I take my bike on the train every day, but luckily I'm on the less congested end of the line. I live close to London and lots of commuters use the train to get to work in London. They do limit bikes on the trains here too. I'm ok where I am, but going into London you are only allowed folding bikes during rush hours because of the crowding and congestion. I have occasionally had to sit out a train here too when it's been too full to get my bike on board.