MXUS Turbo 3k on 170mm dropouts

[al20ov]

Hello everyone, I recently bought a MXUS Turbo 3k laced into a 26" rim from the official MXUS alibaba seller and I told the seller I had a hardtail frame with 135mm dropouts. It works great on my current frame aside from a couple alignment issues (even though I'm running torque arms, my dropouts are chewed up after 7 years of use with a 9c motor) and I was thinking of buying a stealth bomber type frame or an Eleek Lite Pro to finally have rear suspension, built-in torque arms, room for a 20s6p or 20s7p battery, etc... Either way, all these frames have much wider dropouts (think 155-170mm). I measured my axle and it came out to between 210mm and 220mm (inaccuracy due to trying to align measuring tape from top down with perspective, etc...)

So I have two questions:
- When buying off of alibaba, does MXUS actually press an axle based on the customer's dropout width or they just have a generic axle made for any size dropouts and mine just happens to fit perfectly because it's the minimum dropout width for that axle?
- Has anyone fit that motor successfully on wider (fatbike or stealth bomber) dropout frames with washers or shims?

 

[amberwolf]

I measured my axle and it came out to between 210mm and 220mm (inaccuracy due to trying to align measuring tape from top down with perspective, etc...

Two easier ways:
asusming your dropouts don't spread out as you isnert the motor (having to force it in):
measure the distances the axle sticks out on each side of your curent dropouts, note those two down.
measure the distance between the dropouts without the wheel in there, note that down
measure the thickness of each dropout, note those two dwon.
add them all up, that's your axle length.

take the motor out in the clearsky noonday sun and set it on your measuring tape with the axle shadow lengthwise on the tape. the distance covered is your axle length (the sun is far enough awya that parallax of the light is insignificant, beyond the diffusion of the shadow at each end which is minimized at noon on clear sunny day).

So I have two questions:
- When buying off of alibaba, does MXUS actually press an axle based on the customer's dropout width or they just have a generic axle made for any size dropouts and mine just happens to fit perfectly because it's the minimum dropout width for that axle?

The second.

QSmotor could probably do whatever axle you want, and has much better quality motors / axles; the QS205-50H is a far better motor than the MXUS-3K (which is only really good for 3K in a 20" wheel; see the big thread on that motor for other info).

- Has anyone fit that motor successfully on wider (fatbike or stealth bomber) dropout frames with washers or shims?

Many people have used washers/etc to do this with various motors and frames over the years. Others have machined / ground the axle shoulders to fit a wider motor in a narrower frame, as well.

I'd highly recommend getting a frame that has dedicated motor dropouots built to pinch / clamp the axle securely, as that will be bertter than simple torque arms. (there are torque arms that do this, like the Grin Tech v7, but it's more secure if the actual dropout does the job). See the Torque Arm Picture Thread for many variations of TAs and some clamp designs you can make if you don't get a frame with them built in.


Just a note about the frame style: Depending on where you ride, a regular bicycle that's motorized may be ignroed by LEOs or legally allowed, but the motorcycle-looking "suitcase" frames may be harrassed even if legal or seized if illegal.

Also, many of these types of frames are very badly made; there's a recent thread and a slightly older one where a user has a shockmount that's cracking away from his frame and hte metal is rusted even under the paint (was probably never welded properly or cleaneda fterward). Others have had twisted frames, crooked swingarm pivots, crooked headtubes, etc. I don't know that any "EEB" / "stealthclone" frame seller is any better than any of the others; you'd have to directly research each one you're considering.

 

[al20ov]

Two easier ways:
asusming your dropouts don't spread out as you isnert the motor (having to force it in):
measure the distances the axle sticks out on each side of your curent dropouts, note those two down.
measure the distance between the dropouts without the wheel in there, note that down
measure the thickness of each dropout, note those two dwon.
add them all up, that's your axle length.

take the motor out in the clearsky noonday sun and set it on your measuring tape with the axle shadow lengthwise on the tape. the distance covered is your axle length (the sun is far enough awya that parallax of the light is insignificant, beyond the diffusion of the shadow at each end which is minimized at noon on clear sunny day).






The second.

QSmotor could probably do whatever axle you want, and has much better quality motors / axles; the QS205-50H is a far better motor than the MXUS-3K (which is only really good for 3K in a 20" wheel; see the big thread on that motor for other info).





Many people have used washers/etc to do this with various motors and frames over the years. Others have machined / ground the axle shoulders to fit a wider motor in a narrower frame, as well.

I'd highly recommend getting a frame that has dedicated motor dropouots built to pinch / clamp the axle securely, as that will be bertter than simple torque arms. (there are torque arms that do this, like the Grin Tech v7, but it's more secure if the actual dropout does the job). See the Torque Arm Picture Thread for many variations of TAs and some clamp designs you can make if you don't get a frame with them built in.


Just a note about the frame style: Depending on where you ride, a regular bicycle that's motorized may be ignroed by LEOs or legally allowed, but the motorcycle-looking "suitcase" frames may be harrassed even if legal or seized if illegal.

Also, many of these types of frames are very badly made; there's a recent thread and a slightly older one where a user has a shockmount that's cracking away from his frame and hte metal is rusted even under the paint (was probably never welded properly or cleaneda fterward). Others have had twisted frames, crooked swingarm pivots, crooked headtubes, etc. I don't know that any "EEB" / "stealthclone" frame seller is any better than any of the others; you'd have to directly research each one you're considering.

Thanks for the insight, I just took a quick and dirty measurement and didn't really think much about it but I'm definitely going to use the first method you described to get more accurate measurements.

I think I might settle on a Vector Typhoon frame which seems to be very similar to a stealth clone but much higher quality. I share the same concern with that style of frame which might attract unwanted attention, I also looked at the Vector Storm frame because it doesn't look as agressive and more """""dorky"""" but it can only fit up to 100 21700 cells (so 20s5p).

Do you have any recommendations for a frame that's "made" for high-torque hub motors (so reinforced/clamping dropouts) that can fit a lot of cells but also doesn't look like a dirtbike?

 

[amberwolf]

Unfortunately, no. There aren't many ways to pack a big battery into a frame without making it look much less bicycle-like, since most people expect a bicycle to have an open empty framework.

You could use panniers to carry the battery instead; there are assorted cargo bike designs that would work well for that.

There are various custom builds here on ES with frame designs that are more "beach cruiser" or "boardtracker" like, using the main frame as a battery pack containment in various ways (IIRC Juiced used to use a big leather bag in the middle, and might've had leather panniers too, which have also been used in custom builds by at least one ES member who unfortunatley lost that bike to a fire a while back; it was blue, I think).


Some questions to prompt possible alternate paths:
--do you need a big battery for a huge range?
--what do you need lots of power and big battery for?
--are there any other ways to achieve the end goal you're after?