115 with 42x15 with a couple killer hills.
105 with 48x15 (century in 5.5 hrs) into a crazy headwind for about 1/4 of the ride.

It's fun riding fixed for distance, but I often feel that my cadence is either too high or too low. When I run 42x15 I feel like I spin too fast downhill or with a tailwind. 48x15 sucks going uphill or into a headwind, but is awesome when you got the wind to your back and can hold 25-30 indefinitely.

I am training for a non-stop, 320 mile gravel race... lots of my base mileage will be fixed gear.