OK, most of this thread is slightly dated, in that we now have available the Luxos U, inter alia, with a remote switch. I have found this most useful on my upright Audax bike since not only can I operate the lamp from the handlebars but also I can draw surplus power to run my Garmin.
For laid back use though, the cable between lamp and remote switch may have to be extended. Who's going to be the first to be bold/clever enough to educate me as to how simple this would be, given [insert list of stuff from Maplins, etc.]?
Actually, having just written the above, I have remembered that the remote cable plugs into the lamp via what looks like a simple 3.5 mm jackplug (would have to check this) so presumably an extension lead ought to be simple even for electric numpties like me?
