I have read a few places on the net that if you use an overhand grip on BORs you "deactivate" the biceps so they get very little or no work.

I don't think this is true, I feel it in my biceps and can see them contracting in the mirror.

Is this commonly accepted or just some goofy idea passed around in gyms and on the internet?

You won't deactivate your bis. You might use them a little less though. I wouldn't worry about it. mix it up.

Yah mun, and also changing your grip to an underhand grip changes the emphasis to the lower portion of the latimus dorsi and has more emphasis on brachio radialis (like hammer curls)

Wouldnt using the overhand grip, just do more of the top upper forearm as well as the biceps.

I do BOR's with overhand grip.

Cool, the consensus here is what I was thinking. underhand may focus a little more on biceps and lats, but overhand won't cut out biceps.

Overhand just seems a more natural grip for me

Dorian Yates swears by the underhand for lats. I think D.Y. has the best lats in the business.

Also, it is true that you will work the bicep with either grip.

If you try underhand, try keeping your hands only ~4 inches apart... And, remember to bring the bar to your lower waist for more lat usage. Keep your knees bent a little and look forward to relieve your lower back a tad as well.

-Rip

^^^^ rip has good points.

Also,

Use both underhand and overhand grips. Using the same grip on an exercise all the time can only lead to stagnation.

You never really cut your biceps out when you are rowing.

Something that really helps (though hard to explain on the internet) most people row from their hands, because they are holding the bar in there hands.

Try pulling from the shoulder and elbow. Treating your forearm like just a swinging pendulum. Initiate the movement at the shoulders, then drive your elbows back.

Remember, you are NOT pulling on the bar, it just happens to be in your hands. You are pulling your elbows back, with your back and lats.

This takes some learning and is very hard to explain over the internet. But will do wonders for your ability to use your back muscles more and your biceps less.

Once you gain the skill of course.

Hope this helps.

George made some excellent points (as usual ). When I do BOR, I do them both ways. When underhanded I am about 4 to 5 inches apart in grip with knees slightly bent, and I consentrate on trying to pull with my back rather than from my arms and bring the bar all the way to my waist as possible.

With me, the arms seem to fatigue......way before the lats (and this brothers me in the sense that the muscle is not getting hit as it should, and getting a break so to speak), so sometimes, I will do some lat pull down super sets during the sets of BOR (because of the different angle of pull and more use of the shoulders) and this can bring in more of a fatigue factor I am looking for in the lats when they are being trained.

yeah, after I learned what G is talking about I could actually feel my back working during rows.