Bicycle Sidecar

When a bicycle takes a turn the rider will lean into the turn so they can remain balanced at higher speeds. This side car has an axel that allows the bike to tip back and forth while still keeping the wheel of the side car on the ground. This allows the sidecar to move independent of the bike and will prevent the sidecar from throwing the bike of course when either the bike of the side car go over a bump. The side car is also easily removable by removing the axel that connects the sidecar to the bike.

This project will focus of the more on the mechanical principal of the axel and less on the actual fabrication of the seat of the sidecar.

Bracket:

sheet metal 1/8 inch thick

axle 1/2 inch diameter

1 1/2 inch diameter collar

1 cotter pin

2 ball joint end rod

2 coupling nut

2 clevis mounting bracket

3 U-bolts

Seat:

1 inch angle iron

bike wheel

car seat

straps

plexiglass

The bracket designed may not fit your bicycle so be sure to print the DXF file of paper or cardboard to see if it matches up with your bicycle.

The bracket has two bends along the top and the bottom of the bracket. This is to increase strength.

Once a good fit has been acquired cut the bracket and bend along the top and bottom. Notches are included in the file to help with bending.

Using the DXF file the bracket can be cut using a plasma CNC. If a plasma CNC is not available the part can be cut by hand using the DXF as a template.

After cutting the bracket clean up any sharp edges and bend the part using a sheet metal bender or brake vice. The part can now be painted.

Attach the clevises to the bracket such that the axel can be slid through both clevises with the ball joint end rod in place. This will later assist in measuring the height at which the coupling nuts will be welded to the frame. A cotter pin can be used at one or both ends of the axel to make the side car easily removable.

U-bolts can be slid through the slots in the bracket to attach the bracket to the frame of the bike. Heat shrink can be used around the U-bolt to prevent the hardware from scratching the frame of the bike.

When building the frame for the seat it is easiest to start with something premade like a car seat or something similar.

It is important for the wheel of the side car to be supported on both sides to reduce friction and reduce the chance of the frame bending. To attach the wheel a hole can simply be cut in the frame and a bolt slid through the wheel to create an axel.

With the side car standing next to the bike the height of the attachment point can be determined.

Weld the coupling nuts to the frame so that the whole thing stands level. If additional spacing is needed to separate the side car from the bike a short section of angle iron can be used.

To keep fingers and legs out from the spinning wheel plexiglass can be cut at screwed onto the side of the frame. If sections of the frame are unsupported a small section of angle iron can be cut and welded to the frame to provide a tab.

It is also advised to add chest straps and seatbelts.

If the side car pulls the bike to the right or left the angle of the sidecar wheel can be adjusted by changing how far the ball joint end rod is threaded into the coupling nut.

If the spacing is greater on the front ball joint end rod than it is on the back, the wheel will be angled out and the bike will pull to the right. If the spacing on the front ball joint end rod is less than on the back, the wheel will be angled in and the bike will pull to the left.