Something I didn't see mentioned.. if you can get them easily enough, a spare derailleur hanger is worth carrying.

I know that Derailleurs could break and you never know when.. but how often does that happen?

Idea: Cover the edges of the liner with duct tape.

Good idea or dumb?

If the hanger breaks then you're screwed and would have to SS the bike (assuming you have a hardtail and a chain tool). If it bends, you should be able to get it back in shape enough to finish off the ride.

At the shop where I work, it's pretty common for people to bring in bikes with rear derailleurs hanging by the cable, but the derailleur itself is in decent shape. There's quite a few shops in this area too, so these are just the ones coming to us. There's got to be more out there.

As much as I cuss the principle of a derailleur on a mountain bike, in reality they are pretty tough buggers. In nearly ten years of racing downhill, I have never actually broken a derailleur. I've bent hangers, bent derailleurs and I've smashed one hard enough for the mounting bolt to nearly rip the threads out of the hanger (bolt was toast the hanger was saveable); but haven't yet actually broken one . . . yet.
http://www.myemoticons.com/images/pe...ck-on-wood.gif

Thats good... hopefully knock on wood :D i can ride in that same boat.

On shorter rides (under 15 miles) I carry:
multi tool that includes a chain tool
SRAM powerlink
Spoke Wrench
Park Quick Patches GP-2
BIG AIR- C02 and valve
Spare Energy bar
Zefal Magnum 34 oz Water Bottle
Cell Phone
With the exception of the water bottle and phone, this all fits in an underseat pack.

On longer rides of 20 - 50 miles I would might add:
Spare tube
Camelback and additional nutrition
Energy drink in extra water bottle.
A pump just in case.