The Hill Trolley/Bike Trailer thread

I’m helping my kids build a hill trolley (a.k.a. soap box derby car).

Our Mark 1 car uses 20" bike wheels at the rear. Those wheels use their original axles and are supported on both sides by the wooden car chassis.

We’d like to build the Mark 2 using 12" or 16" bike wheels (from hard rubbish) at the back, and to connect those wheels using a single axle.

Does anyone know how to do this without using any custom parts or buying wheel chair parts ($$).

I had intended to strip the axles from the wheels, to use one of those long threaded steel rods from Bunnings as the new axle, and to thread the original cones and lock nuts onto that rod. However, that won’t work because the thread on the bike axles is very fine and the thread on the steel rods is very coarse.

If anyone has a solution, then I’ll also use it to build a bike trailer.

You should be able to track down rods with the correct thread pitch, take the cones to a competent hardware store (not bunnings) and someone should be able to use a thread pitch gauge to work out what you need.

pretty sure ive seen wheelchairs at the recycling centre in balcatta, i doubt they would be asking much for em?

Nothing wrong with running a cowl over the top of the wheel and running axle support on both sides like you did in Mk1. The top of the wheel is the place on a bike that causes the most wind resistance so they’ll be mad aero.

I once stole the wheels/axles from our lawnmower. Worked great until the old man went to mow the lawn one day. Of course I lied, and copped a hiding but still to this day I though it was genius whilst it lasted.

and from that sparked the idea of the first ever ride on mower…

Hey dude just get a rolling chassis of a real car, and remove all the seats except the drivers one. And paint it with spray cans
Genius