Low maintenance Internal hub gearing systems are more appropriate for riding in urban environments especially because gears can be changed very quickly to respond to the stop/go situations that cyclists often find themselves in on city streets.
Gears can also be changed while stationary whereas the dérailleur system used on mountain bikes necessitates that riders change gear while moving before entering a situation,-which can be a bit tricky when riding in the midst of motor vehicles.
Losing your chain when trying to get out of the way of a car could be fatal.

Internal hub gearing systems
Internal 3,4,7 or 8 speed gearing systems manufactured by companies such as Sturmey-Archer and  Shimano are prevalent in Europe and Japan as opposed to the dérailleur systems which are the only choice being offered by 99.9% of cycle retailers in New Zealand.

An excellent weblog on hub-gearing systems:

http://hubstripping.wordpress.com/

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State of the art......

Continuously Variable Transmission.

The NuVinciCVP is revolutionizing the bicycle rider experience with features like:

  • No gears to fear
  • Best, smoothest-adjusting-ratio hub ever produced
  • Uses a set of rotating spheres to transfer torque from pedals to the road
  • Effortlessly glides between an infinite number of ratios
  • Simple twist control for smooth, easy progressive changes in ratio
  • Change ratios any time, even while stopped or going uphill
  • No missed gears, jerks, thumps, hesitations or noise
  • Dependable, performance unaffected by weather, dirt or mud


read a review about Mondo Nuvinci from Bikehugger.

http://www.fallbrooktech.com/NuVinci.asp

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Rohloff 14 Speed internal hub gearing ( on Sheldon Brown' site)


















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Shimano Alfine 8-speed internal gear hub

Comments on Alfine on Bicycledesign Weblog

Shimano Nexus

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Check out some of these web-sites for a look at some examples.
http://www.koga.com/uk/segment.asp?collection=7&segment=56
http://sheldonbrown.com/internal-gears.html

An excellent web-log on Internal Hub versus derailleur gearing systems in Portland, Oregon .