsung, Panasonic or maybe LG cells. If possible get 21700 cells, they are the latest on the market. Also check the specs of the BMS (battery management system) in the pack to make sure the maximum amps output is where you want it. I would say at least 30 Amps. At 48v that would provide 1440 watts to the motor.
Thanks Hoggdoc. Sounds like good advice! Do they make the 750 watt motor for the wider frame, that this bike will probably have? Hasn’t arrived yet. The battery I’m using on my little bike has Samsung cells and has been great.
How’s the noise on those bafang mid drives, compared to hub motors? (Similar power)
 

Hoggdoc

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Thanks Hoggdoc. Sounds like good advice! Do they make the 750 watt motor for the wider frame, that this bike will probably have? Hasn’t arrived yet. The battery I’m using on my little bike has Samsung cells and has been great.
How’s the noise on those bafang mid drives, compared to hub motors? (Similar power)
They make motor kits frames up to 100mm I think maybe even wider. Give Luna Cycle a call they would have all that information. As for sound, they make a different sound than hub motors but not too bad from what I have heard.
 

Greg47

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Thanks again. Have been reading Luna’s site regarding the bafang middles. They program the BBSHD to street legal 750 watt output. It’s a little heavier, but tougher for some of the nasty places I go. My hunt lease is next to the okeefenokee swamp in S GA... Luna prices seem fair as well and the support adds value.
Appreciate your help, Man!
 

Greg47

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2DCDE9B7-DDFE-4C4C-9552-6DB0FA93EC29.jpeg

Mostly finished. Way too fast though. May put a smaller chainring on it.
It’s the year of the tiger.
 

Hoggdoc

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View attachment 3084
Mostly finished. Way too fast though. May put a smaller chainring on it.
It’s the year of the tiger.
Wow that turned out great. How did you do the paint job or is that a wrap of some sort?

You should be able to get into the programming of that motor with a special cable that you have to order and may be turned down or adjust the power delivery so it suits your needs better. Also like you said you could change the front sprocket to a smaller one which would give you more torque and less speed.

Seriously congrats on that build I’m jealous keep us informed on what the progress is and how are you liking it
 

Greg47

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Wow that turned out great. How did you do the paint job or is that a wrap of some sort?

You should be able to get into the programming of that motor with a special cable that you have to order and may be turned down or adjust the power delivery so it suits your needs better. Also like you said you could change the front sprocket to a smaller one which would give you more torque and less speed.

Seriously congrats on that build I’m jealous keep us informed on what the progress is and how are you liking it
Thanks! I used a flat green self etching primer, then stole some coontie leaves from my wife’s garden to use as templates and sprayed flat black through them lightly while holding where I wanted them. Then sprayed everything with 2 part automotive clear coat Matt finish. Very tough finish.
 

Hoggdoc

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Thanks! I used a flat green self etching primer, then stole some coontie leaves from my wife’s garden to use as templates and sprayed flat black through them lightly while holding where I wanted them. Then sprayed everything with 2 part automotive clear coat Matt finish. Very tough finish.
Very creative, like I said I'm very jealous I have a Himiway All Terrain 2021 model. I really like it and must admit it does everything I need it to do. But I really like the idea of a mid drive system so much I have even contemplated adding one to the Himiway.

Anyway once again congrats on your great build!
 
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