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Nothing Special
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Discussion Starter · #1 ·
I've noticed this glaring gorilla in the room when it comes to the rear brakes on most modern sportbikes. Why aren't full floating rear brakes used? I'm not talking about floating disks, I'm talking about full floating brakes.

I've read some comments in various forums about various sportbikes regarding rear wheel hop/chatter under hard braking or late braking. I've yet to hear anyone mention anything about using a full floating rear brake to address wheel hop in this genre of motorcycle ownership.

At first I thought it was some side affect of the modern frame and swingarm designs that negated the need for a full floater in back (I mean, hey, the swingarm in my '03 R6 is TWENTY FOUR INCHES LONG from eye to eye. We'd have killed the pope for a two foot long swingarm when I raced!!!). But then I see pics of modern type extruded frames with monoshock rear suspensions on Muzzy Kawasakis that use full floating rear brakes, so that shot that theory down right away. Seriously, can Rob Muzzy and the likes of Pops (Yoshimura), Sheldon Thuett, and Jerry Cheney be THAT wrong?

Then I thought that maybe since under hard braking the rear wheel isn't really even on the track so perhaps that made the need for a floater unwarranted. Nope, if anything the "near weightless" rear wheel under late braking would benefit even more from a floater.

So I'd love to learn why these wonderful tributes to Britten called modern sportbikes (that we've learned to take for granted!) do not include the use of full floating rear brakes? I mean, why does Yamaha go to the trouble of designing a front wheel bearing carrier that's over five inches wide between bearings (extremely stable setup, taken directly from the racetrack) but they can't see fit to attach a danged brake stay from the caliper to the frame to eliminate 90% of rear wheel chatter under braking? Every sportbike made has a rear suspension "progressive linkage" that is most likely not even needed with today's wonderful shock absorber technology (my guess is that most of the progressive action of modern rear suspensions are just about dialed all the way out since the shocks are so much better today). But yet, you look under any modern sportbike and there the damned thing is!

So we have that bit of eyewash under the bike to keep the squids happy, but something as useful as a full floating rear brake? Why on Earth would we want anything as sensible as that? ;)

Obviously I need to be educated on this, so I'd appreciate any help on the subject.

Thanks for reading.
 

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nom nom nom nom nom nom
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Cost vs benefit


There are some companies that make fully floating rear rotors if you really want one. I'm not really sure what a fully floating rear rotor would have to do with rear wheel chatter. Everything I've ever read on chatter says that it is caused by suspension issues and a combination of downshifting/braking too much which causes a large differences between the speed of the wheel and the ground it is traveling over.
 

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because chances are its more expensive, and most riders have no need for it on the street. hell if you are depending on your rear brake that much on the street you may want to reconsider brushing up the skill which is properly using the front brakes since thats where most your stopping power is.
 

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pin it to win it
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I'm gonna day because most people don't use the rear.
 

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Official Noob Greeter
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yup. and b/c they can't add a ~$200-300 rotor and expect that much more return when it comes to a purchase price. that's just eating into their profit margin.
And its eating into the aftermarket. Would it really cost THAT much more for a company that uses thousands of rotors to make the swap? No. You gotta leave some room for the aftermarket!
 

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Premium Member
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so you think the aftermarket companies "lobby" the oem design to K.I.S.S.?? come on, really? it's a great way to insure yourself a legit living down the road, but how much would that lobbying cost?
 

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track junkie
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Why aren't full floating rear brakes used?
simple. because most track riders never touch the rear brake at all. unless they're either brand new at it or they're toying with the track record. almost every other rider will only use the rear brake if they go off track into the dirt/grass.

s3aturnr
 

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Official Noob Greeter
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so you think the aftermarket companies "lobby" the oem design to K.I.S.S.?? come on, really? it's a great way to insure yourself a legit living down the road, but how much would that lobbying cost?
Not all that much, I would imagine. They are kind of essential, though, as they buy a fcukton of advertising and sponsor people which keeps people buying and modding bikes.
 

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nom nom nom nom nom nom
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And its eating into the aftermarket. Would it really cost THAT much more for a company that uses thousands of rotors to make the swap? No. You gotta leave some room for the aftermarket!
Per unit the cost might be minimal if you bought in bulk from the manufacturer (or if you are the manufacturer). Personally I think the cost would be a LOT more than a standard rotor though. You have 5-10 pieces instead of one, and the additional manufacturing process to assemble it all. That's why front rotors are always much higher than rear rotors. It isn't just the size.

The problem happens when the bean counter sees that he can save $100 per bike with a cheaper rotor, and they are making 25,000 units, bam he just saved the company 2.5 million dollars as long as they keep the retail price the same.

I honestly doubt that the math above was ever done on any mass produced bikes. I'd bet that we don't see them on mass produced bikes because there is little-to-no demand for it. Once one company does it, and it gets a great magazine review, and everyone runs out and buys the latest and greatest, the other companies will follow suit. I just don't see that happening with something like a rear rotor though.
 

