Here's some information I have collected on 180, 160 and 140mm lightweight disc brake rotors:
| Disc brake rotor weights | Weight-180mm (g) | Weight-160mm (g) | Weight-140mm (g) | Rotor Thickness (mm) | Min Rotor Thickness (mm) | Material |
|---|---|---|---|---|---|---|
| Innolite | 48 | Aluminium | ||||
| Scrub Components Raceday | 50 | 39 | Metal matrix / magnesium carrier | |||
| Carver Titanium | 55 | 45 | Titanium | |||
| Scrub Components Workhorse | 63 | 56 | 41 | Metal matrix | ||
| NoTubes Coated Aluminium Rotor | 57 | Aluminium | ||||
| Ashima Ai2 | 66 | Stainless Steel | ||||
| Ceradure | 85 | 72 | 59 | Ceramic coated aluminium | ||
| KCNC Razor | 95 | 74 | 62 | Stainless Steel | ||
| Gatorbrake Crown | 76 | Steel/Ti Coated | ||||
| Alligator Aries | 102 | 76 | Stainless Steel, Titanium Nitride coating | |||
| Alligator Serration/Alligator Windcutter | 104 | 79 | 60.5 | Stainless Steel | ||
| Hygia | 80 | 1.8 | 1.5 | Stainless Steel | ||
| Hope Race X2 | 80 | 65 | Steel / Aluminium carrier | |||
| Ashima AiRotor ARO-08 | 112 | 85 | 68 | 2.0 | 1.7 | Stainless Steel |
| R1 Formula rotor | 87 | Stainless Steel | ||||
| Hope Tech X2 | 153 | 88 | 74 | Steel/Aluminium carrier | ||
| Formula R1 | 89 | Stainless Steel | ||||
| A2Z Teppan Yaki SP5 | 89 | Steel / Aluminium carrier | ||||
| SRAM/Avid HS1 (2012) | 134 | 92 | 76 | Stainless Steel | ||
| Magura Storm SL (2012) | 122 | 95 | 75 | Stainless Steel | ||
| SRAM/Avid XX | 133 | 96 | 87 | 1.9 | Stainless Steel | |
| Carbon Ti | 98 | Steel/Carbon carrier | ||||
| Alligator Starlite | 128 | 98 | 78 | Stainless Steel | ||
| SRAM/Avid XX HSX (2012) | 126 | 98 | 88 | 1.9 | Steel / Aluminium carrier | |
| Avid G3 Cleansweep | 102 | Stainless Steel | ||||
| Magura Marta SL | 105 | Stainless Steel | ||||
| Hayes floating rotor | 114 | Steel / Aluminium carrier | ||||
| Avid G2 Cleansweep | 114 | Stainless Steel | ||||
| Shimano XT Ice Tech SM-RT86 6 bolt | 114 | SS/Alu Sandwich rotor/Alu carrier | ||||
| 12o'Clock Bikes | 116 | Steel / Aluminium carrier | ||||
| Shimano XT RT75 | 125 | 2.0 | 1.5 | Stainless Steel | ||
| Shimano XT RT76 | 152 | 125 | 6-bolt versions, alu carrier/SS rotor | |||
| Shimano SM-RT51 * | 145 | 2.0 | 1.5 | Stainless Steel |
Note: the Shimano SM-RT51 rotor is obviously not "light-weight" but is included in the table for comparison purposes.
Some thoughts on the Scrub Components Metal Matrix Brake Rotors
The Scrub rotors are extremely expensive compared to other lightweight stainless steel rotors, but they are significantly lighter. However, you must use organic pads with these rotors and at present I don't know of any light weight pads that use a fully organic compound.
As a result the weight advantage from these rotors is offset by having to use heavier pads. For example:
| Rotor | Weight (g) | Brake Pad Weight (g) | Total (g) |
| Scrub Components Workhorse | 56 | 18 | 74 |
| KCNC Razor | 74 | 8 | 82 |
| Weight difference | -18 | +10 | -8 |
Lightweight brake rotor designs
The Hygia, Ashima AiRotor and KCNC Razor rotors, whilst being nice and lightweight, suffer from uneven rotor wear because the amount of material for the brake pads to rub against is different across the surface of the brake track.
To illustrate this point, take a look at the picture below. The two green lines indicate the extremities of the brake track and the red line shows roughly the middle of the brake track. If you follow the red line around you will notice that there is much less metal for the pads to rub against at this part of the rotor. This means, the metal that is there receives much more wear and so the rotor wears unevenly across the braking surface.
