Bike Trailer

Table of contents


As work on my garden and flat has progressed, I am increasingly finding limits to what I can do based on what I can carry back from the hardware store, or the builders merchants, or what I can take to the tip. Whilst I have a driving license, I don't currently own a vehicle. Meaning that I have no real means beyond mylegs and my trusting Vulcan. I do however have a bike I like to ride, so the logical progression from here, is to think "Bike trailer".

Why build one

As usual this is for two reasons really

  1. Cost - Commercial Bike trailers are *NOT* cheap.
  2. Specification - The commercial ones just don't do what I want

So, based on this, I am going to build one myself.

The design

A quick google will find a good number of pages on building bike trailers, the best I have found for useful ness is this one. And as such, I am going to base my design on this one. But with a few variations and, IMHO, improvements.

The Two main differences are going to be wheel size, and cargo area.

Wheel Size

I have decided to go with a 26 inch wheel for this trailer. This is cos they are cheap and easy to find. AND, they offer a nice high ground clearance in this design.

Cargo Area

The big factor which will influence the loading capacity of the trailer, and its usefulness, is its center of gravity. Ideally, for stability reasons, we want this as low as possible, so the trailer doesn't tip on corners.

Ideally I want the center of gravity below the axles of the wheels. If I take the design linked to above and just copy it, I will end up with all of the load, above the axles. Which isn't ideal. If I go with the design used elsewhere on that site, of sitting the cargo box in a frame under the main trailer frame, I lose the ability to have a tailgate on the trailer, and thus the ability to tip bulk goods.

This trade off between stability and functionality had me thinking for quite some time, before I worked out a solution.

The box does not have to be parrallel with the trailer frame.

Infact, it will work better if it isn't. The basic idea being, to align the top of the front of the box with the front part of the frame, and the bottom of the rear of the box with the rear part of the frame. This does of course require me to bend the arm at the front of the trailer down abit, so it matches up with the hitch point on the bike. But all in all, I think it will improve things alot.

The hitch

Reading a number of sites out there on building bike trailers, and it seems that a common hurdle people come up against, is that of hitch design.

A bit of research, and some phone calls, show that I should be able to get from the LBS, a Charriot Carriers EZ hitch, like used on the above link. And for the rather polite sum, of 25 quid. This, hopefully solves this problem nicely


December 2006

22nd December 2006

I now have the hitch assembly. It appears there was yet another mix up, and they sent an entire trailer conversion kit, including a aluminium stem (about 3 foot of square section ali, fitted to slot into their trailers, some flags, and some reflectors. Most of which aren't much use to me, perhaps the reflectors are. But anyway, I have the hitch bits I need. I have the wheels all assembled. Now I just need the tubing, which hopefully I can collect from the steel supplier on Wednesday. I may collect the wood for the cargo box today too.

I am thinking of making the box slightly longer than originally planned. To begin with I was going to go for a 2 ft by 4 ft cargo box. With the front part slopping in, so the top is 4ft long, the bottom only 3'6", Now tho, I am thinking of making it 5' long, with a bottom 4'6". This increases the length of things I can carry. It has a neglable effect on the overall weight on the trailer. I am also considering putting some fittings on the side of the trailer, so I can put verticle supports in should I want to transport something sheet like. Need to work on a design some more tho.

20th December 2006

I now have two wheels, two tyres, and two inner tubes. There was a mixup with the hitch, they sent only the bit which attaches to the bike, not the bit for the trailer too. Which is a minor annoyance. They have however sent me the correct part, which should arrive soon. I will keep this part anyway, as it means I can have the hitch on more than one bike if I want to. Saves messing about alot. The major downside in all this is the price of the complete hitch is alot more than expected, at 40 quid. But hey, its all still a bargain!

15th December 2006

Just managed to pick up some wheels on Ebay, 26 inch wheels, ali, mountain bike wheels, 5 quid each. Not bad going. Will need to get some tires for them, but I can sort that out later. Looks like this is continuing to be a bargain.

As I plan on doing more metal work in the future, I bought a sheet metal folder from screwfix this week. Tonight I fitted it to a peice of chip board with a small batton on the bottom, so I can fit it on my work mate while working with it. I will use this to bend the brackets up for the wheel, etc...

Ebay has bought about a pair of tyres too, 20 quid including P&P. Bringing the total cost of the bike so far to:

  1. 2 Wheels - 15 inc P&P
  2. 2 Tyres - 20 inc P&P
  3. 2 Inner Tubes - 2.8
  4. Hitch - 19 inc P&P
  5. Steel tubing - approx 10
  6. Wooden box - 10
  7. Total: 76.8

Not bad, when you consider over 10% of that is P&P for various parts. Even better when you consider it is almost a quarter of the cost of a commercially made trailer.

8th December 2006

Hitch ordered. Phoned the steel stockist, who gave me different info to last time, this time they have the stuff in stock, and its 2 quid cheaper than previously thought. Will wander down and collect it on tuesday. Now to work out how to carry a 6m length of steal weighing about 10kg 1 mile back from the steel stockist.

Looks like wheels are going to be 30 quid each, with a tyre from the LBS, time to see if I can get anything cheaper

7th December 2006

The design is now pretty much sorted, I have a pretty clear idea of what I am after. I have also made some phone calls, and tracked down a tubing supplier, and a hitch. Things are starting to fall into shape. This said, the steel supplier is out of stock till the new year, which is abit of a bummer, but not traggic. Means I have abit more time to work on the design, and get all the parts delivered. I just need to work out whether to bother trying to scrounge some 26 inch front wheels from the local freecycle group, or just goto the LBS and buy two cheep wheels. Will give it some thought

This page last modified Friday, 22-Dec-2006 06:19:23 CET.