After having my bike worked on recently at the LBS I noticed that my rear axle lock nuts are arranged so that the smooth/flat sides are contacting the dropouts. To clarify, I'm discussing the lock nuts that go outside the cones, not the axle/track nuts that secure everything to the frame.

I removed the wheel and loosened the lock nuts for the sake of some photos.

[![photo of lock nut, loosened, from the outside showing the smooth side facing out][1]][1]
[![photo of lock nut, loosened, from the inside showing the rough side facing in][2]][2]

From [observing](https://bicycles.stackexchange.com/questions/18651/lock-nuts-on-new-hubs-seem-strangely-tight-but-cant-seem-to-loosen-them-any-a) [photos](https://bicycles.stackexchange.com/questions/56304/purpose-of-locknutsadjustable-nuts-on-sealed-hub-bearings) of other people's [axles](https://bicycles.stackexchange.com/questions/52157/stuck-lock-nut-on-one-side-of-the-axle-cant-push-the-axle-out-from-the-other-s), it seems like the rough/beveled/textured/grooved/serrated edge should face away from the center/wheel and towards the outside/frame. The **opposite** of how mine are installed.

As far as I can tell from my research, this is the common orientation. Rough side faces out, smooth side faces in.

```
             <rough|smooth]             [smooth|rough>

[etc] [frame] [lock nut] [etc. hub stuff] [lock nut] [frame] [etc]
```

The photos I've found all _seem_ to imply the rough side touching the dropouts is the right way to do it, but I can't find any conclusive results for `bike axle nut which way` or `bike axle nut which direction`.

Is that a general rule for axle lock nuts that the rough side should always face the dropouts?


  [1]: https://i.sstatic.net/dbYmjm.png
  [2]: https://i.sstatic.net/D9XA2m.jpg