there are several options for staying fit in the winter:

spinning classes - these are classes done on a stationary bike

wind-trainers or computrainers or just plain old bicycle trainers. these are cool trainers that you attach to your rear wheel and bike the winter blahs away. the computrainer is a neat one you can get your computer involved with as well.

i also cross country ski in the winter. this is a great way to keep up your aerobic base.

good luck and happy riding!

Han