I have a new bike which is roughly 6 months old and has not been used much. I've ridden roughly 120 miles on it and the gears or freewheel has started slipping when I'm in the lowest gear while putting quite a lot of pressure on it. I am not sure where to start looking as its been over 15 years since I had been on a bike before getting this one and been a while since I've messed around or fixed them and I never have had this problem before.
I don't mind spending money, I'm just not sure if its something that could be fixed as the bike surely hasn't had enough wear and tear for any parts to break.