Introduction: Transparent Gearbox on a Homemade Bicycle

Picture of Transparent Gearbox on a Homemade Bicycle

I wantedcreate afor a long timebikewithgear boxin thebottom bracket

as IExpandeda rimrearhuband built acustomcoaster,
Icould not havegear....andI missed it!

I'minspired by oldbikes(1900),andtractor mowergearbox!

I usedbikegears,plexiglassandmachinedparts

I puttwo weeksto get the ideaand createplans
andabout 2 months torealizethe gearbox!

there are threespeeds andaxisdriveand outputare the same
theselection systemis brass

plexiglassboxisto see themechanism

Step 1:

Picture of

FirstI madeplans andgear ratio

Planswere madetothescaleto facilitatemanufacturing andvarioustestsof setting up

Step 2:

Picture of

the systemconsists ofa shaft on whicha gear isdrivenall the timeand the twootherturn in theblank

whenyou changethespeedwhich wasledstartsto rotatein the airand it isanother thattakes over


for machininggearssupports, aspecial machine(mortiser) was used

I had todisassemblea lot ofspeedfreewheelbikein order to makethis arrangement

Ithenjust solderthe sprockets ontheir support

Step 3:

Picture of

then, and stillbrass, Imachined"sliding"

it slideson the shaftand causes afinger, whichthanks toa spring,causesthe pinionthatis desired, while leavingthe others free

just asa system oftractormower!

Step 4:

Picture of
ThenI set up atemporaryChassismechanismtotry...

- Bottom4sprocketsrotateat the same time
-Righttherethe output gear(the piecewith theredlinesallows to seetherotation)
-Top left, the threesprocketsrotateindependentlyof each other(thebrassShiftingused to lockthe one youwant)

here you can see in works

Step 5:

Picture of

manufactureof the boxto receive themechanism

I askedafriendsto machine thebearinglocation

for the restI did everythingby hand,witha hole sawand ajig saw....not easy!

canperceivethe selectorandbearing housings

space that Ishows withmy fingersused to placethe gearboxon the bike

to assemblethe pieces ofplexiglass,I used aspecialglueplanned forthis

Step 6:

Picture of

tediousbutimportant step, polishing!

I used severalgradesandpaper:

100, 240, 400,800, 1000, 2500 and 4000

thenpolishhasis sufficientvehicle body

Thisisthe same methodtorenovatetheplastic headlights;-)

someonetold meit looks

Step 7:

Picture of

I was missing6 mmin order to closethe boxproperly ....
SoI usedorangeplexiglassto fill this gap

orange ...why?
because I loveorange
becauseaccording to the angleof view, reflectionsgives the impressionthat the entiregearboxis coloredsothatthere isveryfeworange

Step 8:

Picture of
for theselector,I usedpieces ofbrassIbrazedsilver

a smallplexiglasscovercanmake a little moresealedall

here is general aspect

Step 9:

Picture of
the spring of thecablenot beingeffective, I madeanother systembetter finishto tighten thecable

here is the new system

Step 10:

Picture of
remains only tomount thegearboxon my bikehomemade

I dono moredetailsthan thatthe bikebecause for methe main subject isthe gearbox!
a bikecustomissimple to dofor someone whoused to doit

evenwhenI putsome pictures of thebikeas I havealso spenttime on it

on the picturesit isa friendwho drives thebike
on thevideois me


guds777 (author)2016-10-27

cool project, and not to troll you or anything, but it is little hard to read your text when you don't use space in sentences.

vijay mohans (author)2016-03-01

great work. how much you did gain after this gear box, could you please explain and can you please post your work with 3D animation or diagram so it would be bit easy to make it. thanks

moein (author)2013-05-28

you are an ENGINEER . this is the only word i can say now

onrust (author)2013-01-26


wfelix (author)2013-01-21

Beautiful work! Congratulations.
This brings me some ideas to build a quadcycle :D.

robi_ncc (author)2012-12-24

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_ncc2012-12-24

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!

