So I have about 400 miles on my SRAM S300 cranks now (17T FW). They have a 48T ring. I'm a fairly strong rider and don't live in the mountains so it hasn't been too much for me, but today I went on a 34 mile ride and the headwind coming home was killer. For the first time I thought about stopping and taking a break but I powered through it. But over the last week my left knee has been getting more sore. I don't think a 48T is doing my 51 year old knees any good so I believe I will get a 46T All City 314 ring.