Rules for Bikes According to the UCI (cyclingworld gov body):
What follows are technical rules for bikes as lifted from the UCI's web page (this can be kind of hard to find when navigating around their pages, if you want to see it as they print it, PDF format, go here, then scroll to page 34. By the way, that's UCI, i.e., the world governing body for cycling, not ITU, world governing body for triathlon. These rules will be posted here in a matter of days.
But(!) that's not all, folks. Rules for Y2K adopted as of September 1, 1999, i.e., amendments to the below, will be found further below.
CHAPTER III: EQUIPMENT
SECTION 1: GENERAL PROVISION
1.3.001 Each licence-holder shall ensure that his equipment (bicycle with accessories and other devices fitted, headgear, apparel, etc.) does not, by virtue of its quality, materials or design, constitute any danger to himself or to others.
1.3.002 The UCI shall not be liable for any consequences deriving from the choice of the equipment used by licence-holders, nor for any defects it may have or its non-compliance.
1.3.003 In no case shall the fact that the rider or any other licence-holder has been able to take the start incur the liability of the UCI as any verification of equipment that might have been conducted by the commissaires is limited to ensuring compliance of the overall external appearance of that equipment with purely sporting requirements.
Bicycles shall comply with the spirit and principle of cycling as a sport. The spirit suggests that cyclists compete in competitions on an equal footing. The principle asserts the primacy of man over machine.
(Subsection 1) Principles
1.3.004 Bicycles shall be of a type that is or could be sold for use by anyone practising cycling as a sport. The use of a bicycle designed especially for the attainment of a particular performance (record or other) shall be not authorised.
Quality - Security
1.3.005 The rider shall ensure that his bicycle, including any accessories and devices fitted thereto, do not, by their quality, material or design, constitute a danger to himself or to the other participants in the races.
1.3.006 The rider shall assume a sitting position on his bicycle. This position requires that he be supported solely by the pedals, the saddle and the handlebar.
1.3.007 The bicycle should have a handlebar which allows it to be ridden and manoeuvred in any circumstances and in complete safety.
1.3.008 The bicycle shall be propelled solely, through a lower bracket, by the legs moving in a circular movement.
(Subsection 2) Technical specifications
1.3.009 The following technical specifications shall apply to bicycles used in Road, Track and CycloCross racing.
1.3.010 A bicycle shall not measure more that 185 cm in length (EF) and 50 cm in width overall.
1.3.011 Any device, added or blended into the structure, that destined to decrease resistance to air penetra-tion or artificially to accelerate propulsion, such as a protective screen, fuselage form of fairing or the like, shall be prohibited.
1.3.012 The point of the saddle shall be a minimum of 5cm (see article 1.3.019 below) to the rear of a vertical plane passing through the lower bracket spindle. The saddle support shall be horizontal (see figure 1). The length of the saddle shall be 24 cm minimum and 27.5 cm maximum.
1.3.013 The maximum height of the hand support point shall be level with or below a horizontal line passing through the horizontal plane of the saddle top. This point of support may not be situated behind the axis of the steering column.
The overall length [forward projection] of the handlebars may not exceed a limit set 15 cm forward of a vertical line passing through the front wheel spindle.
1.3.014 The distance between the lower bracket spindle and the ground (DA) shall be between 24 cm minimum and 30 cm maximum.
1.3.015 The distance between the vertical passing through the lower bracket spindle and the front wheel spindle (AB) shall be between 54 cm minimum (see article 1.3.019 below) and 65 cm maximum.
1.3.016 The distance between the vertical passing through the lower bracket spindle and the rear wheel spin-dle (AC) shall be between 35 cm minimum and 50 cm maximum.
1.3.017 The distance between internal extremities of the fork shall not exceed 10.5 cm and that of the rear stays shall not exceed 13.5 cm.
1.3.018 Wheels of the bicycle may vary in diameter between 70 cm maximum and 55 minimum, including tubular type. For the cyclo-cross bike the width of the tubular type cannot be more than 35 mm and incorporate metal studs.
(amendment came into force on 25th November 1998)
(amendment came into force on 1st January 1999).
1.3.019 The distances mentioned in footnotes to the articles 1.3.012 and 1.3.015 above may be reduced where that is necessary for morphological reasons.
By morphological reasons should be understood everything to do with the size and limb-length of the rider.
Any rider who, for these reasons, considers that he needs to use a bicycle of lesser dimensions than those given shall inform the Commissaires Panel to that effect when presenting his licence.
