There are 18 medal events for cycling at the 2012 Olympics, between the road, track, mountain and BMX. Each event needs a slightly different incarnation of the sport's talent.
The Olympic road race will be determined by the course, as much as the riders themselves. The start/finish line will be at The Mall in central London, and the course takes riders southwest through the city and through six boroughs.
The biggest feature is the Box Hill loop in the Surrey section of the route. It's not the hardest climb nor the longest, but it can wear down a rider's legs with enough repetitions. It may also inject some unpredictability into the race. Countries hoping for a sprint finish will try to control the race over Box Hill to keep breakaways from being established, but it can still provide chances for clever and strong riders to make a move.
The men's race will be 250 kilometers long with nine circuits of the Box Hill loop, while women will race 140km and go up Box Hill twice. Because each team is fairly small, the race is difficult to control and could become unpredictable.
MEN'S ROAD RACE
Host country Great Britain will line up a strong team, and it will be hoping for a repeat of last year's world championships. A superstar British lineup held the race together for a sprint finish, in which Mark Cavendish took over Australian Matt Goss in a crafty sprint. Cavendish has been the world's top sprinter for the last five years, and is hard to beat in a drag race.
Cavendish will have support from Tour de France contender Bradley Wiggins, who began his cycling career on the track but has successfully transitioned to the road. The British team also includes Davis Millar, who had once been banned from Olympic competition by the British Olympic Association because he admitted to doping. However, that ban was overturned earlier this year.
Several other countries will have strong lineups and riders.
Belgium features Tom Boonen, who has been in incredible form this season. He won a handful of one-day spring classics races, including the prestigious Tour of Flanders and Paris-Roubaix, as well as his national road race. Boonen is strong in breakaways and is perhaps the best rider in a sprint at the end of a hard race, and has set his sights on winning. He skipped the Tour de France specifically to train for London.
The United States has a squad that can compete in several types of races.
Tyler Farrar, 28, has won stages in all three grand tours and can mix it up in a sprint finish. Additionally, young stars Taylor Phinney and Tejay van Garderen, American national champion Timothy Duggan and veteran Chris Horner will give the U.S. more cards to play.
Horner, 40, will be heading to his first Olympics and can act as the team's captain on the road, while the 29-year-old Duggan is a workhorse and won the U.S. national championship in May.
Van Garderen, 24, is a strong all-around talent and blossoming stage race contender. Phinney -- the 22-year-old son of former Olympic medalists Connie Carpenter and Davis Phinney -- competed for the U.S. at the 2008 Olympics on the track, in the individual pursuit. But because that event was removed from the Olympic program, he's available to help the road team as a strong rider with a lot of endurance and a decent sprint.
Other strong riders include Switzerland's powerhouse, Fabian Cancellara, 22- year-old Slovak Peter Sagan, Goss, and 2011 Tour de France winner Cadel Evans.
Canada will be represented in the road race by Ryder Hesjedal, who earned the biggest win of his career in May at the Giro d'Italia.
Another factor may be the Tour de France, which ends a mere six days before the men's road race occurs Saturday, July 28.
WOMEN'S ROAD RACE
Discussions about women's cycling these days rarely take place without a mention of Dutch superstar Marianne Vos, a world champion in multiple cycling disciplines.
In 2006 at the age of 19, Vos won world titles in cyclocross and the women's road race. Two years later in Beijing, she took gold in the women's points race on the track. In the years since, Vos has only affirmed her dominance while racking up dozens of wins. She broke her collarbone in May, but has proven her recovery by winning this month's Giro Donne, a prestigious women's road race.
The British and American teams also feature strong rosters.
The U.S. team features Evelyn Stevens, who has emerged as a star since taking up the sport just four years ago. She left her Wall Street job a year later and won consecutive national time trial championships in 2010 and '11. Stevens picked up her biggest victories this year, beating Vos in an uphill sprint to win Fleche Wallonne in April and winning the overall title at the Exergy Tour in late May.
The 29-year-old Stevens has a lot of power and talent, capable of solo attacks, but the team's best hope in a sprint is likely Shelley Olds. The 31- year-old, who comes from a track background, recently won a stage at the Giro Donne and can compete with the world's best in a big finish.
Also on the American team are veterans Kristin Armstrong and Amber Neben. Armstrong won gold in the time trial at the Beijing Olympics, and won two world championships in the discipline. She is coming back from a collarbone break in May.
Neben, who won the world time trial title in 2008, finished second to Stevens at the Exergy Tour and could be a powerful rider for the U.S.
The British squad is highlighted by defending Olympic champion Nicole Cooke, and she's joined by a trio of riders that give the host nation multiple options for gold.
Lizzie Armitstead is a top-class sprinter who can also win out of a breakaway, while Emma Pooley is a strong climber who can pull off solo attacks. Lucy Martin will offer support for however the race unfolds.
A few weeks ago at the British national championships, Armistead and Pooley finished second and third behind their trade teammate Sharon Laws -- who was left off the Olympic squad.
Among the other strong riders to watch is Swede Emma Johansson, who took the silver medal in '08. Two-time defending world champion Giorgia Bronzini highlights an Italian team that also includes '08 bronze medalist Tatiana Guderzo. Clara Hughes, a former Olympic medalist in cycling and speedskating, headlines the Canadian team.
