why electric assist, and how
Oct. 25th, 2012 11:58![[personal profile]](https://www.dreamwidth.org/img/silk/identity/user.png){kind=small}
piranhawhen i started contemplating buying a bicycle one of the main reasons was that i wanted to use it for transportation -- to go down to ladysmith to work on the boat, to ride to southgate for groceries, to get to some special spots to take photos when the light is good. i knew that i'd chicken out if the transportation aspect got too onerous. i'm just too much out of shape, and whenever i pull myself together and start on an exercise regimen again, illness interferes sooner rather than later, and i fall off the wagon.
so i wanted something that will carry me when i feel crappy, but won't take the exercise completely out of it for when i feel better. i looked at various electric assist systems on the market. the one i bought by bionX is actually way smarter than i expected to find, and it fits incredibly well with what i want.
first off, it is light. the motor is in the rear hub, and i bought the rack + rackmount battery (they also have a frame downtube mounted one which is cheaper). the whole system weighs ~20lbs, thanks to the new technology of the lithium-ion battery; the prior SLA batteries were much heavier. i originally didn't think weight was much of an issue since i weigh a huge amount more than the battery, but it matters when moving the bike -- into the back of the truck, or onto the racks of public transportation. 20 lbs is noticeable, but i can still handle it well. the battery is locked into the rack, but slides out easily once unlocked. it's also got a rear light built in.
the system has 3 different modes: pedal assistance, pure throttle, and regeneration.
the assistance system measures my pedal strokes using a torque sensor built into the rear axle. the motor takes that information and amplifies it seamlessly from 25% to 300% depending on my assistance settings. proportional assistance means if i back off pedalling, the motor does the same. if i really step on it and pump the pedals, the motor kicks it up. the assistance is very smooth, near-instant, so i almost don't even notice it. and -- importantly -- if i need to stop suddenly, it stops immediately (the brake is connected to an interrupt switch).
the throttle mode doesn't care whether i pedal or not; it just goes. this drains the battery incredibly fast, but if i need a speed boost to get up the last bit of the steep driveway at the end of my ride, that's real handy.
regeneration kicks in either if i pull the brake while still moving (downhill, for example), or if i explicitly choose that setting. it's a bit of an engine brake too, which i like a lot because i don't really enjoy going as fast as the downhills here enable me to; it makes me feel safer than to rely on the mechanical brakes alone. i can see regen being great for actual exercising if i feel up to it, because i can switch to a higher gear than i normally would and turn regen on, so i get about the same resistance than the lower gear. and it recharges the battery at the same time, giving me greater range.
both pedal assistance and regeneration have 4 settings each, giving progressively more amplification or more resistance. keep in mind that all the mechanical gears of your bike are in play as well. it takes a while to figure out what gear will work best when with the system, but how complex it is really just matters if you're intent on maximizing your gears' power -- at this point i am mostly staying on the 2nd chainring (of 3), which simplifies the shifting. the assistance can deal fine with almost any hills around here -- there are a couple where i'd have to shift to my granny chainring, but for now i mostly avoid the strain while i am getting used to the bike. i don't actually like going faster than 30 km/h on these roads, so i don't get much of chance to try the larger gears. the assistance does not continue at speeds above 32 km/hr since that's the legal limit here. i love level 4 assist at intersections -- even uphill, it gives a real boost to get me across very quickly, instead of the wobble act i used to do, standing up to pump the pedals. no standing up needed here; it just GOES as soon as the starting pedal reaches bottom. and it is nuanced enough that if i then turn right instead of going straight, it backs off immediately again.
the "command centre" for the system is a small console mounted on my handlebar, which i can easily reach with my left hand. it's got a large display, and largish buttons (still a bit fiddly with winter gloves). but i don't actually need to use the buttons much, since this new system has a separate throttle which is mounted next to my right handgrip -- i can change the assistance and regen levels from there as well as use the throttle. which means i only need to use the console buttons for backlighting when dark, and to cycle through odometer, speedometer, battery gauge, stress meter, and diagnostic modes. the console is easily removed (just press a button and it slides out) when parking the bike.
