Grant Cameron-Smith
Space, weight and functionality
These three words explain the plight of a bike-packer who has to cart "stuff" up and down mountains.
Riding a road bike with just a water bottle is so different to a mountain bike with panniers and all manner of goods. Whereas a road bike will weigh under 10kg, my mountain bike without panniers weighs well over 20kg.
All the small items that need to be packed add up really quickly to a significant weight - which may be unnecessary in the end.

Do I have to take and item with me - or is it a luxury that I can do without?
If I leave it behind, then how may it affect my trip? Will it bring pain or joy one way or another?
Can I readily buy it en-route if I make a mistake and leave it behind?
What does it weigh?
Can I change anything about it to make it weigh less? ie. Can I leave non-important bits of it behind? Is there a lighter weight alternative that is functionally equivalent?

How functional is the packaging?
Can I open it in the rain?
What will happen when it gets wet?
Can I open the packaging in the dark / with one hand / without any implements?
Can I store it differently to take less space?
Does it need any packaging at all?
Now that we've got to this point a decision can be made to:
Take it or leave it
Change the packaging or repack the item.
So we are taking the item. Lets look at it further:
Does it need to be stored individually to prevent moisture? (maybe a zip-lock bag
Does it need protection from bumps and thumps (packed inside something else eg. camera)
Is the packaging superfluous?
EXAMPLE 1 - BICYCLE INNER TUBES

A bicycle inner tube in a small watertight package weighs 260g.
When travelling with tubeless tyres, 2 inner tubes are needed - then of course there are patches needed for them too.
The total weight of two inner tubes plus patches is about 530g.

An alternative bright orange tube called a Turbolito is available and it only weighs about 45g.
For 96g I have two tubes plus a puncture repair kit - saving 434g.
If this can be done for a simple item like inner tubes - imagine the weight that can be saved on:
A tent
Sleeping bag
cooking equipment
Clothing
Emergency bike repair equipment
First aid equipment
EXAMPLE 2 - BATTERIES

Although I have tried to make all my batteries rechargeable, some specific devices cannot accommodate that.
For instance the flat 2032 batteries.
Removing them from their cardboard and plastic retail packaging and putting them into small tube containers saves a huge amount of space, makes accessing them later far easier and cuts down the weight and on-the-road annoyance.

Water-tight containers are really important - and one of these little containers can hold 20 small batteries.