On 18 Nov, 00:37, Judith M Smith  wrote:
> On Tue, 17 Nov 2009 08:54:39 -0800 (PST), thirty-six
>
>  wrote:
> >On 16 Nov, 18:47, "mileburner"  wrote:
>
> >> If you glance over your shoulder and assess the size of the vehicle behind
> >> and then look ahead to see the width of the available space it is quite easy
> >> to establish whether there is enough space for them to overatake or not. If
> >> not, then blocking them makes a lot of sense. If there *is* space, then bear
> >> in mind that you might have to dive into the gutter as they pass.
>
> >I generally ride with 16" clearance to my left.  
>
> Are you sure that it is not 15" or even perhaps 17"?

Certain.   It was commented that I ride a steady line and I checked
the comfortable distance I use by riding by a wall leaving a wet track
on the ground, it is 16" clearance from my upper arm.  Coincidentally
it's the same distance as the dimension beween my drop handlebars.