I got a stress fracture on my left tibia (right under the knee) while I was cross training running. I am out for 6-8 weeks. How long will it take me to regain and build fitness once I get back to cycling
Got Physical therapy planned? , ask the professionals.
Drink more milk (no, nestle's quick doesn't count), consider some calcium supplements, and stay away from acidic, high-fructose/sucrose/any-"ose" cornsyrup bone-rotting soda pop...and no alcohol, forever.
In other words, review nutritional information to find out if anything you've been consuming is damaging your bones/cartilege, and what would be good to consume to encourage your bone health.
Controlled (stationary) cycling gives you the weigh-bearing load your bones need to strengthen/heal without the impact of walking/running.
I'm no pro but from experience I'd say at least 3 months to get back to where you where before the problem (assuming you are off bike for 8 weeks). Around here the end of the season is approaching and allows you to train and recover you fitness in the off-season.
I had to be off he bike for 7 weeks recently. Too bad for me it was end of June through mid August. I got slower and everyone else got faster in a big way. Your timing is better!