I'd like to mount some kind of engine in my bike. To be more specific, i'm thinking about buying one of those cheap 50ccm mini-children-quad engines and strapping it on rear bike rack - it'll probably be unbalanced but screw it, i'm riding ~20km per day from village to city and this kind of aid would be great.
So, question: what is the best way to connect engine with bike wheel? Right now i'm thinking about getting additional chain and reserving one gear from cassette (or whatever rear gear thingie is called, sorry, i'm not native english speaker) for engine chain. It's not bad idea, but there is huge drawback - i'd have to do (less demanding) legwork because cassette would power front gear and pedals. Is there some kind of double-sided hub with two independent freewheels so i could spin only engine or only pedals?
I know there is a lot of pre-made solutions ready to be purchased, but i think i want to fool around, do something fun.
Or just buy a motorcycle? It'll be a lot safer and all...
>>988052
> Is there some kind of double-sided hub with two independent freewheels so i could spin only engine or only pedals?
Sounds like you want a flip flop hub for fixies. Or maybe fabricate something that attaches to disk brake mounts, since driving the wheel from the left side would try to unscrew the cog and put a lot of stress on the lockring.
But have you though about just getting a better bike with decent tires? 20km a day should be easy if you're in half decent shape and don't live on top of a mountain and work on top of another mountain. I do it and it barely even counts as daily exercise. Unless you're trying to do it on a crappy Wal-Mart mountain bike or one of those shitty 40 pound Dutch "city" bikes, since neither are meant to go more than a mile at a stretch.
>>988069
This is /diy/, not /just buy whatever because it'll be a lot safer and all/. You seem to be confused.
>>988082
You obviously new fag.
There's a reason why the suggestsion adding motors to pedal bikes will get you like look of a cunt.
Safety is one thing, road laws another.
If anyone really wanted to do it they can quite easily but the product would be an unsafe, unbalanced piece of junk that wouldn't be useable on any road or footpath. That is why we /buy/ bikes that are built for this purpose.
>>988079
I think i've seen something like that, but i'm not exactly sure about how it works. One of those gears is fixed, right? I want two free-flowing ones, so i can both power the bike with strength of my legs only or by engine only. I guess clutch will "do it", but i'm sure it'd be better if i wouldn't have to power two sides/gears/chains at once.
I'm definitely in decent shape (come on, 20km per day, every day except weekends) and i have rather decent street tires - also, my main bike is pretty lightweight. It's not like i'm getting exhausted after the ride, i just wouldn't mind engine doing legwork for me - and i just really want to make something like that.
>>988086
>the product would be an unsafe, unbalanced piece of junk that wouldn't be useable on any road or footpath.
Uh I'm not sure if you know this, but regular bikes with gas/electric motors on them are pretty common, and there are kits purpose-made for both.
Shit, I have two of them. Both under the limits set by federal/state law and legal to ride wherever I please.
Although the gas ones are somewhat more heavily regulated, particularly on bike trails, because nobody wants to be riding near that kind of noise if they can help it.
>>988094
Do you have electric one? How strong engine do you have to use to make it useful?
I think "real" engine would be cooler to make, but then again subtle leg aid made from one windshield engine and small 12v battery wouldn't be bad at all, and definitely more "sane".
Have you done any research op?
https://www.google.com/search?q=diy+gas+bicycle
>>988105
Yeah, but i failed to find a way to have two independent wheel gear thingies so engine won't make pedals rotate and vice versa.
>>988093
>One of those gears is fixed, right?
Yup. You can put a freewheel on both sides if you want, it's the same thread, but it would ratchet the wrong way on the left side. Some singlespeed freewheels look like they could be screwed on backwards (threaded all the way through), but that would cover the removal notches and probably unscrew under load, although I've had track cogs stay on with no lockring and a surprising amount of backpressure once they're on tight enough.
I think something like this is what you're looking for, and a BMX "southpaw" freewheel for the left side:
http://www.planetbmx.com/shop/profile-freewheel-/-drive-bi-hub-set-rhd-/-lhd-black-or-polished.html
>>988099
>Do you have electric one?
I have two actual bikes set up and two extra hub motors just lying around, though I haven't used any of them for a long time. The battery pack I was using died and I could never justify the cost of new ones. Don't kid yourself, as many advantages as electric bikes have over gas ones, price is not one of them. I recently scored an excellent deal on some bare LiFePO4 cells, so I'll be able to use them again soon.
>How strong engine do you have to use to make it useful?
That depends entirely on what you want to do with it. I'm a lazy shit, so more = better in my case. Back when I rode it on the regular, my main bike peaked at just under 2000W input power, which could get you up to speed pretty fast.
Assuming your in the US, however, you're legally limited to a "750W rated" motor and 20MPH without pedaling. The 750W thing can be played with pretty hard, since that refers to output power and the nameplate info on the motors used for this sort of thing tend to be very conservative in that regard. But do try and not get the attention of the popo by doing dumb shit like 40MPH on an urban sidewalk. Not because I'm concerned for you, but because I don't want these things to be legislated any more than they already are.
If you just want some pedal assist, that's a whole different story, and you can get away with a much less powerful motor and much less expensive setup overall. A small, 200W-ish motor will make casual riding a breeze, as that's roughly the continuous power of a trained cyclist in good shape. It's not going to haul you up hills by itself, but it'll help get you to work without having to change out of sweat-drenched clothes. You'll also get away with a much less expensive, smaller, lighter battery than if you expected to go 30 miles on a charge with no effort on your part.
Also a tip: Lead acid is not worth it anymore. There's not really any reason not to use lithium batteries unless you can get something else for free.
>>988296
>overclocks ebikes
>rides them on sidewalks, albeit slowly
>"Not because I'm concerned for you, but because I don't want these things to be legislated any more than they already are"
People like you are the reason they should be classed, registered, licenced and insured the same as as mopeds.
>>988344
>implying I ride on the sidewalks
>People like you are the reason they should be classed, registered, licenced and insured the same as as mopeds.
Except this is already the case? So uh, not sure where you're even going with that.