1.3.020 The 5 cm distance referred to under article 1.3.012 shall not apply to the bicycle of a rider participating in a sprint, Keirin, 500 m and 1 km event although the saddle peak should not project beyond a vertical running through the lower bracket spindle.
1.3.021 In track competitions, the freewheel, derailleurgears and brakes shall be prohibited.
1.3.022 Provided that they comply with the criteria mentioned in this article, handlebars known as “delta”, “cowhorn”, “triathlete”, which have short handlebar extensions may be used exclusively in the following events:
A forearm or elbow-rest shall be permitted.
In other races, the handlebar type shall be "classic" and no part of the handlebar may protrude forward of a vertical line passing through the front wheel axle
(modification came into force on 1st January 1998).
1.3.023 A tandem shall not have an overall length (E-F) greater than 270 cm nor an overall width greater than 50 cm.
(Subsection 3) Technical innovations
No technical innovation regarding anything used, worn or carried by any rider or other license holder during a race (bicycles, equipment mounted on them, acces-sories, helmets, clothing, means of communication, etc.) may be used until authorised by the UCI Executive Committee. Requests for approval shall be submitted to the UCI before 31st August of any year, accompanied by all necessary documentation. If authorised , the inno-vation will be permitted only as from 1st January of the following year.
Authorisation shall refer solely to the fact that the innovation will be acceptable from a sporting point of view.
For the purposes of the present article there is no technical innovation where the innovation is entirely covered by the specifications set out in the Regulation.
(amendment came into force on 1st February 1999).
1.3.025 If at the start of a race or stage. the Commissaires Panel considers that a rider is presenting with a technical innovation not yet authorised by the UCI, it shall refuse to permit a rider who does not renounce the use of such innovation to start the race.
In the event of usage during a race the rider is automatically eliminated or disqualified.
There shall be no right to appeal against the decision of the Commissaires Panel.
If this technical innovation is not noticed or sanctioned by the Commissaires Panel, the UCI Disciplinary Commission shall order the disqualification.
The UCI shall refer to the Disciplinary Commission, either automatically or at the request of all interested. The Disciplinary Commission will only apply sanctions after having received the opinion of the Equipment Commission.
Outside races, the UCI shall decide whether some item be a technical innovation and whether the procedure provided for in article 1.3.024 is to be followed.
1.3.020 For massed start road races and cyclo-cross events, the frame of the bicycle shall be of a traditional pattern, i.e. built around a main triangle. It shall be constructed of straight or tapered tubular elements (which may be round, oval, flattened, teardrop shaped or otherwise in cross-section); the centre line of each element shall always be straight. The elements of the frame shall be laid out such that the joining points shall follow the following pattern: the top tube (1) connects the top of the head tube (2) to the top of the seat tube (4); the seat tube (from which the seat post shall extend) shall connect to the bottom bracket shell; the down tube (3) shall connect the bottom bracket shell to the bottom of the head tube. The rear triangles shall be formed by the chain stays (6), the seat stays (5) and the seat tube (4).
The maximum height of the elements shall be 8 cm and the minimum width 2.5 cm. The minimum width shall be reduced to 1 cm for the chain stays (6) and the seat stays (5). The minimum thickness of the elements of the front fork shall be 1cm; these may be straight or curved (7). (See diagram “Shape (1)”).
The top tube may slope, provided that this element fits within an horizontal template defined by a maximum height of 16 cm and a minimum thickness of 2.5cm.
“Road races” is taken here to include all races on the road with the exception of individual time trials and time trials for teams of up to four riders.
1.3.021 For individual time trials and time trials for teams of up to four riders, and for track races, the elements of the bicycle frame may be tubular or solid, assembled or cast in a single piece in any form (including arches, cradles, beams or any other). These elements, including the bottom bracket shell, shall fit within a template of the “triangular form” defined in article 1.3.020 [end of article deleted]
1.3.023 For individual time trials and time trials for teams of up to four riders on the road, and for the individual and team pursuits, kilometre and 500m time trials and record attempts on the track, an extension may be added to the steering system. The distance between the vertical line passing through the bottom bracket axle and the extremity of the handlebar may not exceed 75 cm, with the other limits set in article 1.3.022 (B,C,D) remaining unchanged. A support for the elbows or forearms is permitted (see diagram “Structure (1)”).
For individual road time trials and time trials for teams of up to four riders, controls or levers fixed to the handlebar extension may extend beyond the 75 cm limit as long as they do not constitute a change of use, particularly that of providing an alternative hand position beyond the 75 cm mark.