singlespeed rear hub motor for 120mm spacing?

General Discussion about electric bicycles.
Hummina Shadeeba   10 MW

10 MW
Posts: 2012
Joined: Apr 25 2014 10:26pm

singlespeed rear hub motor for 120mm spacing?

Post by Hummina Shadeeba » Nov 15 2019 2:27am

I want to put a rear hub motor in 120mm wide horizontal track dropouts. I also want to pedal a single gear with a freewheel. that's available right?

sleepy_tired   100 W

100 W
Posts: 102
Joined: Jul 02 2019 11:46am

Re: singlespeed rear hub motor for 120mm spacing?

Post by sleepy_tired » Nov 15 2019 4:09am

https://bmsbattery.com/motor/631-16312- ... e-kit.html

I _think_ that should work. It has a spacer that can be removed. Remove the spacer, grind it down if you need to. Don't own the motor and don't know for 100% sure. By default it's configured for 135mm drop outs.

It would likely be easiest to buy the bare motor, modify it to fit, and then have it laced up to a wheel locally. Because if you buy it pre-laced then it'll have to be redished to fit. And shipping costs a lot for a fully laced motor from that company.

Hummina Shadeeba   10 MW

10 MW
Posts: 2012
Joined: Apr 25 2014 10:26pm

Re: singlespeed rear hub motor for 120mm spacing?

Post by Hummina Shadeeba » Nov 15 2019 9:20pm

I think ill get a more powerful 135mm spaced motor and maybe grind the ends or squeeze it and thanks for helping me see that will work. can use a common single speed conversion kit then.



Liking this kit
https://lunacycle.com/mac-motor-asi-hig ... et-wrapper

Hummina Shadeeba   10 MW

10 MW
Posts: 2012
Joined: Apr 25 2014 10:26pm

Re: singlespeed rear hub motor for 120mm spacing?

Post by Hummina Shadeeba » Nov 19 2019 2:17am

Ordered it!
https://lunacycle.com/mac-motor-asi-hig ... et-wrapper

And their cool wolf pack clear battery 52v, all to go on that little 20” bike


If u have any advice on bending the 120mm frame to fit the 135 hub or if I’m better grinding the axle I’d like to hear

Also have no bottle cage mounting spots to attach the battery. Luna seemed to think just drilling and threading the frame tubing would be good enough! Seems sketchy. I was going to get some welded on and the rivet ones seem weak, no?
Attachments
712524CF-A0AC-4698-944C-9794480E4B86.png
712524CF-A0AC-4698-944C-9794480E4B86.png (207.31 KiB) Viewed 2428 times

Balmorhea   10 kW

10 kW
Posts: 546
Joined: Oct 01 2019 8:30pm

Re: singlespeed rear hub motor for 120mm spacing?

Post by Balmorhea » Nov 19 2019 2:56am

Hummina Shadeeba wrote:
Nov 19 2019 2:17am
If u have any advice on bending the 120mm frame to fit the 135 hub or if I’m better grinding the axle I’d like to hear
I say cold set the frame. If you have no experience with such things, or if doing it yourself bothers you, have a bike shop take care of you. They have tools to widen the frame spacing, tools to check side-to-side alignment, and tools to bring the dropouts parallel. Seek out shops with some natural gray hair visible, and unfashionable bikes in evidence.

SlowCo   100 kW

100 kW
Posts: 1441
Joined: Jan 05 2015 5:43pm
Location: The Netherlands

Re: singlespeed rear hub motor for 120mm spacing?

Post by SlowCo » Nov 19 2019 7:24am

Widening the dropout:
https://www.sheldonbrown.com/frame-spacing.html

And use (hose)clamps for attaching the battery holder to the frame.

Hummina Shadeeba   10 MW

10 MW
Posts: 2012
Joined: Apr 25 2014 10:26pm

Re: singlespeed rear hub motor for 120mm spacing?

Post by Hummina Shadeeba » Nov 19 2019 11:44am

I’ll get somewhere to cold set it as apposed to messing with the axle thanks
SlowCo wrote:
Nov 19 2019 7:24am
Widening the dropout:
https://www.sheldonbrown.com/frame-spacing.html

And use (hose)clamps for attaching the battery holder to the frame.
I’d rather make it look slick though. Can’t run a new shiny bike with those things. If u have another idea. As it is now will get some water bottle bosses (think they’re called) welded on for the battery. The esc has threaded holes which I don’t know what to do with either.

john61ct   100 GW

100 GW
Posts: 5121
Joined: Dec 18 2018 2:06pm

Re: singlespeed rear hub motor for 120mm spacing?

