Question about machined rims

[headlight]

Can someone explain the what the difference is between "machined" and "non-machined" rims? What are the benefits and/or applications between the two?
Thanks,<br />
Drew

[DaveM]

On a "machined rim", they machine (grind smooth) the braking surface of the rim after it is built into a hoop. This gives a flatter, more even braking surface. I think it also results in a slightly rougher braking surface which will give more powerful braking. If the rims are anodized, the machined area will have the anodizing taken off so it will affect the look of the rim, but provide much better wet weather braking which is worse on anodized surfaces.
There are good high end rims that are not machined, but I think you will generally get better braking from a machined rim.