Author Topic: Those bicycle motor thingies  (Read 7133 times)

puglogic

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Those bicycle motor thingies
« on: September 28, 2013, 03:35:14 PM »
Dear Mustachians,
I try very hard to research things myself before asking on a forum, but in this case I am not even sure what the thing I'm after is CALLED, so that makes it tough.  But you'll know:

I'd like to take my bike more places, and leave my 20mpg car in the driveway. But where I live, we are in a bit of a canyon, boxed in by very long, steep hills in between us and everywhere I'd like to go (grocery, post office, bank...)   

I've seen on certain bicycles a sort of motor assist thing on the front wheel.  I'm wondering if having one of those might help get me "over the hump" so to speak, so I can pedal to my destinations. 

Does anyone know their official name?   And whether they work?  Are they an add-on thing you can purchase and install on a regular bike?   I have a relatively lightweight hybrid bike that I love.

Thanks for any advice, direction, help. 



geekette

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Re: Those bicycle motor thingies
« Reply #1 on: September 28, 2013, 03:47:18 PM »
My sister in law has a BionX electric assist bike.  It was a kit that was installed on a regular bike, and it wasn't cheap (probably over $1k, but I'm not sure).

It works very well, but when a part broke and her dealer had moved out of the area, she had a very long, expensive slog getting it fixed. Now that it's fixed, she's using it again, and when I go biking with her, she lets me use it.  It really flattens out the hills.  I love it.

capital

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Re: Those bicycle motor thingies
« Reply #2 on: September 28, 2013, 03:57:45 PM »
A bike with an electric motor is simply called an 'electric bike'. Many cities have a shop or two that sells and works on them. You can also buy a 2-stroke gas engine to rig onto a bike if you like pollution.

There are conversion kits that let you motorize your current bike. BionX is at the top end of the market. Electric bikes are extremely popular in China, so there are a lot of low-end imports from China. Cheaper kits have lower-capacity, heavy lead-acid batteries, like a car; weaker motors; and a manual throttle. More expensive kits have lighter, higher-capacity lithium-ion batteries; more powerful motors; and fancy electronic controls that boost your pedalling power.

Here's the first conversion kit I found by googling 'electric bike kit'. You just swap out the front wheel and attach a battery:
http://www.electric-bike-kit.com/hill-topper.aspx

Note that electric bikes are a relatively new technology, and inconsistently regulated. You may not be allowed to ride certain types on bike trails or in bike lanes.

Russ

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Re: Those bicycle motor thingies
« Reply #3 on: September 28, 2013, 04:10:58 PM »
If these hills are really that long and steep, the motor setup might not help that much depending on its power to weight ratio. They're really best for cruising around flat land. When going uphill a lot of the motor's energy will be spend lifting the motor itself. For your application you're probably looking for something pretty high-end, and at that point I'd just ride it myself (you will eventually be able to do it easily, just takes practice).

Just some thoughts.

capital

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Re: Those bicycle motor thingies
« Reply #4 on: September 28, 2013, 04:14:56 PM »
Not without working up a heck of a sweat for most of the year, however, which can be suboptimal when someone just wants to go to the post office or bank. And, depending on the depth of the canyon, sometimes you just want to get groceries without climbing 400 feet.

But an electric bike kit certainly can add 20lbs. to a normal bike.

Russ

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Re: Those bicycle motor thingies
« Reply #5 on: September 28, 2013, 04:29:51 PM »
Not without working up a heck of a sweat for most of the year, however, which can be suboptimal when someone just wants to go to the post office or bank. And, depending on the depth of the canyon, sometimes you just want to get groceries without climbing 400 feet.

But an electric bike kit certainly can add 20lbs. to a normal bike.

Oh of course. OP's gonna have to weigh all the pros/cons themselves with respect to that. I was just trying to point out a different perspective and some potential pitfalls (specifically addressing the "do they work" question, the answer to which is most but not all of the time) lest OP jumps into buying things a little too gung-ho.

puglogic

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Re: Those bicycle motor thingies
« Reply #6 on: September 28, 2013, 06:05:13 PM »
Thank you, all.   Good info and good things to ponder - and good to know finally what to Google. 

