I grew up w/only Fillis irons available. When I got older, my knees/hips would hurt on long rides. The 'flexible' stirrups were becoming popular, but I though they were too expensive. Got a no name brand for under $40, love them. Have a pair w/black rubber, another w/grey, don't remember the brands. The cheese grater rubbers, I can't stand. The irons w/the twisted outside branch, I hate. I now mainly ride in the stirrups popular w/endurance riders, wide for the foot, front to back, and a thick pad underfoot. No more knee issues.