Single Wheeled Bike Trailer

Single Wheeled Bike Trailer
Tired of bumbling along single track trails with two tires on your trailer fighting for the track? Too full of pride to plunk down the dough for a store-bought one? Never again. With this instructable, you'll be the envy of the trail.

I built this trailer to use on my recent ride down the C&O Canal Towpath. The trail is 184.5 miles and runs along (you guessed it!) the C&O Canal, from Cumberland, MD, to Washington, DC. For the most part, the trail is hard packed dirt, although there are places where it's mulch, crushed rock and even paved in a spot or two. I decided to build this after having gone online and found that, while two-wheeled trailers would work, single-wheeled ones are recommended. I looked at buying one, but at ~$325, I didn't look too long.

That's when I decided I could do better. I think I did...what do you think?

I wasn't sure how to go about building it and thought of a couple different ways to do so. PVC was considered, as was copper tubing, but I finally settled on electrical conduit after seeing I could get a 10' length for $2.50! I settled on brazing the pieces together after perusing the conduit connectors and realizing they probably weren't going to be strong enough. The only problem with brazing was that I had no idea how to go about it. (Sure, I learned in 8th grade shop, but that was ages ago!) I did some searching on the web and finally decided to just go for it. In the end I found out it wasn't that difficult (looking at the trailer, you can tell which joints were brazed early in the project and which were done last -- the learning curve isn't' that steep).

Excluding tools, this can be made for less than $20. What you do with the savings (~$300) is up to you.
 
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Step 1Ingredients

You'll need the following ingredients to make this trailer:

Parts
4 x 10' 1/2" electrical conduit
front fork of junker bike*
rear wheel triangle of junker bike*
head tube and seat post of junker bike
wheel (16" or 20" -- I used a 20" tire off my daughter's old bike)**
1" to 3/4" conduit step down washer
1/2" screw-type conduit connectors (3)

*This was made using a 26" mountain bike since it's going on to be used behind 26" mountain bike. I recommend using the same size (or larger) fork/rear triangle as you have on the hauling bike.

**While you could use the wheel from the junker bike if absolutely necessary, having the smaller diameter tire allows the trailer to be parallel to the ground.

Tools
brazing torch and rods (I used MAPP vs. propane for a quicker job)
bench grinder
drill*
hack saw (w/ metal blade)
conduit bender

*This is used to cut the holes in the fork. A metal bit is required. I used a Lenox 3/4" Arbored Hole Saw Drill Bit and it work liked a champ.

Extras
Bungee cords
carrying bins

And now, a word of warning, courtesy of Fletcher:

A word of caution about working with electrical conduit: Conduit is generally galvanized, meaning it's got a thin coating of zinc. Zinc is toxic; grinding, welding, brazing, etc. will vaporize the zinc, raising the risk of inhalation. Before working with galvanized pipe, remove the zinc layer (it's thin, so sanding/use of a wire wheel or brush will do it) in an area with good ventilation. A fan would be a good idea, as would a quality respirator (a simple filter mask won't do.) Conduit is a good, inexpensive basis for building all sorts of things ; just remember to take the proper safety precautions.
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98 comments
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Nov 4, 2011. 11:55 AMmrevesz says:
I am beginning the project of making one of these myself, I dont think I can mount directly to the frame of the bike because my bike is made of aluminum and would likely break if I were to do so. Im thinking of finding a way to mount to the rear axle but Im forseeing problems with this. Anyone have success mouinting to a rear axle? Also I have quick release....
Dec 20, 2011. 10:09 AMgodbacon says:
this instructable Has an axle mount:

http://www.instructables.com/id/Bicycle-cargo-trailer--200-lb-capacity%2c-%2430-for-pa/

