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July 30 (Reuters) - Indoor cycling fitness chain SoulCycle Inc filed with U.S. regulators for an initial public offering of common stock, underscoring the rising popularity of boutique chains that cater to specific workout methods such as spinning, yoga and barre.

Such chains, which often charge per class rather than a monthly membership fee, have been taking market share from traditional big-box gyms.

SoulCycle was founded in 2006 as a single, 31-bike indoor cycling studio in New York City by former real estate broker Elizabeth Cutler and former talent agent Julie Rice.

The company on Thursday said Chief Operating Officer Melanie Whelan took over as chief executive in June. It was not immediately clear who Whelan replaced.

SoulCycle lists luxury gym chain Equinox Holdings, owned by real estate firm Related Cos and buyout firm Leonard Green & Partners LP, as its majority stakeholder.

The company also has a retail clothing line, featuring sweatpants, zip-up shirts and tote bags with printed slogans and skull-and-crossbones.

SoulCycle said it sees an opportunity to expand into the digital sphere, as it hopes to cater to an "at-home" audience and plans to expand it physical presence by opening at least 10 to 15 new studios per year for the next several years.

The company's net income rose about 42 percent to $25.3 million in 2014, while revenue rose nearly 50 percent to $93.8 million.

SoulCycle listed Goldman Sachs, Bank of America Merrill Lynch and Citigroup among the underwriters for its IPO, according to a preliminary prospectus filed with the U.S. Securities and Exchange Commission. (http://1.usa.gov/1SPn5xZ)

The filing did not reveal how many shares the company planned to sell, the expected price or the exchange on which it intends to list its shares.

The filing contained a nominal fund raising target of $100 million. The amount of money a company says it plans to raise in its first IPO filings is used to calculate registration fees. The final size of the IPO could be different.

(Reporting by Sudarshan Varadhan in Bengaluru; Editing by Saumyadeb Chakrabarty and Savio D'Souza)