15k hill run today, and I prefer off-road for all the reasons mentioned above.
No car available, so 48k round-trip by bike to and from the start point.
Out of interest what do you do about securing the bike, taking running clothing, etc when you cycle to/from a run?
I had a small rucksack containing my running kit, which also which had a small cable lock in it.
The car park is in a fairly remote location, off a not-very-busy road.
The bike was not visible from the road, it appeared as an un-inviting car park that you would have no reason to enter unless you were going to go up the hill, which no-one else was doing today.
I locked the bike to the best thing available ( a fairly sturdy fencepost in this case, with enough runs of fencewire above to prevent it just being lifted off).
My cycling kit was left in the rucksack, and the cable lock passed through that too.
There was nothing to stop anyone opening and rummaging in the rucksack.
My bike Garmin was removed from the bike and left in the rucksack, too.
So fairly minimal security, really.
But good enough for this scenario.
There's a photo of the arrangement on my Strava post here:
https://www.strava.com/activities/11260988993