Most powerful rear hub motor for 135mm MTB frame?

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ebike11
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Most powerful rear hub motor for 135mm MTB frame?

Post by ebike11 » Dec 03, 2017 7:00 pm

Just wondering what options there are.
Looking for the fastest rear hub motor that can fit in a standard MTB frame on 84V.
Thanks!

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dogman dan
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Re: Most powerful rear hub motor for 135mm MTB frame?

Post by dogman dan » Dec 04, 2017 7:10 am

Likely the easiest to find would be the larger crysalyte motors, using the faster wind for more speed per volt.

See them at Grin Technology, and buy there too if you live in north America. You live in Korea though, so look for similar motor in china perhaps.

The popular huge muxus of course is not 135mm. ( 145mm I think) Get that, and a steel frame. Bend the steel frame out 5 mm per side easily. The big muxus is what you want if you really want to run motorcycle like power.

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Re: Most powerful rear hub motor for 135mm MTB frame?

Post by wesnewell » Dec 04, 2017 11:05 am

Get a bike with steel rear dropouts and don't worry about the dropout width as it can easily be widened to 150mm or more. Then your motor options are limitless.
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Re: Most powerful rear hub motor for 135mm MTB frame?

Post by Alan B » Dec 04, 2017 12:05 pm

My CroMotor has a 135mm axle. It is very tight for a rear brake, so I use variable regen/ebraking for rear brake instead (and it works great) and only have room for a single rear sprocket. I use a two speed crank to give me two pedaling speeds, my frame won't take a chainring set. My frame is not MTB, but the width is 135mm. I also use dual front disc so there's plenty of mechanical braking. Setup is described in the Borg thread in my signature.

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Re: Most powerful rear hub motor for 135mm MTB frame?

Post by Drunkskunk » Dec 04, 2017 5:38 pm

Cromotor is going to be the most powerful at 135mm. But "most powerful", "fastest", and "best" aren't the same thing.
Smaller motor might be faster depending on the wind, the aerodynamics, and the riding conditions. One of the big Clytes might be better if you plan to haul weight or are going to be using the motor deep in it's torque band.
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Re: Most powerful rear hub motor for 135mm MTB frame?

Post by amberwolf » Dec 04, 2017 9:11 pm

dogman dan wrote:
Dec 04, 2017 7:10 am
The popular huge muxus of course is not 135mm. ( 145mm I think) Get that, and a steel frame. Bend the steel frame out 5 mm per side easily.
Or file / grind the axle flats further down past the shoulders, and use spacers around the remaining unthreaded axle that sticks out past the dropouts, so the nuts apply their pressure to the dropout face as normal.

Worked fine for me. ;)

How far you can go depends on the specific motor and the width of your cassette or freewheel. I used a singlespeed freewheel, so I can go pretty far.

https://endless-sphere.com/forums/viewt ... 5#p1247658
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Re: Most powerful rear hub motor for 135mm MTB frame?

Post by ebike11 » Dec 05, 2017 12:16 am

amberwolf wrote:
Dec 04, 2017 9:11 pm
dogman dan wrote:
Dec 04, 2017 7:10 am
The popular huge muxus of course is not 135mm. ( 145mm I think) Get that, and a steel frame. Bend the steel frame out 5 mm per side easily.
Or file / grind the axle flats further down past the shoulders, and use spacers around the remaining unthreaded axle that sticks out past the dropouts, so the nuts apply their pressure to the dropout face as normal.

Worked fine for me. ;)

How far you can go depends on the specific motor and the width of your cassette or freewheel. I used a singlespeed freewheel, so I can go pretty far.

https://endless-sphere.com/forums/viewt ... 5#p1247658
Image

Image
Oh do you mean you filed down a 145mm axle to fit on a 135mm frame?

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Re: Most powerful rear hub motor for 135mm MTB frame?

Post by MadRhino » Dec 05, 2017 12:55 am

With big motors, you have to make torque plates or custom dropouts anyway.

I’d say most big motors can be fitted pretty easy.
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Re: Most powerful rear hub motor for 135mm MTB frame?

