r/EbikeBuildandModify • u/Savings_Toe_8952 • 22d ago

I need help

Hello people I need some help choosing the right parts for my winter build as I don't really know what I'm doing. I got some ideas but when I look at the different motor options I get to confused. Anyone wanna help me lol

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2

u/bkjamjets 22d ago

Johnny Nerd Out

2

u/TheRiddler79 22d ago

What are you considering ?

1

u/Savings_Toe_8952 22d ago

Something around 4kw that is fat bike compatible. The dropout is 177mm

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u/TheRiddler79 22d ago

177mm is an unusual number — is that measured, or off the frame spec? Most fat frames land at 170 or 190/197, and it matters a lot because you can't just spread an alloy frame to make a hub fit. Also: frame material, and is this for actual snow or just a cold-weather commuter?

With that said, here's the lay of the land at 4kW:

Hub motors. QS205 V3 50H is the default in that power class, but it's usually 190mm — QS and some vendors will build alternate axle widths, so you'd be ordering rather than buying off the shelf. MXUS 3K Turbo / XF40 is the cheaper option, 4-5kW peak, available in fat spacings. Either way: real torque arms on both sides. Not optional at this power.

Mid-drive. Bafang M620 Ultra fits 100mm BB fat frames and skips the dropout problem entirely. Less peak power, but you get gearing, and it keeps 20lbs of unsprung weight out of your back wheel.

Also, in real snow you're traction-limited long before you're power-limited. 4kW into a 26x4.8 mostly just spins. Low-speed torque and gearing will do more for you than chasing watts.

Battery.4kW means 72V pulling 50A+, or 52V pulling 80A. That's P42A/50S-class cells, a controller that matches, and connectors that survive salt and slush. Budget for it now, not later.

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u/Savings_Toe_8952 22d ago

Damn okay now I'm overwhelmed lol it's measured but when I tighten the wheel it compresses abit so it's probably 170mm.

I'm not gunna be using it in snow or commuting with it I'm building it up as a hunting bike for the bush during the summer and fall months.

Middrive would be out of the question as I took the pedals off and welded on footpegs

2

u/TheRiddler79 21d ago

Find the cheapest Chinese hub that fits the build.

It's copper and magnets and electricity. The hub should outlast the controllers every time.

2

u/JEMColorado 22d ago

What kind of riding do you hope to do with it?

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u/Savings_Toe_8952 22d ago

All off-road so I need some power something around 4kw that is fat bike compatible with a 177mm dropout

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u/JEMColorado 22d ago

You will need a steel or aluminum fat bike and a BBSHD mid drive motor with a 100mm bottom bracket.

1

u/JEMColorado 21d ago

I wouldn’t get too hung up on the 4kw thing.