http://www.instructables.com/id/Bicycle-cargo-trailer--200-lb-capacity%2c-%2430-for-pa/step13/Hitch-creation/
May 23, 2010. 11:13 AMeagle1o1 says:
I built a similar trailer for my bike.   My biggest concern was that I wanted the weight to be evenly distributed by the mounting system.  I used an old fork to mount to the bike.   I got hardened nuts that fit the back axle that had a flange on them.  I then got thick walled round steel spacers that the hex of the nut fit tightly into.  On the other end of the spacer another nut fit tightly that had the right threads for a hex head bolt.  I welded (or you could braze) these nuts to the round spacer at both ends.  Then I put a hex head hardened bolt through another round steel spacer whose  outside diameter  is the same as the fork slots.  First you screw these on your back axle in place of your axle nuts.  Then you screw in the hex bolts. (with a washer on the end)  Now you slide the fork slots over the hex bolts.  I drilled holes through the forks to put in quick release pins.  They are not too big or ugly to leave on the bike at all times and it only takes two minutes to attach the trailer. I've gone hundreds of miles and had over 125 lbs on this with no problems.  It also rides very stable this way.  My camera is down, so I'll try to borrow one to take pics and post.  I hope you understand my description  as this is a fast, strong, stable way to mount your trailer.
Nov 4, 2011. 11:52 AMmrevesz says:
Hey Eagle, could you explain that a bit clearer? Im trying to build my own single wheel trailer and I am having a hard time figuring out how I will mount it to the bike. I feel like it should mount to the rear axle but I cant see how that is going to happen. I imagine that where you mount the trailer at the rear axle you have to allow the trailer arms to swing up or down so that your trailer is not completely fixed on the horizontal axis. otherwise if your back bike wheel were to travel over a dip in the road it would be airborn supported by the front wheel of your bike and the back wheel of your trailer(though that is unlikely as the weight of your body would likely cause something to break or move in an unwanted way) So you see what I mean I hope, how do I overcome that problem? - mattrevesz@msn.com
Sep 14, 2011. 9:13 AMsally300 says:
that is really funny i cant amagen riding that thing
May 28, 2011. 11:45 PMhfox says:
What about arc wielding it.
Mar 2, 2011. 2:17 AMddarkeststar says:
I'm inspired.
Knowing that you have a similar kind of skill base as I do regarding brazing and the like and then seeing the result of your efforts I feel very confident that I could recreate this excellent design.
Thanks a lot for posting.
Jun 1, 2010. 11:55 AMthepelton says:
How much would it cost to hire someone to do the brazing, as I don't have the equipment?
Feb 16, 2011. 9:53 PMpickford78 says:
It would cost more than to buy the trailer pre made. I suggest looking at renting a welder from a local tool rental shop. Maybe look at borrowing a welder from a friend.
Feb 18, 2011. 12:09 PMgarrettg84 says:
You might consider buying a brazing torch. You can get a torch for less than you can rent equipment. One of the off the shelf, $20 Can+Torch combos should do you fine.
Sep 5, 2009. 3:41 PMbearcatsandor says:
How hard would it be/what changes would you have to make to add a shock to it (like a Fox float)? Do you think that wold be worth it? If things tend to rattle around a bit, would that keep more fragile things safe? I'd use mine for transporting computers around. Thanks so much for the idea!
Feb 16, 2011. 9:56 PMpickford78 says:
I'd suggest putting springs in the 4 contact points (the forks and where it attaches to the bike) This could be welded or clamped, I suggest welding in reversed polarity to keep the heat off the spring.
Jun 9, 2010. 4:39 PMspangler58 says:
hey can you build me one please i have looking and trying to make one but i dont know how
Feb 16, 2011. 9:52 PMpickford78 says:
Take Metal Shop in school, they will teach you how to do this stuff.
Oct 8, 2010. 5:07 AMnorton220 says:
just my opinion but instead of have to lean it against something, why dont you put a kickstand on the trailer? or something similar.
Mar 2, 2010. 8:45 PMsantacruzsl52 says:
 Sweet! thanks, i was trying to figure out how to attach my trailer to my bike.My first thought was the same as yours, but i looked at pictures and saw the bob trailers had a lockpin setup. So then i though of attaching it to the  rack mount, but the drop outs were in the way, but seeing now that you did it and it worked fine ill be sure to do that tommorow! Ill send you a picture of my finished trailer if your interested, not as nice as yours but I also just rigged it together from a old bike frame and an old aluminum cot. Its strong though!
Oct 9, 2009. 12:49 AMmulligan says:
if i useda 26 inch (or what ever it is) wheel for the back would that work?? its a standard size i think?

also was wondering if it will feel liek alot on there, and up hills is it hard or good?
Oct 25, 2009. 5:52 PMM4industries says:
AAAHHHH!

