anybody here has a single speed/fixie apart from their usual road/ tri bikes. If yes, what sort of purpose does it serve? any benefits and do you enjoy it?
Mostly fun and commuting. A few years back, I did do regular hill repeats on one and it seemed to improve my (standing) hill climbing technique.
Fixies are a ton of fun, especially when you forget to pedal!
My current fixie ride.

Commuting in Manhattan, that’s what I’m using it for. It’s about 100 miles per week. Barely any maintenance is required and lower chances that it gets stolen… Plus it’s fun to ride.
I use my fixie for commuting and riding with my wife when she wants to go out with me. It’s a fun ride and with a front brake (which I have) it’s perfectly safe. It gives you a great workout on the hills, and has helped my technique too. I learned a lot about how to push/pull/spin riding it.
get powercranks instead.
I think it’s fun. I feel like I get a great workout. I have a fixed gear that I ride on the road and a single speed mountain bike. Riding the mountain bike in the short but steep park trails can be tough. I also use the fixie on my trainer for the beginning of the season, it has fewer things to wipe off. The single speed mountain bike is also my low maintenance commuter.
I have a single speed and often ride my 10spd bike without shifting. What it does for me is forces me to work on a different cadence and power output. Also, they can just be fun…
My single speed is my cruising bike. Regular platform pedals, so no bike shoes.
I cruise up to the store if I need something & if I’m going out without my g/f I’ll ride it up to bars/restaurants to meet up with friends.
Rather ride my bike through neighborhoods after 2 or 10 beers than drive my car.
Saw a guy racing the Wildflower Long Course on a single speed! That’s a hilly course too.