Well as most people who know anything about Raleigh Choppers will be aware the majority of them came as 3 speed using internal Sturmey Archer (AW) gears.
They were notorious at slipping in 1st which will cause most men to wince thinking where the gear stick is positioned in relation to our wedding tackle 😦
The gear ratios are 0.75 (1st) 1.00 (2nd) and 1.33 (3rd) and to be honest I haven’t a clue what these figures mean.
Briefly it means: that gearing combined with 145cm cranks (instead of 175cm) and a bike that weighs 45lbs (half a house) and small fat wheels means the bike is ideal to tootle around, posing in town.
But… what I bought the bike for was to attempt the Coast 2 Coast ride which is 140 miles including some very steep/long climbs, namely Whinlatter Pass, Hartside, Garrigill, Nenthead and Crawleyside bank – I’ve gone wobbly at the very thought 😦
Anyway I had decided to change it to a 6 speed with the addition of a bigger rear sprocket (22t) to go alongside the original 18t and adding a derailleur.
My first problem was the bikes never had derailleurs therefore no hanger. To overcome this I asked my neighbour to weld on a homemade hanger prior to the painting process which he did. I’ve since butchered (widened the gap to allow a fat chain to pass through) an old 7 speed derailleur so that it now only goes between the 2 gears (which fitted on the spline once I removed the spoke protector and the 2 spacer shims although it was still tight) I’ve coupled these with a friction shifter on the handlebar stem.
After a lot of adjustments I finally have it working so I have the equivalent of a low and high ratio gear set.
I’ve included some close-up photos so you can check out the conversion.
3 SPEED IS NOW 6 SPEED 🙂
** EDIT: If you are thinking of doing this checkout the later posts to ensure you make the further changes I had to make to overcome the issues I had.
Nigel's Adventure With His Purple Raleigh Chopper 
Can’t find your later posts, need to do something similar before I do London to Paris in may on my mk3 (I’m poor!)
A link or photos would be fantastic, I was thinking about a 3 speed up front with a chain tensioner like on a Wisp moped, but yours looks awesome!
How did you get on btw?
Hi Nick, The full site is available at http://www.purplechopper.co.uk . I was a great yet tough ask going across the Pennines ona 40yr old heavyweight kids bike but it was an awesome experience. I know someone who butchered a 2 speed front derailleur on a chopper. He had to do this as the downtube is too thick. He was doing lands end to john O’groats