I live in Blacksburg so here is my take:
Being a fit climber and have ridden up the back side of Mtn Lake you are going to want to be somewhere in the 39x25 range or you are walking. It is a beast and after the first 97 miles that soften you up significantly, like Johns Creek Mtn around the 60 mile mark, Mtn Lake at the end is simply one word: DEMORALIZING.
Most of the people I know in the recreational circle are running triples or compacts with 12-27. I am running a standard Dura-ace 10 that I run for this ride in 53-38 and 12-27 and I plan on suffering as well on the final climb.
Even if you are extremely fit I highly doubt you will climb the back side of mtn lake 39x16. Not trying to shoot you down, I give you a lot of credit for fixie, but more just trying to warn you. If I was fresh of a 10 mile warm-up I may get 1.5 miles up mtn lake in 39x16 before the legs utterly explode, if even that far. Check out the profile at the on the MoM website, just look at the last 3 miles. Like I said: DEMORALIZING!
I'll be looking for you though, shouldn't be to hard to pick out the fixie. Also how do you plan on decsending Johns Creek Mtn? You can kick it up to 40 easily so on the fixie be careful. This past weeked I showed VaughA that you can kick it to over 50 on some of the local downhills, but you have to remember to brake in the corners or you end up doing an Ullrich into the ditch
