Commuting between car lanes In my commutes I often see cyclists ride quite fast between car lanes (for example when stopped at traffic lights, they get to the front to the lights before it gets green so they don't have to wait till all the cars start moving).

When there is 1m-1.5m, it is quite easy, but how does one master the width of the bike?
Every time, I am on the brakes feeling I am that close to the cars' mirrors but on the same time I see cyclists ride by without even slowing down, even motorbikes...

If even motorbikes get in that space, I must be doing something wrong, so how does one get conscious of the actual width of the bike?
One key factor is your handlebar width. This might seem obvious but I have a friend who recently bought a road bike with drop bars to replace a mountain bike as it has much narrower handler bars.

If you do have mountain bike handle bars I recommend putting your hands right at the edge, that way your brain will best gauge whether your bike will fit through, since your bikes width is also your width, and your brain knows you pretty well! This little trick is what cats use to judge spaces knowing their whiskers are the width of their body.