Take a look at this site,maybe it helps
http://userportal.iha.dk/~20033774/THE- ... _setup.htm
from me i can only add that you can ask your local CNC shop to make a copy of the Formula discs but with centerlock fitting so you can use DT SWISS Hugi240 Centerlock(which is lighter then 6-bolts)with Dt swiss Aero light spokes and x717 rims.Plus don't forget about price, marta's is ok but they cost around 550 euro when XTR list price is 240 plus 60 for XT levers-about 250 euro cheaper.
One of the main problems with the new Shimano XTR disc brake is, that it comes
either with the new center lock rotor, that weigh 139g a piece including the
lockring, or with the XT 6-bolt rotor, that weigh 126grams without bolts (16g).
Futhermore you have to buy the XTR shift/brake unit.
To our luck, the XT disc brake lever (BLM-756) is compatible with the XTR
calibers, so by using this, you can also use the brake with SRAM products or the
old Shimano rapidfire shifters. But still one of the main problems for weight-
weenies with this brake is, that the weight is somewhat more that both the
Formula B4sl or the Magura Marta brake.
Hopefully there is a solution to this, because all parts of the XTR disc brake are
available seperately. By using a front disc brake caliber on the rear, you can use a
140mm rotor, and save some weight. I have used the Formula B4sl rotors, which
is among the lightest steel rotors on the marked. The front 160mm rotor weigh in
at 110g and the rear 140mm rotor 87g. By using aluminium bolts at the rotors,
there is alone on the rotors saved 75g compared to Shimano XT rotors with steel
bolts. Then by using M6x15 aluminium bolts on the calibers and on the levers,
there is another 20g saved. And finally a front caliber is 2g lighter than a rear caliber.
So by using this setup you can save 97g and still have the same brake power as
with the original parts.
All the specified weights can be found under the part pictures pages.
Here is the rundown:
Regular setup
Weight (g)
Shimano XTR calibers 186
Caliber bolts (4pcs. M6x15 steel) 22
Shimano XT 6-bolt rotors (160mm/160mm) 252
Rotor bolts (12pcs. M5x10 steel) 32
Front cable with bolt and fittings (70cm) 30
Rear cable with bolt and fittings (125mm) 43
Shimano XT levers with 2pcs. M6x15 steel bolts 246
Total 811
Lightweight setup
Weight (g)
Shimano XTR calibers 184
Caliber bolts (4pcs. M6x15 Al) 6
Formula B4sl rotors (160mm/140mm) 197
Rotor bolts (12pcs. M5x10 Al) 12
Front cable with bolt and fittings (70cm) 30
Rear cable with bolt and fittings (125cm) 43
Shimano XT levers with 2pcs. M6x15 Al bolts 242
Total 714