Sometimes after. I know most of the forum seems to frown on this, but for me it's just interesting to see how different body types translate into different weights, and also gives me an indication of the size limits of certain techniques. Also helps me find the limits on just much I can compete up in weight while still being safe and competitive. It has nothing to do with looking for an excuse or attributing losses to size difference.
As focused on weight as BJJ and MMA are, you'd think more people would be interested in weight just as a matter of curiosity if nothing else.
When people ask me my weight after rolling, they are usually surprised when I say 135lb. Most guessed me to be about 160-170lb. I don't know if that's a compliment to my ability to use my weight well, or an indication of how crappy people are at estimating weight. Probably the latter. Lol
What ever they say, add 5-15 pounds to it 
Most guys will lie about it, though. A guy we train with will say he weighs 205 when he actually weighs around 225 or 230
Chip beat me to it
Not necessarily anything wrong with that.... but you should have regular training partners who you know approx how much they weigh... It's not like you need to ask everyone al the time to get an idea about the effectiveness of specific techniques.
I would never pose the question that could be framed as an excuse.... If you're side mounted and feeling crushed maybe afterwards ask him and see what he was doing to generate all the pressure...whatever. I don't know... I'm good friends with all my training partners. I'm laughing, talking smack, singing to the music, maybe try an outlandish highlight move only to joke around about its epic failure...I'm having fun.. These are my every day friends. I don't worry about asking them anything. Don't get me wrong. I'm analyzing everything. I jot down a few things that I want to do different next time...
I think there are much more analytical questions you could ask your partner. Mine are all much bigger than me but I assume that they're using all of their weight and pressure on me even if I submit them.
^I assume that they're NOT using all their weight and pressure.
Haha I don't ask them every rolling session.
Might as well just guestimate by looking at them. People tend to either lie or be inaccurate for some reason or another about their weight. Ends up being douchie to ask and the information you get back isn't trustworthy. Related to the "let's go light" guy typically.
As a smaller guy I make my go to response along the lines of "I'm dieting down a lot, pretty sure I'm under 400 pounds now."
It's generally a backhanded question. I recommend not doing that. It insinuates that they have poor technique.
I am guessing you are a whitebelt?
I just shamelessly duck anyone who looks like they're over 175 these days. As a 150 pound 33 year old who's had a lot of injuries over the last 2 years, it's just not worth it.
I'm about 185. There's two guys at my gym who have to mention how I'm bigger than them before, during, or after every roll. The reason I'm beating you isn't because I'm bigger, it's because I've been training longer, harder, and smarter than you. It pisses me off. I don't think they realize it but it insinuates that you only have strength, not technique. It's just another excuse you can give yourself instead of a opportunity to improve. I find it quite offensive actually
It's like when a partner says "man you're so strong!" I'm thinking, I weigh 175lbs and used nothing but basic technique to sweep, keep the mount and cross choke...and your compliment is that I'm strong? Lol
JoejitsuMD - It's like when a partner says "man you're so strong!" I'm thinking, I weigh 175lbs and used nothing but basic technique to sweep, keep the mount and cross choke...and your compliment is that I'm strong? LolThis is the one that irks me. I'm bigger than most admittedly, but when I spend a roll purposefully trying light methodical traps, and get a tap, I know it's their ego fueling that comment.
Soul Gravy - Sometimes after. I know most of the forum seems to frown on this, but for me it's just interesting to see how different body types translate into different weights, and also gives me an indication of the size limits of certain techniques. Also helps me find the limits on just much I can compete up in weight while still being safe and competitive. It has nothing to do with looking for an excuse or attributing losses to size difference.
As focused on weight as BJJ and MMA are, you'd think more people would be interested in weight just as a matter of curiosity if nothing else.
If a technique doesn't work in training why would you assume that the problem is how big your training partner is and not that you're doing it wrong?
Guilty. Same reason with the OP. Also being a small guy, 145 lbs (gained 10 lbs the past 2 months), I think I have the right to ask - especially if I think the guy's 100 lbs heavier than me.
Tomato Can - I just shamelessly duck anyone who looks like they're over 175 these days. As a 150 pound 33 year old who's had a lot of injuries over the last 2 years, it's just not worth it.And yet you're probably the guy who goes the hardest.
Siciliano - Guilty. Same reason with the OP. Also being a small guy, 145 lbs (gained 10 lbs the past 2 months), I think I have the right to ask - especially if I think the guy's 100 lbs heavier than me.What's the point? If you already know he has over 100lbs on you, it's obvious. What's the difference if it's 110 or 130. You're still fucked either way.
Well, I made it a rule recently that I won't roll with anyone above 200 lbs unless it's someone I know and trust. Sorry but I'm in my mid 30s. Been injured a couple of times by overzealous partners. And one was a brown belt who weighs like 240. I can't afford getting injured.