Thread: Planning a bike trailer

I wouldnt bother going over 2.5 mm for your drawbar.

For the red section personalIy I would use 50 x 50, but thats what I usually have lying around. My dog camper trailer build used 40 x 40, but there wasnt that much weight in the trailer. My St Bernards were dieting that week .

I have a muti-purpose trailer I built initially for three bikes but I have since sold them.It has 75x50x2mm drawbar members & 50x50x2mm (red section members). Due to house reno's I seem to be moving more soil and gravel these days. I have loaded this trailer before with 1cubic metre of topsoil which I am told weighs about 1t. There has been no hint of movement or strain on this design. These days I only load 1/2ton on at a time which is a little bit less scary to transport.

For a trailer this size just for motorbikes 75 x 50 x 2.0 would be fine, but if it's going to see double duty as a box trailer, I would suggest 75 x 50 x 2.5mm for the drawbar. You'd only need one length of this for the draw bar, and the leftover piece can be used for the rear cross rail. 75mm allows for more room for numberplate mounting and rear taillights. The rest, 40 x 2mm SHS will be fine.

Thanks for the reply guys, I've decided on the materials I'll use. 75x50x2 for the draw bar and 40x40x2 for the rest, and I'll pinch Yonnee's idea with using the RHS for the front and rear cross bars. This is going to be a 'bike only' trailer with a mesh floor and tracks welded in so no double duty for it, I already have a big solid box trailer for that kind of stuff.

If you use the RHS for the front cross rail as well, the drawbar wont sit level, as the bottom of the front cross will be lower than the side rails.

Also, 2 x 2.5M = 5.0M, plus 1.2M = 6.2M, leaves only 800mm for the front cross rail...

I'd have the rear cross rail at 1600mm, having a 200mm overhang each side of the side chassis rails.

Yea I was thinking about that. I read your build and was thinking about doing the same or I might get a length of 50x50 and use that as well. I need to finish off the plans first so I know how much steel I need to buy.
Also the 75x50 comes in 8 meter lenghts

and dont forget pics pics pics as ya go along always a way to get ideas for other projects is learning off what other people are doing .

Don't worry there will be plenty of pics

While the wife was watching Downton Abbey (don't know if I spelt that right) I done up another plan, well kind of finished off the first one. I'm not set on the hight of the front yet (it's at 500mm), it's too cold to go out to the garage to measure a bike tyre to get the right height so I just left it at that. But thats the basic idea of it all. I have a few bikes in the garage that need work done to them before our next outing so I'll get that done first then I'll start buying some steel and make a start on this.
Yellow is 75x50x2
Red is 50x50x2
White is 40x40x2

Originally Posted by Rat1314

Also the 75x50 comes in 8 meter lenghts

Stupid mental arithmetic... And it was late...


...yeah that's it. It was late!

Just having another look at your plans, and an 8 x 4 is a pretty long trailer for just carrying bikes.

The cheapies run a 6 x 4 chassis with the centre bike part way up the drawbar.

I've also just finished building one for a customer based on a 7 x 4 chassis.

Yea I know it seems long but my box trailer is the same legnth and the back wheel on my bike only clears the tailgate by 7 inches or so. I want to make it like that so there is room for gear around the bikes and also on the draw bar as well, some of the rides we go on we camp as well so we sometimes need to take extra gear. I plan on putting the center bike on backwards as well (thats how we put the bikes on my box trailer) so I can keep the bike off the draw bar.

That's cool. Just be careful of the balance point/axle location. Ordinarily the front channel for the wheels is on an angle facing forward, putting the bikes further forward. Also, having the centre bike forward of the other two helps with towball load, so yours being all three level, you'll just need to be mindful of how far back the axle needs to be. If you're going to sling a spare under the drawbar, then ball weight shouldn't be a problem.

I was going to find the balance points of the bikes before making a decition on axel location. Also I do have a spare to fit to the trailer so I might look at putting it under the drawbar.