That is true, but…..
It will probably upset his day if the recalculated route takes the unfortunate fellow onto the nearest motorways and directly to the end point, instead of taking him along some great twisty scenic roads, as created by RiDE, by bikers, for bikers.
A lot will depend on:
A. The area / roads the RiDE route runs over. In other words, how many alternative roads might be available for the device to chose from at the moment of a recalculation.
B. The way the RiDE route was created. For example, whether it had any shaping or via / way points within it. Or, whether it downloads as, say, a track which has no intermediate points at all.
C. The preference settings of the fellow’s navigation device, as these may (depending on circumstances at the time of a recalculation) dictate how any recalculation is made.
D. Whether the fellow at some point stops running the route and then restarts it and / or his position relative to the route on restart and / or what option he chooses when he does so.
Assuming the fellow DOES want to follow the RiDE route and not find himself potentially having it entirely recalculated, the simplest method is to turn auto-recalculation off….. and to learn how the device functions.