Thru axle 148x12 Boost geared hub motors

hindesite

100 W
Joined
Jul 16, 2019
Messages
189
The discussions I've seen around hub motors all seem to assume dropouts, which excludes most of the better trail bikes that are available.

Does anyone have experience with or knowledge of decent hub motors that will fit 148x12 thru axles, Boost frames?
 
Why not 15mm? Why not 20mm? Why not Lefty? There are so many nonstandard standards to choose from! (That's the problem.)

Grin All Axle front hub motor. No rears I'm aware of.

If you let go of faddish new stuff, there are lots of good options. Remember that today's MTBs are specifically designed for engineered trails that are specifically designed for the bikes. Adding electric power and system mass changes some figures of merit, so a more versatile, older style suspension MTB may be more applicable.

Even more versatile and future-proof if you let go of suspension.
 
hindesite said:
The discussions I've seen around hub motors all seem to assume dropouts, which excludes most of the better trail bikes that are available.
That's because, AFAIK, except for the http://ebikes.ca Grin All Axle front motor
https://ebikes.ca/product-info/grin-products/all-axle-hub-motor.html
(which as it's name implies, you can use virtually any axle for it--you may have to design an adapter for a specific usage, if the ones they sell for it aren't usable), there aren't any commercially-available hubmotors (other than perhaps those meant for cars and the like, which are not for thru-axles) that aren't designed for some form of "dropout" or clamping/pinching fixture that secures the axle flats against rotation...for almost every single one of those motors, that's the only point on the motor that can be used (without user-modification or axle replacement) to transfer the torque the motor makes to the bike frame and allow the motor to push the bike along.

There are a couple of motors (one by Grin, the other by Heinzmann) that use a round axle and a torque arm that secures to the frame and the axle shoulder instead of using tiny axle flats for torque transfer, but they still aren't thru-axle types.


If a front hub with the Grin AA motor isn't an option, or making and installing your own axle in a "regular" hubmotor, or making adapter plates (torque plates) that bolt to your frame to hold a regular hubmotor to it, then your only other choices are non-hubmotor drives of various types, DIY or commercial, to drive the wheel of your choice via whichever method you prefer (chain, belt, friction, etc).
 
Chalo said:
Why not 15mm? Why not 20mm? Why not Lefty? There are so many nonstandard standards to choose from! (That's the problem.)

148x12 is a widely used and specifically rear axle standard, all of the ones you list are front. There are probably very few decent MTB frames that are not 148x12, because this particular standard allows for less dished and much stronger and stiffer wheels.

Chalo said:
Grin All Axle front hub motor. No rears I'm aware of.

If you let go of faddish new stuff, there are lots of good options. Remember that today's MTBs are specifically designed for engineered trails that are specifically designed for the bikes. Adding electric power and system mass changes some figures of merit, so a more versatile, older style suspension MTB may be more applicable.

Even more versatile and future-proof if you let go of suspension.

I have a 3yr old hardtail that I particularly wish to convert, it is a delight to ride and I certainly don't consider it as faddish new stuff. And I'm certainly not about to move to a rigid front fork!

I'd appreciate specific input on my original question, rather than on the philosophies of ebike conversions in general or my life choices, 'K?
 
amberwolf said:
hindesite said:
The discussions I've seen around hub motors all seem to assume dropouts, which excludes most of the better trail bikes that are available.
That's because, AFAIK, except for the http://ebikes.ca Grin All Axle front motor
https://ebikes.ca/product-info/grin-products/all-axle-hub-motor.html
(which as it's name implies, you can use virtually any axle for it--you may have to design an adapter for a specific usage, if the ones they sell for it aren't usable), there aren't any commercially-available hubmotors (other than perhaps those meant for cars and the like, which are not for thru-axles) that aren't designed for some form of "dropout" or clamping/pinching fixture that secures the axle flats against rotation...for almost every single one of those motors, that's the only point on the motor that can be used (without user-modification or axle replacement) to transfer the torque the motor makes to the bike frame and allow the motor to push the bike along.

There are a couple of motors (one by Grin, the other by Heinzmann) that use a round axle and a torque arm that secures to the frame and the axle shoulder instead of using tiny axle flats for torque transfer, but they still aren't thru-axle types.


If a front hub with the Grin AA motor isn't an option, or making and installing your own axle in a "regular" hubmotor, or making adapter plates (torque plates) that bolt to your frame to hold a regular hubmotor to it, then your only other choices are non-hubmotor drives of various types, DIY or commercial, to drive the wheel of your choice via whichever method you prefer (chain, belt, friction, etc).
"148x12, Boost" itself implies a rear hub and a specific standard wrt wheel dish, rotor placement and chainline etc, and I would assume that any thru axle design will also imply the use of a torque arm. AFAIK front hubs do not have the correct spacing for a brake rotor and won't mount a cassette either.

Also consider the implications of thru axles here; wiring pigtails cannot exit coaxially.
 
