New member here. I found this thread through google. I've always struggled with correcting my deadlift form and have now read pretty much everything on the topic the internet has to offer. I've got to say that this thread is the best I've read.
Welcome to the forum
How far beyond the knee-caps do you aim for before you switch to the rack-pull?
For RDL's, I like to work towards lowering to mid-shin, similar to where you would start on a DL from the floor. I work on ROM first and use enough weight for them to feel the exercise working, but still maintain good control and technique. I also slow them down a little. When they're lowering the bar to mid shin, I then focus more on getting stronger/adding weight, until they're using 60KG/135lbs.
I don't rush them, though. I want them perfect, and I want clients to feel their hips being loaded. When you are at the start of the RDL, standing up tall, I want hips thrusted forward into the bar, chest out and chin tucked. Like a perfect "lockout" on a deadlift from the floor. Then you just imagine closing an invisible door with your a$$. Keep the lower back arched and reach back with the a$$. When it's right, you will feel your hamstrings stretch as you reach back with the hips. This is loading the hips. Like a sling shot, pulling back the hamstrings, then you thrust the glutes forward.
Spend some time and be patient with this - it'll pay off.
When you can "feel" your hips being loaded, and you can "feel" that your back is arched, then you will "feel" when your lower back rounds, and that's half the battle. At this point, the other half of the battle is just leaving your ego at the door, because if you lift horribly, you're doing so on purpose for the sake of numbers.
Stay out of the mindset of constantly trying to "test" lifts. Think about "building" them instead. RDL's are a great foundation to build your DL technique on. There's a time and place to test lifts. When you're still learning basic technique, it's not a good time to test. But you can (and should) build!
Also, my system for this now is - RDL's as described. Then deadlifts with the bar elevated 4 inches. I use small steps. So it's not quite a rack pull but not quite a DL from the floor. It's easier to learn set up and getting tight. You've already built the ROM/flexibility with RDL's. When your set up is good, I go to the floor.
So it's - RDL's -> Deadlifts from (4inch) blocks -> Deadlifts from floor.
Did you have any clients that struggled to increase flexibility beyond a certain point? If so, how did you resolve this?
Loads! Pretty much the majority of males i've ever had deadlift!
Do you have a "dynamic warm up" ? This, basically, is how I smash hip mobility. If a client has crazy restrictions i'll ask them to do 2-3 warm up movements every day. The movements depend on the issues, though...