The beef round is a large primal cut consisting mainly of the rear leg and rump of the animal.
Steaks and roasts from the beef round can be tough since those muscles get a lot of exercise. They're also very lean since most of the fat on a beef cow is deposited toward the front of the animal.
Finally, because the beef round encompasses the leg, hip, and knee, it contains a lot of tendons, ligaments, cartilage and other connective tissue as well, which can be chewy if not cooked properly.
Beef Round: Cheap and Nourishing
On the plus side, these are inexpensive cuts that are every bit as nourishing as a beef tenderloin or ribeye steak, which makes the beef round a very economical way to feed a family or any other group of hungry people.
As for the issues of toughness and so on, you're in luck. Because the key phrase above is "if not cooked properly." If you use the right cooking technique, there is no such thing as a tough cut of meat.
There are basically three parts to the beef round—the top round, bottom round, and the knuckle or tip.
The Knuckle (aka "Sirloin Tip")
The knuckle is a clump of muscles from the thigh, running along the front of the leg from the hip to the knee.
The three main muscles in the knuckle are the quadriceps femoris, sometimes just called the knuckle; the rectus femoris or knuckle center; and the vastus lateralis or knuckle side.
If you ever see something called a sirloin tip, guess what? It's the knuckle. And it's not from the sirloin, it's from the round. Calling it a sirloin tip doesn't make it more tender, although it might make it cost a little bit more.
A whole knuckle can be made into steaks and roasts, but there's a bit of connective tissue in there holding those muscles together. A knuckle roast should probably be braised because those seams of connective tissue would be too chewy otherwise.
By the way, there's another piece of meat that sometimes goes by the name sirloin tip, and it's actually the sirloin flap, which actually is from the beef sirloin primal. Sirloin flap is more like skirt steak, though, so it's completely different from the knuckle.
Top Round: Good for Making Roast Beef
Top round comes from the inside of the leg and is therefore sometimes called inside round. In its retail form, it usually consists of two muscles, the semimembranosus, and the adductor.
Comparatively speaking, the top round is more tender than bottom round, but down at this end of the beef carcass, the word "tender" has a much different meaning than it does up around the rib or short loin.
Because it's tough and lean, the trick with top round is that you want to cook it medium rare and then slice it thinly. That makes it ideal for roast beef sandwiches.
But even if you're serving it as a roast, it's a good idea to slice it thinly, against the grain, so that it's easier to chew. And don't forget the gravy.
To achieve a good medium rare roast from the top round, you'll want to start it at a high temperature to brown the outside and then lower it so that it cooks slowly the rest of the way.
If you do this right you'll end up with a nice uniformly medium rare roast without any gray sections around the edges.
Some people even roast top round using a technique similar to the closed-oven method for cooking prime rib.
Top Round Steaks: Yea or Nay?
You'll also sometimes see top round steaks, and the best way to deal with these is to manually tenderize them with a meat mallet or some other mechanical tenderizer. They're actually pretty good for making Swiss steak.
Marinating will add flavor (which top round steaks lack because they're so lean), but marinating doesn't tenderize meat.
Otherwise, if you're looking for an economical steak, cooked in the traditional way, sirloin might be a better choice.
And slicing it thinly against the grain is the most important part. Otherwise, grilling top round is going to put your jaws to the test.
A third muscle in the top round, the gracilis, or top round cap, is sometimes used for stir fry meat, fajitas and so on. And if you ever see something called a Santa Fe cut, it's the top round cap. It's similar to a flank steak. One day I'll write an article about the trend of naming steaks after all these cowboy-sounding places in the southwestern U.S.
Bottom Round and Eye of Round
On the other side of the leg are the bottom round (sometimes called outside round, because it's from the outside of the leg), and the eye of round. If you ever saw something called rump roast, it was bottom round.
The eye of round is another decent choice for roasting, with all the caveats discussed above. Eye of round roasts are best sliced thinly, and they make good sandwiches.
Although you don't see them much anymore, the old-fashioned bone-in round roast is simply a thick roast cut straight across the femur bone. You'll see a cross-section of the bone in it, along with sections of all the other muscles around it. These are decent for making classic pot roast (or an oven-braised bottom round pot roast) and they're comparable to (but leaner than) beef chuck arm roasts (which you also probably don't see much anymore).
Finally, the femur bone is an excellent marrow bone, and the joints have a lot of cartilage on them, making them ideal for making beef stock.