My Version of a YAK Bike Trailer




Introduction: My Version of a YAK Bike Trailer

I have long wished I owned one of those fancy B.O.B. Yak trailers.  I pedal at least a couple thousand miles a year on my bike.  As much as I would love to own a Yak, I have other things I would rather spend $300+ on.  This is my first instructable so bear with me if I miss anything.  I tried to take photos along the way and I have missed a few at the end.  The grinding  and prep work for paint and the process of painting itself did not get documented.  I trust most people know the steps to do that...  Now on with the build!

Step 1: Parts

I used 3 10' pieces of 3/4" EMT pipe for this build and I have a little bit left over.  I also bought a small section of 1/2" allthread, 4 brass bushings, and 2 locknuts for the allthread to fashion the hinge.  I also picked up a 17"x21" wire basket that is used in closet organization kits.  I did order the actual B.O.B Yak skewer attachment from REI.  
EMT pipe $10.50
Brass bushings $10
Wire Basket $8
Skewer plus shipping  $30

So for roughly $60 and a day and half of time, I think I made a good decision.

The wood piece was made as a jig of sorts that I used to help position the top and bottom pieces.  I drilled 7/8 holes then cut through the center of each.

Step 2: The Plans

I found several images of the actual trailer online.  Combine that with what little information I could find on actual dimensions and it's possible to draw a plan of approximately what it looks like.  I just loaded the photos up on photoshop, then used a projector (InFocus IN24) to shine it on the wall.  I played with the distance until the projected image was close to actual size.  I then taped a few pieces of paper together and traced the outline.  This turned out to be somewhat of an issue with scaling width and height properly.  I ended up having to stray from th original plan because somewhere, somehow, I had a slight miscalculation when I bent the top section.  

So basically, I used the tracing as the form for my bends.

Step 3: Bending the Pipe

Using my bender, I bent the sections for the top and bottom of my trailer.  It was a tedious process of bending and checking against the print, then bending some more and repeat....

The last pics show the wood block and the first mock up.

Step 4: Cutting and Prepping for Brazing

The basic idea here is to cut the pipes so they fit a tightly as possible together.  This will make the brazing process much easier.  This is also where the pics sort of stop until the end product.  I started by brazing a horizontal support in the bottom section to set the width.  I then brazed the top and bottom sections together where they meet at the rear of the trailer.  Then I measured and cut the 2 supports for the nose and brazed those in place.  

Once I had the form set, I used a hammer on a block of wood to flatten the trailing sections where the wheel mounts.  I sourced a set of dropouts from the boneyard located in the rafters of my garage.  I brazed these in place, then played with the spacing until the wheel fit.

Step 5: The Steering

This is where I had some problems.  The top rail sticks out a bit further than the bottom making for a iffy swivel point.  I decided to bend a section of pipe and make a support to hold this hinge point a little closer to plumb.  The hinge point was built with a section of emt and a brass, collared bushing brazed to either end.  I used a bolt to make sure the bushing didn't deform from the heat of the torch.  For the other part of this hitch, I sourced the rear section of another frame.  I cut just behind the seatpost and right at the bottom bracket.  In the space between the frame rails, I brazed in the other two brass bushings so the collars of these rest on the collars in the other section.

Step 6: Finishing

I cut and bent one end of the basket and cut a few sections out of the nose end to get it to fit just right.  The basket is steel and I was able to braze it right to the frame.  I added a Bell handlebar bag, a red reflector, and a few bungees just for the picture.  I have yet to receive the skewer.  It is supposed to be here in a couple days.  I have hooked this to a bike and rode it up and down the street.  It tracks just fine.  It was a bit stiff since I didn't have the right skewer and I just pinched it between the skewer that is on the bike.  I plan to add a flag and a fender as well...

Step 7: Updates and Skewer Attachement

The skewer is in and installed.  I loaded up a tote and filled it with junk till I got a weight of 70lbs.  Seems to handle it fine.  The missus and I are planning a camping trip.  We live about 25 miles from a campground and that will be a good road test me thinks...

The trailer dimensions are as follows:

Bottom frame is 24" from apex of the front bend to the rear horizontal brace and 16" wide.  The top frame is 28" from apex to the bends that go down to attach to bottom frame.  This is where I made my mistake and it should have been the same size as the bottom.  That would have meant I wouldn't have needed to modify the swivel bracing.  As for the where the wheel attaches, that can be any length as required for whatever wheel you plan to use.  I just happened to have a spare 20" wheel laying around so I made that work.  The height from the bottom frame to the top at the nose of the trailer is about 9".  This is really close to the dimensions of the actual B.O.B Yak.  The numbers I had for that was 62cm by 35cm.  The length of the swivel point on a Yak is 26cm

Step 8: More on the Hitch and Pivot Points

Here are some good closeup shots of the hitch attachment and the pivot points.  The skewer was $27.50 from REI including shipping cost.  I used some brake parts and a couple wheel spokes to fashion the retaining system.



