Check for rack mounting eyelets on the front and rear dropouts--this is one of the easiest ways to see if you can mount racks (although you can often do so on bikes without eyelets). The chainstays will also be longer, with a several-inch gap between the rear tire and the seat tube (on a classis steel racing bike, the distance between rear tire and seat tube might be less than the width of your index finger). Of course, you'll want a triple chainring. Yes, the frame angles will be more relaxed--think 75 degree angles instead of 73. You can check this with an angle gauge, but eventually you will just "see" it.