Now that you have all of these tools packed and ready to go, what use are they?

To explain, after an hour or two of riding you could be four and six hours away from being able to walk your bike out of any back country you are (were) riding in.  The amazing thing about a bike is the capability of covering acres and acres of trails with little thought of how far you are getting away from civilization.  It's not new math, it's a reality.

For instance, if you ride your bike at 15 MPH down a trail, in an hour you are 15 miles away from where you started.  If your bike breaks down after an hour, you can walk it back at three miles per hour and five hours later you are back where you started.  Alternately, you can carry the necessary tools to do basic repairs and fifteen minutes later you are back on the road.  Net time savings, 4 hours and 45 minutes.

The number two item, a CO2 pump can also be a hand pump mounted on any convenient place on the bike frame.  I like the CO2 pump because it is packed away inside my tool kit and protected from damage when crashing.  That may not be a concern of yours but I have destroyed several frame mounted pumps and the ones I didn't destroy, didn't work that well.  A CO2 pump works really well and really fast. It takes typically three cartridges to inflate a Mountain bike tire.  (I buy cartridges in bulk (fifteen to a box) from Big 5, that are intended for BB guns but work equally well in my CO2 pump at a third of the cost of the ones sold in bike stores.)

The number three item is a chain repair tool.  Chains do come apart under the stress of late shifting (while going uphill.)  Once a link is

weakened, if it doesn't separate right away, the very next time it is stressed, it may come apart.  There is no rock or any other improvised tool that works better then a tool specially made to repair chain.

The operation of the chain repair tool is intuitive and is covered in this tutorial.  The spare chain links (item 10) are used to replace a link that is tweaked beyond repair so that you can still have a chain that is the correct length for shifting through all 24 gears or as many gears as your bike is equipped with.

I carry some small parts as well, such as a spare nut for a presta tube, a spare cap for a presta tube, a shrader valve stem removal cap.  I do carry some non-essential parts when it is convenient, to help other people who are stuck.  For instance, you can't fix a flat on a shrader tube without having a valve removal tool.  Well actually you can, but with a tool you can do it ten minutes faster.

The spare inner tube is for convenience as it saves about fifteen minutes of finding an air leak, and then patching it.  On one trip, I went through my spare tube and all of my patches and ended up having to walk my bike out.  Sometimes, fate just piles up against you.  Other times I have gone a year or more without even using one item in my tool kit.  I typically use my tool kit more often for other people then myself.

Be sure to check your tool kit every six months or so.  Rubber cement for instance, has a nasty habit of evaporating into thin air.  Patches don't work very well with spittle.  Tools can get rusty and may need cleaning and oiling.  When you inspect your tool kit, corrective measures are usually obvious.