Originally Posted by
mkeller234
It's just a guess, but maybe the manufacturers make the rails short to cut down on weight. Not saying that's a smart way to reduce weight.
Shimano removed barrel adjusters from the Deore XT derailleurs because of weight, now that is stupid!
I think the overall rail length would be quite similar (and hence the weight) since the saddle is not getting any longer, what would change is the shape of the rails. There are about 3.5 inches of rail
on the Berthoud in the front that are tucked in and not usable.