Build a Kid's Long-wheelbase Low Racer Recumbent Bicycle





Introduction: Build a Kid's Long-wheelbase Low Racer Recumbent Bicycle

This is a companion piece to my other instructable on building a low racer recumbent. My oldest kid likes to ride bikes, too, and had to have a racer to match mine. It was a much easier build and I'm very pleased with the results.

Step 1: Materials and Tools

  • One whole kid's BMX-style bike with 16" wheels
  • The steering tube and steering components from another bike (or some ingenuity)
  • One length of 1" EMT electrical conduit (around $7 for 10')
  • One length of 3/4" EMT electrical conduit (around $5 for 10')
  • A couple of feet of 1" x 3/32" mild steel or some other stout steel for brackets
  • Enough 1/2" - 3/4" plywood to fit your kid's back and posterior
  • Miscellaneous nuts, bolts and screws
  • Optional: An old 3-speed bike for the rear hub, front sprocket, and chain guard

  • Flux core welder, welding gloves, tip dip, wire brush, chipping hammer
  • Various clamps
  • Angle grinder with cutoff/grit/wire wheels
  • Bench grinder with cutoff/grit/wire wheels
  • Hack saw
  • Bike assembly tools
  • Woodworking tools (to cut out and shape the seat)
  • Files/rasps

You will also need a positive attitude, patience, creative thinking. If you have a child helping, please use common sense and pay extra attention to safety. Explain what you intend to do, why it is unsafe and what you are doing to make it safer. Make this a fun learning experience, not a trip to the hospital.

Step 2: Disassemble and Cut Frame

Strip your donor bike down.

If you are careful with the source bike you select, you should only have to cut the frame in three places.
*where the top-tube hits the seat tube
*where the bottom bracket and chain stays intersect
*where the seat tube and the bottom bracket intersect

If your donor bike top tube doesn't match up with the 3/4" conduit well, you will just want to remove the top tube entirely and replace it. Try to avoid this as it makes things trickier.

Step 3: Extend Top Tube and Chain Stay

Measurements are tough on this one, but you will need to add conduit to stretch the bike out. Base the measurement on the length of the rider sitting down with legs stretched out. The new tubes should allow for the measured length from the seat back (with padding, etc.) to the pedals when they are as far as they get from the rider.

I was able to jam the new top tube piece into the old top tube and weld. If I had more time, I would have smoothed this transition a little more with body filler. Weld the top tube about halfway down the seat tube.

The new chain stay piece will attach centered up where the old one did on the bottom bracket. you will have to make a little bracket for it to attach to both the bottom of the seat tube and the chain stays. If you attach the new tube to the bottom of the seat tube, it will be too high to weld to the old chain stays, so I cut the tube so that I can weld a piece of 1/8" stock to both the new and old chain stays. That bracket is shown below.

I do my best to keep everything straight and have had pretty good luck with eyeballing it. These long bike frames are long enough that you can see if something is off. If you aren't confident in your eyeballing abilities, clamp the frame to something you know to be straight when you weld to form a temporary jig.

Step 4: Steering

Now to create the remote steering. This is where a second head tube assembly from a junker bike is handy. If you are clever, you could fabricate something and just use one bike for the project.

The measurements are iffy on this one. You will want to measure it to the passenger. The easiest way is to assemble the head tube together with handlebars and have your rider hold it somewhere comfortable. Measure up for a riser tube to mount the head tube to, cut, fit, and weld. Try to make sure that the remote head tube is close to the same angle as the donor bike's head tube. Its also good to make sure that you can make the tie rods for steering fairly level.

My tie rod ends were from Wick's Aircraft Supply and are really nice, but probably the most expensive part of the bike. I've heard of people buying them cheaper at Summit Racing Systems (which is only a few miles from me - d'oh!). The images below illustrate how the tie rod ends are connected. The tie rod itself is made from 1/4' scavanged round stock. I cut threads to match the tie rod ends.

To make sure things were secure, I created a gusset for the remote steering tube out of and old crappy kid's bike gear.

Step 5: Seat

The seat is simply plywood with a few brackets holding it together. I covered it with foam and some leftover denim fabric I had. The seat is attached at the bottom with brackets made from tubing split down the middle with wings attached. See the photos for details. The rear bracket is bolted to the old seat adjustment bolt holes. In theory, you can re-drill the bracket and scooch the seat back as the rider grows.

Step 6: Prep and Paint

Go over all your welds again and fill with body filler. Sand the body filler smooth, prime, sand, and prime again.

The paint my son chose was fluorescent yellow and was a flat finish. To make it shiny, I added a clear coat.

The front fork was painted gloss white with a coat of 3M retro-reflective clear. You can really see this bike coming. It's hard to look at in the sunlight!

Painting all the little brackets was time consuming, but worth the effort. I even ended up painting the old Raleigh emblem white and refitting it.

Step 7: Assemble and Ride!

I let the paint dry several days in the sun. It still is soft (a year later!), so I have to be careful with it on the bike rack - I usually wrap and contact points in a plastic bag. I ended up cutting out small grommets and washers out of a 2-liter soda bottle so that the nuts and bolts wouldn't mar up the finish.

