Shiftable Gears



Ok I had a thought. Rear derailer? out of the question. Front! might just work? Crude image below and I will explain.



Fixed the image as noted in post below.

Ok there is multiple rear sprockets I can get in size. I am thinking if I stack 3 of them. 48, 44, 36. Once stacked I can run a stainless steel pipe so that I can mount a crankset front derailer on it. That would allow the chain to pass through and kick from one cog to another on the rear allowing for use of all 3 cogs? More or less giving the capability to have somewhat shiftable gears?

What do you think? By the way I am horrible at explaining myself but I hope that this works. I am not a mechanic I am a computer nerd :LOL:
using the front-derailer is a new concept here i think, i can see how it might be worth a shot, tho...
I searched around looking for information on it but I figure a front derailer can be used as its wider and able to handle the chain and really no "force" is pushed on it to a degree. So you would turn the wheel cogset almost to a crankset cogset so to speak. That was my thought

oops I just noticed I connected the chain to the crank... Yeah its horrible drawing... I was meaning to connect that chain that is on the crank to the engine

Would anybody be able to get me the width of the chain used on a 80cc?

Image Credit to

As seen in this image if needed I should be able to expand the size of the cage with the cage screw? As well I might be able to just bend the cage itself and make the chain fit.

if my brain is working right a derailer like this should fit just fine ontop of those cogs and allow for changing? As most front derailers move up/down as well as in/out.
SlicerDicer said:
Would anybody be able to get me the width of the chain used on a 80cc?
415 or .081 is the size I believe you are looking for.

BTW- "empirical testing" is always the best!
By using front deraileurs, how would you go about keeping the chain tensioned? I am a visual learner, so I would appreciate some pics or somethin that I can put in my mind.
joeranton said:
By using front deraileurs, how would you go about keeping the chain tensioned? I am a visual learner, so I would appreciate some pics or somethin that I can put in my mind.

Bikes with front derailleurs still require a rear derailleur or spring-loaded tensioner in order to work, otherwise you wouldn't be able to change the gears.

Ok another terrible crude image.

The way it will work on this "does not include stack/derailer".

The roller will be one of the rollers I can get for the chain but instead of it being just fixed. I will attach it to a simple hinge and then attach that to the bike frame so it can move up/down. Once that is done I will take a spring attach it to the hinge/roller and then attach that to the bike frame. Once done the spring will be under tension as soon as the roller is lifted. This will allow for a bit of tension to be adjusted as the chain moves up/down and should not need that much more play.. if it does I supose I could come up with something a bit more complex but this is a starter idea.

I may need to make a roller fold in on itself similar to a rear derailer but that should not be too difficult to do. In all honesty I have no idea how I would do it till I have it in my hand. But I am sure there is a way to do it and this is just a start idea... Not to mention these are extremely hard for me to draw :) I need a dang tablet.. maybe I will just render it in Povray and be done with it.
i don't have much input about the gear-topic, but the simple spring-tensioner you'll be needing will be an easy "afterthought"...i'd love to see this work 8)

edit: you were a step ahead of me :LOL:
I wont embed it as it will be huge. I am rendering the bicycle here if you wish to see the start of it. I will be updating it as i get more and more completed. This is just the bike frame and tire so far.

EDIT: This is a mtn bike frame as it is easier to render.

I just completely changed the lighting of it to be able to see it easier. All that is lacking in the rendering above is the labels as well as the front derailer to make a better drawing of it :)
Alrighty! I got the image done.
MBc EDIT: i removed the image tags, click the link for the pic. ".png" files are much too
large for dial-up members to wait for.

This is my idea. I however flipped the chain tensioner around and did a bit of playing with it. The reason for this is due to the way the chain goes around. I assume from just thinking about it that the bottom chain will be the driving and top will be return. However this leaves me with a bit of a pickle as I need to switch it around to where the derailer is on the bottom at the drive chain. I will update the image to reflect this when I have a bit more time. This is why I did not label the derailer or cogset. I will also render the cogset/derailer itself and make it understandable a bit easier.

This is my plans for now of course that does not mean they will not change. I took the design for the tensioner from a normal rear bicycle derailer as it seems that would allow for more slack chain being usable. Right now the pipe that runs from the seat is the rear carrier :)

Ok question.

44, 42, 36, 30? doable? will that sprocket work? or one like it?