Recently went the other way, was fine while pootling around the flat with the kid at kid speed. Bloody scary on the Wednesday night off road pootle.
I can commute with shoes/trainers on SPD pedals, even ride off road a bit. But use traditional pedals and it's all wrong
Yes you'll probably have a fall, your instinct isn't there yet, but it's like riding a bike you suddenly just do it and don't notice.
Give it time though and don't give in straight away. You may need to set it up a few times, find you angle and for/aft etc...
Wrong seat height is just as likely to strain the knees, but really is only something to worry about if it still happens after months of riding.
I think there are three people I ride with, 3 different eras from modern, retro and vintage 'ages' (Luke, spud and Trebz)
I think the young UN's are learning faster›.