OBJECTIVE: Cycling confers individual and population-level health benefits, but uptake is not always equitable across socio-demographic groups. We sought to examine inequalities in uptake and usage of London's Barclays Cycle Hire (BCH) scheme. METHOD: We obtained complete BCH registration data, and compared users with the general population. We examined usage levels by explanatory variables including gender, small-area income-deprivation and local cycling prevalence. RESULTS: 100,801 registered individuals made 2.5 million trips between July 2010 and March 2011. Compared with residents and workers in the central London area served by the scheme, registered individuals were more likely to be male and to live in areas of low deprivation and high cycling prevalence. Among those registered, females made 1.63 (95%CI 1.53, 1.74) fewer trips per month than males, and made under a fifth of all trips. Adjusting for the fact that deprived areas were less likely to be close to BCH docking stations, users in the most deprived areas made 0.85 (95%CI 0.63,1.07) more trips per month than those in the least deprived areas. CONCLUSION: Females and residents in deprived areas are underrepresented among users of London's public bicycle sharing scheme. The scheme's planned expansion into more deprived areas has, however, the potential to create a more equitable uptake of cycling.