I would like to have some details on the calculation of isochrones.
For bicycles, what speeds are taken into account?
Are the slopes of the roads taken into account?
which road and cycle path network is used?
there are a lot of factors that modify the speeds for travelling by bike in openrouteservice. There is some information at Travel speeds · GIScience/openrouteservice Wiki · GitHub which has links to the relevant files that are used in the code for calculating speed for bike profiles. in our current live implementation, we do not take into account the slope of roads.
In general, the type of path preferred is based on the individual bike profile, but in general cycle lanes are used if available, else paths that are marked as allowing bikes to use them, else it uses roads. All the data comes from OSM.