Percentage of MHR is far better and useful for this disussion. BPM figures are too subjective according to individual. Doing the same course at same speed with a head or tail wind will give very different - work or intensity levels. If you use % of MHR, regardless of external factors, your intensity or work is still the same
Of course one needs to establish Max heart rate to acurately calculate these percentages in the first place.
Going back to the OP - have you determined your MHR for cycling? ( not by the 220-age or Polar fit test) this will allow you to work out % of MHR and therefore intensity level/HR zone you are working in.
Regardless, the bpms quoted indicate fairly high intensity level. You don't need that much high intensity training to get the training effect/body to adapt. Thats why interval training is effective - same training effect/adaption, less stress on body/faster recovery.
Sally Edwards has a number of books on HR training - I imagine there are other HR training guides which could be referred to??