Picture of Make a Mini Recumbent from a Kid Bike
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Step 1: CAD system Layout

Picture of CAD system Layout
CAD (Cardboard Aided Design) layout of 12 inch wheeled small recumbent. Yellow lines show the chain line.

You can also see the Center of Gravity (approximately the bellybutton) is about 1/3 of the wheelbase distance ahead of the rear wheel contact point.  This good weight distribution leads to nice handling.

Step 2: Layout donor bike on CAD setup

Picture of Layout donor bike on CAD setup
Donor bike frame (black) positioned showing where Bottom Bracket (BB) will be near cardboard foot. Only the black BB and downtube will be used in the frame as a boom and BB.  We can also use the longer handlebars, later.

Step 3: Layout the Boom once cut from the Donor Bike

Picture of Layout the Boom once cut from the Donor Bike
Prepare to drill the Head-tube* sized whole that will be the miter (sophisticated, snug joint where two objects join at an angle).

The boom is positioned on head tube to see where to drill miter hole.  The drill with attached hole saw** bit is positioned to convey the idea of mitering.

* Headtube is the pink frame's front frame tube through which the bike's fork steering tube passes.

** Hole saw bit is the 1.5 inch diameter white toothed cylindrical saw in the drill chuck.

Step 4: Drill the hole that makes the Mitre

Picture of Drill the hole that makes the Mitre
With miter holes sawn, I cut away some of the black boom tube while leaving some reinforcing "wings" for welding to the head tube.

Step 5: Cut and File the Miter for the Joint

Picture of Cut and File the Miter for the Joint
12 inch bent dry 2.JPG
File and shape the wings.  The wings add joint strength and they help spread the pedal force from the boom to the frame.

Step 6: Use CAD to check chainlines, etc

Picture of Use CAD to check chainlines, etc

Layout the boom and frame on CAD to look at Chain-lines (shown here with Yellow battens)  Also look for leg extension and possible heel to wheel interference.   e.g. sometimes my shoes get scuffed by the front tire while riding some bikes I make, but not this one.

Keep adjusting (cutting or filing) the miter to keep it snug against the head-tube when the boom is positioned where you want it.
gravityisweak7 months ago

This is great! Could you add some huge curved handlebars to this? The steering looks less than comfortable.

Woodenbikes (author)  gravityisweak7 months ago
These little bars are a stretch down to reach. The good thing is they pass under the seat so you have a lot of steering input ability of low speed balance.
With big curved bars you want to maintain steering clearance so they need to be big enough to pass around the chosen (and possibly carved down) seat. A longer forward stem reach could help.
also double check to c if u have the same metals as well.
Cdn Sapper2 years ago
Amazing ible!
Love it! This will be my new project...
MaxineLaRue2 years ago
OooH! I want to see the video too!
This is super-cool.
rockgod12 years ago
Nothing quite like a grown man riding a small girls pink bike, lol.
snotty3 years ago
Nice ride!

But your video has disappeared and it's what really made this instructable. Any chance you could repost the video?
B4SEC4MP3 years ago
This is awesome! Might I suggest adding a wheelie bar!?!? That would take this bike to the next level. The only thing cooler than riding this bike down the street would be riding this bike down the street popping a wheelie!!!
husamwadi3 years ago
hey if you dont want those monkey lights.....heh heh heh :)
husamwadi3 years ago
this is cool, but man! I hope the tires don't pop!

-hey check out this mini recumbent i made, "POW, POW" uurghh, never mind...

Lol, just kidding, but this thing is really tight!

keep up the good work!
Cardboard Aided Design...nice
Woodenbikes (author)  mattthomas9920033 years ago
'Keepin' it real' since 2002.
Questor3 years ago
I notice a tire change.
minor mishap, perchance?
Woodenbikes (author)  Questor3 years ago
Dumpster bike problem... old rubber... tire bead wire was exposed and was puncturing inner tube. (Tire possibly not meant for plus-sized kids like me.) I replaced the tire with another dumpster tire from a high-end baby stroller.
toad3 years ago
Great ride, maybe bolting a rear deraleur somewhere around the headset to take up the slack in the chain. Some thing like a long cage mountain bike one.
Woodenbikes (author)  toad3 years ago
That would handle the chain, but with a rear coaster (back-pedal) brake, one would need to back pedal a whole revolution (winding up chain from the lower run and sagging it into the upper run) before the brake would engage.
caarntedd3 years ago
This looks super dangerous, and super fun. Five stars.
mjursic3 years ago
Love it! Now let's figure out a way to get a decent ratio on it so you're not pedaling like the dickens.
Daftehh3 years ago
my goodness look at it go
avicena3 years ago
when any body think it a junk, it can reused by some way...I like it!!...
The concept alone is great, but the CAD pushed it over into brilliance.

Wonderful work!
I know who I'll be voting for in the contest!
jovino3 years ago
HAHAHAH!!!! Brilliant!
macrumpton3 years ago
Very cute!
It looks like it could use a longer boom for your leg length.
Matin3 years ago
What a Cute and Fun bike!
I am keeping my eye out for small kid bike
How about no weld wood version
BtheBike3 years ago
SA-WEET !! I've been trying to mock up a concept for a cargo bakfiets style bike with a regular and kid bike . this give me a few ideas . great work Wood
berserk3 years ago
Very nice! Would not want to commute on it, but I have not had a bike make me smile like that in a while! :-)
I've been building recumbents since '86 and your first effort looks good. You did make one junior mistake... the bottom bracket threads are in reverse and will eventually unwind themselves loose.
Woodenbikes (author)  PurplePeople3 years ago
The BB shell is the large one piece crank type with press in thread-less bearing cups. (no threads there). The chain drive remains on the right hand (traditional) side of the bike. Nothing is reversed from traditional, so I do not expect anything out of the ordinary.
Yeah... I see that now. My bad. Maybe we'll see you at the races.
ilpug3 years ago
Of all the crazy stuff... I love it!
Alecw353 years ago
maybe you could add a 2 ring chainset to the pink bikes bb. then run front chain to smaller ring. big ring to rear wheel. make the gearing a little bit higher.
tho I geuss its the smaller diameter threadless bb. so wont easily take cheap mtb one piece cranks
Woodenbikes (author)  Alecw353 years ago
One could easily put the larger Mountain bike cranks and chainheel setup in the front BB for a higher gear. However, I'm building this bike to share with little kids so I wanted to use the short cranks to accomodate small and large riders and I wanted to use the small chainring to keep the top speed down the to 10-12 MPH for safety at Maker Faire. (It's crowded with excuberent people riding 8 of my bikes at a time.)
Great concept and fun but the mechanical advantage is probably less than desired
wobbler3 years ago
Utter madness! Somewhere in you there is Coco the Clown desperate to get out. I love it!
lemonie3 years ago