In short the lower caliper is operated by the front brakel ever (via reducing valve te lower the pressure) which pulls the rear end towards the grounds.
The top caliper functions as a normal rear brake.
Advantages according to me and the website: rear end is more stable during braking, more rear tire traction during braking so possibly you can brake later then usaul?
But the front end will likely raise up a little during braking?
Other disadvantage is that it adds more unsprung (correct word?) weight which is worser for turns ans steering the bike.
The top caliper in this configuration pushes the rear end up so maybe in a corner you could possibly steer faster in or have a higher corner speed entry.
But this will put less pressure on the tire so lesser traction => more dangerous for highsider loss of traction?
You could remove the standard braking config and only use the lower calipers config to reduce the extra unsprung weight but then you would lose the abilty to resteer in a corner?
Did some more research and this caliper doenst really serve as a brake, it can rotate in relation with the disc rotor so most of the brake force is transferred towards the swingarm/frame which will be forced towards the ground.
Looks something that could work to me.
But you will lose the rear brake as 'slowing the rear wheel down', altho it will slow down it a bit but not as much compared to a normal rear brake setup.
A lot of what was said in the first post was false. Where the caliper is does not effect squat or anti squat of the bike.
Braking with the rear prior to application of the front can squat the rear, but wont "pull the front up". It may limit sudden chassis dive though.
Rear brake application can stead the chassis if used to a point the rear isnt locked up. When the weight is almost nothing on the rear wheel though, it is easy to lock up. NOt being able to modulate it independently since it is tied with the front means you can exactly control if it is locked or not, without letting off the front brake as well. Shit idea in that sense.
I have no idea what you mean by "lose the ability to resteer in corner"
Unsprung weight negatively effects suspension action. it wont really effect the change of direction being a caliper though, as apposed to rotational mass like a wheel or brake rotor. Rotational mass and its inertia have an exponential effect.
But the disadvantge of this system are more unsprung wait (perhaps) and locking up the rear wheel when it loses traction (wheel in the air).
When you brake hard and the rear wheel loses its traction then you will force the swingarm to maximum positon, then the caliper will stops the rear wheel from sprinning since it no longer force the swingarm towards the ground.
The rear wheel stops and the swingarm slightly goes in (negative springtravel).
When you no longer brake the rear wheel can spin again and the swingarm should be able to move again.
Could this be dangerous in the track, how about the forces you will force on the reaction bars,swingarm and frame?
Bad idea - on the track you really want to be able to control the brakes independently. You say it doesn't brake the wheel at first because the caliper moves? Even if that worked, it has what, a quarter revolution of the wheel at most? That's 1½' of riding distance or so.
Especially Honda has made bikes with linked front and rear brakes but they are for street use. Everyone who raced those few sport bikes made with that redid the system to be independent.
The few race bikes you do see with an extra caliper in the rear have a separate thumb lever complete with its own master cylinder, NOT linked to the front brakes. It's typically used by racers with limited use of their right foot (the first modern thumb brake was developed for Mick Doohan IIRC - after he destroyed his ankle) or ones that are heavy on the rear brake (the foot pedal can be hard to reach in right turns. And even then they usually just substitute the foot control all together to save weight.
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BTW, the reason you don't want them linked on the track is that when you do brake hard, you unload the rear wheel which will then lock up if the brakes are linked. If you don't unload it, you aren't braking hard. FWIW, the gyroscoping effect of the spinning rear wheel plays a large part in keeping the bike stable - if you lock it you lose that.
I dont think that the rear caliper will lock up the tire while it still moves or has traction of the pavement (there is a pressure regulator that allows how much force is used on the rear brake).
When you do brake so hard that the rear wheel is off the ground, then it the tire will lock up.
But even then the tire can still move (back and forth alittle).
Becaus the rear calipers can rotate in comparison wiht the rear axle and it is linked with the swing arm using traction bars and a pivot point.
So i think even if it stops in the air, the moment the rear wheel touches the ground and when you stop using the front brake it can all move again.
Hopefully Jan Greven could supply me with more info and pics.
I should add that Jan Greven used this bike in wsbk and many european championships back in the 90's and/or early 2000's.
It won't work. And why are you so certain that something that may have worked for one racer a decade and a half ago would be the greatest thing since sliced bread when nobody else uses it? If it was so great, why isn't it used by GP, WSB, etc.?
Perhaps you do not only need the adjust the pressue between front brake and rear brake (lets say that the rear brake uses 10% incomparison with the front brake) but you need to adjust that force (10%) variable in relation with how much force you put on the front brake or how far the suspension dives.
Id say for the AVERAGE rider on the street, a linked brake system may work ok. But not some fancy dual brake setup being needed. There are ways to preserve the rear brake pedal and link it to the front still.
but for racing, or high level track riding, linked brakes on a bike is a bad idea.
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