Dished chainwheel - is it normal?

[twosheds]

I have just been cleaning and reassembling my 1950's BSA double chainwheel, and I noticed that it is dished by about 2mm. See picture below. Has anyone else come across this and is it normal? Should I straighten it out? It does appear to be even all the way round, so it runs true, and the dishing is such that it pushes the chainline towards the frame.
Any comments / advice gratefully received.

 

[Woz]

Re:

If it's true I see no reason to start bashing it with a lump hammer.

Is the off-set to help chainline?

 

[Mike Muz]

Re:

Probably a mix of helping the chainline, and allow for the thickness of the cranks, where they bolt on. If they're the original ones to the crank, that is

Mike

 

[keithglos]

I still remember my surprise when I fitted my first Campagnolo chainset (195 and it ran dead true, after several years of truing every chainwheel I fitted, mainly with the hide face and a large king dick adjustable.

Keith

 

[twosheds]

Re:

Thanks for the comments.
I now think it is dished to help chainline. With the whole lot assembled the chainlines are about 42mm and 49mm for the inner and outer chainrings respectively. I have measured up the Benelux rod changer that goes with this, and I don't think there would be enough adjustment for it to shift onto the outer, if it were any further out.

So I'm pretty sure it is not bent, but shaped for a reason.