I think if I were at sea level instead of 7500ft, I might be able to train my 50+ body to do a two-mile steep uphill eventually, as it's a good physical fitness goal.   But more realistically I think I'd probably end up buying a scooter instead. :)

Posthumane

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Re: Those bicycle motor thingies
« Reply #7 on: September 30, 2013, 12:09:34 PM »
I have an electric bike kit that I added to a folding bike for my fiancee. She wasn't able to keep up with me since I'm an avid cyclist and she isn't, and that discouraged her from biking. Now, with the electric kit, she has no problems keeping up despite riding a much less efficient bike (cheap, heavy steel folder with 20" low pressure tires vs. my steel framed 700c road bike) with an upright riding posture.

What Russ said about the motor not lifting its own weight on hills is completely untrue. Hills is where the motor helps the most. The motor I have is 350w, coupled with a 400 Whr lithium ion battery. The whole kit does add about 20lb to the weight of the bike, but consider that as a comparison I can only put out about 100W of continuous pedalling power, and about 200-250W in a sprint. In other words, the 20 lb motor/battery combo can put out more power than I can at my max, and it can do it for about an hour. I can climb hills at about 15 mph with the electric assist bike on which I struggle to maintain 8 mph on my road bike. The electric motor tops out at about 22 mph with the small 20" wheel, so technically I can go faster on flat ground and down hills with my non-assisted road bike, but only for a short time period unless there is a tailwind.

Rickk

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Re: Those bicycle motor thingies
« Reply #8 on: September 30, 2013, 01:10:18 PM »
Google ebike or electric bike.
I bought mine from http://em3ev.com/store/index.php?route=product/category&path=36 - this is for the do it yourself crowd - cost around $1200 with 20aH battery (The battery alone was 1/2 the cost I think).

A highly rated site is http://ebikes.ca/ - This is a Canadian company which is run by an individual highly rated by the ebike community

Forums to learn more:
http://www.bikeforums.net/forumdisplay.php/258-Electric-Bikes - great for bikes
http://endless-sphere.com/forums/ - good for battery technology and electric vehicles

I don't know much about pre-made ones, have only researched retrofit kits.
On the low end of a pre-made one is http://www.amazon.com/Currie-Technologies-Trailz-Electric-Bicycle/dp/B004QHG17O/ref=sr_1_1?ie=UTF8&qid=1380568056&sr=8-1&keywords=currie+ebike  - much noisier but cheap.

Your best bet is to read the forums in bikeforums.net and that will give you a bunch of information on the topic.

*Edit to clarify cost of my setup*
« Last Edit: October 02, 2013, 11:30:48 AM by Rickk »

Kira

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Re: Those bicycle motor thingies
« Reply #9 on: September 30, 2013, 01:11:22 PM »
Here's the first conversion kit I found by googling 'electric bike kit'. You just swap out the front wheel and attach a battery:
http://www.electric-bike-kit.com/hill-topper.aspx

I have a Clean Republic electric bike kit (website above) and I LOVE IT SO MUCH.

Because it is on the front wheel and must pull you instead of push you, it doesn't have as much power as a rear-wheel motor might. But it was super easy to install and does give you that extra oomph. Especially on those long hills, it is invaluable as an assist. You do still have to keep pedaling, but with the combined power of the pedaling and the motor, I have not met a hill I couldn't tackle, and I am really quite out of shape. If you are already able to bike those hills, you will be a-ok with one of these while pulling groceries. If weight is a factor, you can pay a little more and get a lithium battery which is 2 pounds instead of the base battery which is 11 pounds, but the wheel itself weighs maybe a pound more than a regular wheel.

If I were riding longer distances or pulling things I might have gotten a real motor, but this is awesome on its own.

mustachejd

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Re: Those bicycle motor thingies
« Reply #10 on: October 01, 2013, 10:02:55 AM »
Hah, I just registered for a MMM account just so I could ask this question!  And then I did a search and realized that this question had already been asked =P

Based on the responses, the Clean Republic Hill Topper kit looks promising.  Quick question, for those who have used the kit, do you think getting the 10 mile battery should suffice?  I recently moved and want to continue to biking to work.  My new commute is about 15 miles each way, which I thought was no big deal, but then I found out that I have to navigate a series of major hills and have to sweat way more than I want to.  Normally, I wouldn't care about the sweat, but personal appearance is kind of important for my line of work.  I tried mapping out some alternate routes, but no dice. 

