Hi Mom, I am 57, have an adult son, and been building motorized bikes for 6 years.
Does you son know the rules of the road?
Enough to pass a drivers license test?
If not, stop now, he ain't ready.
If he is traffic savvy at 17 then it's just a matter of remaining as safe as possible while riding.
First and foremost is GOOD BRAKES, NO motorrized bike is safe with just a rear coaster brake, heck I am putting dual disc brakes on the bikes I build these days but regardless it's needs a front brake.
Number 2 on my list is a strobing front light for daylight riding.
It makes everyone you are headed towards take a second look and see you are going much faster than they expected and wait for you.
Other than that don't be an idiot riding.
Stay on the right, don't ride on the sidewalk, and for your moms sake always wear a helmet and glasses when riding, only idiots don't.
There is nothing whatsoever in this post I can disagree with, very wise words honestly.
You could probably benefit from getting your mom's perspective not on the dangers of the road, because let's face it, fearful mothers are always irrational about danger, my own mother insists my bike is a death machine even though she owned/rode a CROTCH ROCKET at least for half her life.
Her perspective on how YOU drive on the road is what you need to consider. She wouldn't blatantly lie to you about how you drive, if she thinks you need to improve a bit in a particular skill then it's probably true. If she honestly doesn't think you can drive in a safe manner well... She's probably right, motherly instinct is a hard case to argue against, I've seem my mother right more times than I can count, even after I thought she was dead wrong, go figure.
Do you have a driver's license yet? If so then great, now adjust your driving style to meet the needs of a vehicle that is inherently slower, harder to see, and less looked for compared to other vehicles. Now remove the large steel box the protected you while driving, remember the steel box also made you seen 99% of the time you were seen.
Have you practiced slowing down quickly while ensuring that no drivers are too close behind? Cars low down slower, have brake signals, and the sudden stop is noticed quicker by drivers vs the faster, non-signaled, and less easily noticed stops that a bike makes. Believe it or not the PA motorcycle handbook (read and know your local motorcycle training handbook) says that when stopping you should give extra distance between you and the person in front, because people behind you might not notice, and they will rear-end you, and people in front backing up might not see you either. You need extra room in both cases to escape danger.
Turn signals can be a lifesaver, it proudly shows your intention to people behind you that you might not even see, of your bike hasn't got turn signals then your options are making wild hand signals while looking back a half dozen times while trying to change lanes and checking mirrors (if you have them) or almost getting hit if the driver sees you in time and uses a horn to let you know your too close. If they don't then you just get hit. Luckily mirrors and turn signals are required on the steel box variety of vehicles, so if you have a license at least your used to using them, if you don't have them on a bike consider yourself a handicap on the road since you are actually relearning how to signal and look at things properly.
I don't know what state you're in, but most require helmets for people under 18. In PA individuals riding a motorcycle under the age of 18 who have not passed an advanced motorcycle safety course (basically everyone except the prodigies) are REQUIRED to wear a helmet. Local ordnances might require minors to wear helmets on bicycles. I wear a helmet always except for 2 circumstances in which I feel like I can do without, both are trips only a couple blocks long, but considering how I was recently drop kicked by a plastic cup I'm reevaluating that theory. I do however always wear eye protection. Bugs, cigarettes, and small stones traveling at 70mph are likely to be my least favorite things to get in my eyes while operating a vehicle that takes 2 hands and extra vigilance to operate. Good thing steel box vehicles require windshields. They don't let anything past, sunglasses can still let a bee up past the lens so expect the unexpected.
Most states you get a learners permit at 16, if you're 17 and living in a most-state type of state then you will have nearly 2 years of driving experience. Did you fail your driving test at all? If so you just might not be ready to safely use a motorized bike. Do you tend to roll through stop signs? Find yourself riding up one way roads? Looking once before changing lanes? Assuming drivers see you when they look right at you? Not using hand signals to let people know your intentions? If you answered ANY of these questions wrongly and you do know the right answers, then you should reconsider riding a motorized bike until you really ready to ride among 2 ton vehicles made of steel and can squish you flat in just a moment's notice. I saw people who can't even really read a sign at the dmv getting drivers licenses. I was at counter 8 talking to the lady, a man walks up and starts asking if this was counter 5.. Now obviously she's busy with me so he must not of seen me standing there. And then there's the big sign above the counter and under that says counter 8, each of the 14 counters have corresponding signs, so he much not have seen the 27 signs (I was standing in front of the lower sign) either. Then there's a little red light up sign above each counter that shows the ticket number that the counter is serving, he missed that one too.
And I'm about to go out and drive on the same road as him, he couldn't even see 28 signs and a person while sitting down in a plastic chair.
Think you're ready for the road? Rethink it and be damn sure you can because it only takes one idiot who can't see for s**t to not use HIS signals and pull right out in front of you, luckily he has a sturdy steel box to protect him so safety was the last thing on his mind while he was arguing about something on his cell phone.