I’m a taller lifter - I’m 6 foot 2 and a half so not a giant but a fair bit taller than the average and I also have particularly long legs (do we think the term “leggy lifter” might catch on?). Anyway, I recently started 5/3/1 and found that on the first week of the first cycle I struggled to push out more reps than the requisite 5 reps on my final squat set. I managed to get 8 but that was a real struggle compared to the easy 10 reps I had achieved in my final set on bench press day. I calculated the training max for bench press and squat the same way (using the formula Jim sets out in the book) and used 90% of that training max as Jim says.
Of course, it could have just been an “off day” but I came to the conclusion that, as has been written about on T Nation, being a “leggy lifter” means I have further to travel when I perform a deep squat and so performing a higher rep set is more taxing than for the general population. To combat this I’ve decided to recalculate my training max at about 85% of my predicted 1RM, because, as Mr Wendler says, ALWAYS START TOO LIGHT.
This wasn’t an issue of me exaggerating my 1RM because the 1RM I had originally calculated would have been doable - the problem is that performing a high rep set means a lot of “work done” (force x distance) which means that performing 2 reps is a lot more taxing than performing 1 rep, and performing 3 reps is a lot more taxing than performing 2 etc.
My bench press numbers are also very close to that of my squat (with my recalculated squat training max there is only 5kg difference) but, again, I put that down to the difference in the difficulty of each movement (there’s no way my chest and arms are stronger than my legs!).
I just thought this was an interesting obervation that no-one has really covered before and maybe it’ll help people with similar problems - don’t be afraid to drop the weight on your squat if you’re looking at next week’s lifts thinking “there’s no way I’m lifting any more than 3 reps at that weight!”. And you’ll be increasing your lower body lifts by twice as much as the upper body lifts so your squat should pull away from your bench press if you give it some time.