Time is running out for Londoners to secure a spot in one of the world’s largest duathlons, taking place in the capital early next month.

The London Duathlon is held annually in Richmond Park and has become a popular fixture on the city’s sporting calendar. Widely considered to be one of the world’s premier mass participation run, bike, run events, around 4,000 people are expected to take part this year.

There is still time left to sign up for the September 3 event, but organiser LimeLight Sports Club has seen strong demand for places – particularly among people travelling to south-west London from other parts of the city. The advice is anyone planning on taking part should book soon to avoid disappointment.

As well as the picturesque surroundings provided by London’s largest royal park, one of the main attractions of the London Duathlon is the chance to enjoy racing on a closed route. The event is one of only a small number of closed-route duathlons in the UK, making it a must-attend for people looking for personal best times.

People can choose from three distance options and a relay race - the half duathlon involves a 5k run, followed by a 22k bike ride and further 5k run; the full duathlon is double that distance (10k run, 44k bike ride, 10k run) and the ultra-duathlon option challenges participants to run 20k, cycle 77k, and run a final 20k.

The relay, which is aimed at teams of two or three people, is a 10k run, 44k bike ride, and 5k run and has seen demand for places grow as more and more people look to compete alongside friends, family, or colleagues.

It gives people the chance to take part in a muti-discipline event without having to complete each leg themselves, with cyclists increasingly keen to team up with a runner friend, and vice versa.

The entire event is aimed at people of all levels and is also seen as a great way for runners and cyclists to begin to build their way up to taking part in a full triathlon.

London Duathlon also recently announced rugby charity Restart as its official charity partner, with rugby fans encouraged to take part and raise vital funds to help it continue its work. Restart provides support to professional rugby players and their families when suffering from serious injury, illness or hardship, helping with the cost of medical treatment, rehabilitation equipment and disability support.

And with south west London one of rugby’s traditional heartlands, the hope is more people will now look to take part in the duathlon and support the charity’s important work.

Places are now likely to only be available for a limited time. For more information, or to book, visit: www.londonduathlon.com.