Hi all,
I am looking for some advice for yourselves on an ebike project I’m looking to create. It’s for speeding up my 24mile cross country commute to work.
I am a fairly fit road cyclist, and have reached the limit of what I can do without significant extra effort / training. My commute currently takes me ~1.5hr on my road bike, but would like to bring that to ~1hr with some ‘assistance’.
I have run some simulations both on Steve Gribbles excellent site (https://www.gribble.org/cycling/power_v_speed.html) and through spreadsheets, and it looks achievable. I need to triple my mean power output to take 20-30 minutes off, while keeping total system efficiency as high as possible (aero drag, rolling resistance, weight). I want this to be stealth, and not be a massive power sink like many ebikes I see.
With a sensible road bike + Aero bars, I should be able to maintain 30mph on 0% with 540w wheel power (180w legs, 360w motor). With 80% efficiency from battery to wheel, rising power requirements to 450w.
The bike requires significantly higher power draw on the uphills (>720w at wheel) and 0w on downhills to keep within energy budget. Wasting energy on excessive high speed turbulence is not an option, but spending on potential energy is. I live in the UK with lots of smaller hills, so overheating shouldn’t be a problem.
John Wessels bike https://www.electricbike.com/kepler-super-commuter/ is what I almost exactly envision. It’s very nicely engineered, with the core principles that I aim for, and so I have stolen many ideas from this (Thanks John)
Overall plan:
Budget - £500 donor bike + £300 for: motor+controller+control panel
Donor bike - Will be the best road bike I can get on eBay for the price, definitely with discs, ally frame and Tri bars added on.
Hub motor - I have eventually decided on a geared hub motor, such as in Johns bike. I was originally CADing up a belt driven 90mm outrunner (with sprag clutch pressed over machined down ISO disc mounts on rear wheel), but have decided the loss in efficiency going to a pre assembled epicyclic drive is worth the savings in time and cost - not to mention looking more stealth.
Torque sensor - BB system is elegant and means the bike responds naturally. Seeing the Thun didn’t last (and I really don’t want a square taper!) is there a better modern alternative? Or a PAS system?
Control panel / Controller - Cycle analyst seems the most popular control panel, even if it is quite bulky and not the best looking (sorry!). Also, is there any update on the best controller to use in this instance, or is modifying the Lyens 6 FET or Vesc the best option? I am an engineer by trade, and am happy to modify electronics / code / generally tamper to get it to work!
Battery - I have access to high performance (VTC6) 18650 cells and was going to build them into an 80mm bottle in a very tightly packed 18s2p configuration with 30A Aliexpress BMS. This would go on a bottle holder and provide the 400Wh I think I’ll get away with.
Final questions:
Does this all generally sound like a sensible plan?
Whats the best geared motor? Nylon & sintered gears concern me, are there any with POM or better? Decent clutches?
Best controller / torque sensor / control panel combo?
Many thanks in advance everybody.
I am looking for some advice for yourselves on an ebike project I’m looking to create. It’s for speeding up my 24mile cross country commute to work.
I am a fairly fit road cyclist, and have reached the limit of what I can do without significant extra effort / training. My commute currently takes me ~1.5hr on my road bike, but would like to bring that to ~1hr with some ‘assistance’.
I have run some simulations both on Steve Gribbles excellent site (https://www.gribble.org/cycling/power_v_speed.html) and through spreadsheets, and it looks achievable. I need to triple my mean power output to take 20-30 minutes off, while keeping total system efficiency as high as possible (aero drag, rolling resistance, weight). I want this to be stealth, and not be a massive power sink like many ebikes I see.
With a sensible road bike + Aero bars, I should be able to maintain 30mph on 0% with 540w wheel power (180w legs, 360w motor). With 80% efficiency from battery to wheel, rising power requirements to 450w.
The bike requires significantly higher power draw on the uphills (>720w at wheel) and 0w on downhills to keep within energy budget. Wasting energy on excessive high speed turbulence is not an option, but spending on potential energy is. I live in the UK with lots of smaller hills, so overheating shouldn’t be a problem.
John Wessels bike https://www.electricbike.com/kepler-super-commuter/ is what I almost exactly envision. It’s very nicely engineered, with the core principles that I aim for, and so I have stolen many ideas from this (Thanks John)
Overall plan:
Budget - £500 donor bike + £300 for: motor+controller+control panel
Donor bike - Will be the best road bike I can get on eBay for the price, definitely with discs, ally frame and Tri bars added on.
Hub motor - I have eventually decided on a geared hub motor, such as in Johns bike. I was originally CADing up a belt driven 90mm outrunner (with sprag clutch pressed over machined down ISO disc mounts on rear wheel), but have decided the loss in efficiency going to a pre assembled epicyclic drive is worth the savings in time and cost - not to mention looking more stealth.
Torque sensor - BB system is elegant and means the bike responds naturally. Seeing the Thun didn’t last (and I really don’t want a square taper!) is there a better modern alternative? Or a PAS system?
Control panel / Controller - Cycle analyst seems the most popular control panel, even if it is quite bulky and not the best looking (sorry!). Also, is there any update on the best controller to use in this instance, or is modifying the Lyens 6 FET or Vesc the best option? I am an engineer by trade, and am happy to modify electronics / code / generally tamper to get it to work!
Battery - I have access to high performance (VTC6) 18650 cells and was going to build them into an 80mm bottle in a very tightly packed 18s2p configuration with 30A Aliexpress BMS. This would go on a bottle holder and provide the 400Wh I think I’ll get away with.
Final questions:
Does this all generally sound like a sensible plan?
Whats the best geared motor? Nylon & sintered gears concern me, are there any with POM or better? Decent clutches?
Best controller / torque sensor / control panel combo?
Many thanks in advance everybody.