Build a Bicycle Sidecar




This sidecar was built to transport my 3 year old son on the local cycle paths.

It was constructed from a steel angle frame, with a wooden bodywork and plastic screen.
It was designed to pivot against the bicycle frame so the cornering and riding were less affected by the addition of the car.
The design was reminiscent of sidecars which were commercially available in the 1940's.

The sidecar was fitted with a harness to help the passenger stay safely in place.
A guard was also fitted to the side of the bicycle rear wheel to stop potential accidents between the child and the spokes.

Please note that being in the UK I mounted the sidecar on the left. If you cycle in a country where they drive on the other side of the road, you should consider switching the sidecar to the other side.

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Step 1: Making the Frame

The frame was made from 25mm steel angle 3mm thick. The angle was cut to the dimensions shown in the CAD sketch.
The frame parts were clamped in place using some wooden off-cuts and cable ties, then welded together.

Step 2: Adding the Wheel

The sidecar wheel was a standard 20" bicycle front wheel. The mounting was slotted to allow some degree height adjustment, but this could be ommited if you know what bike you are going to attached the sidecar to.

The wheel mount was positioned midway along the frame edge and welded in place.

The outer frame was a piece of 25mm steel strip bent in the vice. This was bolted to the main frame to allow the wheel to be removed more easily.
Once the outer frame was bolted in place, the outer wheel mount was clamped and welded to complete the wheel fixing.

Step 3: Building the Bodywork

The bodywork was made from plywood. 12mm thick plywood for the base and top deck. 4mm plywood for the curved sides. The overall dimensions were 850mm long, by 300mm wide and 300mm high. Some metal brackets were used on the inside to help keep things square.

The top and bottom deck were cut to the same profile. They were spaced apart by a vertical post with the top deck moved forward by 5". The rear panels were also cut from 12mm thick and a hole cut to allow access to a small boot.

Once the basic box was complete an opening was cut in the top where the passenger would sit. This cut left the thin 4mm sides exposed to damage; so some 12mm ply off cuts were glued inside the sides, to give re-enforcement.

Step 4: Finishing the Bodywork

The wheel arch was two semi-circles of 12mm plywood with some 4mm ply bent over the top and secured with screws and glue.
The wheel arch was not secured to the outer frame so that the frame could be removed to service the wheel without having to remove the whole arch.

To finish, a screen was cut from polycarbonate and mounted using a strip of wood planed to the required angle. Some automotive body filler was used to blend in the edges and fill in any small gaps. The sidecar was painted in bathroom emulsion.

The seat was two sheets of 12mm plywood, covered in 2" of foam with some material folded over and stapled in place underneath.

Originally the body was mounted on springs to the chassis, but this gave unwanted oscillations, so the springs were replaced with soft rubber bushes.

Step 5: Attaching to Bicycle

The pivot was a simple bar held in four mounting blocks. Two blocks on the bicycle and two on the sidecar. The sidecar pivot blocks were made adjustable to allow sidecar tracking to be set.

The sidecar pivots were blocks of aluminium. One was slotted and the other had a single pivot bolt, to allow for adjustment of tracking. The blocks were cross drilled to take the 12mm pivot bar.

The bicycle pivots were steel blocks welded to steel strip.
The rear mount was drilled to fit the rear axle nut.
The front mount was mated with an aluminium block which was notched to help it locate on the chain stay. The notch had some old rubber inner tube glued in it, to prevent damage to the cycle paint.

To give clearance for the pedal closets to the sidecar, the sidecar was mounted with its front mount touching the rear mount on the cycle. This position was held using split pins and washers, but an alternative would be to use 12mm threaded bar for the pivot, with some nuts to hold the sidecar position

Step 6: Finished Images

Here are some general images to show the sidecar with the bike.

Modifications ?
A threaded bar instead of a pivot would be a simpler mounting and would allow fore and aft adjustment of the sidecar position - although this would not be as quick to release.
The sidecar could have been a little longer to give more growing room. It was designed to fit in the boot of our car, but longer would have been better.
The wheel mounts could have had slot which was open at the Bottom. This would give the simplest wheel removal without the need to unbolt the outer frame part.

More sidecar details can be found at :

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133 Discussions


Question 1 year ago on Introduction

I am building an electric bicycle with a side car. I plan on puting a motor on the side car wheel and one on the front wheel of the bicycle.

Will it be rideable? What problem should I anticipate?

Thank you


1 year ago

Ooooh this is a nice project


2 years ago

I've scrolled down in the comments for quite a while to see if anyone had already asked you if they could purchase what you've made here, and I've seen none so far. So I guess I'll have to be what seems like the first comment to ask whether this is for sale or not.