robi_ncc (author)champx2012-12-25

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_ncc2012-12-26

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 (author)champx2013-01-05

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?

nubie (author)2012-12-31

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 Hawaii (author)2012-12-27

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.

vinsexe (author)2012-12-27

félicitation pour ce montage

sconner1 (author)2012-12-25


Edgar (author)2012-12-24

Two great concepts, the Gearbox, and the Bike, and went to my Blog.

oimmuk (author)2012-12-24

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.

zymie (author)2012-12-24

Amazing project!

desertsniper (author)2012-12-24

incredible! well done. i hope you win something for this!

jongscx (author)2012-12-23

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")
Shimano: ("cheaper", but still much more expensive than regular sprockets)

champx (author)jongscx2012-12-24

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 (author)champx2012-12-24

I agree, yours is very classy. I had never seen the old-style gearboxes, thank you for showing.

Ludwig Von Mech (author)2012-12-24

Totally awesome! You did a magnificent job, there. Excellent Job!

manu1975 (author)2012-12-24

Good work!! it would be great to have a video with the gearbox working!!

jbotes (author)2012-12-23

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!

ROBBIE777 (author)2012-12-23

Amazing GearBox and Bike!!! I like it build one of my country is a little bit difficult but not impossible!!! Best Regards

IronYeti (author)2012-12-23

wow. just ... wow. you have combined great style with great geekness.

sockless (author)2012-12-23

Any chance someone could knock up some neater schematics for this, like in AutoCAD?

ZalDcaze (author)2012-12-23

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

MTJimL (author)2012-12-23

You've created a work of art, mechanically and visually.

thorbike (author)2012-12-23

Wow! I love what you've done here, very impressive! Thanks for sharing it too.

wobbler (author)2012-12-23

Clearly a genius at work.

bahi (author)2012-12-23

Amazing, looks professional!

oimmuk (author)2012-12-23

Great work there, not too sure I understand it all but I am not the best at visualization...

champx (author)oimmuk2012-12-23

reassures you it is not easy to understand for everyone, I have a twisted mind ...!

ZalDcaze (author)2012-12-23

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)ZalDcaze2012-12-23

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_bloke (author)2012-12-23

looks great!!

vincent7520 (author)2012-12-23

Mais c'est très bien ce petit boulot ! … Merci !… ;D

Very nice job indeed ! Thanx for sharing ! … 

vincent7520 (author)2012-12-23

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 !…

blanchae (author)2012-12-23

Great idea, what are the gear ratios for each speed? Very nice work, it came out beautiful!

champx (author)blanchae2012-12-23

ratio are:
-1st 12-23
-2nd 15-15
-3rd 17-13

output gear, 26-11

(number of teeth)

jolshefsky (author)2012-12-23

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"?

champx (author)jolshefsky2012-12-23

I think you understand the system

Here is a picture that illustrates the "finger"
the bolt allows the "finger" to be driven by the brass slider

the spring allows the finger go up into the holes of the gears

jolshefsky (author)champx2012-12-23

Thanks. That's similar to what I though. The spring allows the finger to dip into the groove on the shaft if the next gear's pinion is not aligned, and it snaps into place when it does align. Is that right?

champx (author)jolshefsky2012-12-23

you've got it!
But not being very good at English, I managed to clearly explain

for shifting, you must stop pedaling, engage the next gear and pedaling gently until that the gear is engaged

there are brass washers between each gear, they can bring down the finger to avoid two speed is trained at the same time

if there were not these washers, transmission break

champx (author)champx2012-12-23

photos of brass washers

robots42 (author)2012-12-23


kondoruy (author)2012-12-23

Excellent design, engineering knowledge and creativity made ​​possible creations like this, especially the skill to publish "in detail" and the desire to share with the community make it worth our vote.

Frans van Dijk (author)2012-12-23

Very nice, you have my vote.

champx (author)Frans van Dijk2012-12-23

thanks :-)

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