Bitcoin inverse futures are dominant derivative contracts traded in the cryptocurrency market. We aim to understand the mean-variance tradeoff of such contracts through quantitative studies. To this purpose, we derive explicit representations for the expectation and variance of the returns on Bitcoin inverse futures and obtain their first-order approximations. The empirical findings show that Bitcoin inverse futures are more (resp. less) risky than standard futures when the market is in backwardation (resp. contango). We further find that Bitcoin inverse futures bear higher downside risk, as measured by semi-deviation, than standard futures.