What do you mean prone to problems?
I bought a single speed to get away from problems.
The heavy and slow is not a problem for me.
Most of my riding is solo or with wife and kids.
If I'm on a geared bike riding with them it's to easy for me to out pace them
Thanks for info. You are correct that it's square tapered. If that refers to the part of the crank you can see on the non drive side