Little help please...

Hey folks,
so 14 weeks into training for my first 50k, ive injured my knee. Looks like I wont be running again for another couple of weeks. Ive succumbed to the fact that I wont be running that 50k at the end of March. My plan was to use that 50k as a stepping stone to my first 50 miler on June 21st. I have not run in 3 weeks and things are slowly getting better. My hope is to be running by mid March.
So my question is, after 6-8 weeks of no running, how much time do I need to allow to train for a 50 miler? Would the 14 weeks leading up to June 21st be enough time to get back into shape? Ive been cross training so Im still in good shape, but I am wondering how much my endurance is going to suffer.

That's a tough situation. If it were me, I'd still go for it -- simply because I'd hate to give up on a race I signed up for :)

But let's see ... six to eight weeks of no running is a significant hit. You had a decent base before the injury so you're not starting totally from scratch. (What kind of cross training? Aerobic fitness in general is good but if your running muscles can't keep up then you still have a problem. Biking is good if the course has lots of hills.) But you'll have to ease back into training -- maybe 2 - 3 weeks buildup to get back up to your miles, then you have an approximate 2 week taper before the race. So that leaves about 2 months of peak training.

I don't know you or your history -- but for a first 50, you might be cutting it close. You could aim to simply finish, do a lot of walking, be very conservative. The pace you choose (conservative, sustainable) followed by simple determination has as much to do with finishing as training itself. Aiming for a personal best, or a certain fast time, or if there is a certain time cutoff, then that's a different consideration. Lots of factors here. Hope that helps.