Single wheel bike trailer

At the beginning of the spring season, while sun begins to shine in South of France, I decided to build my own bike trailer. I read many trailer comparatives in order to find the best solution corresponding to my needs.
I intend to have a trip along Canal du Midi during the summer for at least 3 days with friends of mine and using backpacks or racks did not seem to be very pratictal. The idea of a trailer in which you can easily put the tent mattress and any stuff you want came to me.

Step 1: 1 or 2 wheels ?

I read many forum topics about the question...
As the road will be a single track for many kilometers, a single wheel trailer seemed to be the best solution.
I discovered two main trailer constructors:
- Bob (http://www.bobgear.com/ )
- Aevon (http://www.aevon-trailers.com/)
These constructors use different fixing solutions. Bob trailers use rear axle fixation whereas Aevon ones use seat tube solution.
I decided to make a trailer as similar as possible to the Aevon trailer.

Step 2: Material collection

I bought :
- 8 meters of 1cm square steel tube (less than 1kg per meter)
- 2 meters of 2,2 cm square steel tube
- 0.5L of shiny black paint
I re-used:
- 2 “heavy duty” axles
- a 16” wheel
- 1 forch from a 16” bike with its mudguard
- 2 meters of used round tubes (old badminton poles)
- Steel offcuts

Total cost : 30€

Step 3: Central section assembly

I welded the forch to the 2,2cm square section. This section aims at consolidating the trailer on its bottom and is also used as a trailer shaft. From the rear of the trailer to the bike hitch, it has been cut in 4 parts :
- Bottom  part of 78 cm
- Front part of 44 cm
- First part of the shaft of 35 cm
- Second part of the shaft of 42 cm

Step 4: Trailer hitch

This step is the trickiest one. In fact, the hitch has to be strong enough to support the effort of a 12 of kg of luggage in bumpy conditions.
The first solution, retrieved from this instructable (http://www.instructables.com/id/SURF-FISHING-CART-TRAILER/step9/Trailer-Hitch/) consisted in using a caster wheel as a hitch. The result was not satisfactory on a single wheel trailer. The trailer was not horizontal, it was inclined on the left.
The final solution is an homemade solution consisting of 2 X 4cm round tubes perpendicularly welded, forming a crosspiece. The vertical part is on bike side and the horizontal one on trailer side.
On bike side, a steel piece has been welded in order to attach the vertical axle. This piece is fixed to the seat tube using 2 U-shaped screws. In order not to deteriorate the seat tube, some inner tube piece has been placed between metal parts and the seat tube.
On trailer side, two perforated iron parts have been welded on the trailer shaft to receive the horizontal axle.

Step 5: Removable shaft

In order to store the trailer more easily, the shaft had to be removable. It was cut 10 cm from the trailer.The coupling between the 2 shaft parts is performed with a square tube welded around the shaft on bikeside and in which the “trailer side” of the shaft enters. Then a screw interlocks the shaft and the external square tube.

Step 6: Trailer pannier frames

2 frames were constructed with 1cm square tube of steel:
- 76 cm x 40 cm bottom frame
- 112 cm x 40 cm top frame
Both frames are linked with :
- 2 x  40 cm sections on front side of the trailer
- 2 x  25 cm sections on rear side of the trailer
The resulting pannier was welded to the 2cm square central axle of the trailer.
At the bottom of the pannier, 2 sections of 38cm were welded in order to consolidate the trailer.
On both sides, 2 round tubes were riveted on the trailer to prevent the bags from falling of the trailer.
When all parts were welded, I brushed it then painted it shiny black.

Step 7:

I tested it on small rides of about 50 km. I loaded it with my backpack a tent and a sleeping bag and went on dust tracks. The trailer had a good behaviour, following the bike track while turning. I did not weigh it but it is really easy to tow and did not handicap me. i will buy a high volume waterproof bag to put in it. Next step is to use it for what it has been designed : an autonomous trip of several days...

Comments

[hogey74]

I like your work and I think you chose the right option. This design puts the trailer weight more towards the middle of the bike, sharing some with the front wheel - a better solution I think. I nearly bought an Aldi child-trailer for cycle touring :-) but it was too heavy and too wide. I think I need to learn to weld and use your design! Maybe in Aluminium? More expensive but lighter. Thanks for the instructable!

[tom31200]

Yup, aliminium would have been nice due to its lightness, but I cannot weld aluminium.
And even if I could, I think it might not be the best solution, cause if you break a piece of aluminium away from home, it will be more difficult to find somebody able to weld it.
With steel, I had to find small sections in order to gain some weight...
Thanks for reading and good luck in your learning of welding (http://www.instructables.com/id/Learning-to-Weld/?ALLSTEPS) !

[hogey74]

Yeah welding ally as a dark art - I've heard that before. Thanks for the link!

