How can I find the right size road bike without a test ride? I am going to buy a road bike. I am considering a Trek 1.2.  

I used the Competitive Cyclist Fit Calculator to find the size of bike that fits me. 


Inseam:             80.5  
Trunk:              59.5  
Forearm:            36  
Arm:                67.2  
Thigh:              57.4  
Lower Leg:          53.7  
Sternal Notch:     138.1  
Total Body Height: 171

  
  All the measurements are in cm.


The ranges that are given in the results are these:  

Seat tube range c-c:   52.1 - 52.6 for competitive fit.  
Seat tube range c-c:   53.3 - 53.8 for eddy fit. 


The purpose of my bike is going to be able to do long distance mainly. I cannot afford another bike for racing but I will most probably be doing Ironman from next year using the same bike. But I personally think that riding 180 km in 8 hr is endurance and not year.

Now which size should I go for?  52 or 54?
Should I just check the standover height of the bike? Or I should I look into something more than that?

I am asking this because in India not many shops deal with Trek road bikes. The Trek 1.2 is only available at one shop. That fellow says he won't allow me to test ride the bike. So I am in a bad situation. I want to buy this bike but the right size. The whole geometry is available in the site I have given. Ask for more information, if needed.
It seems odd that somebody wanting to sell a bike to you wouldn't allow a test ride. Most places encourage you to take the bike for a test ride, at least around the parking lot or around the block, and usually with a bike store employee following closely behind.  If they can't offer you a test ride, perhaps you could persuade them to mount the bike onto a trainer.  That would at least give you some sense of how the bike fits, although doesn't tell you much about how it handles. Another option is to find a bike rental service that has the same model bike that you are planning to buy (some rental services even sell their old bikes). This can give you the opportunity to try out the bike for an extended period.  If you still can't get a test ride, I'd opt for a different bike from a different shop that does allow test rides.  There's nothing particularly special about the Trek 1.2 that you can't find in 100 other bike models, which are available in lots of different stores.  I wouldn't recommend buying a bike without actually riding it first.