Morning all,
Following much hunting around for what I want, I have concluded I need to build my own. I'm an engineer with experience in design, R&D and motorsport and have my full company workshop at my disposal including 3D scanning, CAD, rapid prototyping, profile cutting etc. So, I'm in a good place to develop something.
That said, I don't just want to develop something for me, I'd like to make it more of an open source group project and develop something any of us could put together with minimal and simple assistance.
My spec is to make a simple, fairly light, mid-drive assistance system which can be easily attached/detached.
I'd like to to preferably leave the original bike pretty untouched, save for maybe the chainring, so high-strength components don't have to be replaced with lower spec ones (such as square taper BB's, hubs etc).
I’m going to start off with a simple thumb throttle for testing, until I’ve got the drive setup sorted.
My plan is to then move to a torque and cadence sensed arrangement, to hopefully make the unit totally self contained and to also give the widest range of control options.
I should add that I'm (sort of) UK based, so I'd like it to have 'road legal' capability and I'm not chasing massive power figures. I envisage it as an assistance system, rather than something to save you pedalling at all.
So far, my theoretical spec list is as follows...
RC motor as the prime mover:
https://hobbyking.com/en_us/turnigy-sk8-6374-149kv-sensored-brushless-motor-14p.html?queryID=3a6165b0623055eb7629c4d7afed99ad&objectID=74469&indexName=hbk_live_products_analytics&___store=en_us
Simple VESC to power it:
https://hobbyking.com/en_us/turnigy-sk8-v2-80a-3-12s-single-motor-skateboard-esc.html?queryID=1f66f46c97b42d7b1a35c3a59ca64e5d&objectID=83138&indexName=hbk_live_products_analytics
NEMA 24 based planetary reduction drive, which will be linked via off-the-shelf gears or a belt drive for simplicity (something along these lines, there's all sorts available, recommendations of an affordable and readily available version welcome!):
https://www.ebay.co.uk/itm/203660888117?hash=item2f6b228835
Simple, compact and easily available battery:
https://hobbyking.com/en_us/turnigy-high-capacity-battery-20000mah-6s-12c-drone-lipo-pack-xt90.html?queryID=e4d73d973c9332952aba7c5ce6e53f96&objectID=78412&indexName=hbk_live_products_analytics
CA3 Cycle Analyst to bring it all together and give a large range of 'tuning' and input options, especially when I look to add torque/cadence sensing:
https://ebikes.ca/product-info/grin-products/cycle-analyst-3.html
In terms of the rest, I'm aiming to use simple profile cut steel/ally and 3D printing, so it could be easily recreated by anyone with the DXF/STL files.
Parts I could use help with:
Drive sprocket for the output from the gearbox.
I'd love this to have a freehweel, so the bike can be pedalled without the drag of the system if required. Something like a left hand sprocket/freewheel from a BMX? Alternatively, for now, just a fixed sprocket would do in the region of 13-15T.
Any ideas on where to get one with a simple shaft/key fixing or similar?
Freewheel for the chainring.
This one doesn't bother me, as I'd only use it for assist, so would simply bolt on another chainring on the outer mounting of my cranks. I'm sure some would like a freewheel though, and it'll become essential for cadence/torque sensed drive, so could do with concluding what to use.
I think that's about it for now. As I say, it's very much open project, so please do give any feedback/advice you think you can!
Remember that no one system will suit everyone, so I'm basing this on my personal needs primarily, which I'm sure will suit a bunch of other people. It just may not be 'your' idea of a perfect system.
Cheers, Larby
Following much hunting around for what I want, I have concluded I need to build my own. I'm an engineer with experience in design, R&D and motorsport and have my full company workshop at my disposal including 3D scanning, CAD, rapid prototyping, profile cutting etc. So, I'm in a good place to develop something.
That said, I don't just want to develop something for me, I'd like to make it more of an open source group project and develop something any of us could put together with minimal and simple assistance.
My spec is to make a simple, fairly light, mid-drive assistance system which can be easily attached/detached.
I'd like to to preferably leave the original bike pretty untouched, save for maybe the chainring, so high-strength components don't have to be replaced with lower spec ones (such as square taper BB's, hubs etc).
I’m going to start off with a simple thumb throttle for testing, until I’ve got the drive setup sorted.
My plan is to then move to a torque and cadence sensed arrangement, to hopefully make the unit totally self contained and to also give the widest range of control options.
I should add that I'm (sort of) UK based, so I'd like it to have 'road legal' capability and I'm not chasing massive power figures. I envisage it as an assistance system, rather than something to save you pedalling at all.
So far, my theoretical spec list is as follows...
RC motor as the prime mover:
https://hobbyking.com/en_us/turnigy-sk8-6374-149kv-sensored-brushless-motor-14p.html?queryID=3a6165b0623055eb7629c4d7afed99ad&objectID=74469&indexName=hbk_live_products_analytics&___store=en_us
Simple VESC to power it:
https://hobbyking.com/en_us/turnigy-sk8-v2-80a-3-12s-single-motor-skateboard-esc.html?queryID=1f66f46c97b42d7b1a35c3a59ca64e5d&objectID=83138&indexName=hbk_live_products_analytics
NEMA 24 based planetary reduction drive, which will be linked via off-the-shelf gears or a belt drive for simplicity (something along these lines, there's all sorts available, recommendations of an affordable and readily available version welcome!):
https://www.ebay.co.uk/itm/203660888117?hash=item2f6b228835
Simple, compact and easily available battery:
https://hobbyking.com/en_us/turnigy-high-capacity-battery-20000mah-6s-12c-drone-lipo-pack-xt90.html?queryID=e4d73d973c9332952aba7c5ce6e53f96&objectID=78412&indexName=hbk_live_products_analytics
CA3 Cycle Analyst to bring it all together and give a large range of 'tuning' and input options, especially when I look to add torque/cadence sensing:
https://ebikes.ca/product-info/grin-products/cycle-analyst-3.html
In terms of the rest, I'm aiming to use simple profile cut steel/ally and 3D printing, so it could be easily recreated by anyone with the DXF/STL files.
Parts I could use help with:
Drive sprocket for the output from the gearbox.
I'd love this to have a freehweel, so the bike can be pedalled without the drag of the system if required. Something like a left hand sprocket/freewheel from a BMX? Alternatively, for now, just a fixed sprocket would do in the region of 13-15T.
Any ideas on where to get one with a simple shaft/key fixing or similar?
Freewheel for the chainring.
This one doesn't bother me, as I'd only use it for assist, so would simply bolt on another chainring on the outer mounting of my cranks. I'm sure some would like a freewheel though, and it'll become essential for cadence/torque sensed drive, so could do with concluding what to use.
I think that's about it for now. As I say, it's very much open project, so please do give any feedback/advice you think you can!
Remember that no one system will suit everyone, so I'm basing this on my personal needs primarily, which I'm sure will suit a bunch of other people. It just may not be 'your' idea of a perfect system.
Cheers, Larby