LWB recumbent mid-drive motor choice

[Deleted member 4366]

There are a few clones of these motors that BMSB sell as the Q-series. I put a link somewhere to the actual factory that they use. I think Aikema is the OEM on which they're based:

http://www.aikema.com.cn/En_product.asp

 

[bambuko]

...seeing that you have made up your mind...

not quite
The only things fixed in my mind are:
1 - desire to have full range of gears for both myself and the motor
2 - as lightweight power assist as possible (for 90% of the time when I do not need to use it, it is dead weight)
3 - as minimal power/torque as possible, to minimise the loads on the derailleurs etc

This is the reason I want power assist:

Pushing the bike up this hill is not fun

There are two ways of handling problem like this:
1 brute force
2 clever gearing to utilise what little power that is available

I am trying for the second one

 

[bambuko]

...My understanding is that it still packs a fair punch because it runs at higher speed than a Q100 and uses a higher reduction ratio...

Yes, as far as I know Q75 has 1:13.4 ratio as compared to 1:8 for other motors

...Keyde also uses high speed and high reduction, and it has ample torque for normal riding, although it soon heats up when hill-climbing to the point that the thermal control cuts down its power...

That, I am assuming in "normal" hub direct drive mode?
Should be less of a problem with motor driving the wheel through the full range of gears...

...Q100H is not much heavier at 2.3kg...

Motor is only part of the total weight.
I am hoping that using smaller (but still powerful enough) motor I can also get away with smaller battery pack...

...The weight saving of the Q75 is only an advantage if you're using it as a wheel hub motor or if you have a really light bike...

and it is a lot easier to loose some of this weight from the big tab of lard sitting on a bike as well (I know)

 

[bambuko]

...I think Aikema is the OEM on which they're based...

They seem to have a lot more versions listed as well.
For example Q85 is (supposedly) available with disc brake version, which would make fitting of the sprocket easier (not available on either Q75 or Q85 from BMS).

The other question, still on my mind about these motors - is whether they can be converted as described here

 

[Cyclezee]

The Ezee kit is for 100mm dropout, also difficult to add a freewheel.

The eZee front hub motor is for 100 mm dropouts, but there is also a rear eZee motor for 135 mm dropouts, some members of the forum have these, Jackhandy and Falmouthtony to name but two.

There are now two version of the rear motor, inaddition to the 'screw on freewheel type', there is a CST type as shown below.

eZee Forza Mk2 with RWD​

 

[bambuko]

Yes, for someone with limited machining capabilities, using rear hub motor with either screw on freewheel type or cassette is indeed the easiest option.
For someone with a lathe and milling machine etc, adding sprocket to the front hub should be a simple matter (providing there is enough meat on the motor body to the job).
One good idea for example is to use disc brake mounting for a sprocket adapter (providing the motor has this option).

 

[trex]

are you sure that the 6 threads on the Q85 lid for the brake rotor are man enough to hold the sprocket?

 

[bambuko]

Given that we know max torque available it should not be too difficult to calculate.
Nothing stopping you from adding more or using bigger bolts.
There might be a problem if there is not enough metal (difficult to judge just from the photo) in the "lid".

 

[shemozzle999]

Hi bambuko,

I know you are looking for a mid drive setup but are you aware of the new 2 speed hub motors:

http://xiongdamotor.en.alibaba.com/product/1557178214-220560510/New_Invention_2_speed_Ebike_Motor_Amazing_Torque.html

You can have a multi chainwheel with this arrangement and a far simpler build.

 

[bambuko]

Yes, I know of such things and yes I know there are simpler ways than what I am doing
I have e-bike with rear hub motor. My wife quite likes it.
I tried it ... once

 

[shemozzle999]

Would that have been a dual speed one?

Have you seen this mid motor it would need custom mounting to connect up to you existing BB but might fit some of your requirements?

http://szxfmotor.en.alibaba.com/product/572523871-213635401/light_180W_Patented_Middle_Motor.html

 

[bambuko]

... Would that have been a dual speed one?...

No. I guess dual speed one would be a lot better than what we have
(but nowhere near as good as my 24 speed ... if I manage to get it sorted out)

...Have you seen this mid motor it would need custom mounting to connect up to you existing BB but might fit some of your requirements?...

No, I haven't seen this one. Very interesting, and as you say might be just the job.
It looks to me like hub motor converted to inrunner with an addition of freewheel inside.
Will try to find more about it - thank you!
Although with MOQ of 10 that's about $2k to try it ...

 

[Deleted member 4366]

Have a look at GNG. They have all sorts of mid-drive kits.

http://www.gngebike.com/36v350w-48v500w-2015-gen-2

 

[shemozzle999]

Hi bambuko,

They may consider sending a sample, you can try asking that as an opening question.

I believe some of the site trade sponsors and members may have had dealings with this Company and might be able to furnish you with a contact name maybe even a product catalog.

I find making an initial polite email to the supplier usually is enough to start a dialog where you can then slowly step by step make simple requests for further information bearing in mind the language communication problems.

A lot of the information given out on this site has been off the back of members developing a relationship over time with these types of overseas suppliers so if you have to contact them please do not do anything which might effect that.

 

[Deleted member 4366]

Xofo only deal with the trade. It's difficult to get single items out of them.

 

[bambuko]

These couple of days discussion cleared a lot of things in my mind and helped me a lot (even though some were determined to lead me astray )

I have decided to go with Q85 24V 201 rpm and adapt/convert it to my needs.
I know what I want to do, just need to get my hands on one of these cuties

Thank you all!

p.s.
if anybody got any trashed Q85 or remnants of, give me a shout please - I would much rather test my ideas on some old junk, rather than my brand new and expensive acquisition from PRC