This idea is the reason we bought our first cargo bike, leading us to go into business as Cargo Cycles. Small children (or in our case, a disabled child) may not be strong enough to sit on the cargo bike's standard bench seat. A car seat can provide much more support, and has a secure harness.
Attachment methods will vary depending on the design of your car seat. The type of car seat you use will depend on the size of your child, and what you have available.
My first car seat installation was rear-facing, using the seat from our car. The seat was installed "upright" against the inclined face of the front of the box which gave it a suitable recline to give Sarah the support she needs.
Moving the seat between the car and bike was tedious, so I found another car seat just for the bike. As winter was approaching, I decided to install the new seat forward-facing, so it could fit under the rain canopy.
In the reclined position Sarah needs, the seat was too long to fit in the base of the cargo box. This was overcome by building a simple platform to raise the seat slightly in the box.
The platform is a very simple construction - just two lengths of pine attached to the box with metal brackets, with a sheet of plywood on top.
I attached a car seatbelt to the base of the cargo box, and a child restraint anchor to the back panel of the box. (There are now several drill holes in this box from several mounting variations!)
The base of the seat is located by the seatbelt and side rails, and the back strap of the seat secures to the anchor point. I deliberately offset the seat to the left of the cargo box, so there is room for some luggage on the right (riding with an unbalanced load is not noticeable).
A car seat was never designed to be used with a bike helmet. To fit the helmet in the seat without pushing Sarah's head forward and straining her neck, I had to prop her back and shoulders forward. I did this by making a multi-layered foam insert from a camping mat, to fit under the cover of the car seat. The cushion is four layers thick at the shoulders, tapering to one layer thick at the small of her back, so she sits in the hollow of the seat as designed.
We came up with this design in consultation with Sarah's paediatric physiotherapist - it's suitable for Sarah's particular needs, but may not be appropriate (or even safe?) for other children. Please seek professional advice before modifying helmets or child restraints.
The design works brilliantly, and Sarah has loved riding home from the child care centre twice a week.
Fine Print: Modifications are entirely at the owners risk. Cargo Cycles does not endorse any modification. Modifications may jeopardise warranty. If in doubt, leave it alone.
