In this case the scratches came with the bike. It's a personal ride I borrowed for a few rides.
I'd guess shoe wear. I'm a notorious heal rubber and have similar wear on most bikes I ride (not to mention cranks).
I don't follow the second question (longevity) there is no contact between the cranks and frame they just very close. It's just something to keep in mind re. crank shape.
May 2, 2017, 5:59 a.m. - Andrew Major
In this case the scratches came with the bike. It's a personal ride I borrowed for a few rides. I'd guess shoe wear. I'm a notorious heal rubber and have similar wear on most bikes I ride (not to mention cranks). I don't follow the second question (longevity) there is no contact between the cranks and frame they just very close. It's just something to keep in mind re. crank shape.