I have a SRAM 11 speed 1x gravel/road bike. Most of my cycling is urban and I'm always looking for long slow hills. I have a new crankset on order and I am thinking of what size chainring I should get for my 1x drive train. Currently on the back I have a 11-42t cassette and I have a 40t chainring up front. Statistically I NEVER use the 11t cog on the back and only on rare occasion do I use the 42t cog. Should I stick with the 40t upfront or would I get better use out of a 38t or something different up front?
Thanks

Personally, I'd probably err a bit low in that case. It makes sense for your usage, and it's usually worse to run out of low gears than high gears.

Sounds like you have the perfect choice as you don't seem to use either extreme of your cassette. Though, a 40/11 combo is only about 24-25mph at decent cadence, which isn't hard at all to be at with a slight downhill.

Your usage seems to indicate you've got the perfect gearing already.

On my Lynskey, I use a 42T front / 11-46T rear and, like you, I rarely feel the need for anything different. The only time I wish for more chain ring is on steep paved descents. But on paved roads, I'm not racing . . . so why do I care?

I have the Sram 11 spd and i agree that it sounds like you have the perfect setup. I started out with the stock (Trek Boone) 30-somthing chainring but quickly swapped it for a 50 (or 52) chainring. I still use both extremes of the cassette, especially when its on tne Kikr for Zwift.

I have a 38T on my 1X and find that it is just about right for most applications. Some very steep hills, I'm hurting, but I never spin out on the high end. So a 38T is a good choice IMO. YMMV based on your fitness, terrain, and road condition.