EDIT: A google search for "thru axle hubmotor" found this as the third hit
https://ozo-electric.com/en/brushless-electric-motors/991067-drive-wheel-spoke-thru-axle-tc2540.html
and this
https://ozo-electric.com/en/rear-wheel-hub-motor-bike/140824-tc2540-wheelbuilding-on-double-wall-rim-with-23-mm-stainless-steel-spokes.html
though I haven't read any of the specs to see if they will do what you want. From a glance at the page it appears to be a thru-axle version of the Crystalyte "The Crown" motor, in the TC2540 model. It is subtitled "Direct drive Thru axle motor developed specifically to electrify full suspension MTB with 12x142mm thru axle or Boost 12x148mm standard." so unless 148x12 and 12x148 are different standards (instead of the same one with a variation on the name), it sounds like something that would fit, assuming they adhered to the standards (which is not always a thing for motor manufacturers...). I don't know enough about the standard to tell you if it will work or not.

It does say it uses a "screwing freewheel", so it's probably not a freehub. If you require a freehub, rather than a thread-on freewheel, this one wont' work either, in that case.



Original post below, might not be relevant:
_________________________________________
Unfortunately, unless you make it yourself, there aren't any COTS options I'm aware of for what you need.

If there is one, I've not run across it, though it's been years since I specifically did a search for such motors for someone.

The linked (front) motor is the only one so far commercially available that can be used for thru axle frames.

You might be able to adapt it with custom machining to run on a rear, adding a cassette freehub to it, ensuring the rotor spacing is as needed, etc., but that would be up to you (unless you can convince Grin Tech to do this).

Haven't seen a COTS rear motor for this yet. If you find one, there'd be a fair number of people interested in it, as this has come up before.
 
hindesite said:
I'd appreciate specific input on my original question, rather than on the philosophies of ebike conversions in general or my life choices, 'K?

Okay then, here's a simple answer you might be able to digest: If you use a hub motor that requires axle slots, you will need a frame or fork that has them. There's only one hub motor I'm aware of that doesn't require axle slots.

Or you can pedal harder.

Or you can retrofit your bike with a mid drive like Bafang BBSHD. That's an easy way to avoid the negative effects of hub motor unsprung weight on a suspension bike.

I think with your attitude, you're going to have to make your own mistakes rather than learning from others' hard-won experience. Maybe you'll enjoy that process more.
 
amberwolf said:
EDIT: A google search for "thru axle hubmotor" found this as the third hit
https://ozo-electric.com/en/brushless-electric-motors/991067-drive-wheel-spoke-thru-axle-tc2540.html
and this
https://ozo-electric.com/en/rear-wheel-hub-motor-bike/140824-tc2540-wheelbuilding-on-double-wall-rim-with-23-mm-stainless-steel-spokes.html
though I haven't read any of the specs to see if they will do what you want. From a glance at the page it appears to be a thru-axle version of the Crystalyte "The Crown" motor, in the TC2540 model. It is subtitled "Direct drive Thru axle motor developed specifically to electrify full suspension MTB with 12x142mm thru axle or Boost 12x148mm standard." so unless 148x12 and 12x148 are different standards (instead of the same one with a variation on the name), it sounds like something that would fit, assuming they adhered to the standards (which is not always a thing for motor manufacturers...). I don't know enough about the standard to tell you if it will work or not.

It does say it uses a "screwing freewheel", so it's probably not a freehub. If you require a freehub, rather than a thread-on freewheel, this one wont' work either, in that case.
Thanks, that is a great answer, and close to what I'm after. My search results are swamped by my previous browsing history, so lots of Bafang etc...

From the OZO site I search the motor number and find https://ebikes.ca/shop/electric-bicycle-kits/crystalyte-h/crystalyte-rear-thru-axle-ready-to-roll-kit.html which is the same thing, but in stock. I'm very familiar with Grin's website and hadn't found a way to navigate to that product.

Those who haven't kept up with current fads or the implications of thru axles will note the pigtails exit through the brake rotor centre, instead of coaxially, the torque arm and its connection, and the ability to fit 148 Boost MTB frames.

Falls a little short of what I'm after, but will be of interest to someone, I'm sure.

Thanks!
 
Two that I know of: Bafang H800, which I think never got off the ground, at least in the USA, and ---


Axle
Thru axle
Max. torque
60
Power maximum
450
Power nominal
250
Production date
2023
Speed
7-11 speed Shimano compatible
System voltage
36
Weight
3900g


This is basically all the information they have. No mention of the controller or display, PAS, or anything else that's well, kind of important. There are a couple of other webpages on their site that says this was introduced in 2017 (probably 12x142), then some programming refresh in 2023. The picture in the link 'looks' like 12x142, and that's OK because you can buy 142 to 148 adapters for like $10.

However, I find it hard to believe that a supposedly 250W nominal hub motor can have a peak output of 60 Nm torque. That's way more than the average mid-drive!!! The average 250W nominal mid-drive has about 40Nm torque...and this has 60 Nm? I dunno about that. I have a feeling the peak watts on this motor are far more than 450 but I understand that they want to stay legal to sell in certain areas...
 
Why ?
If you like that bike and it rides great leave it alone it won't be the same with a motor and a battery in a controller.
I would go find a used bike with a big enough triangle for the battery make sure the battery fits get up 1500 watt rear motor like a leaf. Use a torque arm and figure out where the controller is going to be before you purchase the used bike make sure everything fits sometimes you make a cardboard box the size of the battery and see where you can put it along with the size and placement of the controller before you buy the bike.
This way you still have the mountain bike you love and when you buy a battery buy a charger from the same company.
 
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