everyone is cagey when answering questions about the range of the battery, because it depends so much on the weight of the rider, the terrain, road conditions. nominally it's 60km at assistance level 1 under ideal conditions. i am not getting that range out of it, of course, but it's doing well for what i need right now. it's actually surprised me that the regen feature works as well as it does -- i have managed to go 10 km without losing any battery power at all, just by judiciously switching to regen every chance i got. if i get in better shape, that nominal range doesn't seem entirely out of reach.
the system seems build very well; nothing here is flimsy. the motor is brushless and gearless, and therefore needs no maintenance. the rack is srs bzns ;) and the connectors are all well-sealed so they should be able to deal with the wet seasons here. it feels professional rather than thrown together by a hobby entrepreneur in zir basement. there's a 2 year warranty on it as well. seriously, i think the local bike shops should give this a try; it's a far cry from the other systems i've looked at.
overall, i love it. the bike still rides just like a bicycle, not like a scooter. you can ride it entirely without the assistance -- even if you were to run out of battery, it's still a regular bike and handles like it. the assistance is so smooth that it feels almost intuitive, kinda like thinking "i could use a little more power now" and there it is. also, the system doesn't make any annoying noise. this is making bike riding fun for me again, like it was when i was a kid. and it's getting me out there, instead of sitting on my butt thinking that i should really get some exercise, but i've done the available walks around here a zillion times.
you can convert your bike yourself if you already have one that suits you; bionX sells kits for various wheel sizes and gearing. the main thing to watch out for is that you need a threaded freewheel hub (which you can buy for less than C$30 if you don't have one).
technical detail of my system:
motor: 350 watts, 9/40 nm - 6.6/29 lb-ft
battery: lithium-ion, 37V, 6.4A, 237Wh
weight: 20.5 lb
range: 60km (37m)
bionX makes other systems with less or more power.
so i wanted something that will carry me when i feel crappy, but won't take the exercise completely out of it for when i feel better. i looked at various electric assist systems on the market. the one i bought by bionX is actually way smarter than i expected to find, and it fits incredibly well with what i want.
first off, it is light. the motor is in the rear hub, and i bought the rack + rackmount battery (they also have a frame downtube mounted one which is cheaper). the whole system weighs ~20lbs, thanks to the new technology of the lithium-ion battery; the prior SLA batteries were much heavier. i originally didn't think weight was much of an issue since i weigh a huge amount more than the battery, but it matters when moving the bike -- into the back of the truck, or onto the racks of public transportation. 20 lbs is noticeable, but i can still handle it well. the battery is locked into the rack, but slides out easily once unlocked. it's also got a rear light built in.
the system has 3 different modes: pedal assistance, pure throttle, and regeneration.
the assistance system measures my pedal strokes using a torque sensor built into the rear axle. the motor takes that information and amplifies it seamlessly from 25% to 300% depending on my assistance settings. proportional assistance means if i back off pedalling, the motor does the same. if i really step on it and pump the pedals, the motor kicks it up. the assistance is very smooth, near-instant, so i almost don't even notice it. and -- importantly -- if i need to stop suddenly, it stops immediately (the brake is connected to an interrupt switch).
the throttle mode doesn't care whether i pedal or not; it just goes. this drains the battery incredibly fast, but if i need a speed boost to get up the last bit of the steep driveway at the end of my ride, that's real handy.
regeneration kicks in either if i pull the brake while still moving (downhill, for example), or if i explicitly choose that setting. it's a bit of an engine brake too, which i like a lot because i don't really enjoy going as fast as the downhills here enable me to; it makes me feel safer than to rely on the mechanical brakes alone. i can see regen being great for actual exercising if i feel up to it, because i can switch to a higher gear than i normally would and turn regen on, so i get about the same resistance than the lower gear. and it recharges the battery at the same time, giving me greater range.
