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Discussion Starter #1
The older 600 and 750SS had a single brakedisc. Has anyone changed from twin discs to a single disc on a 900SS to save weight? I guess you could save about 2,5 kilograms of unsprung weight, and that´s magic for the handling of the bike.
 

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The older 600 and 750SS had a single brakedisc. Has anyone changed from twin discs to a single disc on a 900SS to save weight? I guess you could save about 2,5 kilograms of unsprung weight, and that´s magic for the handling of the bike.
I've thought about this too, but you'd have to make sure you changed the master cylinder I think also. The effort would be different unless you changed the master too. If you could find a 6 piston caliper to use, then you can have 1 disc I think. The front brakes on our bikes are extremely powerful. I locked up the front and crashed once. I wonder if I really need all that braking power up front.
 

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A motorcycle is a short wheelbase, high center-of-gravity machine, which exacerbates weight transfer during deceleration. These facts suggest that the rear of the bike will effectively "unload" during heavy braking, to the point that the rear wheel will be airborne. Obviously the front brake is where you want all the power to stop the machine, which is why front brakes are so much larger/more powerful than the rears. Roadracers want as much power on the front brakes as possible, using the rears only to initiate a rear slide into a turn or to settle the chassis on initial application.

The base model Ducatis (and others) try to hit lower price points by deleting equipment, like brakes, especially on relatively low-powered machines, like the 600 twins. If you have a larger/faster bike, however, you wouldn't want to go this route, as you will have fading brakes under repeated fast stops. After all, the brakes convert kinetic energy into heat and with just one rotor to do the job it will overheat.

If you really want to lower unsprung mass, change to lightweight wheels, like forged aluminum, magnesium or carbon fiber, depending on your budget, or pursue composite brake rotors that are on the market (for a princely sum). Are you even sure the rotors you have now even have aluminum carriers? Many Ducatis used steel carriers painted gold.
 

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A motorcycle is a short wheelbase, high center-of-gravity machine, which exacerbates weight transfer during deceleration. These facts suggest that the rear of the bike will effectively "unload" during heavy braking, to the point that the rear wheel will be airborne. Obviously the front brake is where you want all the power to stop the machine, which is why front brakes are so much larger/more powerful than the rears. Roadracers want as much power on the front brakes as possible, using the rears only to initiate a rear slide into a turn or to settle the chassis on initial application.

The base model Ducatis (and others) try to hit lower price points by deleting equipment, like brakes, especially on relatively low-powered machines, like the 600 twins. If you have a larger/faster bike, however, you wouldn't want to go this route, as you will have fading brakes under repeated fast stops. After all, the brakes convert kinetic energy into heat and with just one rotor to do the job it will overheat.

If you really want to lower unsprung mass, change to lightweight wheels, like forged aluminum, magnesium or carbon fiber, depending on your budget, or pursue composite brake rotors that are on the market (for a princely sum). Are you even sure the rotors you have now even have aluminum carriers? Many Ducatis used steel carriers painted gold.
If I could afford BST wheels, I'd have them... This is a poor man's way to get a little better performance out of the bike. In my opinion, my bike has too much front brake. It's far too easy to lock up the front, particularly going downhill. I don't want to have to think hard in an emergency either. I don't want to have to think "don't grab a fist full of front brake" because I don't have time to think in such a situation. I don't go fast enough on the street either to warrant huge brakes on the front. Who knows, if I had less front brake, I might have avoided a crash last year.

Yes, the front discs are all steel. If the discs didn't cost over $300 each for aluminum ones, I'd have them too.

The front brakes on my bike remind me of the first generation of power assisted brakes on cars from the 1970's. It took very little effort to apply a whole lot of braking force back then. It was hard to modulate the brakes as a result. I have to be very careful when I apply the front brakes on my bike. I'd rather have confidence that I can apply some pressure without worrying about locking up the front wheel. Of course, I'm not a very experienced rider either and I've never done a track day, so those with much more experience may have different needs.
 

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Discussion Starter #5
Of course I know that you loose a little stopping power, but for a roadbike with a weight of 180 kg with full tank it should be OK. When riding on the road, fading is not a problem. The new brakediscs like EBC XC wave has better performance than the original brembo discs and makes up for some of the performance that you loose when changing to single disc.
This is just an idea how to improve the handling of the bike, so all input that says this is a good idea or the worst idea you´ve ever heard is welcome:)
 

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Chilehead
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When riding on the road, fading is not a problem.
Perhaps not in Sweden (and yes, I've driven there), but here it certainly is!

Best way to avoid fading is to use race pads, they get better the hotter they get (I use Ferodo CP911* on my ST2).

The OEM disks on my SS weigh 1.6kg, not 2.5, but you can get lighter steel disks that weigh only 1.3kg, and CMC disks (for lots of money) that weigh half that.

Tom
 

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We've done a few single rotor conversions on 2V twins. You lose very little if any stopping power--and actually increase stopping power and feel if you upgrade the rotor, pads and master cylinder. You can really improve stoping power with a new 4 pad caliper if it is in your budget.

