Using an mxus XF08 hub motor as a mid motor on a trike.

[Presterjohn]

Hi, I want to use an mxus xf08 250watt hub motor as a mid motor on my trike project. The problem is how can i set the speed limit to 25kph? Normally this is done on the display after entering the wheel diameter. As a mid motor there is no wheel but to comply with UK regs I want to set the speed limit using a sensor on the back wheel. Please could anyone give me a diagram of how to connect it? I am using a PSW power kit that came with the wheel, controller and wiring. Thank you.

 

[glennb]

The primary purpose of mid-drive (vs hub drive) in this application would be to achieve additional gear reduction? So, gear it all the way down, so it tops out at 25km/h in your largest gear, no? Gives you the best launch and climbing capabilities configured thusly.

Otherwise, yes, wheel diameter is the obvious way to restrict speed. Is the diameter setting in your system confined to a range? You can't enter any number you like?

 

[Presterjohn]

Thanks, that idea just ocurred to me too. The snag is that to get to 25kph I would need to be in top gear. The great advantage is that I could gear it down by about 2.5 to one using a countershaft so get a real gain in acceleration.

 

[E-HP]

Looking at the kit online, it uses a KT controller. Depending on the display, you should be able to set max trip speed, after setting up the wheel diameter, etc. 25kph is the default setting I believe, if you bought the 250W version of the kit. Can you post a pic of the controller label?

 

[Presterjohn]

I can set the wheel diameter to a range from 6 inch to 28 inch on the display. So that bit is easy. Sorry , I can't get at the controller because it's inside the plastic housing. The trike goes ok at the moment, it's the hill climbing that isn't up to much. It's the standard KT controller you get with the PSW power back wheel kit.

 

[Presterjohn]

I guess what I am really asking is, can I get at the wire from the motor that controls the speed by cutting into the cable and connect it to a speed sensor on the back wheel?

 

[dgc]

Presterjohn, hi there, I am confused, but if you have a normal pedal / chain wheel setup then behind it mount the MXUS rear hub motor complete with it's gear set be it say 7,8,9 speed etc, then you need a 1 to 1 ratio between the "mid" hub motor and the rear wheels then you just setup the wheel size as normal, I have used the MXUS rear hub motors and they normally have the speed sensor built in. May totally got the wrong idea, anyway, the connector on the motor cable contains the speed sensor wire which I assume is the circular waterproof version which marries to a mating connector on the controller motor cable. The MXUS XF08 250watt hub motor may not have enough power for a trike unless it is lightweight whereas a TSDZ2B mid-drive for example could make use of the rear gears for hill climbing, as per the other replies you have had. A picture would help of what you have, KT controllers are easy to setup with a KT Display.
Not sure what you have brought a rear wheel kit, or individual parts, but a TSDZ2B mid-drive is currently about £190 not sure if tax is thrown on that or not. I do still have MTB with a MXUS rear hub drive but prefer the MTB's I have with mid-drives.

 

[dgc]

There a number of YouTube videos showing a recumbent trike fitted with TSDZ2(B) mid-drives.

 

[amberwolf]

I guess what I am really asking is, can I get at the wire from the motor that controls the speed by cutting into the cable and connect it to a speed sensor on the back wheel?

If it is a geared hubmotor then the speed sensor would be a separat wire from the motor halls. It is commonly, but not always, a white wire. That plus a new wire to ground, would run to your wheel speed sensor, if it's the common two-wire type. If it's a three wire type, you'll need a 5v supply wire to it as well.

If it's a non-geared hubmotor (DD) then it won't normally have a separate speed sensor, so there is no wire you can use--the ones that are there are for the motor position halls and you can't disconnect those unless you want to run the motor sensorless, which can cause various issues.

 

[Presterjohn]

Thank you for the helpful replies. This is my trike

 

[Presterjohn]

I can't use a Tongshen mid drive motor for two reasons. 1/ I need 150mm cranks, I tried 170mm and they are just too long for me. 2/ I needed a 24T chainwheel to be able to get it moving. I've got a mid drive shaft to split the chain length. I used and old Sturmey Archer 3 speed as a mid shaft and fitted an extra sprocket on the spoke holes which takes the chain to the rear wheel. So I have an extra gear lever with 3 extra ratios. I'm making it with a vintage vibe as you can see. I intend to put a Morgan 3 wheeler type body on it.

 

[E-HP]

I guess what I am really asking is, can I get at the wire from the motor that controls the speed by cutting into the cable and connect it to a speed sensor on the back wheel?

If. You’re asking whether you can connect the white wire from the KT hall sensor connector, that is the speed signal input for the KT, and connect it to an external speed sensor instead of the motor, then yes.

 

[Presterjohn]

That's great, thanks.

 

[dgc]

Looks great, that hub motor as before should have the speed sensor built in, it looks like you have the waterproof connector from the photo for the motor, so checking the motor spec it has quote a "Speed Detection Signal(Pulses/Cycle) 1". Can you send a photo of the other side of the trike. Another question I assume the 9 way motor connector doe's have all the pins / sockets present as I have seen some 9 ways connectors with a missing small pin / socket for the speed sensor.

 

[dgc]

For future projects, Bucklos do 152mm, 170mm and 175mm repair crank arms, a pair is about £8.00 on Aliexpress, knew I had seen them, not sure what the offset is but normally used for e-bikes.
I like the idea of a Morgan 3 wheeler type body on it, my father when I was a kid had a Morgan 3 wheeler with a V twin air cooler Jap engine in the front think it was 1000cc.

 

[Presterjohn]

Hi, thanks , I'll keep that in mind. My son does 3D printing so I'm trying to get him to print me a V twin JAP engine to go on the front. My connector does have all 9 pins connected. I was out again on it today and am getting the idea of using the gears to give an extra push on the hill. I haven't ever ridden an Ebike let alone a trike so I am just getting used to it. I'd love a real Morgan V twin 3 wheeler but it's mega money for one today.

 

[dgc]

Not another one, I have 3D printed battery covers / housings, housings for controllers and shields for TSDZ2(B)'s. Yep £40,000 for a 2L V twin Morgan 3, Ouch.