In gravel the bike is never the problem

Hardly anyone stays home for lack of fitness. They stay home for not knowing where to go. The route is ninety per cent of the plan, and it usually lives entirely in one person's head.

What decides a gravel ride

Somebody has to know the way
A track that looks like an unbroken line on the map can end at a fence. Whoever proposes the ride is usually the one who has already done it, and that's worth more than any file downloaded the night before.
The surface outranks the distance
Sixty kilometres of fast gravel and sixty of broken track are four hours or seven. Worth saying which kind of track is meant.