both pedal assistance and regeneration have 4 settings each, giving progressively more amplification or more resistance. keep in mind that all the mechanical gears of your bike are in play as well. it takes a while to figure out what gear will work best when with the system, but how complex it is really just matters if you're intent on maximizing your gears' power -- at this point i am mostly staying on the 2nd chainring (of 3), which simplifies the shifting. the assistance can deal fine with almost any hills around here -- there are a couple where i'd have to shift to my granny chainring, but for now i mostly avoid the strain while i am getting used to the bike. i don't actually like going faster than 30 km/h on these roads, so i don't get much of chance to try the larger gears. the assistance does not continue at speeds above 32 km/hr since that's the legal limit here. i love level 4 assist at intersections -- even uphill, it gives a real boost to get me across very quickly, instead of the wobble act i used to do, standing up to pump the pedals. no standing up needed here; it just GOES as soon as the starting pedal reaches bottom. and it is nuanced enough that if i then turn right instead of going straight, it backs off immediately again.
the "command centre" for the system is a small console mounted on my handlebar, which i can easily reach with my left hand. it's got a large display, and largish buttons (still a bit fiddly with winter gloves). but i don't actually need to use the buttons much, since this new system has a separate throttle which is mounted next to my right handgrip -- i can change the assistance and regen levels from there as well as use the throttle. which means i only need to use the console buttons for backlighting when dark, and to cycle through odometer, speedometer, battery gauge, stress meter, and diagnostic modes. the console is easily removed (just press a button and it slides out) when parking the bike.
everyone is cagey when answering questions about the range of the battery, because it depends so much on the weight of the rider, the terrain, road conditions. nominally it's 60km at assistance level 1 under ideal conditions. i am not getting that range out of it, of course, but it's doing well for what i need right now. it's actually surprised me that the regen feature works as well as it does -- i have managed to go 10 km without losing any battery power at all, just by judiciously switching to regen every chance i got. if i get in better shape, that nominal range doesn't seem entirely out of reach.
the system seems build very well; nothing here is flimsy. the motor is brushless and gearless, and therefore needs no maintenance. the rack is srs bzns ;) and the connectors are all well-sealed so they should be able to deal with the wet seasons here. it feels professional rather than thrown together by a hobby entrepreneur in zir basement. there's a 2 year warranty on it as well. seriously, i think the local bike shops should give this a try; it's a far cry from the other systems i've looked at.
overall, i love it. the bike still rides just like a bicycle, not like a scooter. you can ride it entirely without the assistance -- even if you were to run out of battery, it's still a regular bike and handles like it. the assistance is so smooth that it feels almost intuitive, kinda like thinking "i could use a little more power now" and there it is. also, the system doesn't make any annoying noise. this is making bike riding fun for me again, like it was when i was a kid. and it's getting me out there, instead of sitting on my butt thinking that i should really get some exercise, but i've done the available walks around here a zillion times.
you can convert your bike yourself if you already have one that suits you; bionX sells kits for various wheel sizes and gearing. the main thing to watch out for is that you need a threaded freewheel hub (which you can buy for less than C$30 if you don't have one).
technical detail of my system:
motor: 350 watts, 9/40 nm - 6.6/29 lb-ft
battery: lithium-ion, 37V, 6.4A, 237Wh
weight: 20.5 lb
range: 60km (37m)
bionX makes other systems with less or more power.
no subject
on 2012-10-26 04:58 (UTC)no subject
on 2012-10-26 06:32 (UTC)no subject
on 2012-10-27 02:30 (UTC)I hope it continues to be a useful tool.
Did your vendor give you any idea of how long the batteries will last? My SLA experience is cold weather — 10°C down to −40° — dramatically lowers power in the short term and shortens battery life in the long term.
no subject
on 2012-10-28 20:45 (UTC)