How Effective are spin classes for training for a century?

[Roo]

Hi everyone!!

So I have an issue, I signed up for a century and should be out riding just about every day to train for it (I am VERY new to riding). Problem is, it has been raining non-stop for about a month. So, I have been riding on the trainer (which, okay I admit it has been pretty boring) so I decided to take spinning classes instead. They definitely get my heart rate up and feel like I'm improving my endurance. But, am not completely sure this is the best way to indoor train.

Any thoughts, advice or just a "yep, that sounds like exactly what you should be doing right now" would be awesome! I'm starting to get nervous that I'm not going to be ready for the ride with all of this indoor training. Oh, BTW I have been going to the spinning classes every day and have been able to get longer rides 50 miles in on the weekends.

Thanks in advance for the advice!!
Joey

2011 Specialized Ruby Elite Apex