In reply to tnj:
If you have mighty strong legs with significant endurance already then the bike can't do any harm. If not, a bike is a bit underwhelming. Ski touring and climbing rely hugely on core body and leg power. A bike is little use for that. Bikes are fine for supplementing alpine training, but cannot be the principal element.
My knees are boogred, so I us a bike for anything high intensity (I can't sprint).
Read Steve House's "Training for the New Alpinism". Sets out what you should do better than I could.