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Sherman Connoisseur
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While I love my BrakeTech floating rear, it is one of the item I kind of regret buying. Curse myself for being superficial and wanting my brakes to match :laugh

They do look effing awesome though!
 

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Nothing Special
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Discussion Starter · #15 ·
(WOOPS! Sorry, I somehow unsubscribed from my own thread and then spaced the fact that I authored it. My bad for letting it go unattended ... )

Ok, after reading everyone's replies, it seems that everyone has totally missed what a "full floating rear brake" is. As I said in my opening post, I am NOT talking about some floating ROTOR. A full floating rear brake is composed of a floating caliper mount that has a bearing or bushing in it where the axle feeds through. The caliper mount freely swings on the rear axle even after the rear wheelset has been torqued down, with it's caliper stay connected to the FRAME and not the swingarm. A full floating rear brake caliper is highly instrumental in reducing rear wheel chatter and hop, to about 90% reduction last time I heard the engineers rattle on about it.

Scott Russell used one (as did nearly every Rob Muzzy prepared Kawasaki I've ever seen), nearly every bike that Pops Yoshimura prepared himself was outfitted with one (Wes Cooley, and the like). These are just a few examples of many many "famous" (read successful) racers that have used full floating rear brakes. (Keep in mind the phrase "rear brakes" includes the braking system, not just the rotors). You just have to know what to look for, the caliper stay MUST be attached to the frame, not the swingarm.

If you are unfamiliar with them, you may wish to look into what makes them work so well. And I'd remind those that insist that the rear brake "isn't used" .... you are giving up at least a 10% braking advantage by not using it.

When you combine the binding forces of heavy downshifting with even just a little rear brake hop, you already know what happens. If all you are doing is relying on your slipper to slow down the rear end, you're riding lazily (race track of course). Assist that slipper, smooth out the approach, keep that rear tire on the ground as soon as possible to be able to transition the weight shift (front to rear) as soon as possible to get back on the throttle as soon as possible. Again, just an old school flattracker's approach to doing it. I've always used everything available to me to outbrake the guy next to me. Front AND rear brakes, engine deceleration, a garden rake dragging behind me (joking of course) whatever ...

The full floating rear brake setup prevents the rear suspension from binding up during rear braking. If you are using engine braking as well the rear end hop is magnified ten fold due to the large increase in suspension binding forces caused from the engine being involved in the braking process. If the caliper is free to float without binding up the rear suspension rear wheel hop and chatter is reduced greatly. For this to work properly the rear brake caliper must be mounted on a free floating caliper mount that is allowed to freely swing on the rear axle. The caliper stay MUST be attached to the frame (not the swingarm) for the floating effect to work at all. The mount requires a spacer (so the axle may be fully torqued down), a bearing that fits around that spacer (so the caliper mount can freely swing around the axle even when it is fully torqued) and a caliper mount that fits around the bearing. So an inner spacer, a bearing/bushing, a caliper mount that pivots on the bearing axle spacer, and a caliper stay that connects to the bike's frame. This configuration permits the rear suspension to freely operate (at about 90% of it's normal compliance) under any braking situation no matter how extreme, including engine braking (when used with the rear brakes).

I guess that's the advantage of racing dirttrack prior to road racing .... we learn to use the entire motorcycle and we remember that there is a bike behind our eyes. I think some folks get this "video game syndrome" going on where they only perceive what is in front of them (y'know, computer screen eyes, all you see is what's directly in front of you). I think that the rear of the bike is taken for granted sometimes. Just sayin. y'know?

Whatever makes it work. Everyone has their own way of doing things I suppose. :) See pics.
 

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Make good choices.
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I have no idea the answer to your question, but this is my observation: All those bikes you posted pictures of are antiques. We know that in MGP and WSBK money and engineering is no object, so if they wanted floating rear brake set up they would have them. They must have figured out a new way to solve the problem that floating rear brakes previously solved. You're gonna have to ask your question to a modern motorcycle engineer. We don't have any of those on this forum.
 

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Reads the rulez
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I got $20 that says Barny is, or is directed related to, Shervin.
 

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Meh
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If you are unfamiliar with them, you may wish to look into what makes them work so well. And I'd remind those that insist that the rear brake "isn't used" .... you are giving up at least a 10% braking advantage by not using it.
I am highly skeptical of this statement. I don't know any racers that use the rear brake at all for the purpose of setting entry speed on the asphalt. I know a very small amount of guys that will occasionally use it mid corner to correct things if they're running wide.

Actually, I take that back. Jason Pridmore says he uses it sometimes when he's giving 2-up rides, because there's enough weight on the back of the bike to make it do something. :laugh

If you can lift the rear wheel off the ground with the front brake, or already have the rear getting sideways with front + clutch release, how is the rear brake going to get you 10% more deceleration? The physics just doesn't work.
 
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