Building a bike trailer

[simon_adams_uk]

Has anyone on here built a DIY cycle trailer?
I'm thinking of having a go and would appreciate some hints / tips.

The starting point for my design would be the Carry Freedom Y frame
(http://www.carryfreedom.com/Y-Frame.html)

My first thought was to replace the wheels with castors (eg http://www.toolstation.com/index.html?code=73821). Any obvious problems with using castors as opposed to wheels that I've missed? Is the suspension offered by pneumatic tyres essential?

The second major change would be to replace the metal Y frame with a simpler towing arm that is attached along the LHS of the plywood base. It could be made out of PVC waste pipe with a 135degree elbow in order to connect to the bike's rear triangle. There's some inherent flex in a waste pipe - good or bad? (I'm minded to say a cautious yes).

The connection between trailer and bike would be a combination of a standard 'D' shackle on the trailer and one of those old rear mech protectors clamped (effectively on the wrong side) by the QR.

[All in, the castors, plywood base, pvc pipe as towing arm should all come in under £30.]

S

 

[PrettyboyTim]

I'd guess castors would give you two big problems:

a) The trailer won't neccesarily follow the bike any more. When you go around a corner, the trailer may swing out past you, possibly pulling you over, hitting the curb, a car or some unfortunate bystander. Many roads are slightly cambered outwards towards the edge, and your trailer will naturally roll towards the edge as well, meaning it will be difficult to keep it in the road. You definitely need wheels that always face forwards!

The wheels on those castors look quite small, and will give you problems with potholes and other irregular road surfaces. The last thing you want is for your trailer to come to a halt while you're still moving - either the hitch, railer or bike will break, or the bike will stop and you may suffer an unwanted groin -> headset interaction!

If the aim is to make a trailer as cheaply as possible - have a look at your local dump / recycling centre for some old kid's bikes.

 

[Elmer Fudd]

First instinct ( i'm sorry to say) is totally ditch the idea of castors unless you want to walk everywhere, trust me, above 3 mph they will wobble and bounce like there is no tomorrow !
Why do you want ply ? Use expanded alloy mesh, just as strong and a hell of a lot lighter.
I'd personally go for an attachment to the seat post if I was gonna do this, don't like the thought of something hanging off a QR apart from my wheel.

 

[Elmer Fudd]

Follow Prettyboy's tip, (even tho' I hate him for winning the camera that I was sure had my name on !).
Source a second hand kids bike and build your (mono-wheeled) trailer round that

 

[PrettyboyTim]

But speaking of Carry Freedom trailers, why not base your plans on their DIY trailer, designed to be made from Bamboo or pretty much any other fairly stiff material to hand?

Oh, and by the way, if you need a London source for a decent trailer hitch, Veloroution do the Carry Freedom hitch for £15. I got one for my trailer.

 

[simon_adams_uk]

The castors I linked to are 200mm in diameter so of a reasonable size. I was also intending to use fixed (not swivelling) versions - I can certainly see problems if they don't always point ahead!

As for the hitch on the QR... I can see where you're coming from but it seems to be a tried and tested method on other designs:
http://www.carryfreedom.com/hitch.html

Does the Carry Freedom hitch they sell (£15?) contain both halves (if you see what I mean)?


Thanks for the input!
S

 

[PrettyboyTim]

Yes. It has everything that is in the picture except for the bar that it's attached to. It also came with a spare QR hook that you could attach to a second bike and a bit of flexible black plastic which is attached to the release pin so that you can't lose it.

I still think that if you want to go at any speed at all you'd be better off with some proper wheels. If you're going at any speed at all you'll get an awful lot of vibration through those castors, even if they do have solid rubber tyres.

 

[Elmer Fudd]

Trust me, Castor wheels of any size always go in the direction they think you want to go, not the actual direction you really want to go in, I've used many a hand truck over my working life, you end up kickin' the feckers over and carrying the stuff, far quicker.

 

[domtyler]

Immediately I am thinking "Why the F*** would anyone choose castors over wheels?". Seems a little crazy to me. But good luck anyway

 

[simon_adams_uk]

I may yet persist with *fixed* castors purely as an engineering exercise / waste of time. Please note I'm not using swivelling castors!

Plan B is to use an old sack truck and modify suitably...
S

 

[Wobbly John]

Castors normally refer to wheels that swivel - this would be a disater.

200 mm 'fixed castor' wheels will be heavy, have very little shock absorbtion, and have poor rolling resistance. Your trailer would run verry poorly over bumps and would get airborne quite easily on a bumpy surface.

The shackle idea would work, but the rattling and jerking will drive you crazy.

For a trailer hitch I am now using the M10 size of these

Many people use hitches from comercially made bike trailers, purchased as spares. Webber seem to be a popular choice.

I have a webpage about home made trailers. It needs updating to show the new style hitch I am using, and 2 more designs for home made trailers, including the one wheeled BOB (Bodge of Burden) trailer.

 

[Wobbly John]

Castors normally refer to wheels that swivel - this would be a disater.

200 mm 'fixed castor' wheels will be heavy, have very little shock absorbtion, and have poor rolling resistance. Your trailer would run verry poorly over bumps and would get airborne quite easily on a bumpy surface.

The shackle idea would work, but the rattling and jerking will drive you crazy.

For a trailer hitch I am now using the M10 size of these

Many people use hitches from comercially made bike trailers, purchased as spares. Webber seem to be a popular choice.

I have a webpage about home made trailers. It needs updating to show the new style hitch I am using, and 2 more designs for home made trailers, including the one wheeled BOB (Bodge of Burden) trailer.

 

[Joe24]

I've got some websites that shows how to build one.
Heres a bamboo one.
Heres another one.
Thers a gardener around my area, that uses small wheels, like the coasters but they down swivel round, and the wheels are plastic i think. It sounds horrible, but he go along at about anything below 10mph with. Its made from wood, and when i've gone past it always look like the guy is finding it hard to pedal, and i wouldnt like to see it with little weight it, because it would bounce around all over. It really needs some bigger bike wheels on.

 

[snorri]

castors

 

[Ron]

Ive built a bike trailer for a teenager who wanted to do grass cutting around the village and needed to take his mower with him. The wheels came from one of the mountain bikes that boys throw away every 18 months or so. The rest was welded up from bits of thin scrap angle (for lightness). The wheels obviously had to be supported on both sides and the frame went all round them. Sides and floor were made of hardboard.

This was about 10 years ago. since then it has changed hands and it was brought back to the manufactures (me) for renovations. They then used it for some local camping.

The attachment to the bike was under the saddle, but I've since seen some fixed with an offset bar onto the horisontal wheel support (whatever that is called)