Instructables
Picture of transparent gearbox on a homemade bicycle
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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
 
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Step 1:

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First I made plans and gear ratio

Plans were made to the scale to facilitate manufacturing and various tests of setting up

Step 2:

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the system consists of a shaft on which a gear is driven all the time and the two other turn in the blank

when you change the speed which was led starts to rotate in the air and it is another that takes over


brass washers avoids usury

for machining gears supports, a special machine (mortiser) was used


I had to disassemble a lot of speed freewheel bike in order to make this arrangement

I then just solder the sprockets on their support

Step 3:

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then, and still brass, I machined "sliding"

it slides on the shaft and causes a finger, which thanks to a spring, causes the pinion that is desired, while leaving the others free

just as a system of tractor mower!

Step 4:

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Then I set up a temporary Chassis mechanism to try ...

- Bottom 4 sprockets rotate at the same time
- Right there the output gear (the piece with the red lines allows to see the rotation)
- Top left, the three sprockets rotate independently of each other (the brass Shifting used to lock the one you want)



here you can see in works

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moein1 year ago
you are an ENGINEER . this is the only word i can say now
onrust1 year ago
SMOOTH........
wfelix1 year ago
Beautiful work! Congratulations.
This brings me some ideas to build a quadcycle :D.
robi_ncc1 year 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_ncc1 year 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
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_ncc1 year 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
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?
nubie1 year 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.
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.

http://www.rbracing-rsr.com/calculations.htm
vinsexe1 year ago
félicitation pour ce montage
sconner11 year ago
WOW
Edgar1 year ago
Two great concepts, the Gearbox, and the Bike, and went to my Blog.
http://faz-voce-mesmo.blogspot.pt/2012/12/avancos-contra-o-cancro-sobrevivencia.html
oimmuk1 year 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.
zymie1 year ago
Amazing project!
incredible! well done. i hope you win something for this!
jongscx1 year 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)  jongscx1 year 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
http://de.fotoalbum.eu/images1/200811/68604/204539/00000013.JPG
http://de.fotoalbum.eu/images1/200811/68604/204539/00000010.JPG


My system is also expensive, heavier, less reliable than speed hub has but it is more class and it's mine!
jongscx champx1 year 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!
manu19751 year ago
Good work!! it would be great to have a video with the gearbox working!!
jbotes1 year 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!
ROBBIE7771 year 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
IronYeti1 year ago
wow. just ... wow. you have combined great style with great geekness.
sockless1 year ago
Any chance someone could knock up some neater schematics for this, like in AutoCAD?
ZalDcaze1 year 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
MTJimL1 year ago
You've created a work of art, mechanically and visually.
thorbike1 year ago
Wow! I love what you've done here, very impressive! Thanks for sharing it too.
wobbler1 year ago
Clearly a genius at work.
bahi1 year ago
Amazing, looks professional!
oimmuk1 year ago
Great work there, not too sure I understand it all but I am not the best at visualization...
champx (author)  oimmuk1 year ago
reassures you it is not easy to understand for everyone, I have a twisted mind ...!
ZalDcaze1 year 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)  ZalDcaze1 year 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_bloke1 year ago
looks great!!
Mais c'est très bien ce petit boulot ! … Merci !… ;D

Very nice job indeed ! Thanx for sharing ! … 
People I knew of many years ago, said they used tooth paste and soft cloth to polish the plastic with.
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 !…
blanchae1 year ago
Great idea, what are the gear ratios for each speed? Very nice work, it came out beautiful!
champx (author)  blanchae1 year ago
ratio are:
-1st 12-23
-2nd 15-15
-3rd 17-13

output gear, 26-11

(number of teeth)
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