What front brakes do I need for this bike?

Knowing the standard height of a london brick, you take half the width of stock Raleigh racing drops you can calculate the distance the bike is away from the wall.
Given the standard lens on a digital camera is 35mm you can calculate the field of view and from that the distance away from the bike the photo is taken

Take into account variations in London brick through the 1980's and the cheap import of South African product with the likelihood the lens has linear optical technology on board. I can tell you you need a 65-72mm drop cantilever brake

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