I have a new bike and old understanding of hub and axle standards. I've found that I have a 15mm x 100mm front axle. Easy enough. In the rear, though, I'm not quite sure what I have. The axle is part of the hub, and appears to measure 9mm in diameter. I removed the QR, covered one end of the axle, and used an old spoke to determine the end-to-end width of the axle. It appears to be exactly 145mm. Is 9mm x 145mm actually a spec or am I missing something? 15x100 front and 9x145 rear? I've never heard of that. Should I not count the overlap of the axle with the open dropouts? I think that would make it 135mm, but I'm wondering because I find no wheelsets in that particular combination, making me think I'm doing something wrong. What am I missing?