1 K100 big brakes Wed Dec 01, 2021 7:39 pm
arbalest
Silver member
I have 76 BMW R90/6 sidecar rig. It has the pitifully inadequate single ATE caliper and 260mm disc. An inmate of the ADVRider airhead forum (Matt Fish) has come up with a design to modify the lower leg caliper mount to accept a radial Brembo caliper, and disc adapter to mount Ducati 320mm discs. A left side lower leg is easily modified for use as a right side lower, allowing for dual 320mm discs with radial calipers. A braking system orders of magnitude better than the stock ATE brake. I have purchased the parts from him for a single 320mm disc and caliper. I also have a K100 front end that I am looking to do something with. My K100 front end already had larger discs and dual non radial 6 pot ISR calipers. The calipers and adapters are long gone, so I asked Matt (R90X Designs) if he had adapters to use radial calipers and larger discs on the K100 forks. Here is his reply:
I’m very close to that. The K100 uses similar components in braking to the later airheads. The fork spacing is different, so shims would probably be required. I already have adapters to fit 320 discs to OEM calipers, going to radials would not be to difficult, although the small front wheel could require removing the calipers to mount.
It works with the mono shock airheads using a K1100 style axial 4 pot. https://www.instagram.com/p/CPGkrKPBJal/?utm_medium=copy_link
Basically the forks are just turned around K100 lowers. A spacer under the hub adapter is probably all that would be needed to make this work.
I’d have to make some calculations based on measurements to nail down the offset.
The main reason I haven’t made a radial caliper set up for the mono shock airheads is lack of interest. Owners have a perception that the brakes are good enough on these bikes. I’ve only sold a hand full of adapters. The radial set up would be expensive to make at first. Do you think there is much interest in the K bike community to upgrade the calipers?
I think big discs and calipers would be really nice on these bikes. If I had one, that’s the first mod I would make.
Thanks
Matt
Matthew Cooper
R90X Designs
www.r90xdesigns.com
2835 Franklin Street
Bellingham, WA 98225
Is there any interest in big brakes and 320mm discs for K bikes?
I’m very close to that. The K100 uses similar components in braking to the later airheads. The fork spacing is different, so shims would probably be required. I already have adapters to fit 320 discs to OEM calipers, going to radials would not be to difficult, although the small front wheel could require removing the calipers to mount.
It works with the mono shock airheads using a K1100 style axial 4 pot. https://www.instagram.com/p/CPGkrKPBJal/?utm_medium=copy_link
Basically the forks are just turned around K100 lowers. A spacer under the hub adapter is probably all that would be needed to make this work.
I’d have to make some calculations based on measurements to nail down the offset.
The main reason I haven’t made a radial caliper set up for the mono shock airheads is lack of interest. Owners have a perception that the brakes are good enough on these bikes. I’ve only sold a hand full of adapters. The radial set up would be expensive to make at first. Do you think there is much interest in the K bike community to upgrade the calipers?
I think big discs and calipers would be really nice on these bikes. If I had one, that’s the first mod I would make.
Thanks
Matt
Matthew Cooper
R90X Designs
www.r90xdesigns.com
2835 Franklin Street
Bellingham, WA 98225
Is there any interest in big brakes and 320mm discs for K bikes?