Currently every custom profile is based on a FlagEncoder (let’s say a ‘vehicle’). For every road/edge we store ‘access flags’ for every vehicle. These are simply boolean flags that determine whether a road should or should not be accessible for a certain vehicle. For example all access flags for motorways are set to false for the bike and foot vehicles. Using custom profiles you cannot change this yet, but we are working on this. So if a road is blocked for bikes you cannot simply make it accessible using a custom model without changing the GraphHopper code. In some cases you might be able to use a FlagEncoder that does not block the road you want to use in the first place, because closing roads using custom models is always possible.