Grimy Phil...

How long does a bike have to sit around, unused, collecting dust, for it to settle this thickly? 

"...

When your swift hair is quiet in death,
And through the lips corruption thrust
Has stilled the labour of my breath -
When we are dust, when we are dust!

Not dead, not undesirous yet,
Still sentient, still unsatisfied,
We'll ride the air, and shine and flit,
Around the places where we died,

And dance as dust before the sun,
And light of foot, and unconfined,
Hurry from road to road, and run
About the errands of the wind.

..."

a portion of Dust, by Rupert Brooke, 1887-1915

Sometimes, bikes are like bodies; they can reach a point of no return. Age and wear, if not checked, will take take their toll; a general, and gradual deterioration set in. Fortunately most bikes, even those forgotten ones, untouched for years, can be rehabilitated, repaired, cleaned up. They can once again dance as dust before the sun, on road and trail, and city street.