Picture of transparent gearbox on a homemade bicycle
I wanted create a for a long time bike with gear box in the bottom bracket

as I Expanded a rim rear hub and built a custom coaster,
I could not have gear .... and I missed it!

I'm inspired by old bikes (1900), and tractor mower gearbox!

I used bike gears, plexiglass and machined parts

I put two weeks to get the idea and create plans
and about 2 months to realize the gearbox!

there are three speeds and axis drive and output are the same
the selection system is brass

plexiglass box is to see the mechanism

Step 1:

Picture of
First I made plans and gear ratio

Plans were made to the scale to facilitate manufacturing and various tests of setting up
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moein2 years ago
you are an ENGINEER . this is the only word i can say now
onrust2 years ago
wfelix2 years ago
Beautiful work! Congratulations.
This brings me some ideas to build a quadcycle :D.
robi_ncc2 years ago
First congratulations for beautiful work.

You told that “I put two weeks to get the idea and create plans and about 2 months to realize the gearbox!”

I want to Design my own gearbox. So can you tell me which books help you to get the idea or information to make or design your gearbox?

Please please please help me!
champx (author)  robi_ncc2 years ago
I searched a lot on the internet but I have not found much information ....

I wants to make available the most interesting of my research:

system speed of tractor mower (pic 3)
bikes with the old gearbox in the bottom bracket, (pic 6-8-9)
a gearbox-chain (pic 5)
one shema gearbox compact bike that I colored (pic 4)
other system (pic 1-2)
mine is a mixture of all that

on the schema of the photo No. 7 there is a simple freewheel system
it did not suit me at first because speed we can not pedaling backwards .... therefore the coaster brake that was not possible!

otherwise it is a simple system realize!
4904661856_9cdf0a020a_o.jpg612px-L-gear1.pngtransmission_for_lawn_mower.jpgpedalier couleurs.jpghoffmann-gearbox-003.jpgH1118-L13425964.jpgbv11.jpg128502987.oN1ekV0j.expovvwol12.jpgmagna debon.jpg
robi_ncc champx2 years ago
How do you calculate gear ratio, number of teeth in pinion, speed and torque etc?

And if I want to design my own gearbox what information do I need?
champx (author)  robi_ncc2 years ago
for calculating gear ratios, it is not easy to explain with a translator ....

for example, a standart Crankset about 45 teeth
the sprocket wheel is about 15

I used the principle of:

A = 20 teeth on B = 10 teeth
axis speed equivalent, B will turn two times faster than A

after I did a lot of multiplication and division

the rest has to give you ideas, observe plenty of mechanism and keep only what can be used on your gearbox
robi_ncc champx2 years ago
You told me that "it is not easy to explain with a translator .... "

So can you give me formulas that you use to make your gear box?
nubie2 years ago
You can have a setting that simply connects the pedals to the output.

That would yield 4 ratios with no more chain or sprockets. simply make engagement from the brass selector ring to the output.

Nice project.
Blue Hawaii2 years ago
Wow! Really nice work! Very clean design. Your final project looks like a lot of fun to ride.

I have used the following page to find many calculators when designing my projects.

vinsexe2 years ago
félicitation pour ce montage
sconner12 years ago
Edgar2 years ago
Two great concepts, the Gearbox, and the Bike, and went to my Blog.
oimmuk2 years ago
I believe with his shown skills he might be able to make a Nuvinci style gearbox for coaster system, after all it was invented by Leonardo Da Vinci so there should be no patent infringment, and if he did not seek to market it there should not be any conflicts at all.
zymie2 years ago
Amazing project!
incredible! well done. i hope you win something for this!
jongscx2 years ago
Holy Balls, that's amazing. Do you do this professionally as a bike builder?

In regards to your comment of needing gearing for a wide rear wheel, they have Internally geared rear hubs. They are expensive, but let you have an 4-speed or 8-speed with only a single rear sprocket.

Nuvinci: (these are crazy expensive, but rather "cool") http://www.youtube.com/watch?feature&v=IZoSnzvHADQ
Shimano: ("cheaper", but still much more expensive than regular sprockets) http://en.wikipedia.org/wiki/Shimano_Alfine
champx (author)  jongscx2 years ago
No, I work in industrial maintenance!

I know there are speed hubs but few have the coaster
they are very expensive but if I wanted this system is that I fell in love with the old bike gearbox in the crankset

My system is also expensive, heavier, less reliable than speed hub has but it is more class and it's mine!
jongscx champx2 years ago
I agree, yours is very classy. I had never seen the old-style gearboxes, thank you for showing.
Totally awesome! You did a magnificent job, there. Excellent Job!
manu19752 years ago
Good work!! it would be great to have a video with the gearbox working!!
jbotes2 years ago
Well done this is the most appealing instructable I have seen yet! I would love to know more about how the selector works. Excellent job! Well done!
ROBBIE7772 years ago
Amazing GearBox and Bike!!! I like it build one of this..but..in my country is a little bit difficult but not impossible!!! Best Regards
IronYeti2 years ago
wow. just ... wow. you have combined great style with great geekness.
sockless2 years ago
Any chance someone could knock up some neater schematics for this, like in AutoCAD?
ZalDcaze2 years ago
Im always looking for more ideas to incorporate into my tinkering... ill have to get up off my butt to actually build this trike now tho lol
MTJimL2 years ago
You've created a work of art, mechanically and visually.
thorbike2 years ago
Wow! I love what you've done here, very impressive! Thanks for sharing it too.
wobbler2 years ago
Clearly a genius at work.
bahi2 years ago
Amazing, looks professional!
oimmuk2 years ago
Great work there, not too sure I understand it all but I am not the best at visualization...
champx (author)  oimmuk2 years ago
reassures you it is not easy to understand for everyone, I have a twisted mind ...!
ZalDcaze2 years ago
I Enjoy this idea and was wondering how i would have a gear change system on a custom tadpole trike i am attempting to build... With your gear box its possible to have a decent gear range in a compact design. Also its beautiful in orange!
champx (author)  ZalDcaze2 years ago
there are plenty of other ways to make a gearbox that is beautiful!

For example, taking a speed hub and putting in a plexiglass box
I started thinking about this for custom system I build for my brother

another and put a derailleur shifter and hubs bike in a box

my gearbox is not the easiest or most reliable in the long term, I would have to heat treatment of the gears to be on the strength
(steels used are planned for!)

if you really want to launch you, I can give you ideas
diy_bloke2 years ago
looks great!!
vincent75202 years ago
Mais c'est très bien ce petit boulot ! … Merci !… ;D

Very nice job indeed ! Thanx for sharing ! … 
Yes you're right ! … They did that when I was a kid : it is because at the time (still now, may be) they used very fine marble dust (as fine, or even finer, as talcum powder).
I did buy an older tooth paste that still exists here (Email Diamant : the one with the toreo as an icon) and it works !…
blanchae2 years ago
Great idea, what are the gear ratios for each speed? Very nice work, it came out beautiful!
champx (author)  blanchae2 years ago
ratio are:
-1st 12-23
-2nd 15-15
-3rd 17-13

output gear, 26-11

(number of teeth)
jolshefsky2 years ago
This is amazing! I make bicycle frames myself but nothing as nice as yours.

I was a little confused in step 3 when you mention the "finger" that slides. I think this is a wide, U-shaped bar: one end has holes to screw onto the brass shift slider, and the other has a square tab that locks into the grooves on the inside of each sprocket holder. Could you show a picture of this "finger"?
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