What Motor for Mid Drive diy build

cyclematt

100 µW
Joined
Sep 30, 2022
Messages
7
Complete novice on electric motors but competent in a machine shop.

I’m looking to build a mid drive kit for my bike from scratch but I’m baffled as to which motor to choose from to begin with?!? :|

Anyone able to help? I’m sure there are lots of variables to consider but maybe a list/guide with links of motors available would be a good start for me.

A couple of specifics, I’m looking to power it by a PAS sensor so a brushless motor with hall sensor would be best.

Many thanks
Matt
 
If you have a standard 68-73mm threaded bottom bracket, get a 52V bafang bbshd with 52V battery capable of 50A.

Alternatively you could look at the GNG cyclone 3000 kit, or the CYC x1 stealth / pro.

If you don’t have a standard bottom bracket (eg press fit) it’s a bit harder, maybe choose a different bike.

You need somewhere to mount the battery in the frame or on a rear rack
 
There are several choices if your frame has a standard bottom bracket. However your expectations, location and mechanical abilities will govern which mid-drive kit is the best match for situation. We need more information.
 
cyclematt said:
I’m looking to build a mid drive kit for my bike from scratch but I’m baffled as to which motor to choose from to begin with?!? :|

Anyone able to help? I’m sure there are lots of variables to consider but maybe a list/guide with links of motors available would be a good start for me.

There isn't a list; as there are probably at least tens of thousands of motors you could use for this (likely many more) depending on your specific limitations, including size, shape (where it will go), torque, power, RPM, shaft type (if even using a shaft), motor type (brushless, brushed, which class of brushless (many types available), quality expectations, budget, etc.

Best recommendation for your stated intent is to read thru the many DIY middrive threads here on ES to see what others have already done, and what worked, what didn't, and what kind of power was needed to accomplish various different goals. Many of them are in this subforum
https://endless-sphere.com/forums/viewforum.php?f=28
but some exist in the "build thread" and "technical" and "motor technology" forums as well as others scattered about elsewhere.

As an example, my early CrazyBike2 version used a DIY middrive, there are some details in that thread and on my old electricle.blogspot.com pages.

You can also go to http://ebikes.ca/tools/simulator.html and use it in middrive mode to play with some of the preset motors/controllers/etc or custom-setup your own, under your specific expected riding conditions and usage, to see what level of power it may take in various gear ratios to do what you need it to. Knowing that will probably eliminate some potential motors.



cyclematt said:
A couple of specifics, I’m looking to power it by a PAS sensor so a brushless motor with hall sensor would be best.

A couple of notes:

PAS sensors don't power the motor. They only detect pedalling (Pedal Assist Sensor). A controller is used to "power" the motor (converting the battery power to whatever the motor needs to spin it), and a PAS sensor (of which there are numerous kinds) is one method of detecting your input to command the system to do something.

Which sensor you use to do that with is irrelevant to the motor type you use. The motor type is determined by the job you need the motor to do, and the controller you need to drive it with.

This page
https://ebikes.ca/getting-started/pas-options.html
may help you begin learning about some of the various PAS sensor options; it discusses the various commercially-available ones. DIY sensors of other types can also be made.

The same site also has pages on other things in the Learn section that may be useful.

This site (Endless-sphere) also has a number of Sticky Index threads that link many other useful learning threads; these are at the top of each subforum to hold the topics relevant to that subforum.
 
electric_nz said:
If you have a standard 68-73mm threaded bottom bracket, get a 52V bafang bbshd with 52V battery capable of 50A.

Alternatively you could look at the GNG cyclone 3000 kit, or the CYC x1 stealth / pro.

If you don’t have a standard bottom bracket (eg press fit) it’s a bit harder, maybe choose a different bike.

You need somewhere to mount the battery in the frame or on a rear rack

Thanks for the info, I have looked into the Bafang motor kits, the trouble I face with them is the ISCG05 mount that’s welded onto the frame, I can’t bring myself to chop it off my fame :shock:

Also I’m not sure if there would be interference to the rear swing arm.

The bike is a Whyte G160RS with a 32 tooth front ring and 12 speed rear, maybe an excentric bottom bracket insert would give it enough clearance?

Thanks again
 

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How much power are you looking for?
100-300W assist...
500-1500W no pedaling...
2000-8000W light motorcycle...
1.21GW time travel...
 
cyclematt said:
... I have looked into the Bafang motor kits, the trouble I face with them is the ISCG05 mount that’s welded onto the frame, I can’t bring myself to chop it off my fame :shock:

Also I’m not sure if there would be interference to the rear swing arm.

The bike is a Whyte G160RS with a 32 tooth front ring and 12 speed rear, maybe an excentric bottom bracket insert would give it enough clearance?

Thanks again
That is a question that you are probably going to have to answer yourself (unless you find someone that has already tried it). However I will point you to my detail drawing of the Bafang BBS02:
https://endless-sphere.com/forums/viewtopic.php?f=2&t=117026
 
A-DamW said:
How much power are you looking for?
100-300W assist...
500-1500W no pedaling...
2000-8000W light motorcycle...
1.21GW time travel...

I’m looking for around 80-100nm of torque, 36 or 48v 500w power with pedal assist. Nothing crazy just something to give me a helping hand up some hills so I can blast down them again.

Definitely not time travel 🤣
 
This thread might be exactly what you are looking for:
https://endless-sphere.com/forums/viewtopic.php?f=6&t=96769

I really enjoyed seeing this approach.

Now someone's probably going to laugh at me, I actually run a cyclone 3K at about 200 to 400 watts for assist, the reason for this is I don't have a freewheel on my bicycle cranks chain ring, only a Freewheel on the Cyclone motor, that way if I accidentally hit the throttle at a standstill or otherwise, doesn't rip my legs to shreds at 3000w.
Flipsky 4.20 vesc runs 3C. above ambient temp on 38C. day(100F) in an enclosed box!
 
cyclematt said:
Thanks for the info, I have looked into the Bafang motor kits, the trouble I face with them is the ISCG05 mount that’s welded onto the frame, I can’t bring myself to chop it off my fame :shock:
May I assume that this means you do not actually want to
build a mid drive kit for my bike from scratch
as originally posted, and are just looking for a prebuilt kit to install on it?

If so, that simplifies the problem enormously, and reduces the questions that need answers to only a few.
 
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