Your form is off, not in a dangerous way, just in a not as effective way. You are doing a bent over row that is a hybrid of the 2 bent over rows that exist. They are:
90 Degree Bent Over Row - bend over so your upper body is about 90 degrees (ie parallel to the floor or very close), take a pronated, wide grip (grip it where you bench it), keep your elbows relatively wide and lift it to the bottom of your chest.
The bar should touch your chest or come very similar to where it touches when you do a bench, basically this is the exact opposite movement of a bench press. This is significantly harder than the 45 degree bent over row, and puts more emphasis on the upper middle back, lower back, rear delts, rhomboids, brachialis and brachioradialis. You will use much less weight with this form and the bar will probably touch the ground or come close every rep.
45 Degree Bent Over Row - Stand upright and then bend your upper body 45 degrees forward, think 2 point stance in football. Your knees do not go forward at all, you move your hips back and unlock your knees.
You can take either a supinated or pronated grip, most people go with supinated. Grip the bar closer than the other row, like you would curl it. Once you have bent over maintain that position and pull the bar up to your lower stomach. The bar should follow your thighs (without dragging) up, so it goes up at a slight angle, and it should hit your belly button on the top of your shorts.
This is much easier than the 90 degree bent over row, meaning you can do much more weight. It is also easier for most people to learn. There is very little emphasis on the lower back (until you get really heavy weight) and a lot of emphasis on the biceps when supinated. They both hit the lats effectively. The best example of a 45 degree bent over row I have seen is on Dorian’s video Blood and Guts.
You were bent over 45 degrees but you were bringing the bar up to your lower chest with a wide grip, so you had the grip and pull of a 90 degree row but the body position of a 45 degree bent over row.
So pick one and go with that. The easiest fix for me to tell you to do is to take a palms up grip, narrower than you have now, and pull the bar up your thighs, keep your current body position. You will be able to lift much more weight like that, probably like 185 or something, and IMO get better results.
The slight movement you had with your knees helping you is not a big deal, sometimes it is good to go extra strict to make sure the form is under control and sometimes it is good to move some weight and allow some momentum to help you, just keep your form in check. If you find you are standing straight up you are definitely moving too much.
Hope this wasn’t too long, good luck with it.
