Re: Hello and Greetings..!!!
Welcome. You're right to be skeptical about speed claims. We try to discourage them because they are typically a source of trouble. One thing to keep in mind, "It's a bicycle, not a motorcycle". Bicycles are not designed for some of the speeds you'll see claimed so don't be too anxious to attain that magic 40 mark unless you have taken into consideration, rims, tires, bearings and most importantly, brakes.
With that said, have fun, enjoy your build and above all, ride safe.
Age and Treachery Will Always Triumph
Over Youth and Skill & "Charlie Don't Ride"