I have to replace my rear derailleur on my old Trek 1200 road bike. The wheel has an 8 speed cassette. The old derailleur is a Shimano RSX Integrated 8515 and has 10T pulleys. From other posts I have determined that I don't have to find an "8 speed" derailleur. For example, a Simano RD-4500 (9 speed) should work, but I see that 10T pulleys have gone by the wayside. The RD-4500 (and most others) have 11T pulleys. Will an 11T pulley work? I would think that the number of pulley teath would have to be matched with the chain pitch and I would have to find a derailleur with 10T pulleys? But maybe not? Can I use 11T pulleys?