Spinning class

It's common for your legs to feel shaky coming off the bike after a good class. With spin however it's super important that the bike is properly set up so ask your instructor to fit you. If your quads are super sore they probably need to be stretched out more. Using a foam roller will help.

if you haven't done much in the way of exercise and jumped right into a spin class? yeah, that would be pretty normal.

also, did you have your bike properly set up? did you stretch and cool down afterwards?

but yeah, if you wee pretty much going from nothing to a full on spin class...that'll getcha.

also, your quads are used heavily in all cycling applications...it should not be a surprise that your quads are sore.

You should be fine with a couple of days rest. Absent some kind of injury/physical condition problem, you don't need to wait until the soreness is all gone. In fact, making sure to do some light exercise (walking, say, or *easy* cycling) the very next day may reduce the soreness, along with stretching, foam rolling, and drinking plenty of water. If you keep it up once (minimum) or twice a week or so, the post-spin soreness will be less, quite quickly.

I was the exact same way after my first spin class. Walking down stairs was the worse and I had serious jelly legs! Just keep going! That is my biggest advice to newbies. I do spin 4-5x a week now and its the best thing I've ever done! I still have nights that I am very sore after but it is usually gone the next day.