I didn't answer that bit of your question.
Since you do ask, I'd say it is situation dependent, as you already stated. The Description loads the odds in favour of "considerable strength", which should prompt a referee to consider what happens if PC/NPC doesn't "have enough stat."
Possible suggestions on what to do depend on situation. If Traveller just wants to drive bike off a forecourt and onto a flat motorway, then I'd say let them. Maybe even let them do a bit more daring stuff if the situation is low-grav.
For steep slopes, I see no RAW. Traveller Careers has the idea of Qualifying Characteristics. That is the nearest to a parallel rule mechanic. You could evolve your own referee arbitrated characteristic check, that parallels Characteristic Qualification, when the terrain demands it. Set the TN so that only STR greater than 12 succeeds with a roll of 8+. Or something like that. Failure to "qualify" means the Traveller fails to surmount the obstacle/terrain in some disastrous way. This would be my drift with that sort of text description
I don't know about you, but I like the way I can take this description and 'mold it' like clay into a role-play context. Not treat it as A.N.Other hard-and-fast d6 yardstick. User comments about this will be welcome.