Post by john61ct » Nov 19 2019 12:01pm


Hummina Shadeeba wrote:I’d rather make it look slick though. Can’t run a new shiny bike with those things. If u have another idea.
https://clamptitetools.com/collections/kits



SlowCo   100 kW

100 kW
Posts: 1441
Joined: Jan 05 2015 5:43pm
Location: The Netherlands

Re: singlespeed rear hub motor for 120mm spacing?

Post by SlowCo » Nov 19 2019 12:55pm

That's a great tool, thanks for the link!

Balmorhea   10 kW

10 kW
Posts: 546
Joined: Oct 01 2019 8:30pm

Re: singlespeed rear hub motor for 120mm spacing?

Post by Balmorhea » Nov 19 2019 12:56pm

Hummina Shadeeba wrote:
Nov 19 2019 11:44am
As it is now will get some water bottle bosses (think they’re called) welded on for the battery.
If you're cool with having to repaint the frame, that works.

Here's another option:
https://www.merlincycles.com/dmr-hinged ... 65637.html

Image

The link lists 28.6mm and 31.8mm diameters, but they also come in 34.9mm.

Hummina Shadeeba   10 MW

10 MW
Posts: 2012
Joined: Apr 25 2014 10:26pm

Re: singlespeed rear hub motor for 120mm spacing?

Post by Hummina Shadeeba » Nov 19 2019 2:39pm

I’m gunna gamble with the riveted version. Looking around they seem pretty solid

Post pics when done

sleepy_tired   100 W

100 W
Posts: 102
Joined: Jul 02 2019 11:46am

Re: singlespeed rear hub motor for 120mm spacing?

Post by sleepy_tired » Nov 19 2019 2:46pm

If the frame is aluminum then resizing to 135mm is ill-advised.

but if it's steel, go for it.

Hummina Shadeeba   10 MW

10 MW
Posts: 2012
Joined: Apr 25 2014 10:26pm

Re: singlespeed rear hub motor for 120mm spacing?

Post by Hummina Shadeeba » Nov 19 2019 10:36pm

Yes steel. Strangely think was Luna on the phone said carbon could be done a bit. Surprised.

I’m going to rivet to mount the frame to mount the battery and that seems ideal but wondering how to attach as nicely w the esc and it’s threaded holes. Bolted to the frame somehow.
https://lunacycle.com/asi-bac-800-contr ... v-version/

And I’ll waterproof/caulk everything n be done. If only can find an ideal connection for esc to the frame with those mounting holes

With the bike in the mail and unknowable I’d like to fit the battery n esc, in that order, going down the backside of the seat tube.

And there’s this as shown as backup plan. Pretty slick in itself and he’ll of a lot easier
Attachments
F14CDA76-F335-497E-9961-3D8664903C2F.png
F14CDA76-F335-497E-9961-3D8664903C2F.png (414.08 KiB) Viewed 2347 times

john61ct   100 GW

100 GW
Posts: 5121
Joined: Dec 18 2018 2:06pm

Re: singlespeed rear hub motor for 120mm spacing?

Post by john61ct » Nov 20 2019 12:13am

SlowCo wrote:
That's a great tool, thanks for the link!
The real big one will take 1/4-inch-diameter wire, as in clothes hanger gauge, and secure a wind genset mounted on a steel pipe to the top of a telephone pole on a cliff or hilltop, ready to withstand named storms.

Very smooth appearance, nearly invisible, if the join/twist point is in the hidden spot.

A small shallow setscrew / grub screw will prevent any rotation, no need to actually drill any through hole.

Tiny notches using a taper file will secure the wires from slipping longitudinally.

Hummina Shadeeba   10 MW

10 MW
Posts: 2012
Joined: Apr 25 2014 10:26pm

Re: singlespeed rear hub motor for 120mm spacing?

Post by Hummina Shadeeba » Nov 23 2019 2:29pm

http://www.bikecalc.com/wheel_size_math

after finding the sram apex brakes don’t reach the wheel brake track and then realizing 20” wheel size means 1 of a possible 3, as u can see above, and the big wheel dish wanting an axle grinding besides a frame bending, and drilling and riveting, im discouraged and I have a nice old 90s steel Kona mtn bike in orange glitter and their nice steel fork, that’s a size 15 or 16”, I’m 5’8 so a nice similar: too small. a huge time saver and look forward to higher speed.

ill post pics of both

Balmorhea   10 kW

10 kW
Posts: 546
Joined: Oct 01 2019 8:30pm

Re: singlespeed rear hub motor for 120mm spacing?

