Ok so been out on the new mongoose 3 times this week, once in conditions it couldn't cope with and chain came off. I am having problems with the left hand gears ie. big cog (sorry about the lack of technical terms) Chain is not moving smoothly and I am having to push the gear lever hard round which apart from anything else isn't very easy. I am doing something wrong, is there a simple solution or do I have the hassle of taking the bike back at the weekend. It's bad enough that I'm so unfit without this hampering my speed when I get going!