[DB.Cooper]

Not so dark, with the right equipment (not too expensive either,) Im sure you can do it!

[cbuchanan5]

I just finished a single wheeled trailer inspired by yours (and others). I actually made it first using a BOB type hitch that I made from the sacrificial bike's parts but it ended up being very unstable under any sort of weight and was stripping paint from the mounting holes on my bike (two convenient holes by the axle). I think my CG was way two high and the configuration was just wrong. So, I took the hitch off and made an aevon/seat-post type hitch/arm. It ended up working just great. The trailer handles amazingly now (took it around town with a 15 lb load for 30 min; not much but it can take more I'm sure). What I like about the seat-post hitch is that the trailer doesn't lean as much when turning or leaning the bike. The kickstand is nice because I can't put one on my bike and parking the whole thing would be pretty hard otherwise. I'll have to put pictures up and explain more about it.

But thanks for the instructable!

[cbuchanan5]

https://plus.google.com/photos/106125035263977206142/albums/5759321042353193009 Here are some pictures of it. Overall it came out pretty nice I think. It handles well and should be good for a decent amount of weight. Also, the shock makes the ride smoother when going over bumps I was actually glad I was able to find a way to use the seat-post as a pivot point because it makes the hitch less bulky.

[User1]

Nice design on your trailer. I've been some what out of the tires for folders loop, but when I was in it, the Primo Comet 20" Tire were some of the best tires to get. I would say get a nice high pressure tire and you'll avoid it becoming an "anchor" and that is some protection on flats than what you have on it now.

Thanks for sharing and I wish you the best.

[tom31200]

Thanks for the advice !
I already replaced my tire, tube and wheel with new ones which are stronger (especially the hub of my new wheel). The old tire will be used as a spare one for long trips. It costed me as much as the whole trailer :-)

[Emo]

Nice design! The only week point I can see is the connection of the hitch. I am building a cart myself and considered to connect the hitch to the seat tube. My local bicke repaire shop talked my out of if. The seat tube is not designed to take horizontal load. So I connects my hitch to the bicke frame itself. Still WELL DONE!

[glorybe]

Many single wheel trailers are very difficult to back up with. You will run into this when you want to push the traffic button to cross a major road. You will almost always need to back up four or five feet after pushing that button. For trips to the store if it is close by two back wheels are actually more convenient. But I will say that my single wheel, which looks very much like a Bob unit is very true tracking and is not a burden on level ground. I often carry fifty or sixty pound of groceries without two great a strain on a beach cruiser with balloon tires and seven gears. If I had to climb bridges or hills I would pull that trailer with something like an 18 speed gear system and a lite weight bicycle or learn to love pain.

[glorybe]

This is a nice build. I'll grade at an A-. To get an A+ the load should be closer to the ground. Lower the center of gravity of the load and the bike will be more stable.

[tom31200]

Really agree with you ! I build my trailer without the bike. I had some dimensions but it was not really easy to test the behavior without bike ;) I know that if I want to improve it, I will have to shorten and change the angles of the shaft. But for the moment I did not have problems, as I did not ride really technical tracks.

[bonsa1]

That is a great build! I see you have a nut and bolt holding the removable shaft in your photo. The nut is on the top and the bolt is on the bottom. If ever the bolt unscrews it would fall out, whereas if it was reversed the bolt would stay and you would just lose the nut. I think you turned it around in other photos but I cannot be sure. That way you will have no disaster. My Dad told me, but of course I always did learn the hard way. Enjoy your ride.

[tom31200]

You are right regarding the bolt. I did not ride my trailer this way. It was just after painting, not for ride purpose. Thks for your concern about security ! :)

[elic]

I built a trailer using the Aevon trailer solution. It needed a big radius to make a u turn, so, I bought a BOB fork and changed the way of connecting the trailer to the bike. This way, I assure you, for the same bike and the same trailer, the BOB's method makes the ride much more easier and comfortable.

[bruce.desertrat]

I went the other way, building a 'bob' like one, utilizing a rear skewer hitch set from Bike Nashbar, which cost $13, and pieces from various scavenged materials, like a 3-wheel stroller and a steel tube futon bed:

http://www.flickr.com/photos/35245797@N00/4538906852/in/photostream/

It's worked quite nicely, it rides much better with a load in, though, bounces around a lot when empty.

@heathbar4: on mine the vertical swivel is at the rear skewer, the horizontal is at the front of the trailer.

[heathbar64]

Nicely done. I had never seen a one wheel trailer before. On the bob trailer which attaches to the axle, how do they make it swivel?

[tom31200]

Thks for the comment! On the bob trailer, as you can see on the picture, swivel is allowed by the vertical axle right behind the rear wheel. Horizontal rolling is done around the rear wheel axle.

[chaitanyak]

thanks for sharing! i like the way it turned out.

[rimar2000]

Very interesting design, and well made.