Been struggling with a knee injury, and today is the first time back on the bike in 2 weeks. Coming back to training can be tricky, here are some things to think of:
1) Wait, then wait some more - I know you've trained for months and now feel its all going away but if you aren't right then you'll just exacerbate the last stage of recovery and postpone your real return to form.
I've waited and waited until the knee feels solid and there is no pain.
2) Work out what went wrong. Why did you get injured? I've got a weak right knee (date it all the way back to a school days rugby injury) but my recent problem actually related to tightness in muscles around my hip which pull on my thigh muscles and cause the knee cap to mis-align.
The 2 weeks off have been about stretching out these thigh muscles, and then waiting for the knee cap to stop being irritated. If you don't know what has gone wrong you may be prone to repeating the problem as soon as you restart.
3) Be sensible - I felt good today on the ride, and everything else was 100% - enthusiasm, energy - so its possible to blast off, be ambitious, and try to recoup the lost 2 weeks of training in one session - but don't.
I turned for home as I planned - because I know it will be this afternoon and even tomorrow morning that I finally understand that the knee has been able to cope with the limited ride it has had today, and even then I need to continue to take it easy.