I gave everything a good dose of quality bike grease and cleaned up and lubricated the chain. After mounting and adjusting the brakes and the shifting mechanism, we were ready for a test drive. It was a little twitchy at first, but he got the hang of it quick.

I added a few photos with measurements so you can get an idea of seat size, etc.

This bike turns heads everywhere we go with it. My son likes the ride and loves the attention he gets. Because it's a 3 speed and comfortable, I can take him with me on rides that I couldn't before.



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    67 Discussions

    If you want to buy "tie rod ends" from your local specialty hardware store you are going to want to ask for "heim joints"

    Great instructable by the way I love it!

    hey Homba, love the build. I'm getting stuff together to build one and was wondering if any major differences using a 20" kids bike instead of 16". I have parts of a 20" left from my first build.

    for the steering i would have just cut the frame and re welded it so alls you need is a longer peace of pipe

    This has inspired me to at least try to build a recumbent unicycle. Now that would look cool cruising down the street.

     Thanks much for sharing this and your other plans.  Both look great.  I'll be using your plans as inspiration to build my first recumbent.  Thanks again.

    I wish I could - not enough used bikes for raw materials laying around. If you can get a hold of a bike and borrow/beg a welder, you should try a build - this is not a difficult project. There's only 5 welds or so on the frame and 4 welds for the seat brackets. Everything else can be done with simple hand tools (hacksaw, files, etc) and a drill. A grinder and wire wheel attachment would help, but is only a time-saver.

    Budget - definitely ... scrounge bikes from the trash, EMT tubing is well under $10, and a can of primer and a can of paint is cheap. The most expensive items would be the tie rod ends and a die to cut threads (but you could probably just buy threaded rod cheap) No Welder - maybe ... you might be able to do some clever bolting, but it won't be very strong and might be dangerous. A welder can be pricey unless you're clever and a little risky and build one of the frightening 'ible welders. I would get everything cut out, cleaned up, and ready to weld and see if you can nicely ask your local school or trade college if the students could weld it for you. I've had some success with that in the past. Pizza and a couple of 2-liters of soda are usually appreciated. Do you have an uncle or brother-in-law or a co-worker that you can beg to weld it? Offer to scrounge an cut out a frame for him/her if they will do the welding. I've done that before to get access to a tool I couldn't afford. If you give it a lot of thought, I bet you can come up with a solution. My uncle has tons of tools (he used to own an auto-repair shop), so I would often bring over lunch to get access to a tool I needed. He'd often get interested and help out, too. If you put it out there, you might even find someone on the site that lives close that would be kind enough to help out. You can do it! Just get into that creatively-cheap-a$$ mindset and come up with a solution to your lack of resources - trash picking, thrift store-ing, scrounging, and bartering are great skills to develop and have :)

    I've seen that one - I say go for it. Front wheel drive is odd at first, but you get used to it quick. Good Luck!

    do you know where i can get a 20" bike for about $10-$20?(for front wheel drive.)

    I always either do thrift store or trash pick ... if you put it out there to neighbors and relatives that you are looking for free junk bikes, that will often work. You might not get exactly the bike you are looking for, but I bet you'll end up with more old bikes than you can use (I've had that happen in years past). At this point, I find mostly 80's era 10 speed road bikes, crappy walmart/target "Magna" brand pieces of junk, 16" kid's bikes, and 20" bmx bikes. I use the 10 speeds if they are good quality, strip the magnas for parts if they are any good, use the 16" and 20" for stuff for my kids and recycle what's left over. Having said that, it's been around 2 years since I've done any bike building. My kids are growing out of what we currently have, so next spring may be the time to start up again.

    well,what frame materials do i need,i think one of my neighbors(lots of tools with him,you should see his garage...)has a welding tool(im not 100% sure...) that i might be able to get help with...

    You need EMT from the local hardware store (Lowe's, Home Depot, etc.). It is metal electrical conduit and the cheap bike builder's friend. They are almost always galvanized (zinc coated). Please make sure that you sand/wire wheel/chemically remove the coating 2 inches or so away from where you will be welding. Also weld outdoors and use a fan to blow the fumes away from you (blow it across the work in front of you). Burnt zinc fumes will give you metal sickness which isn't deadly, but it's really unpleasant and long-term not too good for you. There is and 'ible somewhere that shows how to remove it with drain cleaner or toilet cleaner (can't remember the details, so you might want to look it up). I always sand the ends with emery paper until you get to the shiny metal underneath. If you can find a copy of "Atomic Zombie's Bike Builder's Bonanza" from your local library, it's definitely worth a read. The author (Brad Graham) is on the site and has posted a couple 'ibles as well. I didn't end up building any of his designs, but they are a good starting point if you haven't done anything like this before.

    It should - you'll probably want to bump your tubing up to the next size (or measure the bike frame tubes and match them).

    I guess I missed the step where you explain the steering mechanism. Could you give me some detailed information on it? I have a couple of donor bikes and I'm currently learning welding, MIG, TIG and 70/13 as well as fabrication. Thanks