A little about my history and then to the subject.
I have been training karate for about 6 years. The club where I train focuses mainly on kihon and kata. That is why I only recently (about year ago) discovered that karate is much more than kicks and punches. Now I have been studying lot's of locks, takedowns and practical kata bunkais.
Nowadays I teach one of my friend (green belt). But the thing is, he is 30 kg heavier than me and stronger too. I have no problem using blocks and punches against him, but I can't make any locks works. Also escaping from his grabs (wrist, collar) is nearly impossible. Against partners that are my size, locks and escapes are no problem. I have also noticed, that it is very hard to find videos, where locks and escapes are demonstrated against much larger and stronger opponent. I think that karate should work against larger opponent and therefore locks should work too. I understand that my technique is still somewhat lacking, but I would like to hear your opinion in this subject.
So, what do you think about self-defence against larger and stronger opponent? Are there some locks that are easier to apply to larger people? What about escaping grabs?