An Post–Chain Reaction () was an Irish-Belgian professional cycling team that competed at UCI Continental level. The squad was managed by Sean Kelly and Kurt Bogaerts.

It contested one-day and stage races at events across Europe, with riders taking overall victories on the UCI Europe Tour at races including Vuelta a Extremadura in Spain, Rás Tailteann in Ireland and Ronde de l'Oise in France. There were also successes in higher-category races including the one-day Schaal Sels in Belgium and two stage wins at the Tour of Britain. Six elite national road and time trial championships were won by riders contracted to the team.

The squad was based in Belgium at the Sean Kelly Academy in the Flanders town of Merchtem. It was originally registered as an Irish team before switching to Belgian registration in 2010 to gain access to more races in that country. The team became Irish-registered again in 2014 and declared an ambition to move up to professional continental level. However, the team disbanded at the end of the 2017 season after failing to find sponsorship for 2018.

2006 season

1988 Vuelta a España champion and seven-time Paris–Nice winner Sean Kelly launched the first Irish professional cycling team in 2006 with the name Sean Kelly ACLVB–M Donnelly. Its sponsors were ACLVB, the General Confederation of Liberal Trade Unions of Belgium, and M Donnelly, a Dublin-registered company with interests in various technical, sporting and commercial lines of business.

The team did not win a race in its debut season but there were podium finishes for Jehudi Schoonacker on stage seven of Rás Tailteann, known at that time as FBD Insurance Rás, and Paídi O'Brien in the Irish National Championships Road Race.

Eighteen riders competed for the team in its first year, ten from Ireland and eight from Belgium. Kurt Bogaerts was part of the Belgian contingent in his final year as a professional cyclist. He was appointed general manager of the team for the 2007 season.ProCyclingStats - Sean Kelly Team 2006

2007 season

Murphy & Gunn–Newlyn, another Irish continental team, was launched later in 2006. For the 2007 season, the two teams merged to form the Murphy & Gunn–Newlyn–M Donnelly–Sean Kelly squad.

The wait for a first victory would go on but Paídi O'Brien finished second overall at FBD Insurance Rás after taking second place finishes on stages one, three and five. Future four-time World Time Trial Champion Tony Martin took the overall win by seventeen seconds. O'Brien also finished second in the Irish National Championships Road Race, with teammate Mark Cassidy in third.

At the end of 2007, it was announced that the team would retain three title sponsors as well as the name of its founder for 2008. An Post, the national postal service of Ireland, would replace Murphy & Gunn as main sponsor while professional services company Grant Thornton replaced the Newlyn group as a co-sponsor.

2008 season

For the 2008 season, the team now known as An Post–M Donnelly–Grant Thornton–Sean Kelly became more international after fielding just one rider from outside Belgium and Ireland in its first two seasons. Professionals from Britain, Sweden, Germany and the Netherlands joined the one Belgian and four Irish riders that remained with the team after 2007.

The team's breakthrough success came at the 2008 Vuelta a Extremadura. The team was victorious on stage 1, a team time trial, with a margin of thirty seconds to Madeinox-Boavista in second place. Paidi O'Brien crossed the line first and wore the leader's jersey on stage two before it passed to teammate Benny De Schrooder on stage three. The Belgian held the jersey until the end of stage four, with English rider Daniel Lloyd taking the lead into the fifth and final stage. Lloyd finished in the leading group to seal a first overall victory for himself and the team by 36 seconds.

2008 also saw overall victories for Stephen Gallagher at FBD Insurance Rás in Ireland and Daniel Fleeman at the Tour des Pyrénées which was held in France and Spain.

Lloyd and Fleeman left the team after the 2008 season, both joining .

2009 season

The team took six professional victories in 2009, of which five went to former Belgian National Road Race Champion Niko Eeckhout in his first season with the team. The thirty-eight year old two-time Dwars door Vlaanderen winner said this would be his last professional team and that he had already discussed moving into management with team boss Sean Kelly and general manager Kurt Bogaerts. He also brought new sponsors, with the construction and truck repair companies owned by his brothers giving financial and logistical support to the team.Nieuwsblad.be - Brotherly love keeps Niko Eeckhout in the peloton

Eeckhout followed up the team's 2008 success at the Vuelta a Extremadura with two stage victories at the Spanish race, and took a stage and the points jersey at Rás Tailteann. He also scored one-day race wins at Grote Prijs Stad Zottegem and Memorial Rik Van Steenbergen, as well as a second-place finish at Dwars door Vlaanderen.

Steven Van Vooren took the other win with overall victory at Ronde de l'Oise. David O'Loughlin and Paidi O'Brien finished second and third respectively in the Irish National Cycling Championships road race.

2010 season The team switched registration from Ireland to Belgium for the 2010 season. Despite being based in Flanders, the team's owners and sponsors were Irish and had maintained its official domicile there since launching in 2006. However, being a foreign-registered team competing below the Professional Continental level meant the team was ineligible for many Belgian races, including the Tour of Belgium and E3 Harelbeke. Team General Manager Kurt Bogaerts noted that moving to Professional Continental level would be prohibitively expensive, but switching to Belgium was possible as long as there were at least eight Belgian riders in the squad. He expected this would allow the team to compete in 10-20 more races per season.