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    27 Discussions

    It would be more sensible to use flat bar. I made a rack out of 1 x 1/8th stainless steel flat bar.

    You can buy a Yak type of trailer on E-Bay for $69. with free shipping made of steel. They pay for shipping as well. But having used this type for a couple of years there is one big drawback. Try loading groceries onto a one wheel trailer without flipping a bike over sideways. Even with a fancy kickstand it is still an issue. Once loaded and under way they handle wonderfully but for trips to the local stores trailers need two wheels to load easily without flipping the bike over on its side. What would make them better is a center stand on the trailer so that the trailer self balanced when standing still. I mean the type of center stand you find on a motorcycle and not a side stand.

    Great stuff... Can't figure out the swivel point for the life of me... Are there bearings in there? Is it water tight?

    Great Instructable I have been wanting to build a trailer! Yours turned out amazing.

    I need to make a quick note on this. After my maiden voyage with this trailer, I ended up changing the bit that is between the trailer and the bike. In step 7, you'll notice that the hinge point is a bit high, giving the trailer a nose up kinda thing. This made the trailer quite unstable above 15mph. I changed that angle and got the trailer riding a little more level. Made the ride much safer.

    Nice job. I was just getting ready to build my own when I found your instructable.
    If I can find the right frame out there I want to make the Ibex suspension version.
    I will be welding, not brazing, so I'm not yet sure what I will do about the bushing issue at the hinge.
    My last trailer used paracord webbing, which worked well, but the wire mesh is nice too.
    Nice wheel.

    1 reply

    I have a couple great stories about this trailer. First off, I did a 40 mile ride into the wind loaded with about 90lbs of camping gear and it did great. On the way home, I got a little goofy trying to unclip as I was braking for a stop and the trailer wiggled just enough that it flexed the bike frame and put the rear derailleur right into the spokes. Granted, 90lbs is ALOT to haul behind an aluminum road bike. Then just this past RAGBRAI, I was talking to a dude who had two BOB YAK's in tandem behind a Surley. I told him about my version and he had actually seen this instructable. The guy was pretty cool and I think he was from Oregon... And just this past weekend, we had a decent enough day that my beer brewing partner and I loaded up a 5gal keg of beer and CO2 cylinder on the trailer and rode to a football party. Good times....

    The wheel was actually on a bike I got for free. It is the perfect size. God forbid I ever have to true the damn thing tho...

    Be sure to to have great ventilation when brazing/welding galvanized. Sand off as much of the coating as possible. Toxic fumes are created when galvanized is heated this much.

    Have you had any trouble with the skewer bending? I have read some places that it's a recurring problem.

    Great stuff, Nice build. Ima get on this right away. Always down for saving a few hundred bucks.

    sweet instructable very impressive. just getting the parts together to build one myself. in using the back end off a suspension mountain bike as it is already near the dimensions that are required (£4.99 on ebay) also already has a down tube welded in the right place to braze brass bushes to. also thought about a rack over the trailer wheel to act as mudguard and also for a set of panniers but may be a bit much!!!

    Top notch job I've been debating trying to build one of same design for years you have inspired me.

    That looks like pro quality workmanship and I have been a pro fabricator. It might be easier for most folks to cut that bottom loop out of plywood but your method does look awfully nice.

    Thanks for the updated pics! I think the only thing you could do to improve the instructable (ie - make it more clear for people like me) is to show the hinge parts taken apart, and being installed. With the black on black it is a little confusing...

    Overall, a spectacular build. Can't wait to attempt one!

    Fantastic instructable! I hope to make one of these in the near future. Any chance you can take a picture of the mount for the trailer's wheel?


    1 reply

    For sure! All I did was cut out the rear dropouts from a donor bike. I just flattened the ends of the pipe that make up the bottom of the trailer frame then stuck the dropous in then brazed them in place.

    This looks almost exactly like my B.O.B. I would suggest that if you intend to use this on an extended tour, you might wish to braze on bottle holders. I found them to be invaluable when I was on tour with my trailer for long stretches between sources of water.