Spin class

I have now joined the Y with the intention of going to spin classes over the winter to try to keep some biking fitness in me. I would like to have a good start to next season and hopefully build on that because my goal will be to get a top ten in next years Centurion. Now if anyone had ever suggested to me years ago that I would be happy being in the top ten in anything I would have told them they were nuts but times change.
I must admit I didn't think my age group (55-59) would be so competitive. This year I worked hard, dropped my time by a significant amount yet I only improved a few places to 17'th out of 97 riders. In order to be in the top ten I would have had to knock off another 6 minutes or so . Six minutes may not seem like much but at 30 kph that's 3 km which is certainly a significant distance.
Today was my first spin class and what a workout it was. I now understand how Susan and Brian improved so quickly this year. The class was an hour long and the instructor, a very nice young lady, kept us sprinting, climbing, standing, sitting and sweating for the entire time. If they handed out an award for who sweat the most I would have won it hands down. Both my jersey and bike shorts were drenched at the end of the session. On Sundays there is a 2 hour session but I think I'll pass on that one until spring rolls around. I want to keep some leg in me but 2 hours on an exercise bike seems a little much to me.
Next time out I will wear my heart rate monitor and report back on the results. It should give me a pretty good idea on how good a workout it is.