Yeah, do a search… this topic has been done a few times. But like you said it is personal preference. It’s based on where you live, how many hills/downhills there are and how manly your legs are.
Do some experimenting and you will find your sweet spot
You will also find people will be talking about gear inches.
Use this to work out what you have and what you need to get the inches you want. Currently you are running 80" which is pretty big but it might suit the kind of riding your doing.
whats the difference between having 42:15 and 48:17
the gear ratio for both is around 2.8
but apparently having a larger chainring and larger cog is different to having a smaller chainring and smaller cog
so ah, jonno, you think that ratio might be a good one?
about the ease-of-skid factor, i think an ok rule of thumb is to go below 70 gear inches if you’re going to use your legs as a brake all the time. unless you’ve got big man legs.
47/17 is my favourite ‘city’ ratio, a bit over 74". i’d rather go faster on the flat and use a brake occasionally. brake pads are cheaper than new tyres.
but yeah, there’s sooo many other threads on this topic.