Introduction: DIY Balance Bike
During this summer holiday I decided to give my 20 month old son his own set of wheels, he had already been eyeing the bigger kids on their cycles for some time and I a summer project to hone my woodworking skills as well. Some internet research got my mind set on a balance bike. As it so happens I had some lumber lying around the house for over a year hoping to put to good use.
This is one of those projects which I almost entirely eyeballed with no pre-determined design or plan. If you have any questions about dimensions I can measure it and let you know. The main raw materials for this project are the 12" wheels, 1/2" X 3" soft wood planks from a pallet (wood unknown), screws and some nuts and bolts (6mm dia). I did not use any nails or glue (except for some shims and spacers) and the entire bike can be taken apart and reassembled whenever required.
And last but not the least enjoy making it with your son / daughter if possible (safely ofcourse). Living in an apartment it was kind of hard to actually hide from him while making it, atleast he learnt a few tool names and how to use a spanner, screwdriver and pliers :-)
Step 1: Rear Fork
To start with, first estimate the proportions of the balance bike with respect to your childs height, hand position and comfort. In my case I decided to have the center of the two wheels at about 2 feet distance. This would give me enough space for the seat as well as space for turning the front wheel. Since my son's inseam was less than the diameter of the wheels, the seat would need to be pretty low and between the two wheels. Remember the knees have to be slightly bent when they sit so they can firmly push the bike forward with their feet. The steering handle bar distance should be such that if they say turn left their are still able to hold on with their outstretched right hand to the right side of the handle bar.
First I tackled the easiest part, the rear fork. Two pieces of wood were measured, cut and drilled to hold the rear wheel axle between them. The other end has some pieces of wood cut and inserted to act as spacers and thin plywood was also inserted to act as shims.
The front end of the fork pieces was cut at an angle (to match the angle of the down arm), edges rounded and sanded for safety. This will be more apparent in later steps.
Step 2: Front Fork
The wooden pieces required for the steering are as shown in the first picture. It is held together by a long nut and bolt and the fork itself is inserted into chiseled holes on the top piece like a mortise and tenon joint. Everything is a tight fit and can be disassembled if required.
The steering axle is a steel pin about 8 mm in dia from a lever of a swivel chair, though a long bolt would also do. The positioning of the steering axle, the front forks and the thickness of the down arm determine how much the steering can be turned.
The distance between the forks is determined by the wheel axle spacing, measure it carefully and make the spacing of the forks slightly less so that when the horizontal nut and bolt is tightened it kind of grips the wheel tightly from either side.
More details of the steering axle in next steps.
Step 3: Down Arm
The most difficult part for me was shaping and sizing the down arm. With no pre designed plans to work with I first estimated the position of the seat then layed out the parts of the bike on the floor so I could estimate the angle and length of the down arm.
This consists of two identical pieces sandwiched together by another nut and bolt.
Next I drilled the hole for the steering axle. Unfortunately since I did not have a drill press and did it by hand, the hole was not exactly vertical and came out the other end off center by about 4 mm. This may seem small but it translates into a bigger problem due to the length of the front forks.
To fix this problem I had to fashion two aluminium bushes from blown pressure cooker safety valves that I had in my scrap pile after clearing out their holes with a metal drill bit of same dia as the steering axle pin.
Once the angle of the down arm is finalized, place it with the rear forks and drill holes all the way through for the bolts that will hold the rear forks and the down arm together. Make sure to drill perpendicular holes, preferably on a drill press. Wish I had one :-(
Step 4: The Seat
The seat is fairly simple. After laying out the wooden pieces relative to the other parts and marking them with a pencil I cut a tenon and inserted it into its corresponding slot in the seat back rest and secured it from the rear with two screws to form the slightly angled " -/ " shape. The back rest I made relatively high so one does not accidentally come in contact with the rear wheels while riding on the bike.
Some sawing and chiseling on the front end of the seat made sure it fit snugly against the down arm. The back rest goes all the way down between the rear forks and is held by screws from either side of the rear forks.
Most importantly, remember to round and sand the seat edges and if possible also add a padded seat cushion if possible. I'm thinking rexine with velcro, so it's removable in case you have to clean it or change the padding.
Making the seat height adjustable was not a priority for me and was making things a bit difficult. I think I should still be able ot increase the height buy about an inch or two in future if needed.
Step 5: Steering Axle
The picture shows the construction of the steering axle. If the hole is drilled right you don't need the bushes. Temporarily assemble the down arm with the steering to measure the distances for the spacers. The spacers are required and will allow the steering to turn since the down arm is at a downward angle and will interfere with the steering base when the steering is turned if spacers are not used.
Step 6: Assembly
The first picture shows the parts layed out on the floor with one fork each removed to give a cross sectional view of the assembly.
The second picture shows the underside of the bike to give a better view of how the bolts are used to hold the down arm, the rear forks and the seat all together.
I did not get the bolts the exact length I wanted so I bought the next available longer size and gut them flush with the nut using a hack saw. All nuts and bolts had washers so they wouldn't dig into the soft wood when tightened.
Step 7: Finishing
To finish off the bike I sanded all the wooden parts and used two coats of clear polyurethane to give it a waterproof finish. I used a clear coat so the nice wood grain would show through.
Unfortunately my son was a bit apprehensive riding it at first since he is still a bit too young to hold the bike upright on his own, so I made a slight modification to my original design and replaced the rear wheel with two balance wheels from a bigger bike. Once he is comfortable with this arrangement and gets comfortable with the bike I plan to put back the original wheel so he can balance it on his own.
I'll also be putting some reflective tape and possibly some flashing lights to make it more visible in the evenings when he is playing with it outside.
With the above changes and the finished bike I must say I feel very excited and glad that my son is now enjoying it thoroughly.
Balance bikes being a new concept here in India it is a bit difficult to explain the lack of pedals to curious folks and some what amusing when they don't know what to make of it. Anyway, I hope this inspires more people to take up woodworking as a hobby and share the joy of DIY with their children. Enjoy !!!
Step 8: The Seat
I finally got around to adding the sorely missed seat. I used a piece of packaging foam (EPE foam I think) wrapped with a scrap piece of rexine and held together with duct tape. A piece of para chord loops around the back rest, passes through the seat and is tied at the front.
I was originally going to pin the rexine to the wood using brass tacks, but decided with the above approach and see how it goes in case I need to change something later. Now that that monsoons are over, I am eager to see my son put it to good use outdoors.