You know, the older I get, the stranger so many of the things we do, and our society and culture promote, seem so ridiculous.
Our obsession with breasts, for example. I LOVE 'em! But, have you ever really sat down and thought about why they're there? Makes no sense.
OK, sorry for digressing.
Here's the thing. 20 years from now; 30 years from now; 40-50 years from now, your son is going to think back on the hours spent out in that garage with you working on that bike, and they are going to be the best memories of his life. Long after you are gone from this world, he will think back on those times, and you will live on in his memories, bringing him joy and comfort. Remembering those times, he will do the same with his children, continuing the cycle of parenting. As someone whose father never did anything like that with him, I can tell you I would give anything to have memories like that of my childhood.
My friend, there are several life lessons here, but, I think you may be the one losing them in translation. Winning some contest is irrelevant; spending great time with your dad is priceless. Your son does not know that yet, but, if you really stop and think about it, you do, and you can use this to teach him that.
The old Nissan commercials said "Life's a journey; enjoy the ride". It's not about winning a 4.00 trophy and making all the other kids whose parents value them only when they win cry, it's about cementing the bond with your son and treasuring the time you spend together.
There's a quote from a guy named Charles Swindoll that has made a huge difference in my life. He says you have no control over fate, and especially over what other people will do or think, that the only thing in this world you have any control over is you; specifically, how you look at the world. Attitude is a choice, and life is 10% what happens, and 90% what you choose to do about what happens.
Of all the lesson you can teach your son, I believe this one will best prepare him to go out into the world and live a happy life. I spent the first 45 years of my life believing I only had value when I won, that not winning made me a loser, etc. I'll spend the rest of my life working at unlearning that.
Don't let a bunch of morons who are so stupid they'd vote for a store-bought bike be the barometers of your son's self-worth. Teach him to compet, and to compete hard, but, at the end of the day, the win comes from his assessment of his efforts, not someone else's.