PaulD's lightweight mid drive development

Discussions related to motors other than hub motors.
This includes R/C motors, botttom bracket, roller and geared drives.
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PaulD   100 W

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Re: PaulD's lightweight mid drive development

Post by PaulD » Sep 02 2019 1:05pm

neptronix wrote:
Aug 27 2019 7:07pm
If you still need another tester, i have a pair of recumbents here, as well as some long 1-30% grades to scale.
I'll send you a PM, Neptronix.

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Re: PaulD's lightweight mid drive development

Post by Grantmac » Sep 02 2019 2:49pm

Going to have a crank option for us heavy aggressive types? PF30 capable?

450w peak or sustained?

Any clips showing noise?

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Re: PaulD's lightweight mid drive development

Post by PaulD » Sep 02 2019 3:10pm

Grantmac wrote:
Sep 02 2019 2:49pm
Going to have a crank option for us heavy aggressive types? PF30 capable?

450w peak or sustained?

Any clips showing noise?
I am working on system that mounts like a direct mount chainring, allowing other cranks/BB, but it's early in development. You can use a PF30 to threaded adapter to fit the kit now.
The 450W is peak, but it can put out that power for quite a while depending on conditions. Thermal limiting prevents overheating.
I don't have any video yet, but I'll try to get one this week.

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Re: PaulD's lightweight mid drive development

Post by Grantmac » Sep 02 2019 4:47pm

Mainly wondering how it would compare to thesee "250w" factory bikes that peak above 1kw and put out +100nm.
Sounds like it won't have the same kind of power.

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Re: PaulD's lightweight mid drive development

Post by PaulD » Sep 02 2019 5:30pm

Grantmac wrote:
Sep 02 2019 4:47pm
Mainly wondering how it would compare to thesee "250w" factory bikes that peak above 1kw and put out +100nm.
Sounds like it won't have the same kind of power.
Which mid-drives are you referring to? Bosch and Shimano are around 70Nm.
https://www.bosch-ebike.com/us/products/drive-units/
I'm not trying to compete with bikes like the Flyon if that's what you are referencing.
I wanted to create something similar to Bosch and Steps in performance, but allow much lighter builds... And without having to layout $4k+ for a complete new bike, instead utilizing a bike you already own.
Also, I wanted to minimize battery weight, trying to keep things light and efficient. Not much point in having 1000W on tap if you have a 4lb battery. But, to each his own.

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Re: PaulD's lightweight mid drive development

Post by Grantmac » Sep 02 2019 6:30pm

Was thinking of the m600 actually, but a little surprised the Bosch puts out so little. I thought they were closer to on par.

Does your motor operate efficiently at a low cadence or is it more of a spinner?

The versatility of being able to relatively quickly add or remove the system for non-powered cycling isn't lost on me.

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Re: PaulD's lightweight mid drive development

Post by PaulD » Sep 02 2019 10:58pm

I chose the middle ground for optimum cadence. Early prototypes favored lower pedal speeds, but some beta testers wanted more power at 70-80 RPM, so I decreased the final gear ratio a bit. Savvy users can adjust the gear ratio by changing out the sprockets. The #25 front final drive sprocket is a stock part from andymark.com with 1/2" hex bore. Vex Robotics sells something compatible as well.
The drive isn't really meant to be removed quickly. With the freewheel on the motor side, there isn't really any resistance, just the 4 or so pounds of motor, controller and mounting plates.

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Re: PaulD's lightweight mid drive development

Post by 2old » Sep 13 2019 1:26am

Installation of the kit was easy since I had the instruction manual (on Revel's site) and nine utube videos for guidance. The donor bike, a Kona Honzo, weighed slightly less than 36 pounds with motor/battery and ancillary components. The motor nestled nicely along the down tube unlike other DIY mid-drives that hang down like a cow's udder. Power seems similar to Yamaha and Bosch that I've ridden or owned. The bike handles extremely well with the low-centered weight addition and pedals easily with the motor turned off. I'll be riding it frequently, and provide additional information if there is anything to report.

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Re: PaulD's lightweight mid drive development

Post by Mahe » Sep 13 2019 12:31pm

Hi Paul, and everyone,
PaulD wrote:
Sep 02 2019 10:58pm
Savvy users can adjust the gear ratio by changing out the sprockets. The #25 front final drive sprocket is a stock part from andymark.com with 1/2" hex bore. Vex Robotics sells something compatible as well.
Could such an adjustment help to use the motor with a higher battery tension?

As I mentioned to you privately, I need a very large battery capacity for serious bike travel (in the sense of long distance, mountains), and sadly it seems that there is not much offer in 36V (talking about > 1000Wh, ideally 1500Wh). I thought about having many of these tiny 378Wh in parallel (like 4 of them) but the cost would become prohibitive (I suppose the overhead of having high quality individual packaging). And I'm not sure how much is healthy for the charge balancing + more amps needed for charging at constant time. A good alternative option I found is the large 14S9P triangle pack from em3ev, but it is 52V...