Post by Balmorhea » Nov 24 2019 1:53am

Hummina Shadeeba wrote:
Nov 23 2019 2:29pm
after finding the sram apex brakes don’t reach the wheel brake track
Dude. Caliper brakes come in all sizes, from 39mm reach to 120mm reach. Just get a different set of brakes. I recommend Tektro.

Hummina Shadeeba   10 MW

10 MW
Posts: 2012
Joined: Apr 25 2014 10:26pm

Re: singlespeed rear hub motor for 120mm spacing?

Post by Hummina Shadeeba » Nov 24 2019 11:02am

Yea I know there’s longer reach brakes but one of many things. Schwinn 20” size rims being smaller I wonder if a problem for the hub and I’d rather get the slightly bigger rims instead.

torn. The mini bike would be cool but the 26” is surely going to ride better


Do I really need a torque arm if my dropouts are horizontal? Maybe could even shim it to be tight.

Balmorhea   10 kW

10 kW
Posts: 546
Joined: Oct 01 2019 8:30pm

Re: singlespeed rear hub motor for 120mm spacing?

Post by Balmorhea » Nov 24 2019 6:23pm

Hummina Shadeeba wrote:
Nov 24 2019 11:02am
Yea I know there’s longer reach brakes but one of many things. Schwinn 20” size rims being smaller I wonder if a problem for the hub and I’d rather get the slightly bigger rims instead.
Any Schwinn-specific rim sizes were gone for good by 1982 at the latest. There are only two 20" bicycle wheel sizes that are still widely available:

ISO 406 (20" x decimal, by far the most common, and most likely what you have)

ISO 451 (20 x 1-3/8" or 1-1/8", only used for little kids' BMX racing bikes, some recumbents, and a few folders)

Do not concern yourself with any other 20" bicycle wheel sizes. Your bike doesn't have them, and you can't buy 20" wheels in other than one of these two aforementioned diameters. Hub motor kit wheels that are available in 20" will only be ISO 406, no exceptions.

The tires on the minivelo will have a number like 32-406 printed on them, which is the tire width in millimeters followed by the ISO rim diameter.
Do I really need a torque arm if my dropouts are horizontal? Maybe could even shim it to be tight.
Dropouts are often made from soft ductile steel, and can easily spread open when pried by a hub motor axle. At a minimum, I would use two tabbed washers with the tabs turned towards the closed end of the slot.

It's not a lot more trouble just to use a torque arm. For a hub with modest torque, a single arm on the solid end of the axle will do. The one on the hollow end is mostly an emergency backup anyway.

Hummina Shadeeba   10 MW

10 MW
Posts: 2012
Joined: Apr 25 2014 10:26pm

Re: singlespeed rear hub motor for 120mm spacing?

Post by Hummina Shadeeba » Nov 24 2019 11:44pm

thanks for the info!

i like the tabbed washers facing inside the dropouts and didnt know what they were about. got me looking for other longer tabbed washers. ARE THERE ANY OUT THERE?

ive been looking to make 451 wheels and I wonder why you say they always do the smaller 406 with motors? I thought there'd be some minimum length the spokes should be and theyd be doing the 451 size. I assume doing the 451 rim with the hub will be fine. fits my nice new brakes then.

any lacing pattern best for the motor? its 36h.

any recommended rivets for mounting the luna wolf battery on the downtube? would do 3 or 4 something steel. good idea or bad?

this bike will get a lot of comments especially after the change. i pushed it out from my house while waiting for cranks (which they forgot) and first person i walked it past, an 85 year old lady, she says nice bike! she cant ride anymore with her hip she said but told me she was 85. pretty awesome ill have to tell some old person to get off their ass and go ride till at least their hip breaks.

Balmorhea   10 kW

10 kW
Posts: 546
Joined: Oct 01 2019 8:30pm

Re: singlespeed rear hub motor for 120mm spacing?

Post by Balmorhea » Nov 25 2019 1:27am

Hummina Shadeeba wrote:
Nov 24 2019 11:44pm
ive been looking to make 451 wheels and I wonder why you say they always do the smaller 406 with motors?
It's a hugely more popular size, with better tire and rim availability and size range. Everything for 406 is cheaper and easier to get than 451.
I assume doing the 451 rim with the hub will be fine.
There's no reason you can't do that. Tires and rims will be fewer to choose from, more expensive, in a much smaller range of widths, and with mostly outdated designs. That's the case for any oddball rim size.

