Rear hub and sprocket question ;)

Discussions related to motors other than hub motors.
This includes R/C motors, botttom bracket, roller and geared drives.
Post Reply
rg12   1 MW

1 MW
Posts: 1561
Joined: Jul 26 2014 4:22pm

Rear hub and sprocket question ;)

Post by rg12 » Jan 22 2022 10:24am

I want to order this motor: https://www.aliexpress.com/item/3305674 ... mainSearch

for my new e-downhill build.

Some questions as an expert on anything electric BUT mid drive systems :lol:
I have a thruaxle dropout, so which hub do I need that can fit which sprocket type?
I want the largest sprocket I can get (am a torque guy :wink: ) and hopefully it exists (hub and sprocket that fit on a thruaxle) on aliexpress so I don't bother with spending on shipping and running to different websites.

also, the qs motor in the link comes with a 14T motor sprocket and I need it to fit the rear sprocket (pitch, width etc) and to match a chain to it.
* Will a bicycle half chain work or does it have to be like a light motorcycle chain?

calab   100 kW

100 kW
Posts: 1209
Joined: Dec 11 2013 1:00am

Re: Rear hub and sprocket question ;)

Post by calab » Jan 22 2022 11:41pm

I see that mid drive motor comes in 428 Sprocket or belt, thats a problem. You want that because the price is low? You will have to adapt the 428 to the wheel in some manner like what the gasoline bicycle motor guys do which is bolt it to the spokes. Look for another mid drive motor that uses bicycle gears.

This one looks like the same wide teeth https://www.qsmotor.com/product/2000w-mid-drive-motor/

These ones use bicycle sprockets that slide on with a key and pinch bolt and come in various tooth counts
https://www.cyclone-tw.com/product/1

DingusMcGee   10 kW

10 kW
Posts: 710
Joined: Feb 23 2015 7:11am

Re: Rear hub and sprocket question ;)

Post by DingusMcGee » Jan 23 2022 7:45am

Type #428 and #420 sprockets are the same pitch as 1 speed bike chain and sprockets which is 0.5" between the pins. But yes, #428 cogs at 3/8" wide are too wide for #410 bike chain at 1/8" wide. Simply grind down the sides of these #428 motor sprockets until #410 bike chain fits. You will have to taper the tips of the teeth also by grinding. Other narrower size bike chains?? Likely same pitch but very narrow teeth.

Do not grind down the central core (hub) of these motor sprockets as they will then not be as stable on the motor shaft as the original full size sprocket was on the motor shaft nor will the ground at the hub result in a tight fit unless washer-ed up?

See setup I used:

viewtopic.php?f=28&t=113974#p1686059

rg12   1 MW

1 MW
Posts: 1561
Joined: Jul 26 2014 4:22pm

Re: Rear hub and sprocket question ;)

Post by rg12 » Jan 23 2022 11:59am

Umm why do you guys talk like it isn't possible to replace the motor sprocket?

and why not keep it as is and buy a chain and a rear sprocket that fits it?

any idea about a hub that will hold the sprocket and a disc on the other side? it's a 12mm thruaxle hub

DingusMcGee   10 kW

10 kW
Posts: 710
Joined: Feb 23 2015 7:11am

Re: Rear hub and sprocket question ;)

Post by DingusMcGee » Jan 23 2022 12:43pm

...able to replace the motor sprocket?

Good luck. Search the internet for what you want. Cannot find it, then make it or have some one make it for you.

#428 chain will work and so will #520 but these sizes are a quite big.

Hubs? See White Industries Enos.

rg12   1 MW

1 MW
Posts: 1561
Joined: Jul 26 2014 4:22pm

Re: Rear hub and sprocket question ;)

Post by rg12 » Jan 23 2022 1:57pm

DingusMcGee wrote:
Jan 23 2022 12:43pm
...able to replace the motor sprocket?

Good luck. Search the internet for what you want. Cannot find it, then make it or have some one make it for you.

#428 chain will work and so will #520 but these sizes are a quite big.

Hubs? See White Industries Enos.
So let's start from the back, which rear sprocket can fit a bicycle hub with a pitch that fits a regular single speed/bmx half link chain?

DingusMcGee   10 kW

10 kW
Posts: 710
Joined: Feb 23 2015 7:11am

Re: Rear hub and sprocket question ;)

Post by DingusMcGee » Jan 23 2022 7:36pm

See sticky thread about chains & sprockets.

viewtopic.php?f=28&t=46630

Post Reply