Side by Side Bicycle




About: I like figuring out how things work and learning new skills. I am a software engineer and so making things is an outlet for me.
The Side by Side bicycle, also known as a "sociable", or more recently as a buddy bike, appears to date back to 1896.  Unlike a tandem, where the riders are inline to one another, here the riders are side by side.  To build one, you start with a regular bike and make 3 modifications: pedals, seats, and handle bars.  To accomodate riders of different weight, my idea was to to slide the seats left/right such that the heavier rider sits closer to the frame.  This adjustment is limited however since the farther the seats are extended in either direction, the more uncomfortable the pedaling becomes.  Perhaps you will not need this feature.  To reduce interference between the riders, the seats can be staggered as described and illustrated in this patent issued in 1979.  This reference notes the use of a chain for the steering mechanism but I believe it's easier to build a linkage tie rod.  Riding side by side is so much fun and exciting!  The Side by Side is safer than my "Antique Bicycle", although it too requires skill which is quickly attained through practice and teamwork as demonstrated in my Side by Side video... 

Step 1: Bill of Materials

Here's what you will need to build the sociable bicycle:
  • A bicycle
  • A welder
  • Extra set of bike pedals/cranks
  • Extra bike seat
  • Tubing
  • 2 heim joints to make a steering tie rod

Step 2: Pedals

When pushing off, each rider will have their foot resting on the pedal closest to the frame in the bottom most position (left side rider - right foot, right side rider - left foot).  So cut off the left side crank and weld it back on so as to form a U.  Now remove each pedal and in its place, weld a 6" long by 3/4" wide steel rod.  I initially had welded a 1/2" rod to the original bolt from the pedal but  was not strong enough as it twisted some while pedaling.  You then make a custom pedal that will fit the 3/4" rod.
Simply use 5" of tubing that will slip over the rod and weld two 3/8" bent rods as in the picture.
With the custom-made pedal in place, weld at a 90 degrees an extended crank and pedal.   To make this extension, you will need to weld a rod to an extra crank to achieve the required double length -- about 13 inches.  You will not want to place too much of your weight on the outside pedal so use the inside pedal for pushing off and when stopping.

Step 3: Seats

To the seat post, weld a tube to form a T.   Using a tube that wil slide inside the tube just welded, cut it to the length you want the seats apart from each other.  Slide it in and now weld 2 short new seat posts at each end to accept the 2 seats.  You can make both posts adjustable or just .one as I did since the original seat post can also be adjusted.  Drill a hole across both tubes, insert a bolt and tighten with a nut.  If weight combination of the riders does not work well, remove the bolt and slightly slide the inside tube with the seats to adjust.  Drill across the inside tube starting from the holes already drilled on the outside tube and reinsert the bolt.

Step 4: Handle Bars and Steering

Only the left side driver will steer the bike so the left side handle bar will have a steering linkage.   Weld tubing as shown to the left side of the head post tube. I used another bike's bottom bracket to make the steering mechanism.  I welded a heim joint to the underside as well as another heim joint where the original handlebar used to be.  I then connected the 2 heim joints with a tube acting as a linkage to make the steering possible.  You will want to trim down the length of your handle bar so it does not interfere with the other rider.  You could instead use a tie rod or perhaps sprocket and chain for the steering mechanism.  Install the gear and brake controls onto this handle bar. Now weld a fixed handle bar for the right side driver and you are ready to ride!  Since all that welding requires removing of paint to expose the steel, you will want to prime and paint at this time.

Step 5: Riding

As the driver, place your right foot on the inside pedal (closest to the frame) at the bottom most position.  Left foot on the ground.  Hold the handle bars firmly while the passenger sits on the seat and puts both feet on the pedals.  At this point, three feet are on pedals and the driver's left foot is acting as the "kickstand."
You then push off while releasing the brakes.  I find a few pushes helps to get enough momentum for balancing.  Get seated and start pedaling while the passenger begins to help with the pedaling.  The bike will lean slightly to one side when there is a difference in the riders' weights but this is normal as it helps in maintaining good balance.  Once stopped, both riders should place the outside foot on the ground.  Now enjoy an exciting ride in the park with someone special while socializing all the way.  Oh what fun it is to ride side by side!  

Step 6: Riding Solo

Riding solo on the Side by Side was surprisingly easy once you get past the fear of riding while
the bike leans to one side.  You can hold on to a pole as you mount it to get an idea for how far
the leaning needs to be to stay balanced.
To start, keep your weight on the right foot/inside pedal while leaning the bike away from you and
maintaining a straight and firm hold of the handle bars. You then push off with the left foot. 
If you do not lean enough, you will begin turning left and sitting then is not possible.  Since you will
need to sit before you can pedal, the lean with some forward momentum is critical. 
I find I can readily make sharp left turns and go around in circles without any leaning whatsoever. 
Turning right is more challenging since you will need to lean the bike more as you steer slightly right. 
Also, you do not want to turn right too sharply, especially while you have your outside left pedal
down, since too much leaning will cause the outside right pedal on the right side to hit the ground. 
Turning right is done slowly. 
With a little practice, I find I can go in a straight line or go around in circles in either direction.
As demonstrated in my "riding solo a side by side" video, I'm able to get around!
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    54 Discussions


    3 years ago

    Thoughts - if you set the crank up so the two "inside" feet were oppposite then you could slide the seat almost completely central and it would be easier to ride solo. You could also leave the original steering tube and arrange some kind of release for one of the handlebars to move it to the middle position again.

