Bike types: what the rules define, and what the labels mean.

What the UCI calls a bicycle

The UCI's technical rules start from a definition. Article 1.3.007 of UCI Regulations Part 1 (text modified 1 January 2019) describes a bicycle as a vehicle with two wheels of equal diameter, the front one steerable and the rear one driven through pedals and a chain. Individual disciplines may make exceptions: the UCI's clarification guide points to mountain biking, where the two wheels may differ in diameter, and says only one chain may be used. This page reads the UCI articles as reproduced in the Japan Cycling Federation's copy of the UCI clarification guide, uploaded in March 2026, whose exact edition date we could not confirm.

Article 1.3.011 says the detailed specifications in Articles 1.3.011 to 1.3.025 apply to road, track and cyclo-cross bikes. Mountain bike, BMX, BMX freestyle, trials, indoor cycling and para-cycling bikes are governed by each discipline's own part of the regulations, which we did not read.

Road, track and cyclo-cross: one frame rule, different equipment

Under Article 1.3.020, all three must use a traditional diamond-pattern frame built around a main triangle. The differences lie in brakes, gears and tyres:

Cycling Canada describes cyclo-cross as racing that switches between riding and carrying the bike over woods, mud, meadows and short hills, on a bike similar to a road bike but with wider, grippier tyres. The time trial rules have their own page: time trial position rules.

Gravel bikes

Wikipedia describes a gravel bike as a drop-bar bike built for unpaved roads, with tyres typically around 40 mm wide (sometimes 45 to 50 mm), nearly always disc brakes, mostly tubeless tyres, geometry somewhere between a road bike and a cross-country mountain bike, extra mounts for bottles and luggage, and lower gearing than a road bike. It contrasts these with cyclo-cross bikes, which it says use 700c wheels, tyres up to about 33 mm and quicker handling. Wikipedia places the start of the modern gravel category in the 2000s, with purpose-built gravel bikes appearing in the 2010s.

The UCI's gravel series has its own equipment rule. In a notice of 22 March 2023 the UCI Gravel World Series said any bike may be ridden at its qualifier events except e-bikes, time trial bikes, recumbents and tandems, while the UCI Gravel World Championships accept only bikes with dropped handlebars, so mountain bikes are not accepted there. More on the racing is on the cyclo-cross and gravel page.

Time trial bikes

Wikipedia describes the time trial bike as a racing bike for solo races against the clock, more aerodynamic than a road bike, with a shorter wheelbase and the rider placed nearer the front wheel. It says triathlon bikes are similar but use a steeper seat tube angle and are not bound by the UCI's saddle setback rule. In UCI events, the frame still has to meet Article 1.3.020, and the rider's position is limited by Articles 1.3.013, 1.3.014 and 1.3.023.

Mountain bikes

Bike Perfect (Ryan Simonovich, updated 23 September 2022) sorts mountain bikes first by suspension: a hardtail has no rear shock and either a suspension or rigid fork, while a full-suspension bike has suspension at both ends. It then groups them by intended use and gives typical rear travel for each:

These are one publication's typical figures, not a standard. The racing formats behind these types, from cross-country Olympic to downhill and enduro, are on the mountain biking page.

BMX, trials and para-cycling bikes

The UCI recognises three trials categories by wheel size, according to its 2026 explainer: 20-inch (wheels of 18 to 23 inches), 26-inch (24 to 26 inches) and Open (any size from 18 to 26 inches). BMX bikes are covered on the BMX, trials and indoor page. For para-cycling, Cycling Canada names four cycle categories raced on road and track: bicycle, tricycle, handcycle and tandem, and Cycling New Zealand links them to sport classes (B for tandem, C for bicycle, H for handcycle, T for tricycle). The para-cycling page has the classes.

E-bikes

An e-bike is a pedal bike with an electric motor, and what counts as one in law depends on the jurisdiction. The e-bike classes and laws page sets out the US federal definition, California's three classes, the EU rule and the UK's EAPC rules. Battery standards and fire guidance are on the e-bike batteries and fire safety page.

A note on US product rules

The US Consumer Product Safety Commission's bicycle regulation, 16 CFR Part 1512, treats "sidewalk bicycles" (seat height of 25 inches or less) differently from other bicycles, and exempts certain competition track bicycles and one-off custom bikes. It is a rule about bikes as sold, not about where or how they may be ridden.