Strava, the social fitness app that has become popular in the road cycling community, has raised $18.5 million in a Series D funding round with help from Sequoia Capital, a venture capital fund whose more recent successes include Instagram, WhatsApp and Square.

The round, which was also funded by existing investors Madrone Capital Partners and Sigma West, will allow Strava to fuel the expansion of its service around the world and strengthen its leadership in digital sports.

“Strava is building tomorrow’s sporting network in the manner that Facebook and LinkedIn have developed today’s social and professional networks,” said Michael Moritz, Chairman of Sequoia Capital and now advisor to Strava. “Even for the hapless and occasional athletes at Sequoia, Strava has become the essential and amusing way to post and compare our woeful performances and share them with friends and family.”

Strava is favored by many runners and cyclists because it’s premium service, which costs $59 a year, allows them to not only analyze their performance but compare it to other Strava users who have run or ridden the same routes. Strava.com also offers many social media tools that enable virtual competitions and support. Strava’s free app is available for both iOS and  Android devices and compatible with the Garmin Forerunner smart watch and Garmin Edge cycling computer as well as the Soleus Sync and Timex Run Trainer watches.

Based in San Francisco, where it was founded in 2009, Strava expanded its business in 2014 to connect athletes in 11 languages across 23 different sports.  Today, approximately three million activities are tracked and shared by the Strava community each week.

“Since day one we have focused on building a network that serves to motivate and entertain the world’s athletes,” said Mark Gainey, co-founder and CEO at Strava. “With Sequoia joining our team, we are better positioned to execute our mission and strengthen Strava’s leadership in digital sports.”

Strava raised $3.5 million from Sigma Partners in its Series A round in January, 2011 and $12.6 million from Sigma and Madrone in a Series B round seven months later, according to the CrunchBase.