Alternatives for cycling

Hi guys, I have one thing that bothers me - whenever it rains and the wather is bad I can't train cycling and I feel like having these breaks is bad for my training. Is there any alternative for cycling to train these muscle groups and lose fat? I now that one can always buy a stationary bike but I don't have enough room for one in my flat. What else can I train to achieve same effects?

Cheers!