Why offset the rear rim to the hub and not the hub in the frame? I'm currently reading The Bicycle Wheel by Jobst Brandt, and I'm reading all of the issues with offsetting the rear rim toward the drive side of the hub...


  Asymmetry in a rear wheel built for a multispeed gear cluster makes it weaker
  against side loads coming from the right side. This means that the wheel bends
  to the left more easily than the right. The greater the offset, the weaker the
  wheel. In order to reduce offset for six-, seven- and eight-speed clusters, hubs
  have been built with narrower flange spacing. Although they reduce the
  disparity in tension between left-side and right-side spokes, they weaken the
  wheel against lateral forces.


So, I'm curious, why is it the standard to do so? Why not center the rim to the hub just like the front, and then offset the frame's drive side rear triangle to accomodate the difference? It may shift the chain line a bit, but this doesn't seem like anything that challenging to adjust for. The strength and durability benefits are huge, and the only downside I can see is that you couldn't arbitrarily change rear hub widths (not that it seems they change that often anyway), or you may have to introduce the offset again. Why don't bicycle manufacturers start doing this instead? Do they make frames that you can use a rear wheel built with the rim centered on the rear hub?

Rear Wheel Offset -->
The biggest functional reason actually would be chain line. 

You could make the hub shell wider, and run an offset dropout to allow the space for the gears, but then you would have to run a similar offset on the bottom bracket to maintain a usable chain line.

Running the offset on the bottom bracket would affect Q factor positioning on many riders, and while some riders like or need additional stance width, most do not.

Because a change like this requires such a radical redesign of pretty much every bicycle component, it would require a consensus from the entire range of bike manufacturers to be put into practical or wide spread use.

So you could call it tradition, but I think momentum would be more accurate. The existing body of design work would need to radically change to accommodate something like this, and that is a lot of "mass" to shift. 

Since existing wheel structures and designs are working for riders as is, most companies choose to stay within the range of difference that allows the bike frame and other component designs to be affected as little as possible.

After all, there is no guarantee that an offset design would work in practice, and the benefit to it isn't major, given that existing designs work.