I'm sure I'll feel pretty stupid after reading your answers...

GoldenMotor.com

spinningwheel

New Member
Feb 27, 2010
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phoenix, az
I'm as new to this motorbicycling as they come, so forgive my ignorance. I've long contimplated the possibilities of motorizing a bicycle, but I've yet to actually do it. It was when I began looking online to find ideas on how I would go about building my first, that I realized how widespread this hobby, sport, passion, ( Im sure there are many other words to describe "MB'ing" depending on who you ask) etc.. really is. I'm most interested in the gasoline( I call it ) pedal assist style setup. Though there are obviously many variations, it seems the majority have a common basic design. Having only seen still photos, and never having ridden one, I have a couple questions that will probably seem kind of stupid, but oh well... I guess I'd feel stupider if I were to build my first MB not having asked. I'm sure your answers will breed a ton more questions. So bear with me... please.
First, If the motor is basically spinning the same sprocket you pedal, Where are your feet while your full throttle down the road? on pegs? Or do the pedals not actually spin the equivalent of you pedaling 30 mph? Is there like a dual set of front sprockets... the manual sproket sits still like you were coasting, while a second is driven by the motor? Where can I see drawings of how this works? And lastly, can you run say a 5 speed or something converting the same rpms in front to many more in back as you gain momentum? Again please forgive my ignorance...I'm new here.
.xx.
 

bairdco

a guy who makes cool bikes
Aug 18, 2009
6,537
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living the dream in southern california
if you woulda delved deeper into how these work, you woulda figured it out.

but, since i'm a drunken insomniac, i'll give you the basic answers.

the motor driven sprocket is on the left side of the wheel. it's either the stock, bolted to the spokes set-up, or a hub adapter from manic mechanic (look at the advertisers to your left.)

your pedal sprockets and chain still drive your wheel, but when the engine is engaged, that side coasts, and the engine spins the wheel. it's not a plastic Big Wheel or a fixed gear type of set up, so you ain't pedaling at 35 mph.

as far as running gears, you can get a "jack shift/shaft kit from sick bike parts dot com and that'll fix you up. but you won;t be doing 80 in 5th gear, you just won't have to pedal off the line.

just start reading this forum. every question you have has already been answered, ten times over.
 

Allen_Wrench

Resident Mad Scientist
Feb 6, 2010
2,784
26
36
Indianapolis
A motorized fixie? If anyone has ever done that, please somebody record it and post it on you tube. It sounds like a high-speed heel swatter. How would you be able to walk after riding that insane, horizontal eggbeater and having nowhere safe to put your feet?
 

corgi1

New Member
Aug 13, 2009
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KCMO
Ok,I can picture that.....Thats those shoes and pedals that lock....back gear dosn't stop,....And once you start riding....,You can't stop or you fall over....I see,makes it easy on the trainer making you practice for races...
 

bairdco

a guy who makes cool bikes
Aug 18, 2009
6,537
264
63
living the dream in southern california
In all seriousness, you'd want to have a freewheel somewhere, or else you'd end up overrevving the engine during deceleration or downhills.

And if you're using a fixie hub in the back and a freewheel in front ... well, that's not a fixie bike, is it?

(Here I am, just built my first bike this winter, and I think I can correct a builder! Sheesh.)
the motor side sprocket is already a fixed gear. about as fixed as it gets. the clutch is your freewheel.