Mirrors- I use one on my main ride and to be honest I rarely use it---Or thought I didn't. Couple of months ago I used a different bike and kept looking for the mirror.

Forget who suggested it but a tip passed on a few years ago about looking behind you- Was to place your hands at the centre of the bars before doing it. That works.

I'm the original poster again. I think your comment about 'core muscles' touches on my problem. Maybe. I have stenosis in my back. Everyone over 50 does, but I have it worse than most. My L4-L5 is supposedly 'severe' and I've been offered a laminectomy to correct it. My feet are very numb and have been for many years.
Anyway, I think bike balance no-hands comes from doing a sensitive little shimmy with your lower back and pelvis. I think that is what I've lost. I don't suppose it matters WHAT is preventing me from doing it, but it would be kind of nice to know why.

1) I can still ride no hands, but not with the confidence I once had. I think the bike makes a big difference in riding no hands. I could cruise, totally relaxed with no hands on a 1981 Nishiki Olympic. When it was stolen, i replaced it with a cycle-cross bike. Much more sensitive steering so no more riding no hands.
2) Turning to look back is a problem for me. I find myself wobbling left and right. I rode 800 kms on the highway this summer and the practice of turning to look back made me more stable.

I am congenitally coordination-challenged to the extent that I was not able to learn to balance a bicycle until age 12 (after which I was hooked for life, having finally discovered one of the few sports I have truly, deeply loved). My hand-eye coordination, large muscle control, and sense of balance are well below average. As a consequence, I lack self-confidence in any activity which requires agility, so I don't attempt things like downhill skiing, surfing, unicycling, inline skating, or hands-free cycling. I tried using an eyeglass-mounted mirror in the 1970s, but quickly gave up. A few years ago I tried a helmet-mounted mirror, and now I hate to ride without it.

Thats cool - however for myself, I think I would find it very very hard to get to used to riding with a helmet mounted mirror

Why ride no-handed? It is an additional hand position to use. On a long ride I find it relaxing to ride no-handed for a while. It is a good time to do some upper body stretches.

Growing up as a paperboy you learn to ride no handed, throw accurately while riding, carry large loads, kick dogs, tear away from gangs of bad kids at high speed, etc.

Riding no-handed is just another weapon in your arsenal.

Yes indeed, seems like I could ride no-handed without thinking about it and can't remember actually LEARNING to do it. Big balloon tires on a heavy bike. I don't know about the 'trail' geometry of that old bike. I was probably greater, and I thought for quite a while, when I got back into biking, that the BIKE must be the difference. But I see young people riding these new road bikes no-handed all the time. I also remember riding that newspaper bike to the last day possible, to avoid walking. In the snow. And falling due to invisible ice. But back then I was bullet proof, and now I most certainly AM NOT!

Anyone consider frame/fork alignment issues, not to mention correctly centered wheel positions?
You should be able to ride properly aligned bike (and wheels) no-handed, unless your fork rake distance is extremely short/negative.
You may want to have the bike checked out; it might not be the rider.

My road bike is a Specialized Allez, and I have a Giant mtn bike with new big tires. Can't go no-hands on either. I'm sure it's my body that's lacking SOMETHING.

If you ride the bike enough, riding no-hands just comes naturally. Mechanically, the bike just needs to be perfectly-aligned, with true wheels, and the headset needs to be adjusted with just enough preload, so it's a good test of headset adjustment. When you rise off the handlebars, a quick and very gentle shake of the hips should move the bars slightly and show you how much control you have over the steering. If the bike doesn't respond immediately, and starts to drift off to one side, it means your headset is too tight and you'd darn well better get those hands back on the bars! When you get back, loosen the headset preload slightly.

You should be able to put on and take off a vest or rain jacket, or zip/unzip a full zip jersey while riding. I'll pull out a sandwich from my back pocket and eat it while riding; it saves so much time compared to stopping. You should be able to look back while riding no hands. I will sometimes ride no hands around the 200-meter board track I train on in the winter. Confidence is necessary, but the bike will track around the steep bankings as long as you're going fast enough! Paradoxically, the real test of your no-hands ability is how SLOWLY you can ride a bike no hands. The top riders will often ride around the track no hands during their lap of honor, bouquet raised in one hand, waving to the crowd with the other, up and down the banking, very slowly!

A trick for looking back without wobbling: looking ahead, pick a spot on the road just off to the side, like a paint mark or patch. Watch this as you pass next to it and as it recedes backwards. You are now looking back! Some guys will stabilize by lifting the arm on the side they're looking, and moving it back as they look back.

I ride no hands frequently but need to lean a bit to the left to get in balance. Does this indicate that the headset tension is off or is it (as I assumed) just an indicator that the bike itself is somewhat unbalanced?

I like to unscrew the lid off a water bottle then drink out of it like a glass while riding no-hands. That lets you chug a big amount and stay hydrated.

Well glad I did a search first. Was going to see if anyone else 50+ rides no-hands! Tonight I did 31 miles on the MTN Bike and I easily road 1+ miles of no-hands. I need a taller handlebar stem (my seat is on max height) so to give my hands a break, I road no-hands. I love coasting riding no-hands.

I always use my hands when I ride. Haven't figured out how to shift or brake or scratch my nose without them.

My coach had me ride on the rollers this past winter season. I feared the task so much I made this amimated movie. I have found that it is easier to ride the rollers no hands than one might expect. Once I took the leap of faith and utilized my core muscles to drive the bike , as Hermes says, it was a simple task.

https://www.xtranormal.com/watch/8195...ng-the-rollers

I didn't realize that I was riding no hands after killing myself in a sprint to win a race last year in Columbus OH. Usually after any effort as hard as I had just completed I would want to lie down a bit.

I think I read someplace they later lost the competition after the biked was x-rayed and they dicovered the bike had a hiden gyroscope...

On my road bike and my most XC-oriented MTB I frequently just tilt my head down and look under my armpit.

I can look over the shoulder also but I remember it taking a lot of practice to get it down. Then after getting the left shoulder look down it took a lot more practice to get the right shoulder look dialed in.

Most roads are crowned so if you're doing this on a road and riding on the right side of the road you'll likely need to lean to the left a bit to maintain balance.

This works.

I have mirrors on my bikes, but in traffic, I'll use this method to verify.

I had a bad crash in 4th grade, breaking a hand and smashing my face. Maybe because of that I never had the guts to learn to ride no handed. I really wish I had.

I have 9 bikes, I can ride any of them no hands, but it is much harder on my Dahon with 16" wheels, and for some reason, on my 85 Trek 600. I use handle bar mirrors regularly, as I can't see anything with glasses or helmet-mounted mirrors, and I wander all over the road if I try to look back. I'm a mere child of 71, maybe as I mature it will get easier.

I've been thinking it was the newer geometry of our late model bikes. But maybe my problem of not being able to ride no-hands like I did as a kid is, I'm a LOT bigger now. I used to weigh 100 to maybe 140 lbs. I'm all grown up now and weigh 260. With me on the bike it's like balancing a light bulb on that little soldered tip at the very bottom

Look behind you? I wouldn't want to go against one of Satchel Paige's rules: "And don't look back—something might be gaining on you."

Actually, I look back constantly, but I love that quote.

Something is always gaining on me - age!!

That's a good reason not to look back, 'cause it's always there.

Yoga and stretching, and you can get both eyes back. Mirrors? - Isn't that like the car drivers we see who never turn their heads and can't see their blind spots?

I think hands free is worth working on but the bike you're on seems to have a big influence. You didn't mention track stands, that's a useful skill.