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@Quad: had to look on my car's spit-o-metre, but it's ~45Km/H. That, of course, assumes there's no prevailing southerly or northerly acting upon me as well. (The I-5 corridor, particularly in the Vancouver area, is effectively a big wind tunnel because of its proximity to the Columbia River. SR14 even more so, as it (mostly) runs parallel to the river!
Incidentally, when I have ridden along the highway I have used the shoulder. Gets kinda' rough when I hit the occasional patch of broken glass or truck-tyre fracments, tho....
Update: Well, WMC beat me to it. I don't know how s/he does it, but WMC beat me to it. Build off WMC's post and I will remove mine.....