So you want better brakes on your R100GS??? Why not try something already available from BMW???? Like one of these calipers…. The mounting tab spacing of the R100GS caliper is the same as the left 4 pot Brembo from a R1100xx, K1100xx, R1200C or an early R1150GS (up to 11/2001). I can’t take credit for finding out that this works as there are a few references posted here on ADV Rider about the conversion. The only modification needed is to remove 0.158” off the caliper mounting tabs. This keeps the rotor centered to the caliper. I double checked the measurement and came within a few thousandths of and inch….good enough. One thing that concerned me, was milling that much material would make the tabs too thin. The stock 2 pot Brembo is 0.489” thick The left 4 pot Brembo before milling tabs ( 0.609") Area of material removed (0.158") Thickness of tab after milling (0.451") With 0.158" milled off the mounting tabs, the 4 pot Brembo is 0.038" thinner than the stock 2 pot Brembo. I have 6 calipers, but only one has been modified. I need to double check the fit and centering of caliper to the rotor before having the other five milled. I have a friend w/ a R100GS who is interested in trying the 4 pot caliper, but I'm waiting on an order of Galfer green pads to arrive. So look for more postings once it is installed. The bike will also (if he wants to spend the money) get a stainless line. The five other calipers will be offered here with Galfer green pads and stainless lines.