I was so cold and tired by the end of the day yesterday that there was simply no way I was going to go back downtown for spin class, double or otherwise! (It's about a mile's walk each way from the subway to Chelsea Piers - contraindicated in v. cold weather...)
But I did get down there this evening for Tuesday's equivalent. It was good - either I should be working harder or I should reset my HR zones (it is hard to say, I'll see how it goes in coming weeks - of course there's also a stretch in the middle where the switch-over between classes happens when one is not working particularly hard), but whatever, it's all useful!
1:41:19 (avg HR 131, max HR 155)
zone 1 (43:59), zone 2 (42:15), zone 3 (8:15), zone 4 (3:14)