Anyway, it seems that the 20 and 40 mile kits are overkill, especially since I would probably use the electrical assist for maybe 2.5 miles of the entire trip.  What do you guys think? 

Russ

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Re: Those bicycle motor thingies
« Reply #11 on: October 01, 2013, 10:26:40 AM »
What Russ said about the motor not lifting its own weight on hills is completely untrue.

Huh, my bad then. Must have just been something shitty about the one I tried, or I wasn't doing it right or something. Glad someone is around to correct me ;-)

Posthumane

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Re: Those bicycle motor thingies
« Reply #12 on: October 01, 2013, 10:31:55 AM »
Anyway, it seems that the 20 and 40 mile kits are overkill, especially since I would probably use the electrical assist for maybe 2.5 miles of the entire trip.  What do you guys think? 
I think the 10 mile battery would be fine for short trips, but definitely get the lithium ion (4.4 Ah) one, not the SLA one. One thing that's not clear to me on the site for the hill topper is whether the motor incorporates a freewheel mechanism or not. Usually geared motors have a freewheel clutch in them so that the motor doesn't cause any drag when it's not in use, whereas direct drive motors often do not have this meaning that you have to have some power on the motor at all times to keep if from actually slowing you down. The Hill Topper kit lists the motor as a "planetary" motor which to me implies that it does incorporate a planetary gear set like mine, and therefore would likely have a freewheel as well, but I would confirm that before buying.

Huh, my bad then. Must have just been something shitty about the one I tried, or I wasn't doing it right or something. Glad someone is around to correct me ;-)
No worries. There probably were some kits in the past which had issues like this, especially if they were geared more for speed rather than climbing, or if the battery was an old, worn out lead acid unit.

Edit: Forgot to mention, but if I was buying a kit again to fit to a specific bike, I would probably get a rear wheel kit instead of front. The front is more versatile as you can easily transfer from one bike to another, but I find that on steep hills the front wheel spins/slips sometimes on my short-wheel-base folding bike.
« Last Edit: October 01, 2013, 10:35:23 AM by Posthumane »

mustachejd

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Re: Those bicycle motor thingies
« Reply #13 on: October 01, 2013, 11:17:07 AM »
I think the 10 mile battery would be fine for short trips, but definitely get the lithium ion (4.4 Ah) one, not the SLA one.

Why is that?  Just because it's that much lighter?

Left

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Re: Those bicycle motor thingies
« Reply #14 on: October 01, 2013, 11:46:32 AM »
Not to hijack the thread but,I've been researching this myself, wondering if anyone knows of anything like this.
What I want is a a motor that runs entirely off of a generator and a capacitor, instead of a battery. I've tried to look into a generator (not sure what the correct name is) that bike lights run off of. And plug that into the motor. My goal is to have the pedaling generate enough electricity and power the motor. I don't care if it won't run motor if I'm not pedaling, I don't need it to. This way I'm hoping to cut down on battery weight.

The problem I've found is that on average from a few different motor types, they require about 200-600 watts (not sure if I'm talking correct electrical unit, I don't understand difference between joules, amps, watts, volts, etc). The only generators that come close to that amount are wind turbines that seem they might be small enough to fit onto a bike. I've thought about removing the wind mills and somehow modifying it to let my pedals turn it instead of wind mill pedals. Somehow fitting it into the pedals. I know this isn't feasible, cost/size/etc, but is there a product that does this already that I haven't come across? Since a wind mill cost $100-1000+, I haven't taken to trying it.

I have however bought a few $5-15 toy wind mills, and connected them to toy motors just to see it work. Problem is the parts don't scale well and if scaled to real bike size, I'd be better off riding an e-bike with a battery.