I understand 52V would work with your motor, by reprogramming the controller, but with sub-optimal efficiency. Am I correct to assume that the motor would then spin 14/10 times faster unloaded? What kind of efficiency loss are we talking about, at constant speed and load? (assuming it is easy to adjust amp delivery by 10/14)

Alternatively, one would need a smaller sprocket by a factor 10/14, is that right? (~13T instead of stock 18T, but I see only 16T on andymark for #25 chain) Or 14/10 larger chain ring? (66T ... 92T? but that would be quite big...)

Any other solution?

Or do you plan to provide a 48V/52V version at some point?

Thanks

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Re: PaulD's lightweight mid drive development

Post by PaulD » Sep 13 2019 10:21pm

Mahe wrote:
Sep 13 2019 12:31pm
I understand 52V would work with your motor, by reprogramming the controller, but with sub-optimal efficiency. Am I correct to assume that the motor would then spin 14/10 times faster unloaded? What kind of efficiency loss are we talking about, at constant speed and load? (assuming it is easy to adjust amp delivery by 10/14)

Alternatively, one would need a smaller sprocket by a factor 10/14, is that right? (~13T instead of stock 18T, but I see only 16T on andymark for #25 chain) Or 14/10 larger chain ring? (66T ... 92T? but that would be quite big...)

Or do you plan to provide a 48V/52V version at some point?
Thanks
Hi Mahe, yes, I understand there aren't many options for high capacity 36V packs.
Yes, the motor would spin 1.4X faster, unloaded. The problem with adjusting the gearing by 1.4X is that the top speed of the motor would be too high. I haven't done any testing at high voltages, and with 1000's of miles on test bikes with the present configuration, I don't really want to offer a change that could affect reliability.
For now, the only solution I can offer is multiple battery packs.

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Re: PaulD's lightweight mid drive development

Post by Mahe » Sep 14 2019 7:00am

PaulD wrote:
Sep 13 2019 10:21pm
The problem with adjusting the gearing by 1.4X is that the top speed of the motor would be too high.
Do you mean with respect to heating and wearing down of internal pieces? Makes sense. 40% is significant. So there is no safe workaround to internal rewiring.
PaulD wrote:
Sep 13 2019 10:21pm
I haven't done any testing at high voltages, and with 1000's of miles on test bikes with the present configuration, I don't really want to offer a change that could affect reliability.
For now, the only solution I can offer is multiple battery packs.
I understand. Perfectly sensible at this stage. Thank you for your prompt reply.

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Re: PaulD's lightweight mid drive development

Post by PaulD » Oct 03 2019 6:04pm

Mahe wrote:
Sep 14 2019 7:00am
PaulD wrote:
Sep 13 2019 10:21pm
The problem with adjusting the gearing by 1.4X is that the top speed of the motor would be too high.
Do you mean with respect to heating and wearing down of internal pieces? Makes sense. 40% is significant. So there is no safe workaround to internal rewiring.
Efficiency, heating and wear, and risk of the magnets coming loose are the main concerns.

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Re: PaulD's lightweight mid drive development

Post by jvm37 » Nov 05 2019 5:04pm

Paul I have sent you a couple of emails
I am interested in buying one of your kits
Please take a look

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Re: PaulD's lightweight mid drive development

Post by PaulD » Nov 05 2019 5:22pm

jvm37 wrote:
Nov 05 2019 5:04pm
Paul I have sent you a couple of emails
I am interested in buying one of your kits
Please take a look
I just checked my spam, and I'm not seeing your messages. Which email address did you send them to? Maybe the web contact form is broken. I'll test it out.

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Re: PaulD's lightweight mid drive development

Post by jvm37 » Nov 05 2019 5:34pm


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Re: PaulD's lightweight mid drive development

Post by sn0wchyld » Nov 05 2019 7:11pm

you may want to obscure that email address (ie abc at def ... com) else you'll end up with a bucket load of spam.

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Re: PaulD's lightweight mid drive development

Post by Joost5000 » Jan 03 2020 12:57pm

Any update on the production run of the mid drives. Also, I’d love to hear about any of the “v2” tweaks.

-Dave

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Re: PaulD's lightweight mid drive development

Post by PaulD » Jan 07 2020 3:12pm

Joost5000 wrote:
Jan 03 2020 12:57pm
Any update on the production run of the mid drives. Also, I’d love to hear about any of the “v2” tweaks.

