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:

FirstI madeplans andgear ratio

Planswere madetothescaleto facilitatemanufacturing andvarioustestsof setting up

Step 2:

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

whenyou changethespeedwhich wasledstartsto rotatein the airand it isanother thattakes over

brasswashersavoidsusury

for machininggearssupports, aspecial machine(mortiser) was used

I had todisassemblea lot ofspeedfreewheelbikein order to makethis arrangement

Ithenjust solderthe sprockets ontheir support

Step 3:

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:

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:

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:

tediousbutimportant step, polishing!

I used severalgradesandpaper:

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

thenpolishhasis sufficientvehicle body


Thisisthe same methodtorenovatetheplastic headlights;-)


someonetold meit looks likeasprocketsaquarium......lol

Step 7:

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:

for theselector,I usedpieces ofbrassIbrazedsilver

a smallplexiglasscovercanmake a little moresealedall


here is general aspect

Step 9:

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

here is the new system

Step 10:

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