Cycling (much) is not helping getting flexible in your hamstrings, that's for sure. Neither does sitting at a desk / on a couch for many hours a day.
You may have a posterior pelvic tilt (generalisation: this is the more common type for men) which also is not helping your forward bends. And then of course there's also age, which may not directly cause inflexibility, but may mean getting more flexible takes longer. Could also be that your fascia (the connective tissues) is tight and limiting your range of movement.
"Pilates classes regularly for 15 years" sounds a lot, but if this is 1 hour / week it may just be not enough when you have many hours of "shortening" activities
When I started doing Pilates twice a week I could just touch my ankles (with knees straight, obviously) and after a year I could touch my toes. Now, another 2 1/2 years later doing Ashtanga 5-6 times a week, I can put my hands flat on the floor. Progress is slow
(and yes, I too can get a little envious when someone shows the same progress in mere months...)