Russ

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Re: Those bicycle motor thingies
« Reply #15 on: October 01, 2013, 12:02:31 PM »
Not to hijack the thread but,I've been researching this myself, wondering if anyone knows of anything like this.
What I want is a a motor that runs entirely off of a generator and a capacitor, instead of a battery. I've tried to look into a generator (not sure what the correct name is) that bike lights run off of. And plug that into the motor. My goal is to have the pedaling generate enough electricity and power the motor. I don't care if it won't run motor if I'm not pedaling, I don't need it to. This way I'm hoping to cut down on battery weight.

The problem I've found is that on average from a few different motor types, they require about 200-600 watts (not sure if I'm talking correct electrical unit, I don't understand difference between joules, amps, watts, volts, etc). The only generators that come close to that amount are wind turbines that seem they might be small enough to fit onto a bike. I've thought about removing the wind mills and somehow modifying it to let my pedals turn it instead of wind mill pedals. Somehow fitting it into the pedals. I know this isn't feasible, cost/size/etc, but is there a product that does this already that I haven't come across? Since a wind mill cost $100-1000+, I haven't taken to trying it.

I have however bought a few $5-15 toy wind mills, and connected them to toy motors just to see it work. Problem is the parts don't scale well and if scaled to real bike size, I'd be better off riding an e-bike with a battery.

This sounds like it belongs in the Free Energy thread...

real talk though, you won't cut down on battery weight by doing this. regular caps weigh way more per unit energy, and you'll have to spend a hell of a lot of money on cutting-edge stuff to get anywhere close to batteries. In lights, the generator powers the light directly and the capacitor for the standlight hardly has to hold any charge. I think generator lights draw like 5W max running and 1W or less on stand, for reference

plus a bunch of other negatives...

Kira

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Re: Those bicycle motor thingies
« Reply #16 on: October 01, 2013, 12:50:38 PM »
Hah, I just registered for a MMM account just so I could ask this question!  And then I did a search and realized that this question had already been asked =P

Based on the responses, the Clean Republic Hill Topper kit looks promising.  Quick question, for those who have used the kit, do you think getting the 10 mile battery should suffice?  I recently moved and want to continue to biking to work.  My new commute is about 15 miles each way, which I thought was no big deal, but then I found out that I have to navigate a series of major hills and have to sweat way more than I want to.  Normally, I wouldn't care about the sweat, but personal appearance is kind of important for my line of work.  I tried mapping out some alternate routes, but no dice. 

Anyway, it seems that the 20 and 40 mile kits are overkill, especially since I would probably use the electrical assist for maybe 2.5 miles of the entire trip.  What do you guys think?

It does seem to be 10 miles of actually having it on, not 10 miles of biking. I bike 4.5 miles to work and 6.5 back, and I have successfully used it for one back and two to work trips (15.5mi), and I have it on a lot of the time cause I'm lazy, though it did die at the last. If you are truly only leaving it on for 2.5 miles a trip, you would be just fine.

Kira

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Re: Those bicycle motor thingies
« Reply #17 on: October 01, 2013, 12:53:36 PM »

I think the 10 mile battery would be fine for short trips, but definitely get the lithium ion (4.4 Ah) one, not the SLA one. One thing that's not clear to me on the site for the hill topper is whether the motor incorporates a freewheel mechanism or not. Usually geared motors have a freewheel clutch in them so that the motor doesn't cause any drag when it's not in use, whereas direct drive motors often do not have this meaning that you have to have some power on the motor at all times to keep if from actually slowing you down. The Hill Topper kit lists the motor as a "planetary" motor which to me implies that it does incorporate a planetary gear set like mine, and therefore would likely have a freewheel as well, but I would confirm that before buying.

My wheel does not have any noticeable effect on the bike's motion if it's not on when going forwards. It resists a very tiny bit going backwards but nothing that has prevented me from doing anything.

I also haven't had issue with the wheel slipping, but I probably weigh a good bit more than the average MMM biker. :)

Posthumane

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Re: Those bicycle motor thingies
« Reply #18 on: October 02, 2013, 08:20:58 AM »
My wheel does not have any noticeable effect on the bike's motion if it's not on when going forwards. It resists a very tiny bit going backwards but nothing that has prevented me from doing anything.

I also haven't had issue with the wheel slipping, but I probably weigh a good bit more than the average MMM biker. :)
If it resists a bit going backwards but not forwards then it does have a freewheel mechanism on it. Mine does the same thing. In that case that is actually a pretty good price. The slipping wheel is only noticeable when going up a steep hill for me (like first gear, standing on the pedals to keep moving steep).


