I used to like st kenelms pass for prolonged climb training. My favourite hill for sprint training is wheeleys lane from the ring road up towards harborne, good for the centre of brum, not easy to rep though given the traffic. You have to be careful when trying to time the lights right for the KOM…. Not to mention when cars try and overtake with a line of cars parked on the other side before realising you’re going a lot quicker than they expect!
The climb out towards Bartley green is good for training and if you keep going up past the Bartley reservoir, church hill into frankley hill lane into egghill lane gives you a nice continuous hill that you can go up and over down the far side and back up again so you can alternate climbs which helps with the monotony.