Tell your dad that you'd like to spend more time with him. Perhaps grab a pizza, or a beer together in private. Tell him that you'd like to make a day of it!
So after a fun day, somewhere around 3pm, tell him that you're thinking about getting yourself a bike and you'd like to stop by a certain shop to take a look at a specific model in which you are interested. Call the LBS ahead of time to let them know about your expected visit and your actual intended goal.
Once there, carefully observe your dad. Let the salespeople know that you'd like to have free uninterrupted range for about the first fifteen minutes, or so, after they've initially greeted you. Observe your dad intently. Watch his eyes fixate on particular models. You will mount bicycles, both with and without suspended forks. See which ones he seems the most interested. Tell him that you really value his opinion and that you're buying one of those bikes upon that very same day for yourself. Then say, "Hey dad! Let's go test ride these bikes together!" Ask one of the salespeople to set you both up for test rides, and go!
Make certain that you keep your dad talking about the bicycle is on and the ones he saw back in the shop when you were there, while on the test ride. Ask about the level of comfort and ease or smoothness of shifting. You tell him how you feel, and then you ask him about how he feels. Once you have all the info you need, then admit that you'd really just like a day or two to actually think about it.
Next, thank the salespeople for their time. Then wink, smile, and wave goodbye...
Return upon the following day to make the purchase.
Your dad has to be the one to mount the bicycle. Otherwise, you will be gambling and playing a game of chance that could potentially ruin the entire experience.
Bicycle companies have their own standards by which to size their frames. A size 56 cm made by Trek could very well be a size 54 cm made by Surly. These bicycle frame sizes can also change from model to model, just like they can change from bicycle company to bicycle company.
Bicycle frame sizes do NOT directly translate from bicycle company to bicycle company.
Take your bike to your dad's house along with the new bicycle and go on a short ride with your dad, just to make certain that things are alright with both your dad and his new bicycle.
Last edited by WestPablo; 06-05-14 at 06:03 AM.