I think the 10 mile battery would be fine for short trips, but definitely get the lithium ion (4.4 Ah) one, not the SLA one.
Why is that?  Just because it's that much lighter?
Not only is it much lighter, but it actually will save you money in the long run if you use the bike a lot due to a much better cycle life. Lead acid batteries start to have a noticeable drop in capacity after as little as 500 cycles with hard use, whereas lithium ion batteries can sustain over 2000 cycles without a significant capacity drop as long as you keep the depth of discharge to less than about 80%. Another issue is Peukert's law (http://en.wikipedia.org/wiki/Peukert's_law) which expresses how much a lead acid battery's capacity drops with high rates of discharge. Lithium Ion batteries typically have a much lower internal resistance than deep discharge SLAs and therefore have less voltage drop under high discharge currents, giving you better capacity under load.

BTW, here's a video of me riding the electric assist folder into the city: http://youtu.be/hFotYl0ueyg
The hill that starts around the 12 minute mark is about a 6% grade, and I'm going up at about 15 mph.
« Last Edit: October 02, 2013, 08:25:40 AM by Posthumane »

Kira

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Re: Those bicycle motor thingies
« Reply #19 on: October 02, 2013, 09:00:40 AM »
I think the 10 mile battery would be fine for short trips, but definitely get the lithium ion (4.4 Ah) one, not the SLA one.
Why is that?  Just because it's that much lighter?
[/quote]
Not only is it much lighter, but it actually will save you money in the long run if you use the bike a lot due to a much better cycle life. Lead acid batteries start to have a noticeable drop in capacity after as little as 500 cycles with hard use, whereas lithium ion batteries can sustain over 2000 cycles without a significant capacity drop as long as you keep the depth of discharge to less than about 80%. Another issue is Peukert's law (http://en.wikipedia.org/wiki/Peukert's_law) which expresses how much a lead acid battery's capacity drops with high rates of discharge. Lithium Ion batteries typically have a much lower internal resistance than deep discharge SLAs and therefore have less voltage drop under high discharge currents, giving you better capacity under load.

BTW, here's a video of me riding the electric assist folder into the city: http://youtu.be/hFotYl0ueyg
The hill that starts around the 12 minute mark is about a 6% grade, and I'm going up at about 15 mph.
[/quote]

Very interesting! I hadn't been able to find much info on the SLA batteries on Clean Republic's website, and was concerned because I once had to use it before it had been fully charged. I ride almost every day and try to only charge it once per day, but it looks from what you said that the battery might not last the year. But they also have a one-year warranty on the batteries so I haven't worried about it too much.

The other thing I was concerned about was that I had read that lithium batteries don't perform well in the cold, and I do plan to use it in cold weather - any thoughts on lithium vs lead acid in the cold?

Posthumane

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Re: Those bicycle motor thingies
« Reply #20 on: October 02, 2013, 09:14:36 AM »
No battery performs well in cold weather, though I don't think Lithium Ion chemistries are any worse than other typical chemistries. You can expect a temporary drop in capacity of about 15% or so at 0 Celcius (32 F) compared to ambient (20 C / 68 F). Certain types of lithium polymer cells are more sensitive to low temps, but you likely won't be using those on a bike.

mustachejd

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Re: Those bicycle motor thingies
« Reply #21 on: October 02, 2013, 09:30:55 AM »
Thanks so much for all your responses!  Will still do more research (because what MMM'er wouldn't?), but it looks like the 10 mile lithium battery should be just fine for the likes of me. 

AlexK

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Re: Those bicycle motor thingies
« Reply #22 on: October 02, 2013, 11:56:19 AM »
I've had several types of electric and gas powered bicycle assist setups. Right now I have a gas powered setup and I love it. It is 12 lbs and the bike rides normally with the engine off, with engine on it goes 27 mph and gets 180 mpg. Also it sits off to the side so I still can fit a rear rack and panniers. The engine is single speed so not great at steep hills but moderate hills (6% grade) are fine. I have the Staton rear axle mount kit with Tanaka 32cc engine.