I think carry one is fine if you're with a group, as you can always pool resources. |
However, the fundamental rule of being able to get yourself home outside of a complete mechanical disaster still applies.
For this monster miles thing I'm going to have to resist the urge to take more than I need, but it does mean I can put little things in like a spare derailleur hanger. The chances of breaking one are low, but they weigh next to nothing.
PSN ID: Mikenetic