A bike might not seem like the most obvious mode of transport in Bangkok. Traffic is chaotic and weird stuff happens. For example, sometimes there are elephants wandering between the trucks, tuk-tuks and cars. People cross the road willy-nilly, you have to really keep your eyes open. But an experienced cyclist will be absolutely fine, and the guide will help as well.
There are quieter areas in the city where you can easily get on and off your bike in safety and explore. It’s nothing like riding a bike at home, and it’s a really cool experience.