Alright cold fusion, lets get serious.
what is your previous RC experiance with regard to batteries?
I will link you to lipo threads if you have not looked at them already.....if no previous Lipo experiance I recomend you read Dogmans excellent advice in several of his posts. search,read & understand. A ping will definatly be safer...but thats not where the devil lives
using a single reduction, forget 50mph....you'll destroy everything way sooner than reasonable.....the only bike i've set up that ran 50+ comfortably had 2 80-100's at 180kv & I still had a custom 2-speed transmision.
with a simple reduction to drive the rear wheel I will recomend a 30 mph max speed. This motor will deliver spirited performance & not be teribly overlaoded at lower speeds.
if your going to use an rc controller, the only reasonable option is an castle ICEHV160. ($$$$) You need to add additional caps to keep it protected. Again, lots of talk about that on the forum.
whatever advice you follow for battery chemistry....you'll want at least 20amp hours (assuming your running a castle controller & 12 cells)
now...Your bike selections looks sturdy & a fair step up from the bike shaped object's at the local wallmart. I think it will do fine.
reality check complete.