Awk1993, you raise an interesting point. If we run the numbers you used in your example, then you’re right: the RPE chart and the suggestion to “increase by 5%” seem to produce different results. I’m also just starting The Bridge, so I’m new to the RPE/percentage systems as well. I wanted to explain my rationale for the discrepancy you’ve noticed.
From The Bridge: “By adding 5% bar weight while maintaining the rep range, we typically see an increase in RPE by 1.” Note the word “typically.” With RPE, we can’t expect perfect predictability in our numbers, only “typical” predictors. Since RPE is a scale of “perceived” exertion, which is an individual and ever-changing variable, there can be no reliable system of calculation. Even the RPE/percentage chart is only a rough estimation. Unlike the SSLP with its predictable weights, the percentage system is sort of based on “line of best fit” estimations of RPE, which is inherently difficult to predict on the individual scale.
As such, it’s understood (I think) that beginners are going to suck at gauging RPE at first. After all, most of us have probably never done it before. It seems pretty challenging, and a total mental paradigm shift under the bar. It will take some time to get the hang of it, but when we go into the gym we need to start somewhere. That’s where the percentage chart comes into play. Percentages, unlike perceptions, are calculable. No one is saying that the numbers will always directly correlate with our perceptions, only that those numbers are commonly suggestive of general RPE ranges given an e1RM (don’t forget that e is for estimated, which means the entire chart is only an estimate). So when we have two pieces of conflicting information like you’ve noted, I think we ought to assume that they’re both attempting to guide us toward accurate weights, but stemming from different observable phenomena. For this reason, the suggested 5% increase for each 1 RPE increment need not map directly onto the RPE/percentage table. In short, it might be best to imagine every percentage having a (~) in front of it, indicating its uncertainty.
You asked, “how would you know where your opening @ 7 should be if the table doesn’t work?” I would say you know where your @7 should be when you actually lift it. The percentage estimates will get you close (as they are meant to do), but it’s ultimately your call. When you recognize that you’ve completed a set @7 according to the RPE criteria (“fairly quick like an easy opener”), then you’ve completed your @7 set.
Let me give an example from my first day of The Bridge. I calculated my estimated close grip bench sets using the RPE/percentage charts and my previous lifts. Now, having only done the SSLP, I’ve never done “close grip” bench, only “normal” bench. I made the assumption that the close grip bench would be considerably more difficult than normal, so when I calculated my 4 rep bench numbers @7, @8, and @9, I subtracted ten pounds from each, thinking lower numbers would probably feel more difficult. When I got to the gym and actually tried the first estimate (170x4@7), I found that it was way easier than I expected. So I didn’t count that set as my @7 because, obviously, it wasn’t an RPE 7. I went up fifteen pounds and that felt closer to an @7. My subsequent two sets (@8 and @9) were 20 lbs and 25 lbs greater than my initial estimates, respectively. So I kind of felt it out as I went. Instead of worrying about what specific weight was on the bar, I had to focus on what the weight actually felt like. Now, on the other hand, my first-day estimates for squat were pretty much dead-on. But for both of the lifts, my main focus was trying to determine how difficult the lift was, rather than focusing on the number on the bar.
This stuff isn’t easy, but we’re the kind of people who are all about challenges, right? I don’t expect to get all of this perfect, but I’m hoping that after 8 or 10 weeks, I’ll have a better understanding of RPE, and be able to better gauge what my body is capable of at any given time. Hope this helps!