The current rotor on my '92 GSPD is an aftermarket "floating rotor". Two other bikes of mine also have this rotor and they seem to be great. However, the one on the PD has a lot of FLOAT! It's to the point that it rattles when going down a bumpy road. While at the recent 2026 Super Tech, another attendee relayed that the rivets used to hold that rotor on are made of aluminum and do wear out, allowing for the play I'm experiencing. His recommendation was to replace it before it became dangerous.
My inquiry here is, has anyone tried the Sieberock Big Front Brake Rotor Kit for the R100GSPD? I'm sure replacing the existing one with another of the same would be just fine. But, in doing some research, I came across this kit that increases the rotor diameter to 320mm, thus providing greater braking leverage. In order to accomodate the larger rotor, an adaptor is used to allow the existing caliper the proper clearance it needs. The product description says that replacing the brake line may also be necessary.
Before taking the leap of extra money spent, I thought it would be worthwhile to see if anyone in the club has any advice regarding this kit.
Thanks,
J.T.
• Everything you're saying is true.
> The EBC barrels do eventually loosen and rattle around.
> A larger dial rotor would increase the breaking power.
> Acting on a larger disc would require a mod to the caliper mount.
• I know nothing about the Siebenrock brake kit, but it sounds sort of neat. And I know they make very high quality Airhead accessories. If you buy one, please come back to this thread and post photos.
• I will point out that until you do 2 lower cost steps, whatever brake rotor you choose may not perform to its best. To ensure optimal brake performance...
> Replace the OEM rubber brake hoses with modern brake hoses wrapped with stainless steel mesh. (So called "stainless steel" brake hoses.) Not only are the OEM hoses known to fail, but the OEM rubber hoses can lose up to 15% of the braking pressure created by the master cylinder.
(See this article... https://www.airheads.org/community/parts-is-parts/brake-hose-failure-causes-cures/#post-6217 )
> Replace the brake pads. OEM pads may be older compounds sitting around in dealer warehouses since the 1980's. By buying off-brand pads (like Siebenrock or EBC) you are much more likely to be buying modern compound pads.
Owning an old Airhead is easy.
Keeping an old Airhead running great is the true test.
Wobbly,
Thanks for confirming what others were saying about the worn floating rotors. If I do decide to spend the extra $s, I will be sure to update this post with my opinions about the upgrade. As to the other two points you made, new pads would absolutely be in order for such a modification. Any luckily, I already have a braided SS line on the bike now.
J.T.
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