The Dahon Neos is specifically designed for use with small wheeled folding bikes. It mounts by bolting into a special dropout in front of the rear wheel. This enables it to protrude very little from the frame and it also allows the cable routing to be very straight. Both of these are important features which minimise damage when the bike is folded. It is also a low normal design with a very short cage - designed for ease of use on bikes with a single chainwheel.

It was developed by Dahon in association with SR SUNTOUR, and you can see some evidence of the old, crazy, SunTour, freethinking DNA in its design (see the SunTour S-1 and SunTour SX-100). I like the fact that it has a nine tooth guide pulley and a ten tooth tension pulley - eccentricity is not dead.

• Derailleur brands: Dahon, manufactured by SR SUNTOUR
• Themes: Small wheels on my wagon
• Country: USA manufactured in Taiwan
• Date of introduction: 2004
• Date of this example: unknown
• Model no.: unknown
• Weight: 220g
• Maximum cog: 30 teeth? (Dahon only seem to use it up to 30 teeth, but I have been told that it can accept a 32)
• Total capacity: 19 teeth? (Dahon only seem to use it with a single chainring and 11 to 30 cassette).
• Pulley centre to centre: 42mm
• Index compatibility: 7 speed
• Chain width: 3/32”
• Logic: low normal
• B pivot: unsprung
• P pivot: sprung
• Materials: largely steel with an aluminium rear knuckle and a plastic front knuckle