Hmm. Ft Lee to Bronx. Seems like about 10 miles. Did you want a road bike for other uses, or just for this? I'm not crazy about road bikes in NYC. I used to commute from Queens to Manhattan using a road bike and I backed off after my 3rd car on bike accident. If you think you get hit lot on your motorcycle... well.....I don't want to discourage you, just wondering, since it seems like you are making the purchase just for the commute, could you possibly use some kind of junker mtb or hybrid thing where you are riding in a more stable position rather than locked onto the pedals and in the drop position.
I've had a lot better luck commuting around here using a crappy mtb It is sturdy , nobody wants to steal it, and if a car gets in my way I can detour right over anything without worrying will my skinny tires get stuck. JMO.
I agree that Mosholu is probably the way to go. I haven't done that route in a while but when I used to ride from Queens - Westchester we would ride up the Bronx on the west side of it and then cross on Mosholu. You could check out
www.nycc.org for some routes...they even have a message board you can post on, that doesn't require sign-in, just post away.
Sorry to sound like such a worry wart. One of my teammates from running, Liz Padilla, was a fine rider and she died a gruesome death from a car on bike accident, she had no chance at all. She was the recipient of the first Ghost Bike here in NYC :-/
Have fun but ride safe!!! I still commute too but just want you to know what you're dealing with. On the bright side, I haven't heard of a real bad accident in Northern Manhattan or Bronx in a long time. They are mostly on 9w or in midtown. Heidi