When I bought the Bridgestone Moulton last year, decided not to bother fitting a computer, but missed knowing my speed, average and distance.
So today I succumbed to buying a basic wired one from Wilkos, and fitted it. Had to rearrange items on the handlebars to make enough space, but was thwarted in trying to make the cable inconspicuous by it being only just long enough for a 17 inch wheeled bike, aggravated by having to put the sensor at the bottom of the front fork to get it close enough to the spoke magnet.