Build diary for electrifying 'Big Bird' the yellow craigslist recumbent

[goosenoose]

use case: 40 mile roundtrip commute, a few hills but otherwise mostly flat paved bicycle trail. capability for sustained 25-30mph (+?) cruising speed w/ PAS

desirables:

• a speed limited throttle to permit uphill/standing starts
• regen.. proportional regen would be awesome
• stay around/below $1k for the motor and battery

options under consideration:

1. toseven dm02
   1. pros:
      1. ability to utilise existing gearing
      2. perhaps a simpler install for intended donor bike? electronics in mid drive. compact display/pas setting option.
      3. torque sensing pedal assist
      4. perhaps upgrade to dm01 for more speed/torque?
      5. price ($400~550)
   2. cons:
      1. additional wear on bicycle drivetrain (much more concern if getting larger dm01)
      2. no regen (additional wear on brake components, which might be fine tbh)
2. leafbike 1500w 700c motor kit
   1. pros:
      1. also pretty simple install; have done before on a 20" folder
      2. dd hub so... possibility of regen but would need to look at other controllers... and learn something...(con?)
      3. definitely capable of cruising speed requirements
      4. price ($500~)
   2. cons:
      1. filing dropouts was not a nice experience before
      2. no torque sensor pas without figuring out how to kitbash this with another controller setup
3. grin kits (reviewing options.. wip)

 

[neptronix]

With 700c wheels i'd be thinking about geared hub motors or mid drives usually, recumbent or not, due to the low RPM a big wheel spins at.

If you must go the way of the DD, consider the RH212 or Grin all axle for an improved power to weight ratio over the leaf 1.5kw.

Consider a GMAC for a high torque, large wheel situation if we're dealing with long grades >5%
Otherwise if you don't have any seriously long and difficult climbs, a Shengyi SX2 would be the ideal geared motor for your demands, and is also the most efficient hub motor you can buy AFAIK!

Mid drives are great but consider that this kind of bike is weak at climbing hills.. for your speeds, you probably want a 750w-1kw rated mid drive so that you don't see massive loss of speed on hills.

 

[goosenoose]

thanks nep, honored for your reply. long-time lurker of your leafbike and other build posts.

yeah, was thinking the same regarding the larger wheel. i recently found a 20" lwb recumbent (rans tailwind) not too far from me for $300 that would probably make for a better donor bike for said use case. i think i also want to add 'can fit in a car if i break down for whatever reason miles from home' to the list of desirables. had that happen with a sidewall puncture from road construction debris and... it was not fun hiking a dd-hubbed tandem bike five miles home.

re: shengyi. that's actually the one i'm configuring in motor simulator. discovered that grin has an option of it with a locked freewheel. only question in my mind is with the suitability of a geared hub drive used constantly over a long distance (40 miles daily?). in the beforetimes, i remember seeing that the mechanicals in these sort of hubs had a risk of peanut-buttering from sustained use / pairing with higher voltage batteries (i'm looking at 52v 20ah battery from bicyclemotorworks).

re: rh212, also looking into that. gmac and all axle sadly are out of the budget of this particular project.

re: 750w-1kw rated mid drive... yeah, i agree. kind of feel like i am where i started with the toseven dm01 (was what i was originally thinking would fit the bill).

// break

so mainly looking at the dm01 vs shengyi now.

 

[Papa]

i recently found a 20" lwb recumbent (rans tailwind) not too far from me for $300

Sweet deal. The Tailwind was actually a CLWB, even though it sat on a 66" WB. Excellent ride &overall demeanor, especially the RANS seat. I had a serious crush on the suspended Gliss, but couldn't scrape the 2k cash at the time.

 

[neptronix]

Geared motors' gears only turn into peanut butter if you overheat them pretty badly.

30mph is a nice ~600w draw on this motor.. notice that the difference between batt power and mtr power is only 80 watts, that's approximately how much heat we're making, and the motor can shed approx 125w continuously, so there's some room to climb hills but not mountains.



Can't advise you on the toseven drives but i can say a DM01 would handle what you need and a bit more. it'd weigh almost twice as much though.