Current Projects Posts

Child’s First Pedal Bike

Child’s First Pedal Bike

Having previously made a balance bike I now need to follow this up with a pedal bike. This has proved to be quite a challenge. Having come up with a design from the child’s existing measurements using BikeCad I needed 14 inch wheels. These are almost impossible to find as is a suitably small chain set. Eventually after much searching I decided to buy a donor bike for some of the parts. I wasn’t able to find a suitable one in a hurry on Ebay so headed to my local Argos (other retailers are available) and purchased ┬ávery heavy 14 inch bike. Like all similar bikes it has very fat tyres and weird caliper brakes that make contact on the undersurface of the rim. The chainset is basic press fit with cheap bearings and lightweight 1/8 inch chain. Surprisingly the bottom bracket was a standard adult width and the dimensions of the bottom bracket very close to a standard PF86, though not quite. Having started down this road it looks like I will have to bite the bullet and use the wheels, chainset and brakes and maybe the chainguard.

Variable Head Tube Angle Frame

Variable Head Tube Angle Frame

I have mostly selected the head tube angle on my frames based on what I have picked up as being the norm for the intended purpose of the bike. Usually this is within a very narrow range, and sometimes influenced by the angles of available lugs. I have to admit I have not been able to discern much difference in handling between any of the bikes I have ridden and I assume one simply quickly adapts to any differences in handling.
In my wisdom I decided that it might be a good idea to build a frame whose head angle (and hence trail) I can adjust, and I have chosen, taking in design constraints, 55 to 83 degrees, which should take me either side of ludicrous. Furthermore I want the frame to fit wheel sizes of 20 inches, 26 inches and 700c and accommodate up to 57mm tyres so I can test handling of most wheel sizes. The rear dropout spacing will have to be variable from 120 to 135mm and the bottom bracket height will have to be adjustable. Of course it may not work!