Use mapmyride to find out the kind of topography you can expect. 90k would be grand on a fixed (depending on your gearing and hilliness) however, don't expect to be competitive the following day.
@scaryeire started
London Fixed Gear and Single-Speed is a community of predominantly fixed gear and single-speed cyclists in and around London, UK.
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Use mapmyride to find out the kind of topography you can expect. 90k would be grand on a fixed (depending on your gearing and hilliness) however, don't expect to be competitive the following day.