Not too long ago my boyfriend had signed for adoption on a dog, and recently has been thinking about purchasing a bicycle, so I think that this would be the perfect gift for him for his birthday coming up in about a week!
Also, I don't mean to come across as someone who thinks for the right price, money can buy anything. I'm just a full time waitress who doesn't know JACK about building.

Please, please, please respond!

1 reply

Reply 2 years ago

Hi There,
Thanks for asking about making these for sale, but I only made the one and I have since given it away after my children out grew it.
The problem with building another would be finding all the parts again which took months to scavenge and I don't get much workshop time these days.
I am also in the U.K. and depending on where you are I expect shipping to be prohibitably expensive.
Sorry not to help more. There used to be a commercial product called the chariot sidecarrier which I have seen people use with dogs, Perhaps you can find one in the classifieds?
Good luck in your quest.


3 years ago

"If you cycle in a country where they drive on the other side of the road, you should consider switching the sidecar to the other side."

From what I have read, mounting a side-car on opposite side of the chain drive (as you have it) is considered pretty standard by most bicycle side-car builders, to keep the chain (and any thrown debris from the chain, like dirt, oil, grease, water, etc.) away from the cargo.


3 years ago

When I read this - what the author has done and shared - and the family orientation aspect to the project, and then I read the other ideas which are given and received in the best possible spirit - I come away thinking that the world is a pretty good place.


5 years ago on Introduction

what you have built is called a leaning sidecar (look up flexit) very cool i think i would do this with a solid mounted car because once you get past the terror the first cople of times you fly the car its a lot of fun. my motorbike is sidecar equipped due to my bad right leg not letting me ride full sized motorcyles

2014-03-24 15.35.59.jpg

6 years ago on Step 2

if you put one slot vertical, and the other horizontal, you could adjust camber and toe in, in case there was an error in placement for welding.


7 years ago on Step 6

You could also save time in construction by using a plastic barrel, and if you watch how you cut the hole in the top, you get your seat back at the same exact time save even more time.
Plastic barrels come in all sizes from small medium and large so it will be basically the same technique to build one for an adult.
I saw an article years ago about a guy who used a steel barrel for a homebuilt sidecar for his motorcycle and it looked pretty cool. Plastic barrels have been used to also make travel trailers for motorcycles and bicycles, as well.

1 reply

Reply 7 years ago on Step 6

Great idea.
I've seen motorcyle sidecars made from steel drums (and bath tubs!).
You are right that it would save a lot of trouble with the bodywork construction and a plastic drum would be light and easy to work.
Thanks for the tip !


Reply 7 years ago on Step 6

I haven't tried it but my feeling is that the current pivot design would not be strong enough. A larger sidecar would mean more over hang at the front which would put more strain on the pivot. Perhaps an arm attached to the headstock which is also pivoted would be the way to go ?

mostly water

7 years ago on Introduction

Excellent work! Thank you for so many ideas. Here are two back.

IDEA #1: using the frame from a kid's bicycle trailer would ease construction. A dual passenger model is usually rated for 100lbs. Frames are either aluminum tubing or steel angle iron (from what I have seen). You have your choice of outside wheels to keep. Height is a bit fixed, but you can find 16" or 20" wheel models.

Pacific Cycling makes them for InStep and Schwinn. In the US, these are avail for not much $. Walmart has the Instep for $100, and $160 for the Schwinn. Used you can find them for $40-$100.

IDEA #2: a kid's car seat would be a very good seat for the sidecar.

I am glad you mention other body options. I too was thinking of fiberglassed cardboard :)

I am still wondering about how to attach the car to the bike. My son Jacob has Cerebral Palsy. A trailer is ok, but I rather he ride beside me :). Jacob weighs about 50lbs, so that + growth is my design requirement.

Cheers - john.

1 reply
stevebodmostly water

Reply 7 years ago on Introduction

Hi John,
Thanks for the comments.
A trailer would be a good starting point as you suggest. The removed wheel could be kept on the back as a spare - in case of punctures :-)
And you may be able to reuse some of the bodywork construction too, those trailers often have lightweight windproof covers.

Cardboard in fibreglass is an easy to make composite material. It is a good idea and I have seen bicycle cargo trailers made this way. Try it and let me know how you get on.

Yes, yes, yes to a car seat. I thought about this too, but didn't have room in this design. Car seats are very comfortable, safe and have proper restraints. Some car seats use what are called ISOFIX mounting points. You could use the same attach points to fix the car seat to the trailer, this would be very rigid.

You mention transport for your son. Sidecars are much more sociable than trailers. A trailer may be more efficient and more streamilned, but the enjoyment of riding side by side should not be under estimated.

Good luck with the build.

Ghost Wolf

9 years ago on Introduction

Question can it be built for a full sized person?

Love your project very clean picture are not blurry and the instructable is straight forward. In other words 5 stars