Because of the dramatic improvement in performance that can be gained by dropping rotating, unsprung mass from a race bike, I decided to modify my rear brake rotor to reduce some extra weight. Most race organizations allow a modified or aftermarket rear brake rotor. I almost never use the rear brake anyway, so I wasn’t worried if the braking force was reduced a little. The OEM rear brake rotor weighs 1 lb 12.9 oz., my modified rotor weighs only 12.1 oz., so I dropped more than a pound from the rotor. Definitely a substantial difference.
I was able to install the rotor on my bike and go for a quick test around a big parking lot. I was expecting the braking force to be drastically reduced, but actually, it was barely noticeable. I could tell it took a little more pressure to slow the bike, but it was still very easy to slow the bike or lock up the rear wheel. I’m calling that a success. These are available here if you want one for your bike. There is an available core refund if you send me your OEM rotor in good condition.
You can remove another couple ounces of unsprung, rotating weight by changing out the OEM rotor bolts with these titanium rotor bolts at the same time.
Here’s some before and after shots of the modified rotor.