I bought a few pairs of cheeper cycling shorts on amazon (about £10 each) as I've just started to commute by bike and noticed a bit of a sore bum after my commute. Unfortunately after using them for a few days they don't seem to have any real effect for me. I commuted today without them and haven't noticed much of a difference.

Next plan of action is trying something a bit better quality and see if that has any effect.