Raleigh three speeds typically came with 46 teeth chainrings. The rear sprockets on Raleighs come in different sizes and are changeble with snap ring pliers. I do not know about Triumph rear sprockets. According to Sheldon, Raleigh aquired Triumph in 1954, so there is a good chance the two are interchangeable. Also according to Sheldon, Shimano bmx sprockets can be ground a bit to fit the Raleigh hub. So if your hub is Raliegh standard, (Sturmey Archer), that leaves your gearing choices wide open.