What you lose is the ability to absorb energy (heat) for heavy track riding- because the 2nd rotor acts like a heat sink. If it is not set up correctly you can get brake fade a lot earlier. The single rotor is never a problem for normal street or canyon riding.

If you go to a single rotor, get a 5.5mm or thicker rotor with floating buttons. All high end rotors have aluminum carriers. Add a good a good quality pad like the Ferodo, or Carbone Loarraine with ceramic coated backs. Install a 19x18 GP radial master cylinder and use good fluid like Brembo or Motul 600. Change/flush the fluid often.

-M
 

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We've done a few single rotor conversions on 2V twins. You lose very little if any stopping power--and actually increase stopping power and feel if you upgrade the rotor, pads and master cylinder. You can really improve stoping power with a new 4 pad caliper if it is in your budget.

What you lose is the ability to absorb energy (heat) for heavy track riding- because the 2nd rotor acts like a heat sink. If it is not set up correctly you can get brake fade a lot earlier. The single rotor is never a problem for normal street or canyon riding.

If you go to a single rotor, get a 5.5mm or thicker rotor with floating buttons. All high end rotors have aluminum carriers. Add a good a good quality pad like the Ferodo, or Carbone Loarraine with ceramic coated backs. Install a 19x18 GP radial master cylinder and use good fluid like Brembo or Motul 600. Change/flush the fluid often.

-M
Cool! wonderful! thanks for the support! As soon as I get some money together, I'll place an order with you guys.
 

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You might safe some weight with the single disk, however i do not think you will reduce the change of locking up your front wheel by going to 1 brake.
With a proper braking technique you can lift the rear wheel of the ground no problem, however if you grab a ton of braking at once (instead of letting the weight movement occur before really aplying brake pressure) you will lock up the front even if you only have one disk.
If you're going for lighter steering this might help, however if fear of locking up the front is your main motivation I think you're better of building some braking skills.
 

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If I could afford BST wheels, I'd have them... This is a poor man's way to get a little better performance out of the bike. In my opinion, my bike has too much front brake. It's far too easy to lock up the front, particularly going downhill. I don't want to have to think hard in an emergency either. I don't want to have to think "don't grab a fist full of front brake" because I don't have time to think in such a situation. I don't go fast enough on the street either to warrant huge brakes on the front. Who knows, if I had less front brake, I might have avoided a crash last year.

Yes, the front discs are all steel. If the discs didn't cost over $300 each for aluminum ones, I'd have them too.

The front brakes on my bike remind me of the first generation of power assisted brakes on cars from the 1970's. It took very little effort to apply a whole lot of braking force back then. It was hard to modulate the brakes as a result. I have to be very careful when I apply the front brakes on my bike. I'd rather have confidence that I can apply some pressure without worrying about locking up the front wheel. Of course, I'm not a very experienced rider either and I've never done a track day, so those with much more experience may have different needs.
Dirkwright,

I'm with the other poster who recommended you learn how to brake on a motorcycle, not reduce the bike's capability to stop. The front brakes are your friend, but not when you try to stop on loose surfaces, like gravel, with normal street tires. Getting the front tire to skid on a dry, paved surface takes a very strong pull on the front brake lever indeed. A track day could cure your apprehension as you can brake very hard on a straight section of track with no negative consequences. In fact, you could try using your rear brake only, fronts only and then both front/rear. With over forty years riding motorcycles, including three years roadracing, I use the fronts almost exclusively; the rear I only use for holding the bike from rolling when stopped.
 

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In my opinion, my bike has too much front brake. It's far too easy to lock up the front, particularly going downhill.
what kind of calipers and what size of master
cylinder do you have ?
what kind of brake pads do you run ?


... Install a 19x18 GP radial master cylinder...

that is a crazy suggestion, to run a 19mm master
cylinder with one calipper that has four 34mm
pistons.
that would result in a calipper to master surface
ratio of 12.8 : 1.

without having experienced that, i'd like to call
that non-rideable.

stock 1098 configuration in example goes with
a 18mm radial master and two P4 34 calippers
to end up with a ratio of 28.5:1

---

stock 30/32mm calippers have got a surface of
3022mm² each, to use one of them, a 13mm
master cylinder is a "good" choice, that will keep
the ratio at 22 : 1

stock ratio with two 30/32mm calippers and the
stock 16mm master is at 30 : 1 by the way.
 

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Dirkwright,

I'm with the other poster who recommended you learn how to brake on a motorcycle, not reduce the bike's capability to stop. The front brakes are your friend, but not when you try to stop on loose surfaces, like gravel, with normal street tires. Getting the front tire to skid on a dry, paved surface takes a very strong pull on the front brake lever indeed. A track day could cure your apprehension as you can brake very hard on a straight section of track with no negative consequences. In fact, you could try using your rear brake only, fronts only and then both front/rear. With over forty years riding motorcycles, including three years roadracing, I use the fronts almost exclusively; the rear I only use for holding the bike from rolling when stopped.
Thanks. I wish I could afford a track day. I can tell you that I can lock up the front of my bike very easily, particularly when going down hill. I did it in my dry paved driveway several times. It's scary as hell for me to lock up the front. I try to go to a parking lot to practice my emergency braking when ever I get the chance.
 

