I've done a good bit of reading around and there is a lot of literature on detraining in professional and amateur atheletes.
But very little on to what extend it can be postponed or prevented by crosstraining.
I've picked up an SI joint injury that's hard to kick and is preventing me from getting on the bike more than once a week, right in the middle of my build phase. I was doing 5-6hrs a week on the bike in intervals and now I can get one hour in, and the rest of my time is spent in the gym lifting, running and doing intervals on a rowing machine and crosstrainer. I'm likely to need to keep doing this for at least 2 months.
To what extent are traning gains sport-specific? Am I likely to lose much? If so - will it be at the aerobic, anaerobic or muscular endurance levels? A big impact on power curve?