A couple years ago, my neighbor threw out a 10" bicycle during the annual spring clean-up trash day. My son was only 1 year old at the time, but I knew that he'd eventually want a bicycle. The bike was perfect - tires still hold air, but one of the plastic training wheels was busted, and the other was cracked. I grabbed the bike, just intending to replace the training wheels when the time came. Fast forward to present and my son is almost big enough to start learning how to ride a bike, so I decided to fix (or make) new training wheels.
It's way more cost effective to go buy replacements for $10, but where's the fun in that? I doubt anyone will use this method to fix their kids training wheels, but I'm writing this just to show that it's possible. And maybe I'll show how to do a process in a way that you haven't thought about before...
I was also looking for a reason to try a "tiring" method that I plan to use on a [very far future] Penny Farthing bike build, and this fit the bill.
Step 1: Cut the Hubs
I used some scrap oak hardwood flooring for the hubs of the wheels. I used a table saw to trim the tongue and groove and square up the stock. I then stood the piece on it's side to remove the grooving from the underside of the scrap.
Using a speed square, I drew 45 degree lines from the corners of the short edge. This will give both the center and the opposite edge of the square. Use a compass to draw the circle to the desired size.
I used a portable metal-cutting bandsaw that I have mounted on a homemade stand with a homemade work table to make the following cuts. Cut the hub blank into a square and make some relief cuts up to the diameter of your circle. Using a 1/16" drill bit, drill through the center point of the blank. Position the blank on the bandsaw table so that the square edge of the blank is against the side of the blade and the midpoint of the square edge is at the blade teeth. The blade should be at a tangent to the circle drawn on the blank. Mark the table through the center hole of the blank and drill a hole in the table. Use a finishing nail through the blank and into the tabletop as a pivot for cutting the blank. Note: a tablesaw can also be used in a similar manner, but should be done utilizing a pivot point that is made into a tablesaw sled.
Step 2: Gettin' Groovy
I used a 1/2" cove bit on my router table to cut a groove around the circumference of the hub. I positioned an auxiliary fence so the cove would be centered in the edge of the hub. I cut a cove in one section of the hub. With the router off, position the blank directly over the bit and transfer the center mark and drill a pivot hole in the fence. Use the same nail as earlier to rotate the blank and cut a groove all the way around the blank. My cove bit wasn't the sharpest and the oak is pretty hard, so I got some burn marks. These can be sanded out if desired, but they'll get covered up anyway.
Step 3: SPEED HOLES!!
This step is purely for performance - because you can't go fast without SPEED HOLES!!
I marked out a center line for the holes and decided to go with a 5 hole pattern. I used a protractor to mark out the 72* segments (360* / 5 = 72*). I used a forstner bit in the drill press to drill the holes. I decided to drill both hubs at once, so I used the nail to join them at the center point. After the first hole was drilled, I used a socket through the hole to index the two hubs together.
After the first 5 holes were drilled, I decided to do some smaller holes centered between the larger holes. Once all holes were drilled, I followed up with a light touch of a large step bit to give the holes a little visual depth. Then I hit them with some sandpaper.
I tried to avoid tear out by using some scrap wood underneath, but i still got some tear out especially on the smaller holes. In hindsight, I should have drilled 1/16" pilot holes while they were stacked and then used the forstner bit from each side of each piece... you live, you learn.
Step 4: Axle Modification
The plastic wheels are held on with a non-removable axle. There is a washer on each side of the wheel. The outside end of the axle has a large flat head that keeps the wheel from sliding off the axle. The axle itself is 3/8" diameter, and I would guess that the end that goes through the bracket is stepped down to a smaller size because the axle can't be pressed out through the back. The back side appears to be swaged to form a head that keeps the axle in place. I had to break the wheel off the hub for it to fit through my bandsaw. I cut the outside head off, as close to the end as possible. The wheel (or what's left of it) and washers were then slid off. I removed any burrs and chamfered the end of the axle with a file. I used two standard 3/8" washers and one of the existing washers on the backside of the wheel and the remaining washer on the outside of the wheel. I then used a spring-loaded center punch to mark the axle to drill a hole to accept a cotter pin.
I support the axle with a wooden v-block and use a center drill bit in the drill press to get a starter hole. I then drill the axle with a 1/16" bit. The chuck on my drill press is too large to hold a 1/16" bit. I recently salvaged a small 1/4" capacity chuck and it's shaft from an old worn out drill, so I chucked the smaller chuck in the drill press, then chucked the 1/16" bit into it and drilled my hole. Tip: Old hand drills are great garage sale finds that can usually be had for a dollar or two. Even if the drill itself doesn't work, the chucks can be scavenged (which cost $25+ new).
The washer-washer-small washer-wheel-washer-cotter pin is then installed on the axle.
I had a bit of an issue with the second axle. While drilling the cotter pin hole, the tiny drill bit decided that it had done enough work for the day and took a break...and flat out broke...inside the axle. After many failed attempts to remove the short piece of drill bit (drilling from the backside, cutting material away around the broken piece to try to fish it out, etc) I drilled the head off the backside of the axle. My assumption was correct that the axle is stepped down and swaged. Luckily I had a 3/8" bolt that had a long enough shoulder to take the place as the axle. I cut the head and threads off the bolt, chucked the non-threaded section into the drill press and filed a small section on one end so that it would fit through the hole in the bracket. I used a ball-peen hammer to beat the crap out of the backside of the axle to get it to deform enough so that it would be solid. You can see my hammer strikes in the last photo. Other than the hammer marks, it performs as well as the factory swage job. :)
Step 5: Adding Tires
Here's the step I've been looking forward to. Adding tires made from rubber hose. I had some power steering hose (3/8") laying around. It's rubber with a woven fiber core. I wrapped it around the wheel and cut it a bit too long so I could trim as needed. Gradually trim until you get a good fit.
With the hose cut, I strung some heavy stainless steel wire through the hose and looped it back through again. This will allow the wire to tighten evenly around the circumference of the wheel. I placed the hose in the groove of the wheel and pulled both ends of the wire to cinch the tire to the wheel. I then used twisting pliers (aka safety-wire pliers) to cinch the wire even tighter. I clipped the excess wire off and tucked the twisted end back into the hose.
I think this method will work nicely on larger diameter wheels. These are under 3.5" diameter so the hose has to bend at a very tight radius. Because of this, there is a little bit of a gap where the ends of the hose meet.
Step 6: Finish Up
Once both are finished, install them back on the bike and adjust to the proper height. My son should be getting close to big enough to ride this thing so he should be excited when let him try it out.
If you've made it this far, thanks for reading through. I hope that you can apply some of these techniques to one of your projects in the future. Let me know if you have any questions and please vote!!!