A rider from the team claimed a national championship for the first time when Matt Brammeier took the first of his four consecutive victories in the Irish National Cycling Championships road race. Liverpool-born Brammeier had previously represented Great Britain but switched his allegiance to Ireland prior to the 2010 season. Nico Eeckhout took stage wins at Ronde de l'Oise and Etoile de Bessèges, and Mark Cassidy and David O'Loughlin both won a stage at FBD Insurance Rás.

2011 season

Lithuanian rider Gediminas Bagdonas joined the team for 2011 and quickly established himself as a stand-out performer. Bagdonas delighted the team's title sponsor at Rás Tailteann, which became known that year as An Post Rás, with wins on stages two and four on his way to the overall victory. He won a stage on his way to another overall victory at Ronde de l'Oise before taking his second Lithuanian National Time Trial Championships title. He rounded out a fine year with victory on stage seven ahead of a high-quality field at the 2011 Tour of Britain.

An Post also signed the promising Irish sprinter Sam Bennett who quickly showed his quality with second place on stage one of An Post Rás. The future winner of stages at all three Grand Tour races would take his first victory for the team at Grote Prijs Stad Geel. Andrew Fenn took a stage at Le Tour de Bretagne Cycliste and won the one-day race Memorial Philippe Van Coningsloo. Nico Eeckhout's sole victory came early in the year at Driedaagse van West-Vlaanderen and Mark McNally claimed overall victory at the Mi-août en Bretagne.

2012 season

The team name changed to An Post–Sean Kelly for the 2012 season after sponsorship arrangements ended with Grant Thornton and M Donnelly.

Gediminas Bagdonas had another strong season, taking five victories representing An Post. These included his first Lithuanian National Road Race Championships title, two stages of An Post Rás and victories in the one-day Memorial Philippe Van Coningsloo and Ronde van Noord-Holland races. He also won three stages and the overall victory at the Baltic Chain Tour representing the Lithuania national team, finished 3rd in his national time trial championships, came 59th in the 2012 Olympic Games road race and took the points jersey at An Post Rás.

Aged forty-one, Nico Eeckhout scored two of the biggest one-day wins in the team's history with victories at Schaal Sels and Omloop der Kempen. Roy Jans claimed the Kattekoers, a race Eeckhout had won twenty years previously, and Kenneth Vanbilsen took the win at Ronde van Vlaanderen U23 representing the Belgian National Team.

Bagdonas left the team at the end of 2012, joining .

2013 season

The team brought in a new co-sponsor and became known as An Post–Chain Reaction. Chain Reaction Cycles was a Northern Irish cycling business that began as a bike shop in Ballynure and by 2013 had grown into an international retailer. This was also the final year that the team was registered in Belgium.

The squad achieved five professional wins in 2013, all of which were individual stages. Sam Bennett took three of these, winning stage five at the 2013 Tour of Britain and stages three and eight at An Post Rás. He also came second on stage two at the Tour of Britain, losing out to Gerald Ciolek in the sprint to the line. Bennett joined , later known as Bora–Hansgrohe, at the end of the season.

Shane Archbold took a stage win at the Rás, and Olympic and Commonwealth Games medallist Glenn O'Shea won a stage at Ronde de l'Oise before transferring to Garmin-Sharp in midseason. Jack Wilson was the Ireland Under-23 Road Race champion.

Niko Eeckhout had two podium results and retired at the end of the season at the age of forty-three. As planned when he joined the team in 2009, he remained with the squad as a directeur sportif.

2014 season

After four years of being registered in Belgium, the team returned to Irish registration in 2014. General Manager Kurt Bogaerts stated towards the end of 2013 that Belgian rules regarding the number of domestic riders were becoming an issue, and that the team would benefit from more invitations to significant races such as Tour d'Azerbaïdjan as an Irish team. He also spoke of plans to race as a professional continental team in 2015 while maintaining a development squad at continental level.stickybottle.com - An Post–Chain Reaction to register as Irish

Robert-Jon McCarthy took the only UCI Tour victory of the season in team colours, winning stage one of the year's An Post Rás. He wore the leader's jersey on stage two and also led the points and youth classifications but lost over ten minutes to his rivals on the second day and dropped down the order. Irish-born McCarthy had elected to represent Australia having moved there as a teenager, and also won a stage at the 2014 Herald Sun Tour riding for the Australia U23 National Team.ProCyclingStats.com - 2014 Herald Sun Tour Stage 3

Ryan Mullen took a hat-trick of wins at the Irish National Cycling Championships in his first season with the team, claiming the Elite Men's Road Race and the under-23 Road and Time Trial titles. Teammate Sean Downey finished the elite road race over a minute behind Mullen in second place, with former team rider Paidi O'Brien in third.ProCyclingStats.com - 2014 Irish National Championships Road Race

Future Olympic track gold medallist Owain Doull spent 2014 with the team in his first year as a professional. He won stage three and took the overall victory at Le Triptyque des Monts et Châteaux riding for the Great Britain National Team, with Tiesj Benoot and Alex Kirsch joining him on the final podium.

Shane Archbold was winless on the road but came second on stage five at the Tour of Britain and claimed the gold medal in the scratch race at the 2014 Commonwealth Games.

2015 season