upgrading gears

[BillB]

I have an old fashioned lever shift down the tube of my Dawes, what is the best way to change to a handlebar shifter?

[thirdcrank]

If you are happy with one that protrudes from the end of the handlebar, you need only buy a lever of that type, plus a cable stop (which will fit on the boss currently holding you gear lever) fit a longer cable with a bit of outer cable between the lever and the cable stop and off you go, with the lever on the friction setting, probably.

Beyond that, gear controls are pretty specific to gear mechanisms so you could end up buying all sorts of parts and even making all sorts of modifications.