Stefan, I'm trying hard to adjust to normal for age advice. Looking back over old photos, my daughter organised a school fundraiser mtb day when she was 12 ( so most of the kids would have been 13) . I tagged along as part of the support.
The "beginner " group were kids with no or limited previous mtb experience, and most of them were borrowing bikes from the school . These are bikes that had been destined for land fill, but the year 9 students had an elective where they could restore / fix up donated bikes. Variable state of reliability would be a fair description....Anyway, it was a 2.5 hour group ride, we started off on single line green trails but by the end of that 2 hours were doing easy intermediate stuff - drops of about 60 cm , small jumps, berms etc.
NONE of those bikes were as capable as a vado.
I'd be surprised if a 14 yo on a vado is still crawling along after a couple of hours, and judging by what I saw on that day I'd be suggesting temove the rack.
Sorry, no pics of the group, I'm not posting pics of other peoples kids on a public forum. BUT , the second " intermediate" group were tackling this on those borrowed bikes by the end of the day ( and learning how to deal with snapped derailleurs) - it's a near verticle drop into a berm shaped rock, That's my son at 13 on his sisters bike ( size large scott genius) . Imagine doing that on a hardtail with a rack....