Instructables
I was looking at getting a BOB Ibex trailer for hauling all of my trail building and maintenance tools out to the trails because I'm sick of walking them in. I figured I would give a go at building my own, so here is my attempt.
I believe the BOB trailers are very well designed, particularly the patented attachment method, so I didn't stray to far from their design.

I've included  photo of the BOB Ibex trailer for comparison.

Step 1: Components and materials

I started by collecting the primary components so that I could do my layout around those.

Wheel: I was thinking of going with a 20" bmx wheel, but ended up using a 16" wheel like the BOB trailers. I found a few used kids bikes with 16" wheels, but went out and bought a new one for this build.

Shock: I found a coil rear bike shock on ebay from a moped dealer for about $13 including shipping. Would have liked to use an air shock, but they were more costly. I found some 1/2" axle bolts at my local Ace hardware store along with some nylon spacers.

Swingarm and rear triangle: I used an old BMX fork I had lying around as the swingarm for the rear wheel. The pivot is a steel bike hub the local bike shop gave me. Another fork was used for the vertical part of the rear triangle.

Frame: The frame is fabricated from 1/2" EMT (electrical metal tubing). 10' lengths from Home Depot cost $2 each. I used 4 with some waste and leftovers. CAUTIONARY NOTE: I use a flap wheel to remove galvanizing from the EMT before welding.

Miscellaneous: I used various pieces of steel plate (1/4" and 1/8") and steel angle and channel I had lying around from previous projects. Old spokes are used as retaining pins. Also used some scrap 1" EMT. Bottom was made from expanded steel.

BOB quick-release axle: This is the key to the Bob patented bike attachment. I probably could have made something similar, but I knew this was tried and tested. I got mine from Amazon for $26. There is a different version for use on bikes with solid rear axles.
 
Remove these adsRemove these ads by Signing Up
AndrewNott2 days ago

I think I have a winter project now, I always thought this was possible. THANKS!!

Tetano11 months ago
You have forgot the brake!
marple200 (author)  Tetano11 months ago
Bike has sufficient brakes. Trailer does not need them.
Tetano11 months ago
You are forget the brake! :)
mpintovsj1 year ago
Excelente proyecto !!
cglaw20131 year ago
excellent
surfer18201 year ago
Excellent design, thank you. I don't think I read the final dimensions, do you mind telling me the width and length of the carrying bed?
marple200 (author)  surfer18201 year ago
Inside dimensions are 30" long at the center and 21" wide
ray741 year ago
This is cool :)
Can you tell me how your trailer's fork dropouts are connected to the bicycle's chainstays?? I see the purpose of the retaining pin, but can't make sense of the dropout. I assume the dropout just sets on the axle shaft's threads??
marple200 (author)  DiamondBack1 year ago
The instructable has now been updated to show a photo of the BOB quick-release axle and describe the dropout attachment.
http://www.amazon.com/BOB-Quick-Release-126Mm-140Mm/dp/B000RH94TO/ref=sr_1_1?ie=UTF8&qid=1356953249&sr=8-1&keywords=bob+trailer+quick
The dropouts fit onto the notches on the ends of the quick-release.
marple200 (author)  DiamondBack1 year ago
I guess I should have included a photo of the special quick-release skewer/axle that I mention.
It extends out farther than a standard axle and has a groove that the dropout fits onto.
The make a version for solid axle wheels if you don't have quick-release wheels.
I will add photo and link to this item.
rimar20001 year ago
Excellent design, very well worked, congratulations.

I have a doubt. Forgive me if you explained it yet, since I do not speak English I struggle to read the entire text. In the images I am concerned with the point marked in red in the attached photo. If the union is solid, you could have problems crossing a speed bump or a small hillock. The rear suspension is very good to absorb unevenness in the road, but not a sudden level change.

OOPS, I can't upload the image, the editor does not allows to do it now. Well, I will try to explain: in you first and last photos, the entire trailer seems be solidly attached to the bicycle. I think it needs a vertical movement in that site.
marple200 (author)  rimar20001 year ago
You may have missed it in step 4 where I note:
"The dropout connection to the special Bob quick-release axle skewer allows the trailer to pivot in the up/down direction around the bicycle's rear axle."
OK, thanks, I see that now. Pardon!