How do you decide wich weight category is best for a given athlete? are there any criteria that determine wich bodyweight to achieve your best bodyweight-to-lift ratio other than lower bodyfat? (like height or bone structure)
Where you are strongest is the place to go. I am referring to absolute strength, not relative strength. We are judged on how much we can lift, not how much we can lift relative to our weight. There are some cases where going up in weight class can be a benefit.
I have heard Coan comment in articles that if you are over 6' you need to be over 300lbs, more like 350lbs bwt. And lifter under 6' can be less. YOu need to take you height, and then look at your natural build, i.e., the size of your frame. For example, I am 6', and only 230lbs with a moderate (middle) build. I don't have a large frame (you can read fat a litte). So really I am not build ideally for powerlifitng with a moderate build, and 6'. It at this time is not practical for me to move into the 275lb class. Not strong enougth, and I just don't want to die at 50 years old of a heart attack and be listed in some power mag. More likely I would be 198lbs class with less fat.
This does not address your question directly, but sometimes a bdwt class choice is a competitive strategy. At the recent IPF Masters World, four of the five women entered in the 82.5 kg class bailed out up or down in class to avoid lifting against the eventual sole entry and winner, Pecante of the Philippines. Her performance at a meet the month before scared them off.
this actually is a multi-dimensional question......of course one thing that has to be determined is if you are talking about competing raw or with gear.....the gear definitely clouds the issue...so I will answer as if you are asking about raw lifting but to answer it WITH a question, one might say "how badly do you want to win"...or "what level do you want to compete at?" of course there are exceptions, but my point is...a 5ÆŒ" 220 pounder is usually going to beat a 6Æˆ" 220 pounder....simply due to more mass and better leverages of course I am talking about MUSCLE mass also...not sloppy fat weight gain -------- another way to look at it.....a long term standpoint.....lets say you are 5Æ" 165 lbs and you want to squat 600 lbs raw....uhmm, okay..how many guys 5Æ" 165 do you see squatting 600 raw? they would be the exception rather than the rule... --------- there is some interesting discussion in the book "supertraining"...talking about the dynamic strength deficit and body mass etc etc...I dont have the book here so I am going from memory just to give you a rough idea of the concept Mel Siff was talking about mass training....when do you need more mass....if you think about it, it is very similar to your question first of all..what is a strength deficit?....ok, first you establish your limit strength...really the only way to do it is to use electrosimulation, lol...but anyway....then you figure out your maximal strength (without electrostim etc)...the difference is your strength deficit so if you have a large strength deficit, it means that you have a lot of mass and potential that is going to waste....so you dont really need to train for mass (or you dont need to go up a class, lol)....instead you need to train for maximal strength and maybe explosive strength etc to tap into your potential if you have a small deficit then in a sense you are "tapped out" at your current mass level and you need to gain weight/mass/cubic inches to give yourself more potential you can see this plainly if you look at bodybuilders...they have all the mass in the world but arent nearly as strong as powerlifters of the same weight...they would have a HUGE strength deficit....so the LAST thing a bodybuilder would need to do strengthwise is train for more mass (or try to go up a class) but if you have a guy who is 148, 2 years ago he benched 440, last year he benched 450, this year he benched 455...it would seem he is "tapped out" at 148...he might want to do some mass training and go to 165 to increase his potential ceiling etc... one thing you can do is look at others your own height/weight....see what they are lifting...compare apples to apples as far as roids and gear etc....if there are guys your same height and weight totalling 500 lbs more than you then you probably have some potential at your weight class that you can still tap without worrying too much about moving up yet