Digging through my "disc box" I realized I had enough variety to do a Comparo....
The scientific equipment consists solely of this circa 1950 "antique" scale that I stole from my wife about 12 years ago. It was once proudly displayed on our kitchen counter, but she now refuses to accept it back into the house as it has been tainted by Garage Grime.... Good! I need a scale!
Disc #1 (the "control" disc) is a bone-stock (other than the pretty blue smurf paint) 7mm thick, 6 Hole H1/H2 disc.
Weight 6lbs 10oz.
Disc #2 is one of John Aylor's "Moo-dified" EX500 compatible discs.
This Disc has been thinned to 6mm, and is Undrilled. (One could shave another pound off of this by drilling holes and/or thinning to 5.5mm, which IMHO is still safe)
Weight 4lbs 10oz.
Disc #3 is a KH500/KZ 4-hole disc that has been thinned to 5mm and is drilled to a pattern Denco used back in the day..96 holes increasing in size as you move out from the hub.
For those of you who think 5mm is too thin in a single disc application, I would have to strongly disagree.
I had two of these done, and one has now been on the KH750 for well over 10,000 miles with zero problems... (warping, etc)
This particular disc is going on my current 4/5 hybrid project.
Weight 4lbs 7oz.
Disc#4 is standard thickness (7mm) H1/H2 disc with 48 large holes drilled
Weight 5lbs 14oz.
Disc #5 is a "Hyperlite" Roadrace disc correct for KH500 and KZ 4-hole wheel. Disc has an aluminum carrier with bolt-on rotor.
I had this disc fitted on the KH750 for a year or so with EX500 caliper, but it warped due to it being too thin (4mm) for use in single application. Hindsight being 20/20, I should have used it as a dual set-up as I have (er, had) 2 of them...
Weight 3lbs 14oz.
Disc #6 is also a "Hyperlite" Roadrace disc correct for the H1/H2 6-hole wheel. It too is 4mm thick. (I also have 2 of these... just waiting for a bike to use them on
)Weight 3lbs 12oz.
So, in a nutshell, by thinning a standard disc to 5mm and drilling holes similar to Disc #3 (96 hole Denco Pattern), you can shave about 2lbs 3oz from stock.
John's "moo-dified" disc if drilled and thinned even further to 5.5mm, which I think would still be fine, could get you easily into "Hyperlite" territory, without having to worry about warpage in a single disc application. Couple that together with a slightly lighter caliper (EX500), and you have a pretty sweet front brake.....
The End.
