Originally Posted by Velocirapture

Here's an excerpt from the UCI 'REGULATIONS: CHANGES PROPOSALS PART 1 – GENERAL ORGANISATION OF CYCLING AS A SPORT' (Rules amendments in force 01.01.14),


from here: http://www.uci.ch/templates/BUILTIN-...Y2NjU&LangId=1

which, in summary, says you can have your saddle tip up to the bb centre-line, so long as you are in drop bars, but if you add pursuit bars, the 5cm behind rule applies:

1.3.013 The peak of the saddle shall be a minimum of 5 cm to the rear of a vertical plane passing
through the bottom bracket spindle. This restriction shall not be applied to the bicycle
ridden by a rider in a sprint event on track (flying 200 m, flying lap, sprint, team sprint,
keirin, 500 metres and 1 kilometre)