Track cycling has become one of the big talking points of the Tokyo 2020 Paralympic Games.
British cyclist Sarah Storey set the tone by smashing her own world record on the way to claiming a 15th Paralympic gold medal on Day 1 of the 2021 Paralympics.
Jaco van Gass continued GB's momentum in the Izu Velodrome with gold on Day 2, with teammate Fin Graham taking silver in another one-two for Britain on the bike.
Jody Cundy, Aileen McGlynn and Crystal Lane-Wright have also picked up silver medals in the opening events in track cycling in Japan, with hopes high of more medals for GB.
Here's a rundown on what all the different cycling classifications mean.
What is para cycling?
Para cycling is cycling for people with impairments resulting from a health condition.
Athletes with physical impairments either compete on handcycles, tricycles or bicycles, while those with a visual impairment compete on tandems with a sighted pilot.
Para cycling is divided into track and road events, with seven events in total.
Why are there different cycling classifications at the Paralympics 2021?
Athletes at the Tokyo 2020 Paralympic Games have a variety of impairments.
In order to maintain a fair competition for all, the para sport classification process ensures that winning is determined by skill, fitness, power, endurance, tactical ability and mental focus.
The Para sport classification assessment process identifies the eligibility of each Para athlete’s impairment, and groups them into a sport class according to the degree of activity limitation resulting from their impairment.
Classification is sport-specific as an eligible impairment affects a para athlete’s ability to perform in different sports to a different extent. Each para sport has a different classification system.
Para cycling C1, C2, C3, C4, C5 classification explained
Para athletes who are able to use a standard bike compete in one of five sport classes C1-5.
Para athletes in these sports classes might have amputations, impaired muscle power or a limited range of motion, and also impairments affecting coordination such as ataxia and athetosis.
Sport class C1 is allocated to Para athletes with the most severe activity limitation, while sport class C5 is allocated to those who meet the minimum disability criteria.
For example, para cyclists with a double below-the-knee amputation who use a prosthesis are likely to compete in sport class C3, while those with a below-knee amputation and a prosthesis on one leg would compete in sport class C4.
Handcycle sport classes H1, H2, H3, H4, H5 explained
There are five different sport classes for handcycle racing, with the lower numbers indicating a more severe activity limitation.
Para athletes competing in the H1 classes have a complete loss of trunk and leg function and limited arm function (for example, as a result of a spinal cord injury).
Para athletes in the H4 class have limited or no leg function, but good trunk and arm function.
Para cyclists in sport classes H1-4 compete in a reclined position.
Para cyclists in the H5 sport class sit on their knees because they are able to use their arms and trunk to accelerate the handcycle. Para athletes in this sport class might have leg amputations, paraplegia or mild to moderate athetosis or ataxia.
Tricycle T1, T2 classifications explained at Paralympics 2021
Athletes who ride a tricycle are unable to ride a bicycle safely due to impairment affecting their balance and coordination. They are divided into two classes - T1 and T2.
Sport class T1 is allocated to athletes with more significant loss of coordination or muscle power than those competing in sport class T2.
Tandem TB classification explained at Paralympics 2021
Para cyclists with visual impairment race on a tandem bicycle with a sighted cyclist - called a pilot - at the front. Para cyclists with visual impairment either have a low visual acuity (less than 6/60) and/or a visual field of less than 20 degrees.