The women's road race takes place Sunday, July 29.
Cancellara is the returning men's Olympic champion, and has been a dominant time trial rider in recent years, winning four world championships since 2006. But he was unseated last year by Tony Martin, a 27-year-old German who figures to be the biggest obstacle for Cancellara repeating.
Wiggins, who finished second at last year's world championships, will be Britain's biggest hope. Phinney will be the lone American in the time trial, and will likely be competitive. He won the U.S. time trial title two years ago, and earned the victory at the opening time trial at the Giro in May. Hesjedal will be Canada's lone entry in the men's time trial.
Armstrong has her sights set on repeating as women's champion, while Neben will also contest the event. German Judith Arndt and Pooley, the last two world time trial champions, should also contend for medals with Hughes and New Zealand's Linda Villumsen.
Competitors in the men's time trial will race 44 kilometers, while the women's course is 29 kilometers long. Both events take place August 1.
Great Britain cleaned up in track events at the 2008 Olympics, winning gold in seven of 10 events, as well as 12 of 30 medals overall.
But if the 2012 track cycling world championships in Melbourne are any indicator, the Great Britain team will face a big challenge from Australia at the Olympics. The Brits won 13 medals there, while the host Aussies took 15, with both countries winning an equal amount of gold medals (six).
Those two countries also dominated the Olympic events at track worlds, winning eight of 10.
The track program has changed since 2008, when there were seven men's events and three for women. Now there are five for each -- the keirin, sprint, team sprint, team pursuit and omnium.
The sprint and team sprint events are essentially head-to-head races between two competitors. With the sprint, riders compete in a 200-meter time trial to determine rankings for a 16-rider tournament. The team sprint event begins with a qualifying round, with the best eight teams advancing.
In the keirin, an eight-lap race, cyclists contest a sprint after following a motorbike, which leaves the track with 2 1/2 laps to go (600 meters). The best 12 riders from a series of heats advance to the second round, from which six riders go through to the medal round.
The team pursuit pits squads of riders against each other, starting on opposite sides of the track and ending when one team comes within one meter of the other. If neither does, whoever finishes the race distance quickest wins. Men have teams of four and race 4 kilometers, while women have teams of three and race 3 km.
The omnium is comprised of six events -- the flying lap, points race, elimination race, individual pursuit, scratch race, and time trial -- that require a variety of skill, as they range from short sprints to endurance events. In each event, the winner gets one point, the second-place rider gets two, etc. The rider with the lowest point total at the end wins.
Among the top riders to watch will be Great Britain's Sir Chris Hoy, who won three gold medals in Beijing -- in the sprint, keirin and team sprint. He was the first Briton since 1908 to win three gold medals in a single Olympic Games.
An 11-time world champion, the 36-year-old Hoy returns as part of the sprinting team. He finished behind France's Gregory Bauge and countryman Jason Kenny in the sprint at this year's worlds, but won a world title in the keirin.
Both of Great Britain's team pursuit squads set world records at this year's worlds, edging the Australian teams each time.
Additionally for Britain, Victoria Pendleton is back to defend her gold medal in the women's sprint. She won the world title in April.
Sprinter Anna Meares, a three-time Olympic medalist and multiple world champion, leads the Australian track team. She is the reigning keirin world titlist.
The United States is sending six riders, including Sarah Hammer, who won a bronze medal in the women's omnium at this year's worlds. Hammer will race the omnium, and be joined by Dotsie Bausch, Jennie Reed and Lauren Tamayo in the women's team pursuit. The team took silver in the event at the 2001 world championships.
On the men's side, Bobby Lea will contest the omnium and Jimmy Watkins is competing in the men's sprint.
Canada will send seven cyclists, including Tara Whitten, who has won two world titles in the omnium. Zach Bell, who won world championship silver in the men's omnium in April, will also compete for Canada.
Track events get underway Thursday, August 2, when medals will be awarded for the team sprint, and men's team pursuit gets underway. The final track medals will be awarded August 7.
There are only two mountain bike events -- a cross-country mountain bike race for men and women. The fields are fairly exclusive. Just 50 men will be competing, and only 30 women.
France's Julien Absalon is the two-time defending gold medal winner in the men's race, while German Sabine Spitz will defend her gold in the women's race.
The United States' Georgia Gould earned an automatic selection because she ranked inside the top 10 in the individual world cup rankings, and will be joined by Lea Davison in the women's race. Samuel Schultz and Todd Wells will race for the U.S. in the men's competition.
Canada will have strong medal hopes in the women's race with two-time world champion Catharine Pendrel, who will be joined by young star Emily Batty. For the men's race, veteran Geoff Kabush will appear in his third Olympics, alongside Max Plaxton, the reigning two-time Canadian national champion.
This will be just the second Olympic appearance for BMX, which was won by Latvia's Maris Strombergs and France's Anne-Caroline Chausson in Beijing.
The United States will send five riders to London for the discipline.
Connor Fields won the Olympic Trials in June, defeating Beijing silver medalist Mike Day to earn his spot. He's currently the second-ranked rider in the world being world champion Sam Willoughby of Australia. Fields will be joined by automatic qualifier David Herman and discretionary pick Nic Long.
Arielle Martin and Alise Post will compete in the women's BMX event for the U.S.
France's Magalie Pottier is the current women's world champion and top-ranked rider.