The UCI rules have an extensive section dedicated to equipment, and specifically to that used for time trials. Much of it is addressed by the frame or component manufacturer, but there are specific rules related to seat and handlebar setup adjustment in particular that are the responsibility of the rider.

Commencing with the 2009 Auckland Championship Time Trials these aspects of setup are going to be scrutinized much more carefully at all levels of competition, and riders will be expected to comply with these requirements by adjusting their setup (if required) before they are allowed to race.

The primary things to comply with are.

1. The tip of the saddle should be 5cm or more behind a vertical line passing through the centre of the bottom bracket (with a 5cm tolerance for morphological reasons).
2. The morphological check for saddle tips 0 to 5cm behind the bottom bracket requires dropping a plumb line from the forward knee with the rider mounted on the bike and the cranks in the horizontal position. If the plumb line passes through the pedal axle or behind it the morphological exemption is approved and the saddle position can remain.
3. The tip of the aero bars (not including shift levers or bungs) should extend no further than 75cm forward  from a vertical line passing through the bottom bracket (with a 5cm tolerance for morphological reasons)
4. The morphological check for aero bar extensions between 75cm and 80cm requires the rider to mount the bike and assume the aero position on the bars. If the angle between the forearm and upper arm is 120 degrees or less the morphological exemption is approved.
5. Under no circumstances can the saddle tip be forward of the bottom bracket centre, or the aero bars extend more than 80cm forward of the bottom bracket centre.
6. ONLY ONE OF THESE MORPHOLOGICAL EXEMPTIONS IS ALLOWED PER RIDER – NOT BOTH. The expectation is that shorter riders are more likely to require the saddle exemption and taller riders are more likely to require the aero bar exemption. The rules prohibit one rider getting an exemption for both.
7. The forearms should be horizontal on the aero bars when the rider is in the aero position. And the hand position on the bars should be defined (not allowing a second position where the arms are no longer horizontal).

Other related rules are as follows.

1. The saddle should be between 24cm and 30cm in length
2. No part of the aero bars should be higher than the top of the saddle.
3. The main triangle frame tubes should be no deeper than 8cm and no narrower than 2.5cm, and in no circumstances should they have an aspect ratio (depth to width) of greater than 3:1. (With commercial frames built since 2000, this is generally a design criteria that has been applied by the manufacturer if they expect their frames to be used at all in UCI sanctioned events)
4. The seatstays and chainstays should be no deeper than 8cm and no narrower than 1cm, and in no circumstances should they have an aspect ratio (depth to width) of greater than 3:1. (With commercial frames built since 2000, this is generally a design criteria that has been applied by the manufacturer if they expect their frames to be used at all in UCI sanctioned events)

Recent clarifications of the rules for aero sections
The UCI recently clarified the scope of its restrictions on aero sections and how they relate to bike components. Previously it was generally believed the restrictions applied to frames only. Specifically, the rules prohibit component cross sections with an aspect ratio greater than 3:1 (where the depth is 3 times the dimension of the width). Most recent commercial frames comply with this requirement as the section rule has been in place since 2000. The application of this rule to components has implications for seatposts and handlebars in particular.

The UCI has decreed that non-compliant handlebars should not be used after 1 July 2009, and non-compliant seatposts should not be used after 1 January 2010.

At the Auckland Champs Individual Time Trial we will endeavour to make riders aware of any equipment that may fall foul of this rule now or in the near future, but the rule will not be enforced at this event, pending discussion with Cycling New Zealand about application of this aspect of the rule.

Confusion about this rule has lead to suggestions some frames are illegal where in fact it is just the dedicated aero seatpost in them that is illegal. Cervelo P2C, P3C and P4 frames are legal but the seatposts aren’t, so Cervelo are apparently developing a seatpost to suit these that is UCI legal and these are expected to be available before the 1 January 2010 deadline.

Other frame/seatpost combinations and handlebars are affected in the same manner and if in doubt you should check your own components, measuring the width and the section depth perpendicular to the mean axis of the part in question.

Cranks and wheels are not included in this rule, as they are rotating parts, though the UCI stipulates that the depth of cranks should not exceed 8cm.

For additional information or to view the rules in full and in their original context, please use the following links.

UCI website.
Part 1: General organization of cycling as a sport. (Equipment is in Chapter III)

Technical regulations for bicycles, a practical guide to implementation. (This has been updated recently to remove inconsistencies and is worth another look for those that have seen the initial versions only.)

Forum page with reference to email from Cervelo about their seatposts.

Peter Alexander - 19th July 2009