Doge

I'd think you might want to get your workout another way and use the group ride for social / fat burning. The net result might even be better.
You can change the bike. You can try a lower/fixed gear and see about spinning. If you are trying to also get faster on your solo rides, that might not be the best.
As the parameters were you are using a group ride to workout, I'm answering based on your OP, which is hard as group rides and working out might be different depending on your ability relative to the ride.

Many racers do not use group rides for anything but social as they are too fast or too slow for race training. Many more use the group ride as the race and don't race (I'm not a fan, it is just the reality).