I have been riding my hybrid bike for a little over a year now and decide this passed weekend i wanted to try some dirt trails. From what i read about most hybrids before i bought it was that they were acceptable on dirt trails... Well maybe i was on the wrong trail but i quickly realized my bike wasn't made for this. Had a lot of fun but now want a mountain bike for the off road riding. Ill admin im cheap, and will more than likly buy a used bike. This are the few i have been looking at but im still not that familiar with all the components and if they are good or bad.

1) https://albuquerque.craigslist.org/bik/5824147490.html - Trek Mamba

2) https://albuquerque.craigslist.org/bik/5786662951.html - Specialized HardRock Sport

3) https://albuquerque.craigslist.org/bik/5782381722.html - GIANT XTC Should i be worried about all the scratches and scrapes on it ? I understand it happens but not sure if this means the bike has been neglected.

I am fine with doing tune ups or maintenance on a bike but its all the components i don't really know about as to which is good for trail riding and whats not. Let me know what you think of with of the 3 and if there is something i should stay away from.

Thanks !

Get the one that has the correct frame size for you, you've put up links to 3 different bikes with 3 different frame sizes.

Giant 20"
Trek 17.5"
Specialized probably 15.5"

Those bikes look similar but the prices and sizes really vary. Sometimes, pictures don't say much, so go look at them and take a ride too.
That will help you decide.

+1

First find out what size frame you need and then search for a bike in that size.

How tall are you? Are you specifically looking for a 29er or...? I ask because the geometry is going to be different on each. I ride a large with 26" wheels but I usually ride a medium in a 29er.

Thanks every one for taking the time to look and reply. I more than likely need a large frame ( im 6ft ) so ill need to pay more attention to the listings. If i have any other questions ill ask.

Although others will undoubtedly disagree, since you're a relative newbie I'd stay away from private party sales because you won't necessarily be able to inspect the bike adequately. Many good local bike shops (LBSs) also sell used bikes and they check them out thoroughly. My two cents.