The Cyclo conversion wins on several counts. Firstly, and perhaps controversially, I would say that any of the old school Sturmey hubs with more than three gears are rather poor products. The original three speed however is a gem, a pleasure to use. To have more, and a wider range of, gears than offered by the Sturmey three speed is obviously a bonus. Secondly, early derailleur gears are largely crap in function. Changing is slow and clunky. It's no wonder that serious road men kept with single speeders for so long... However 1930's technology derailleurs can cope with two and even three gears ok, the less changes you have to make however the better. So, given the above it's evident that a hybrid gear system is a pretty good thing.
Looking at the brochure Cyclo offered a fairly wide range of gearing with the conversion - look at that plate sized low gear pictured. Great for hill climbing but you would want to persuade your changer to select it way before you actually needed it. So, essentially the hybrid system offered a climbing gear for the Sturmey hub. A great boon for touring when common practice was to dismount for hills and walk.
Also interesting is the Cyclo twist grip changer. A very rare item nowadays.
Hybrid systems remain poopular within a niche of the cycling community and are very easy to home build. Any old derailleur will do and instead of seeking out the original Cyclo sprocket you can use two 3/32 Sturmey dished sprockets back to back - just remove the spacer used with the single sprocket. It is pretty much as easy as that.
For anyone with a further interest there's a good article on the Classic Lightweights site.
|Cyclo / Sturmey hybrid gear|