Post by ebike11 » Dec 06, 2017 6:02 pm

MadRhino wrote:
Dec 05, 2017 12:55 am
With big motors, you have to make torque plates or custom dropouts anyway.

I’d say most big motors can be fitted pretty easy.
Yes i see....but i have access to tools or services where i am to do that type of modification...so im looking for the largest possible motor for standard MTB dropouts.
Looks like Cromotor so far

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Re: Most powerful rear hub motor for 135mm MTB frame?

Post by markz » Dec 06, 2017 7:49 pm

Wow thx AW, never seen that before, its great for my rear motor that I want to fit up front, been scouring the interweb for fat forks, pondering alum weld current front fork, Townie's an odd ball, going 2wd myself, all my motors are rears, dont wanna buy weaker narrow front.
amberwolf wrote:
Dec 04, 2017 9:11 pm
dogman dan wrote:
Dec 04, 2017 7:10 am
The popular huge muxus of course is not 135mm. ( 145mm I think) Get that, and a steel frame. Bend the steel frame out 5 mm per side easily.
Or file / grind the axle flats further down past the shoulders, and use spacers around the remaining unthreaded axle that sticks out past the dropouts, so the nuts apply their pressure to the dropout face as normal.

Worked fine for me. ;)

How far you can go depends on the specific motor and the width of your cassette or freewheel. I used a singlespeed freewheel, so I can go pretty far.

https://endless-sphere.com/forums/viewt ... 5#p1247658
Image

Image

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Re: Most powerful rear hub motor for 135mm MTB frame?

Post by amberwolf » Dec 07, 2017 1:01 am

markz wrote:
Dec 06, 2017 7:49 pm
Wow thx AW, never seen that before, its great for my rear motor that I want to fit up front, been scouring the interweb for fat forks, pondering alum weld current front fork, Townie's an odd ball, going 2wd myself, all my motors are rears, dont wanna buy weaker narrow front.
Just keep in mind you'll have a very long axle stub sticking out each side of the front fork, with a stack of washers between the threaded area and the fork dropout face. Might look like something from Ben Hur. ;)

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Re: Most powerful rear hub motor for 135mm MTB frame?

Post by SamRich » Dec 07, 2017 1:11 pm

I've been considering this one for a while:
Image

https://www.aliexpress.com/item/Standar ... 0.0.2bVycJ

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Re: Most powerful rear hub motor for 135mm MTB frame?

Post by markz » Dec 07, 2017 11:19 pm

You could look into buying a front hub motor and using a rear hub motor to get more power. For instance a QS or mxus 3kw direct drive rear, with a d.d. 9c clone up front. Geared motors like the MAC from em3ev are pretty powerful. Can use the motor simulator at www.ebikes.ca and you can click the ADD button for 2wd.

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Re: Most powerful rear hub motor for 135mm MTB frame?

Post by dogman dan » Dec 09, 2017 8:21 am

Yes, with a single speed instead of 7 gears in back, lots of room to change the axle.

I just meant to say that if you want all 7 ( or 7 of 8)gears, a large crystalyte fits fine in regular bikes. Ok, so 3000w is lame these days, but I get all I need out of 2000w or so. Running 60v, my cargo bike with an old 5304 clyte can hit 35 mph easy, and with tailwind even 40 mph, with 1800w continuous. It will climb any paved mountain road in my state, towing a trailer too. I can also dial up to 3000w, with a CA adjustment, and 72v battery.

The newer big crystalytes should be able to handle 4000w in bursts. And get you top speeds near 50 mph with 84v. Again, just get the faster wind for the most speed per volt.

In general, you can also flex out most alloy frames to 140 mm, just 2.5mm of flex per side. So cramming in a big motor might only need a minor grind to the axles to make it go. If possible, just make some bolt on torque plates that allow a wider motor, with gears, and lengthens the rear 5 or 6 inches.

If fast and cheapest is your need, then you are looking at the muxus, single speed gear, and up voltage till you are stupidly fast. grind it to 140 mm, and cram it in.

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