you can measure it yourself: http://www.sheldonbrown.com/gloss_bo-z.html
@Cohen started
London Fixed Gear and Single-Speed is a community of predominantly fixed gear and single-speed cyclists in and around London, UK.
This site is supported almost exclusively by donations. Please consider donating a small amount regularly.
you can measure it yourself:
http://www.sheldonbrown.com/gloss_bo-z.html