Hi, newbie here. I just bought my first real bike (non-walmart). I got a Diamondback Sorrento...after some shopping around for an entry level bike. I live in Columbia, MD where we have miles of paved bike paths that I'm riding it on, but there's also a lot of hills! I really like it so far except for one problem. I'm having trouble shifting the front from 2 to 1...unless I'm going like downhill. If I'm going up even a slight incline it won't shift into first gear...and will sometimes throw the chain. I'm a big guy, 6'1'' and about 260lbs. Am I asking too much out of it? Do I need a better front Derailer (sp?)?

Here's a link to the bike specs if that helps: http://www.diamondback.com/bikes/mtn...l/sorrento-11/

Thanks for any advice!