-Dave
Hi Dave, I'm aiming for the end of February. There are a lot of changes coming, so I hope it will be worth the wait. Here is the tentative list of updates:
  • Power Increase - We have been testing at much higher power levels with good results. Final max power is TBD.
  • Throttle option - Users will be able to decide if they want a throttle or the 6V headlight connector
  • "Quick" release motor plates - This will allow removal of the motor/controller assembly with 4 screws
  • Improved cadence sensor reliability
  • Cleaner cables and overmolded connectors - no more nylon braid sleeve!
  • A few others that I'm not sure will make the final cut

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Re: PaulD's lightweight mid drive development

Post by Nightdiver13 » Jan 07 2020 4:25pm

PaulD wrote:
Jan 07 2020 3:12pm

Hi Dave, I'm aiming for the end of February. There are a lot of changes coming, so I hope it will be worth the wait. Here is the tentative list of updates:
  • Power Increase - We have been testing at much higher power levels with good results. Final max power is TBD.
  • Throttle option - Users will be able to decide if they want a throttle or the 6V headlight connector
  • "Quick" release motor plates - This will allow removal of the motor/controller assembly with 4 screws
  • Improved cadence sensor reliability
  • Cleaner cables and overmolded connectors - no more nylon braid sleeve!
  • A few others that I'm not sure will make the final cut
Any chance that this more powerful version will work with 48v or higher batteries?

I might have missed this somewhere, but what is the current chainline and is it achieved with any sort of special offset chainring?

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Re: PaulD's lightweight mid drive development

Post by PaulD » Jan 07 2020 5:54pm

Nightdiver13 wrote:
Jan 07 2020 4:25pm

Any chance that this more powerful version will work with 48v or higher batteries?

I might have missed this somewhere, but what is the current chainline and is it achieved with any sort of special offset chainring?
There have been quite a few requests for 48V. What is the reason you want to use 48V? Some people have 48V batteries sitting around, that's understandable. If you just want more range, there are some larger 36V packs available from Grin.. EM3EV has some too. At under 800W or so, I don't really see an advantage to higher voltages.

The chainline for a 68mm BB shell is 49.7mm., 52mm for 73mm BB shell. This is adjustable +/- 2mm with spacers to accomodate different chainring sizes and frame clearance and for Boost spacing. The kit comes stock with a standard narrow-wide 104mm BCD chainring.

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Re: PaulD's lightweight mid drive development

Post by Joost5000 » Jan 07 2020 6:39pm

PaulD wrote:
Jan 07 2020 3:12pm
Joost5000 wrote:
Jan 03 2020 12:57pm
Any update on the production run of the mid drives. Also, I’d love to hear about any of the “v2” tweaks.

-Dave
Hi Dave, I'm aiming for the end of February. There are a lot of changes coming, so I hope it will be worth the wait. Here is the tentative list of updates:
  • Power Increase - We have been testing at much higher power levels with good results. Final max power is TBD.
  • Throttle option - Users will be able to decide if they want a throttle or the 6V headlight connector
  • "Quick" release motor plates - This will allow removal of the motor/controller assembly with 4 screws
  • Improved cadence sensor reliability
  • Cleaner cables and overmolded connectors - no more nylon braid sleeve!
  • A few others that I'm not sure will make the final cut
Hey Paul!
Thanks for the update! I was hoping the throttle made the cut. I mainly run pas, but it’s nice to have when trail riding to get over an obstacle/hill. The other stuff is nice to have.

I’ve been there and back with the high torque high power systems. I don’t want to bike around with 15-20lbs of battery. Not to mention the stress on the drive train. To each his own.

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Re: PaulD's lightweight mid drive development

Post by Nightdiver13 » Jan 07 2020 7:26pm

PaulD wrote:
Jan 07 2020 5:54pm
There have been quite a few requests for 48V. What is the reason you want to use 48V? Some people have 48V batteries sitting around, that's understandable. If you just want more range, there are some larger 36V packs available from Grin.. EM3EV has some too. At under 800W or so, I don't really see an advantage to higher voltages.

The chainline for a 68mm BB shell is 49.7mm., 52mm for 73mm BB shell. This is adjustable +/- 2mm with spacers to accomodate different chainring sizes and frame clearance and for Boost spacing. The kit comes stock with a standard narrow-wide 104mm BCD chainring.
Thanks for the info. Regarding the voltage, the reason I asked was just thinking about opening up more options for third-party batteries, both in terms of capacity, but also form factor and build style. There's just more variety available in higher voltages it seems.

I'm thinking about this from the standpoint of my own usage scenario which would be best served by 1000+ Wh in a rectangular form factor for discretely tucking under my cargo deck. But you could also consider it from the angle of making a system that is targeting the DIY crowd as flexible as possible.

Of course there could be a laundry list of reasons why going over 36V doesn't make sense from your end of things, and that's completely understandable. Regardless, really looking forward to see your future developments!

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Re: PaulD's lightweight mid drive development

Post by Grantmac » Jan 07 2020 10:45pm

Still running the BAC500? What sort of torque figures?

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Re: PaulD's lightweight mid drive development

Post by Nobreaks » Feb 13 2020 6:17am

Hi Paul .
Great work!
Very interested in buying a Midrive kit as well
Is Australia to far for u to freight once you have stock to sell

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Re: PaulD's lightweight mid drive development

Post by PaulD » Feb 17 2020 12:38am

Grantmac wrote:
Jan 07 2020 10:45pm
Still running the BAC500? What sort of torque figures?
Yup, BAC500, aiming for 75 Nm.

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