Building a soapbox racer

My sons school is having a charity soapbox race.
And I’ve foolishly volunteered to build one.
Thing is, being a typical competitive dad, I don’t just want to build a soapbox racer, I want to build the winning soapbox racer.
It is going to be down the school playing field, which is not a particularly steep, or particularly smooth so I think it will need reasonably large wheels.
The problem is finding some. Nobody buys the old traditional prams that were the traditional source of wheels and axles for soapbox racers.
Bike wheels are plentiful but not with suitable axles.
Has anybody got any bits that might help me in exchange for a few beer tokens?
I’m open to anything – wheels, axles, an old racer or chassis you’ve got cluttering up the shed – any kind of help would be gratefully received.
I’m in Hampshire but I’m travelling to North Wales on holiday soon so could make detours to collect.
Cheers!
Mike

Bike trailer wheels are single point axles, mine is just a refinement of a quill stem but using a QR to tighten it up. Should be easy enough to knock one up using old parts.

Either that or use old wheelchair wheels.

I built one using trolley wheels with pneumatic tyres and roller bearings from Machine Mart. It was fast and handled fantastically but was quite heavy.

You need to buy some Royce stuff.

I got a set of old school pram wheels from the tip – had to ‘book’ them after a chat with the chaos who work there as there was a waiting list. A promise of a slab of beer bumped me up the list quite quickly.

This is what you need.

and this is what you should build 🙂

You need wheelchair wheels!
24in (Usually) and single sided axles. Decent ones are QR too, with a push button in the middle.

Front was a rear axle off an Alfa, rear is from a trailer. Bit HD but did the job 🙂

I built one earlier this year with a couple of donor BMXs off gumtree that I paid a total of £15 for. I used the forks at the rear so that the brakes worked and ran a threaded rod through the rear wheels for a fixed front axle. The BMX wheels work great, and I managed to get the centre of gravity below the axle line, with a wide track, so it goes round corners fairly well too. My daughter and I had a lot of fun building it together.

If you have a Clas Ohlsen near by they have a good selection of wheels. Also we’ve built a kart out of a large wheelie bin, laid down its like a bob sleigh, we used new wheel barrow wheels. It was very quick, stable and had ready made body work. I bought a new wheelie bin from the council for £20.

@ Bol – that’s the sort of thing I am looking to build.
Is the main chassis made of wood?
I like the fork arrangement at the back, how did you stop them from twisting?
Loving the recycled sledge!
Thanks for the insiration,
Mike

Bol, that’s terrific! Her little face says it all, really; talk about chuffed to bits! 😀

Yes, the chassis is wood. Just some cheap lengths from B&Q with a bit of ply sandwiched between them. I stopped the forks from twisting (pretty much) by clamping them in a groove between two blocks of wood with coach bolts with an extra coach bolt through a hole drilled through the steerer. That was the scariest bit of the build as you only get one try at drilling the hole right per donor bike! It’s not rigid – you get a bit of twist in sharp corners, but it’ll do. If I was building it again I’d have a heftier piece of wood supporting the forks, for a bit less give (and so I could drive it) and probably raise the back end up a bit for better ground clearance. One of the things that worked best was attaching bungie ropes from the front axle to the chassis to prevent it from jack-knifing – which I remember led to quite a lot of grazing when I was a kid.

Good luck with it. It’s inspired me to take ours out for a run again this week.

The last one I watched there was a kart that had welded two identical bmx’s together using some scaffolding poles.

This meant that the brakes, steering and platform was all sorted. You then just need to build a body.

It’s probably the quickest and cheapest way.

A bit like this?

Effective – yes
Pretty – no.

I think I prefer Bols design more at the moment, although I’m still open to ideas.

@bol

This has now gone to the top of my ‘What I don’t need ,but must build’ list 🙂

Gonna build one with mine when she’s old enough, reckon brakes might be a good idea though.

That two bike abomination looks quite sketchy, bet it handles like a pig too. Especially with one side on suspension and the other not.

One thing I forgot to mention was how interesting it can be to have left and right brakes on different levels. I was careful to set them up with the same pull and power, but wasn’t quite clear enough with my daughter about the need to pull them both evenly – as the last few seconds of this video will demonstrate (if it works)

That two bike abomination looks quite sketchy

…by the look on the drivers face 😕