I've ridden a fixed gear bike for years now, but I've only just questioned if I have been doing something wrong when adjusting the chain. You see, I have to tension the chain (pulling the rear wheel back) every now and then, roughly once a month because the chain becomes very loose with regular riding. At first I tried to keep the chain as tight as possible, so that there's pretty much no latency in the pedals when the bike is stationary (don't know if this is the correct expression) but then I read somewhere that doing this with fixed gear bikes can damage the drivetrain, and you should actually have a little latency and thus a slightly loose chain.
In short, my questions are: Is it normal that I have to tighten the chain probably at least once a month because it gets too loose with casual riding, no more than a 100 miles per week?
Is it correct that with fixie you shouldn't keep the chain too tight because it can ruin the drivetrain?