I was riding up the hill on St. Aldates in Oxford earlier. It's a big wide road which it needs to be because there are lots of bus stops/parked delivery lorries/taxis stopping etc. Anyway I was about 100 metres behind a pair of cyclists who were going pretty slowly grinding big gears while I was catching them quite quickly. I was keeping an eye on them because they left it until the absolute last minute to pull out to overtake a parked van and did so without any shoulder checks causing them to almost be hit by a passing bus. As I caught up with them there was a double decker bus which I was hoping to get a tow up the hill from. They were cycling in the gutter as I passed them following the bus. Slightly further up the hill the double decker slowed down because another bus in front needed to overtake a parked van. As it turns out the double decker was about to stop anyway and indicated left while starting to pull in. I noticed this, dropped back a little and adopted a strong primary so I could overtake it. However at exactly this moment the couple caught up with me and I noticed in some disbelief them trying to overtake the stopping bus down the inside. I was expecting just about expecting the first cyclist to get crushed when he only then realised the danger he was in and braked suddenly. Amusingly the second cyclist then bumped into the back of the first cyclist though fortunately she didn't knock him off. I'm not sure where I'm really going with this but it doesn't surprise me that buses and HGVs are involved in so many cycling accidents when cyclists like the couple I saw are so unaware of other road users and their intentions.