23-27 MARCH 2011 2011 World Championships, Netherlands
4-8 APRIL 2012 2012 World Championships, Melbourne, Australia
8 APRIL 2012 Olympic Track Ranking closes, qualification places allocated after this point
Following changes to track cycling's Olympic programme in time for 2012, there are five events for each gender in London: the sprint, team sprint, keirin, omnium and team pursuit.
A total of 188 cyclists will take part, and each nation can send up to a maximum of 16 - up to one athlete per individual event, and one team for each gender's team pursuit and team sprint (a reduction on previous Games).
Qualification is decided by the Olympic Track Ranking, compiled by world governing body the UCI using the best results from all eligible riders across the 2011 and 2012 World Championships, World Cup Classics in 2010-11 and 2011-12, and the last two Continental Championships.
Working down the rankings, which close on 8 April 2012, the UCI will allocate places according to the quotas above until the Olympic competition is full.
There are no plans to offer invitational places after this procedure has closed, although the UCI has reserved the right to do so in exceptional circumstances.
If an athlete qualifies a place in one event, they can also enter others - provided this does not exceed their country's national quota as outlined above.
Sir Chris Hoy took the ceremonial first lap around the 2012 velodrome
How are British competitors doing?
Britain's phenomenal track cycling campaign at Beijing 2008 will be tough to replicate in a home velodrome in 2012, not least because the UCI's new qualification system allows GB to enter just one athlete per event (most events accommodated up to two in Beijing)
GB can at least be relatively certain of fielding a full-strength squad in London.
British Cycling does not expect to receive a specific host nation allocation, but the team should still come close to the maximum any country is allowed: nine men and seven women, 16 athletes in all.
Where British cyclists stand regarding Olympic qualification will become clearer nearer to publication of the final rankings in April 2012.
For now it is safe to say Britain would not anticipate much need to fall back on guaranteed host nation places, given the strength of the squad.
16 OCTOBER 2011 UCI men's world rankings and various Tour rankings are confirmed, allowing some qualifying places to be allocated
31 MAY 2012 Women's elite rankings are established, remaining qualifying places allocated after this point
Both the men and women have a mass start event and a time trial on the road at London 2012.
Up to five men and four women per nation qualify via their UCI ranking - but athletes who earn places do so for their country, not themselves, and these may be reassigned by their country to another cyclist.
The complicated qualifying procedure for the men's mass start relies on UCI rankings, drawn up according to world ranking and then various continental Tour rankings. These are confirmed on 16 October 2011.
After that, there are additional places available from 2011 continental championships - though not for Europe or Oceania.
For the women, participation in London is determined by the UCI rankings - themselves determined by World Tour results - as of 31 May 2012.
In addition, extra places are available according to the results of the last women's continental championships before 2012, though again not for Europe or Oceania.
Places in the time trial can only be earned by first reaching the mass start event.
With no European Championship route into the Games, British cyclists will qualify either via world ranking (being in the top 15 is a virtual guarantee of a place) or European Tour ranking (where being in the top 16 is similarly desirable).
However, the number of caveats to the qualification system means there are various other ways of gaining entry to the Games, even though GB does not expect any allocation of host nation places. See
the full qualification system document
MAY 2010 Results since this date will have impact on final Olympic qualification rankings
25-27 MAY 2012 2012 World Championships in Birmingham, UK
28 MAY 2012 Olympic qualification rankings close, qualifying places allocated after this point
There is one BMX medal available for each gender at London 2012, with 32 men and 16 women in the fight for podium places. A maximum of five competitors can come from any one nation - three men and two women.
The UCI rankings as of 28 May 2012 are the main route into the Games. The top five nations get three competitors in the men's event; those ranked sixth to eighth get two, and ninth to 11th get one each.
Countries which do not qualify that way can qualify places at the 2012 BMX World Championships, by finishing as one of the six best-ranked nations not to already have earned Olympic berths.
There is then one invitational place available.
The women's system is similar. Nations ranked one to four by the same cut-off point get two riders, those ranked five to seven get one, and the three best-ranked nations at the 2012 Worlds not to be already represented at the Games get one each, with an invitational place on offer.
Shanaze Reade is by far Britain's best hope of a BMX gold medal in 2012, and she should have no recourse to a host nation place in her bid for the Olympic title - although there is one place in the men's and women's races available to GB if they fail to qualify any other way.
The 2012 World Championships, which are the secondary route to the Olympics, will be held in Birmingham in late May.
Results since May 2010 have been used to calculate the BMX rankings, but events in 2011 will be the focus of qualifying. It is not yet possible to tell where Reade and other Britons will finish in the rankings.
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