This isn't so much for the OP, who wanted slim fit, but for others who live in colder climates and were drawn to the thread.
I have two pants that I wear when it starts to get colder.
The first,
https://www.montane.co.uk/en/men/clo...ar/terra-pants, are great for low 50s into the 20s. Nice and light, but windproof, with snaps to secure the cuffs away from the chainring and zips on the outside thigh to open up to allow the heat out (thought I've used them only a few times, as the pants are very breathable).
The other pair,
RUGGED II MOUNTAIN PANT MEN | featured-outfit-trekking-s15 | featured-outfit | Haglöfs, I wear commuting, Fat Biking and backcountry skiing. They are absolutely bombproof. They have thigh zippers to vent heat, camlock straps at the cuffs to keep them out of the chainring and do away with the need for gaiters, etc.
Both of these you just have to search online to find the best price. I'm 5'10" 175, wear a large in both, although the Haglofs are a bit room and I could have gone with a medium.