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You might safe some weight with the single disk, however i do not think you will reduce the change of locking up your front wheel by going to 1 brake.
With a proper braking technique you can lift the rear wheel of the ground no problem, however if you grab a ton of braking at once (instead of letting the weight movement occur before really aplying brake pressure) you will lock up the front even if you only have one disk.
If you're going for lighter steering this might help, however if fear of locking up the front is your main motivation I think you're better of building some braking skills.
Well, obviously I need to practice more on my braking. Lighter weight is always good, as far as I know.
 

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Mr Leakered
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Just thinking out loud. If you've practiced e-stops like you say, then it sounds to me that your front tire might be a bigger problem than the brakes.

I used to be able to lock the front tire on my old bike before the rear would come up. It just happened to be with the Dunlop D208s I was running. New Michelins changed all that was well as having a lot more capability in corners.

Just something to think about.

One more thing to consider. For a newer rider, weight equals stability to a certain extent. Having low unsprung weights that allows quick direction changes can mean that you might be point in a direction you don't want to go quickly.

Have a good one.
 

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stock 30/32mm calippers have got a surface of
3022mm² each, to use one of them, a 13mm
master cylinder is a "good" choice, that will keep
the ratio at 22 : 1

stock ratio with two 30/32mm calippers and the
stock 16mm master is at 30 : 1 by the way.
The 750 Sport had one front disc, and uses a different master cylinder than the twin disc 750 Supersport. I suppose I could just use the master cylinder from the 750 Sport. I don't know any details about it.
 

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Just thinking out loud. If you've practiced e-stops like you say, then it sounds to me that your front tire might be a bigger problem than the brakes.

I used to be able to lock the front tire on my old bike before the rear would come up. It just happened to be with the Dunlop D208s I was running. New Michelins changed all that was well as having a lot more capability in corners.

Just something to think about.

One more thing to consider. For a newer rider, weight equals stability to a certain extent. Having low unsprung weights that allows quick direction changes can mean that you might be point in a direction you don't want to go quickly.

Have a good one.
Well, the tires were not warmed up at the time. Maybe that had something to do with it. They are Dunlop Qualifiers, which are very good tires as far as I know.
 

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Thanks. I wish I could afford a track day. I can tell you that I can lock up the front of my bike very easily, particularly when going down hill. I did it in my dry paved driveway several times. It's scary as hell for me to lock up the front. I try to go to a parking lot to practice my emergency braking when ever I get the chance.
This is an interesting topic as it discusses something I've heard before from my bicycle and motorcycle riding buddies - the use of the front brake on a two-wheeler. Fact is, the front brake is what you need to use to stop quickly, not the rear. On a bicycle, where the rider's weight is far greater than the machine, the rider has to pay attention when braking hard, and on a mountain bike, where you are not "in the handlebar drops" like a road bike, you have to shift your body weight rearward to prevent going over the bars on some steep downhill stops.
In my view a motorcycle is easier than a "push bike" to stop, as the body weight shifts are not so necessary. But both vehicles, versus a car/truck, require that the rider pay full attention to his/her surroundings, like the condition of the road surface. Your eyes must constantly be surveying the road, to choose the best line of travel. If you are not willing to be that attentive, maybe a motorcycle is the wrong vehicle for you.
 

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This is an interesting topic as it discusses something I've heard before from my bicycle and motorcycle riding buddies - the use of the front brake on a two-wheeler. Fact is, the front brake is what you need to use to stop quickly, not the rear. On a bicycle, where the rider's weight is far greater than the machine, the rider has to pay attention when braking hard, and on a mountain bike, where you are not "in the handlebar drops" like a road bike, you have to shift your body weight rearward to prevent going over the bars on some steep downhill stops.
In my view a motorcycle is easier than a "push bike" to stop, as the body weight shifts are not so necessary. But both vehicles, versus a car/truck, require that the rider pay full attention to his/her surroundings, like the condition of the road surface. Your eyes must constantly be surveying the road, to choose the best line of travel. If you are not willing to be that attentive, maybe a motorcycle is the wrong vehicle for you.
Oh, of course, I agree. I remember when I took the MSF, they were amazed at how quickly I could stop during the emergency braking drill/test. It was like ~boom~ I'm stopped. My mistake was not practicing this same test on my bike... I was shocked when I finally did it, at how easy it was to lock up the front and to loose control. I use the rear brake, but not nearly as much as the front. I also use it mostly for slow speed control and for holding the bike in place at stop lights.
 

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If braking can be just as good with a single disc, then it makes me think that having twin discs on some of these bikes is just a fashion statement.
 
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