Keep in mind that if you use a rim to suit your skinny tire road bike brakes, you'll be limited to only skinny tires that fit inside the brake. That has an impact on ride quality, tire durability, and tolerance of less-than-smooth surfaces. If you use the common 406 size with longer reach brakes, you can use narrow or wide tires as you like, within the limits of the frame.
any lacing pattern best for the motor? its 36h.
With 20" rims, I have only been able to use radial lacing. The insertion angle to the rim is too extreme otherwise. I've had no trouble with this so far.
any recommended rivets for mounting the luna wolf battery on the downtube? would do 3 or 4 something steel. good idea or bad?
You definitely want steel rivnuts and not aluminum. And you need to stay well away from the ends of the tubes where stresses are higher.

For my own bike, I'd most certainly use clamp-on frame bosses rather than rivnuts, because of the risk of initiating cracks at the drilled holes, or spinning the rivnuts when trying to remove the mounting screws later.

Hummina Shadeeba   10 MW

10 MW
Posts: 2012
Joined: Apr 25 2014 10:26pm

Re: singlespeed rear hub motor for 120mm spacing?

Post by Hummina Shadeeba » Nov 25 2019 11:57am

Thanks again for all ur info.

I’ll do 4 rivets

Any other tabbed washers u could recommend that have longer tabs? The tabbed washers seem like they could be up to the job if longer and with more leverage.

https://www.leedsbikes.com/product/doub ... 0YQAvD_BwE

User avatar
E-HP   100 kW

100 kW
Posts: 1217
Joined: Nov 01 2018 9:20pm

Re: singlespeed rear hub motor for 120mm spacing?

Post by E-HP » Nov 25 2019 1:07pm

Hummina Shadeeba wrote:
Nov 25 2019 11:57am
Any other tabbed washers u could recommend that have longer tabs? The tabbed washers seem like they could be up to the job if longer and with more leverage.
How thick are your dropouts? If it's a steel frame, the tabbed washers probably won't provide much. You could get away without them is my guess.

Based on the Grin simulator, the 6T motor doesn't look like it has a huge amount of torque to deal with.

Hummina Shadeeba   10 MW

10 MW
Posts: 2012
Joined: Apr 25 2014 10:26pm

Re: singlespeed rear hub motor for 120mm spacing?

Post by Hummina Shadeeba » Nov 25 2019 7:30pm

The dropouts are 7mm thick and has windows cut out and also there’s the threaded hole going horizontally. My pics are too big and takes me ages to convert
its here:
https://www.aliexpress.com/item/3303377 ... 4c4djAfbTN

The tabbed washer is 3mm thick. I’d like to get two made 5mm thick. and instead of 5mm long tab do 15. I could cut a sheet and bend it but rather buy it. Why wouldn’t that work? or maybe just use four of these same ones I have?

no place around me wants to bend the frame and I don't want to either.



im going to hopefully find a machinist to grind the axle flats further along to fit this frame.
Last edited by Hummina Shadeeba on Nov 25 2019 8:24pm, edited 1 time in total.

User avatar
E-HP   100 kW

100 kW
Posts: 1217
Joined: Nov 01 2018 9:20pm

Re: singlespeed rear hub motor for 120mm spacing?

Post by E-HP » Nov 25 2019 8:18pm

Hummina Shadeeba wrote:
Nov 25 2019 7:30pm

The tabbed washer is 3mm thick. I’d like to get two made 5mm thick. and instead of 5mm long tab do 15. I could cut a sheet and bend it but rather buy it. Why wouldn’t that work?
I don't own one, but based on posts on ES, the motor doesn't have a much torque off the line (and a poor hill climber), so with 1/4" steel dropouts, I don't see any reason to add washers or torque arms.

Hummina Shadeeba   10 MW

10 MW
Posts: 2012
Joined: Apr 25 2014 10:26pm

Re: singlespeed rear hub motor for 120mm spacing?

Post by Hummina Shadeeba » Nov 25 2019 8:35pm

wow so you think it would be fine without even tabbed washers, just the flats of the axle in the dropout. well it comes with the tabbed washers already and making me think can get away with just those. or weld on a bit longer tab onto an already made washer.

but if this one guy who does machining around isn't going to flatten the axles Im done trying to make this and will move on to the easy to make mountain bike here.

Post Reply