No shop class at my school!
Aug 13, 2009. 5:18 PMjefferywelch says:
First off have to say thank you for posting this trailer it is great and works. I just finished my trailer this afternoon and I took it for a 7 mile ride with 25 lbs of gear on it for the maiden run and it was on/off road and it held up great. I made a few design changes from the original and have included a few pictures to help. First I did not use a front fork for the rear tire assembly I just bent the conduit to form the rear end. I flattened the ends of the conduit and drilled a 3/8 inch hole to install the 16" tire. The front assemble was the front forks from a little princes bike which is where I also go the tire from. I included the whole neck assemble so that was the bracket to hold the top rail in place and this way could also use the original bearings to keep a very tight and smooth operating system to connect the trailer to the bike. As you can see I used a few braces for the bed of the trailer. The conduit cost $1.65 at home depot and all together the supplies cost a total of 25 dollars. I did go to Craig’s list and get the little princes bike for 7 dollars and a free mountain bike from the local bike store that was being scraped. I really love this trailer and find it very easy to tow and hardly realize it is behind me. Thanks again and hope this helps.
start trailer.jpgtrailer hhitch.jpgFinish trailer.jpeg
Sep 29, 2009. 9:44 PMstudes4ever says:
Hey there. I really like what you have done with this trailer. I am preparing to build one based on this design. Can you send me any pictures of how you attached the trailer to the bike. I think I have come up with a plan that is both simple and elegant, but I would like to see what you did too.
Sep 30, 2009. 11:54 AMjefferywelch says:
Sorry for the long wait on pics been out of town will get to it this weekend and post some more details. So far it is a great trailer and have used it with 50 lbs on it and everything is going great.
Jul 26, 2009. 7:18 AMcclev1967 says:
awesome build, this is exactly the type of trailer i want to build. even unpainted it looks great. thanks for sharing, if it didnt fall apart with all you had packed on it, then id have to say you did something right, im going to start building mine today. and i want to eventually incorporate a way for it to haul a kayak on it. agian thanks for the great info on your trailer.
Aug 7, 2009. 10:31 PMcdltpx says:
I wish to build a trailer too but I want to build for one task the collection of AL cans to transport to point of sale. A dual frame that is collapseable so when trailer is empty is will have a low drag. Have the system to fit the bags to make transfer at POS a breeze. Not everyone wants to be involved in this but rather than go to a gym to loose my 100 lbs I wish to do something that will pay me back with $ something that has more than one objective. I use to like to ride my bike but as a trucker the pounds have accumulated over the years I want this to change with in a year. I like your design it works well all you need to do is rig dual kick stands so you can stop your bike on the plains. Went to a police auction and bought so much bike crap it needs to be fashioned to other things. I have quite a few bikes that are ready roll they need to get cable replaced and the usual adjustments but it would not kill me to augment one for this task. I could have my good MB and factory AL trailer for grocery trips and the other home made and yackydy bike for industrial use. Great for fishing too who wants to get their food grade trailer nasty.
Jul 29, 2009. 7:05 PMk_man93 says:
would it be possible to avoid all of this and use some other sort of structural support? I know that conduit is probably the most sturdy choice, but I cannot braze it because i do not have immediate access to a torch... any suggestions?
Jul 21, 2009. 11:33 PMruncio says:
Great project! Can you drive any passenger in bike trailer, example your wife!? How kg you can drive in your trailer, max kg!?!
Jun 27, 2009. 3:43 PMdrgnmstr69 says:
Great idea for a low cost trailer.With the problem with thw zinc on the condiut,you can use vinegar to remove the zinc from pipe so that you don't have to worry about the fumes.What about a floor for the trailer like the ones on other trailers?It does look it will hold up really well.Great job.
Apr 20, 2009. 4:06 AMjpvskv says:
Great Instructable! A fix for the rear wheel guard would be to braze two supports between the guard and each of the forks.
An alternative for the connection to the bike would be to go up and over the rear bike wheel up to the seat post as seen on the Atomic Zombie site here: http://www.atomiczombie.com/product-cyclebully.htm You could also do a U joint from the seat post from a block of metal.
One last suggestion: Use a 2x6 the width of the trailer and stood on end for support of the trailer/bike so you don't have to lean it up against anything at all.
Jun 11, 2009. 7:30 AMUC FATHER TIME says:
You could make a sort of frame stand like a motor cycle.Put it near the trailer wheel and use a cable to actuate it,just stop reach down grab a handle pull to contact the frame stand to the ground and push the bike back. And an extention spring holds it up when not in use.
Apr 20, 2009. 3:35 AMjpvskv says:
Your first picture in the intro shows the fork with the bend of the fork facing away from the road surface. I would turn that around so that the bend faces down and that helps put gravity in your favor. It looks like you can do that by the way you assembled it. I am working with conduit too. I use a 110 volt welder to build a seat for a recumbent I built. I suggest using a fan or working in a breeze. Wearing a welding helmet helped prevent me from inhaling any toxins, thank God.
Apr 19, 2009. 6:53 PMgemquest says:
Great instructions and pictures! I was thinking maybe the connection bar from a baby tow trailer might work?
Apr 3, 2009. 8:51 AMrangeside says:
Nice build. I'm looking at doing almost exactly what you've done here, keeping your building changes in mind (ie thing i would do differently next time) I'm wondering how its holding up lately? The design and support point seem to take all the directional stresses and forces into account (I'm no engineer myself) But sometimes time takes advantage and points out structural flaws. Your instructions were really good. Thanks for taking the time to share with everyone! I'm planning to do the same, but maybe on the second build after I figure out if and where it might break. Any other suggestions would be great, Again much appreciated for the share of experience and knowledge with this build. Happy trailing
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