    As a 100 KG person I'd be terrified of the cantilevered seat support snapping off, bending, or even simply rotating under me. Two longer seat tubes would provide more structure, but the framing would increase heel strike risk. As is, the rear of my inside thigh could touch the horizontal seat post/beam.

    Who has control of the brakes/gears?

    And a non-technical question, who is "legally" in control, should there be any problems?


    3 years ago

    Thanks a lot Carlitos thats a way i ll be able to share my electric bike wiith my lovely girlfriend and in that way i don t need to buy a second bike for her !!!

    in the countries that dont allow this i just take the bus !!! ah ah ah !!

    thanks !


    4 years ago on Introduction

    Is this something that requires a lot of practice to be able to ride? For example could a person that hasn't ridden a bike for many years be able to do this? Also, how hard is it to coordinate balance between the two riders?


    4 years ago on Introduction

    i've owned a side by side buddy bike for over 25 years. i ride it a lot with my girlfriend.

    i just watched the video on this page of
    your first attempt at riding the side by side bike. while you may have
    already figured out what i'm about to write, there is a MUCH easier and
    safer way to start and stop.

    the driver balances the bike with his
    inside foot on the inside pedal and his outside foot on the ground. he
    squeezes both brakes, making the bike immoveable. THEN the passenger
    gets on completely, starting with her inside foot. She does not get on
    or off the bike EVER until the driver has returned to the one-foot-down
    position with both brakes holding the bike in place. When they come to a
    stop at an intersection, the driver puts his outside foot down and the
    passenger keeps both feet on the pedals.

    in the video, it looked like your handlebars were set too low. can you raise them?

    also, i've added toe-clips to the pedals of my buddy bike. it helps a lot, especially because the bike is the opposite of aerodynamic..

    1 reply

    Reply 4 years ago on Introduction

    Hi Mark, Yep we've had that all figured out. I now ride it with my 5 year old daughter. I have attached an extra set of pedals (that just turn) and handlebars for her to reach comfortably. It never fails to bring a smile and I think she enjoys the attention as much as I do.


    5 years ago on Step 2

    It is interesting to see that the pedals here are 180 degrees out of phase. Some of Embacher's collection is on display here in Portland, OR, as "Cyclepedia". The sociable in the collection, a "Buddy Bike" has the pedals in phase: both riders have their left feet down at the same time. Cornering would feel more natural to both riders (outside foot down). But getting started would stress one of the crank arms more, and I wonder how this might affect the sensations of balance and rhythm on the bike, for better or worse?

    1 reply

    Reply 5 years ago on Step 2

    Less stress on the cranks when out of phase since you have most of the weight on the inside pedal when starting or stopping. Easier to build in phase though. Disagree with the link's comment that riders need to be same weight and that riding solo is impossible. I doubt author has experience. Thanks for posting.


    7 years ago on Introduction

    Carlitos, your design is good, interesting, well thought-out and well done. But I think that in some places this bicycle is not legal. Example: traffic law in my country (Argentina) forces bicycles to run in single file, it is to say one behind the other.

    Some people ignore this law, and them they take almost all the street when cycling in group. But that is another matter...

    3 replies

    I'm not crazy!

    Saw one of these on the road this summer but because of traffic was unable to show the others in the car.

    Had almost convinced mysely that the design was too unstable to work.

    4 replies

    I've owned a Sociable for 30 years. It deserves the name: you sit close, you can converse in quiet tones. This was the original "bicycle built for two." The most natural place for your arm is around her waist.

    Actually, it's extremely stable -- much more so than an ordinary single bike or a tandem -- because it tips over so slowly. Why? A bike's axis of rotation passes through the points where the rubber meets the road. The Sociable's two riders are farther away from the axis of rotation than the rider of an ordinary bike, so the rotational moment (aka "inertia") is about 50% higher.

    A Sociable has a short wheelbase, like other bikes but unlike a tandem. You can ride it in amazingly small circles, feeling comfortably balanced. It doesn't care whether rider weights are balanced. In fact you can ride it solo, no passenger on the other seat. (it leans to one side, and you have to keep a constant push on the handlebars in order to ride straight, but it's doable, and you're riding single only as far as your sweetie's home, right?)

    On the other hand . . . it also has MUCH higher wind resistance, and upwind pedaling can be really tough. Storage takes a surprising amount of space.

    carlitosLarry Breed

    Reply 7 years ago on Introduction

    Hmm. I'm curious to try this solo. Though not easy, I suppose a tight rope walker could hold the pole on its end and still stay balanced by leaning the other way. I'm guessing your sociable's seats are not adjustable to accomodate riders of different weight? If the bike was stationary and the riders were of equal weight, sliding the seats to one side 1" would effectively be the same as a solo rider being 2" off to one side. Regardless, I'm guessing it makes a difference being able to adjust.

    This was so great that I just had to try it! I sourced all the parts for free at the local recycling center, I can't wait to go back and show them what I did with the 'junk' they gave me! Thank you so much for the brilliant instructable and inspiring me to make one myself, my wife loves it!

    2 replies

    I just made a pretty good discovery on my side-by-side:
    Instead of having both center pedals down at the same time, put them 90 degrees apart, so when one rider has their pedals up & down, the other rider has theirs front & back. This makes for a much smoother ride with more even power distribution, it's like changing the firing order on an engine :)