Training & Nutrition - My friend pedals with his heels

One of my friends that I go riding with has a bad habit of putting his heels on his pedals instead of the balls of the feet. I keep asking him to do pedal properly but he just says that it feels more natural to him to do this. What kind of damage is this causing to his feet and legs, if any? I'd like to have a better argument to convince him other than saying, "Well, that ain't right!"

I ride different parts of my legs by changing my foot position. But not on the heels.
Compensating for leg strength with weight?

As much as I hate to say, he is a stronger rider than I. He's been doing it for the last few years and pounds out 20-40 mile rides a couple times a week on his platform pedals riding like that. I've only been biking for 4 months, with a 25 miler as my longest to date. He is stronger, no doubt. He just seems to like riding like that. He is not nearly as geeky as I am though. He's never read biking forums or anything for that matter. He just does it for general health reasons, not for the love of the sport. However, I am wondering if his lack of true enthusiasm because it's painful to ride like that. He always denies it, but the guy never seems to mind pain anyways, so I wouldn't put it past him to just say, "Nahh, it's nothing."

Is his saddle close to correct hight and his knees not forked out?
Who knows? ..maybe just his physio.
As to how to ride long distance, I think it would come into play.
I shift saddle and pedal position often to relax certain muscles.
To me, pedaling with heels makes me think of thigh strength, not lower leg.
How foreward is his saddle I wonder?

Mind you, I was commuting behind a roadie on a mtb, (I say roadie as the size of his legs, age and 'grace' on his bike.) No dis, good winter commute choice.
Bad riding posture as his legs were noticably outward, off the knee fulcrum =no power.

My knees are turning inwards slightly @ max downwards force sitting, riding my calves onto the pedal.
Climbing sitting, i'm using thighs.
Eh.

Also if he has done this for a while, his body is conditioned to it.

Otherside:
I have a hard time walking sometimes if I ride alot as my feet\legs\thighs are muscle-wise lined up straight.
I'm not bow legged, but it seems my feet are pointed too straight foreward when walking.

Funny.

One of my friends that I go riding with has a bad habit of putting his heels on his pedals instead of the balls of the feet. I keep asking him to do pedal properly but he just says that it feels more natural to him to do this. What kind of damage is this causing to his feet and legs, if any? I'd like to have a better argument to convince him other than saying, "Well, that ain't right!"

He's not doing any damage, but he won't win any races either.

His seat is about 2-3 inches too low, from what I could eyeball. I haven't looked at his fore-aft saddle position yet. I'll do that the next time I ride with him. So he isn't hurting himself by doing this? I might be able to convince him with the more efficient/more power angle.

His seat is about 2-3 inches too low, from what I could eyeball. I haven't looked at his fore-aft saddle position yet. I'll do that the next time I ride with him. So he isn't hurting himself by doing this? I might be able to convince him with the more efficient/more power angle.

It might be uncomfortable at first.
I'd say I have 4 'positions', 2 on saddle, 2 off.
2 are different muscle group workings, 2 crossovers.
I rotate and save for climbs.

Also, riding with your knees in contact with the toptube is not wrong.
Extreme pedal exertion, my knees will be clipping the toptube, extreme cornering, I'm forcing it with my leg.

To me, the saddle should be slightly high\low. Not the highest, the lowest correct high, compensated by the knees going inward. Sounds stupid, maybe you know what I mean.
Riding XC mtb this is an issue -as you need a little crotch clearance.

Bow-legged cyclings not going to go far, but it may be about his physique or genetic build. Some people walk that way.
I don't, but ride very 'correct', as I said, sometimes still have to get my land legs.

I might take up running as a cycling supplement.

Wait until you are a stronger cyclist than he is and then make your point. You'll have more evidence on your side.