OK... I did the maths on this ages ago on another thread, which is what I just searched for...http://www.retrobike.co.uk/forum/viewto ... light=disc
A brief search elsewhere shows Magura Marta MT8s at just 279g per end, that's everything, hoses, levers, calipers, rotors, the lot.
XTR V's come in (using your figures) at 280g per end before you factor in the cables and the increased rim weight. I included gore cables and used Mavic 717 rims in my calculations as they're available in both disc and non-disc versions.
Using my figures in the thread referenced above, there was 20 grams in it between Magura Martas and a set of XTR V brakes. I'd say that was pretty inconsequential.
My point I guess, is that in reality, decent modern disc brakes are really not much heavier than a good set of V's were. Its another myth that the luddites like to put about to justify not spending money on decent brakes
In my opinion, that just about says it it all. Anyway, you have to ask yourself, who wouldn't put up with, say, a 100 gram weight penalty if the result was a set of brakes that worked predictably and reliably under all riding conditions? But then I don't have a lot of time for all this weight weenie stuff anyway, like where somebody will post a weight for a Kona Hei Hei (or something like that) but that low weight includes a pair of skinny little slick tyres and and bars about 400mm wide. Slicks on a mountain bike, FFS.......
So yes, for a period correct 80's or 90's build then obviously you're going to fit canti or linear pull brakes, but it's just kiddology to claim that it's because they're better. If Magura or Shimano or Hope disc brakes had been around in the late 80's don't you think that mountain bike designers would have been specifying them and that riders would have been crying out for them?
And how many riders on the World XC circuit do you see using these "superior and lighter" rim brakes? Next to none, that's how many.
For DH ? None.
I rode mountain bikes with rim brakes for years (I still sometimes do) and no matter how well set up they were, no matter what the pads and rim materials were, under certain conditions (where they were constantly wet) they were crap compared to any decent disc brake. I have a bike with Magura HS-33 hydraulic rim brakes and they are as well modulated and at least as powerful and sensitive as a good disc brake.........until you're riding a series of very
steep downhill switchbacks covered in long wet grass and the rims are permanently wet from that grass.
If it wasn't for the fast that I could never replicate the iconic Paul Brodie paint job on my '88 Explosif it would have had caliper mounts fitted long ago. Even I can't quite bring myself to do that though....
Anyway - these excessively light (in my opinion) brake discs like those Ashima ones. Again it's weight weenie-ism gone mad. I think maybe something like that is verging on being not fit for purpose - and that weight saving just isn't worth worrying about. It's not going to turn some old fart like me into a trail god overnight. If it could then I'd be sending a bulk order off to Ashima ASAP, 'cos I've always fancied being one of those (a trail god, that is).
This quest for lightness is an understandable thing and I'm sure that at the highest level, where the riders themselves are like human machines tuned to perfection, every few grams saved might make the difference between getting a podium place or not. It's all part of the winning edge thing - like the trails rider Yrjo Vesterinen back in the late 1970's. I remember being amazed (at the SSDT in 1980) how much lighter his Bultaco was than a standard(ish) one like mine. But I wasn't Vesterinen back then any more than I'm Julien Absalon now and 50 grams lighter or heavier (or 500 grams even) won't make a blind bit of difference to my performance (or lack of - whichever fits).
I like nice components on my bikes and I'm pretty fussy about set-up but I like stuff that works and is reliable, 'cos I may be old but I do try
not to ride like an old woman. I enjoy working on bikes but I enjoy riding them more than working on them and good disc brakes are pretty maintenance free.