The trial is a bid to cut the contractor’s carbon footprint by reducing the number of construction vehicles travelling into and around the capital.
The bikes can carry materials of various sizes and weights including bags of sand and boxes of fittings.
Each bike can carry up to 250kg and is fitted with an electric pedal assist motor and GPS tracking.
The average 18 tonne delivery lorry can carry a load of 10,000kg.
The bikes are currently being trialled on phase two of the Illuminated River project for Westminster City Council.
Adam Barnes, Senior Contract Manager at FM Conway, said: “As a cyclist with average experience, I was initially a little bit hesitant to ride the cargo bike.
“With the prospect of having a delivery load added to the bike this only heightened my nervousness around the planned ride. However, any concerns I may have had were quickly reassured.
“As soon as I got on the bike to do some practice laps of our yard in Southwark, I immediately realised the ease of riding with the use of the electric assist motor.
“As to be expected, you must be aware of the slightly larger frame, but the handling and engineering of the bike make it very user friendly.
“Being on the ride has really given me a better perspective for the use of cargo bikes from both the view of the rider and the operational potential within the industry.
“I am now more motivated than ever to incorporate their use into our site logistics model within central London and further investigate their use in site operations in other areas of the business.”