My daughter had really been enjoying riding on all manner of toddler-sized ride on toys so my wife and I thought it was time she learned to ride a bike. Pedalling could come later, for now what she needed was a balance bike. Only problem was, despite her height, she was too short for most of the balance bikes on the market (plus they were expensive with plastic wheels...ugghhh).
So I had the idea of slightly modifying an old bike we found during the local junk collection.
To make the balance bike you'll need:
1. Donor bike/s (I actually used 2 bikes to get enough good parts to make the balance bike)
3. Spanners, sockets or adjustable wrench.
5. Safety Gear!
Optional tools to make the job easier/faster/more fun include:
1. Angle grinder with cutting disc and sandpaper/flapper disc
4. Chain Breaker
5. Extra safety gear!
Step 1: Strip the Bike/s
I used two bikes to end up with the finished balance bike, taking the frame from one (bike 1) and adding the handlebars, wheels, seatpost and seat from the other (bike 2). You could just use one bike, in which case just keep everything you remove when stripping and put it back on afterwards. You could also skip steps 9 and 10 if using 1 bike.
The basic idea was to undo and remove everything from bike 1, cut bike 1 down, and then add back the bits from bike 2 using similar steps. If you're not familiar with bikes I highly recommend taking photos every time you undo something or remove something so that if/when you need to put it back together, you have a reference.
High level stripping sequence was:
1. Remove front wheel
2. Remove chain
3. Remove back wheel
4. Remove chain covers/guards (outer)
5. Remove pedals (these are threaded opposite ways)
6. Remove cranks (undo the washer with grooves in it using a screwdriver, old chisel or similar.
7. Remove bearings (be careful, these can go everywhere)
8. Remove chain cover (inner)
9. Remove brakes (from handlebars and forks)
10. Remove handlebars and stem (undo the bolt at the top of the stem).
11. Remove seatpost and seat
12. Remove seatpost clamp
Notes: I found it easier to put the bike in a vice once the front wheel was off. Most these items can be removed by simply undoing whatever nuts or screws are holding them in place. The pedals are a little trickier, for reference on how to remove these head over to youtube. I used my chain breaker to remove the chain, but just cutting it with a hacksaw or angle grinder would do the job, just make sure you clamp it firmly before cutting. Also you don't really need to remove the wheels if you're going to reuse them, but I didn't want to accidentally damage them when cutting down the frame. Lastly the seatpost clamp on my bike had been spot welded to the frame, but a little attention with a file and some gentle persuasion with a hammer soon had that off.
Step 2: Cut Down the Frame
As I said in the intro, the main reason for building this balance bike was to get the seat low enough that my daughter could ride it comfortably. This meant that both the top tube and the upper rear stays needed to be completely removed, and the seat tube cut down to size.
To do this I clamped the stripped frame from bike 1 in a vice and used an angle grinder to cut at the locations indicated in the photo above. BE CAREFUL WHEN CUTTING. You don't want to accidentally damage the dropouts for the rear wheel, the steerer tube, or mostly yourself!
Once cut I used a flapper wheel (sandpaper disc) on the angle grinder to smooth off the rough edges so no-one would cut themselves. You could use a file or sandpaper to do this manually too.
Step 3: Trial Fit
To make sure I had the height right I wanted to do a trial fit, which meant putting the wheels and seat back on. Once done it was a simple case of putting my daughter on the bike, seeing if she could touch the ground, cutting a bit more off the tube and seatpost, and repeating the process. She mostly cooperated however mileage can and will vary.
Once I had the height right I cut a notch/groove in the seat tube using the angle grinder (similar to what was on the donor bikes) so that the seat clamp would be able to grip the seatpost properly. It doesn't have to be perfect, just mostly straight and about the same length. Then I fitted the seat and checked the height again using the process above before tightening it all up.
Note: I didn't bother painting the bike as it was in pretty good condition, but if you were doing this as a present or wanted it to look incredible then this is where you'd strip/sand/prime/paint. I won't go into details here, just do some research on painting aluminium/steel.
Step 4: Fitout
With the height correct it was time to put the handlebars back on and make sure all the wheels and seatpost were done up tight. Remember to refer to your photos if you can't work out which bit goes where. Also you don't need to fit the pedals, cranks, bearings, chain covers or chain, as these will only get in the way of your little ones legs.
One thing to note is the orientation of the back wheel. This can be fitted with the cog on either the left or the right and this matters if the bike is fitted with a back-pedal brake (most kids bikes are). Easiest way to work it out is fit the back wheel and give it a few spins (bottom of the wheel spun towards the back of the bike, ie ground goes backwards). If it feels like it's catching, slowing down prematurely or just not running freely, take it off, turn it around, and try again. This makes sure your toddler isn't working any harder than they need to.
Step 5: Enjoy!
One final triple check that everything is done up tight and the balance bike was ready for a trial run!
For those worried about strength, I weigh 85kg (~187lbs?) and can sit/ride on this bike without it flexing or breaking. I certainly wouldn't take it off a kerb with me on it, but there's no way my daughter is going to generate that kind of force.
I will just mention that if you ride a bike you should wear a helmet, and that this balance bike is a good place to start the habit. Get a good kids helmet from your local bike shop and you can't go wrong. Plus they love wearing their 'pretty riding hat'.
I hope you found this instructable useful, it saved us a decent amount of money and meant my daughter could start her riding adventures earlier.
Step 6: Future Modifications
Presently my daughter doesn't like riding the bike too much because it's quite wobbly (and she's not 2 yet, so still getting the hang of balancing). One thing I do want to do is replace the 'riser' handlebars with a set of flat bars so that they're easier for her to use.
I may also decide to sand it back and give it a good coat of paint (and a new basket) but that may have to wait a while.