No one mentions strength and stamina? I only ever have a problem when I get tired - either weak or winded.

Take the following elements and go for a ride:

Strength
Skill
Stamina
Steed (bike)
Schwalbes (tires)

Now, start taking them away, one by one, but in different order...

For me, keep my strength and stamina until the very end, because if those go first, all the skill, steeds, and schwalbes are not going to get me home.

EDIT - I was riding as straight as I could: