I'm looking to upgrade my 05 Marin B-17. Everything is currently stock. I am not concerned about weight, it is no issue (to an extent, I am only 5'3" and 135 lbs riding a 19" frame). What can I upgrade to increase durability, since this will probably be the only upgrades I will be doing for quite a while? I was thinking about having the rear derailleur upgraded, since its only a Shimano Alivio. What is the difference between the SRAM components and Shimano components? From what I can tell, SRAM looks to be more durable, but I am not sure. Any ideas are welcomed, I'm open for all suggestions. Thanks a lot.