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Discussion Starter · #1 ·
I was looking at my friend's Triumph 675, and noticed that his front brake lines run from the MC, to the right caliper, then there's another line from there that goes to the left caliper; the stock r6 has 1 line going to the MC, then splits to the left and right caliper; and my Fren tubo is a direct fit so I have 2 lines going from the MC to each caliper. That being said, is there a difference in how the pressure gets distributed and what are the pro's and con's of each.

Thanks.
 

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Is this a segment?
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I've had conversations about these different setups recently and was told that at the upper end of the quality spectrum - there is little difference.
Apparently some bikes on the world circuit run a single line that splits into two - much like the stock R6 routing.
 

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slow guy
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Pressure is equal, it's the simplest form of a hydraulic system. The only thing you gain with 2 separate lines is a little bit more volume in the system.
 

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Discussion Starter · #4 ·
The 1-to-2 design, i understand, but I don't quite understand the thought process, or the reasoning behind how the 675 lines are.
 

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Discussion Starter · #6 ·
K, I thought there would be something more to it.
 

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UR B-hind Da 8 Ball
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K, I thought there would be something more to it.
:yes less brake hose and fewer fittings.....less cost:sing


BTW, it can be a PITA to bleed that type of system (without a vacuum bleeder, anyways) if you get a bubble in the line that goes over the fender.
 

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track junkie
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when i put braided lines on my zx-6r, it went from a stock line that was one line to the right caliper and a line from there to the left. the new lines were equal length and started at the master cylinder.

it is my belief that in the stock set-up i had, it presses the right caliper first, then the left and is slightly uneven in braking force between the two sides. i don't believe that the difference is much at all, tho.

since i'm a little OCD by nature, it made me feel much better to have the equal length lines. i did feel a difference in brake fade and initial pressure, but i don't think i noticed any differences caused by changing from essentially a "series" system to a "parallel" system.

s3aturnr
 

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Riding his own ride...
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If the lines you put on were ss braided then they don't flex like the stock rubber lines. that's what you feel. Even then it's not a huge difference, but there is a difference by going to lines that don't flex. The largest thing people feel with aftermarket lines are the new pads they normally put on and fresh fluid and a good bleed job. Do it all at once though and it's normally a pretty drastic change.
 

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slow guy
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when i put braided lines on my zx-6r, it went from a stock line that was one line to the right caliper and a line from there to the left. the new lines were equal length and started at the master cylinder.

it is my belief that in the stock set-up i had, it presses the right caliper first, then the left and is slightly uneven in braking force between the two sides. i don't believe that the difference is much at all, tho.

since i'm a little OCD by nature, it made me feel much better to have the equal length lines. i did feel a difference in brake fade and initial pressure, but i don't think i noticed any differences caused by changing from essentially a "series" system to a "parallel" system.

s3aturnr

For it to be series the fluid would have to go into the brake caliper and come out on the other side of the piston, which isn't possible being that the pistons are single acting cylinders. So, it was a parallel circuit from the factory where Pressure would be equal to both calipers, brake fluid/hydraulic fluid is basically not compressable(yes I know technically it is but it's so little) The force applied at the master cylinder will be equal everywhere in the system, so both calipers are also equal. This is hydraulics 101. Also being that we don't have proportioning valves anywhere it simplifies it even more so.
 

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Discussion Starter · #12 ·
I think I just found the answer to my question, which is a culmination of what's already been said. Whether right or both calipers are engaged is actually negligible because you only have 1 rotating mass that brakes are acting upon. Its not like in a car where if your right side brake engages before the left it'll pull your car to the right.

And as mentioned before, since the whole hydraulic system is pressurized, any added pressure, caused by the actuation of the brake lever, will be distributed evenly through-out the system.

Given all of that, line's ability to resist expanding from the added pressure, provides for a more linear braking performance, which in turn is what provides for a better feel when braking.

Anything else that I missed??

And here i was earlier thinking those Triumph Brits were a little wonky. :lmao
 

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I eat what my R6 cooks!
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I think I just found the answer to my question, which is a culmination of what's already been said. Whether right or both calipers are engaged is actually negligible because you only have 1 rotating mass that brakes are acting upon. Its not like in a car where if your right side brake engages before the left it'll pull your car to the right.

And as mentioned before, since the whole hydraulic system is pressurized, any added pressure, caused by the actuation of the brake lever, will be distributed evenly through-out the system.

Given all of that, line's ability to resist expanding from the added pressure, provides for a more linear braking performance, which in turn is what provides for a better feel when braking.

Anything else that I missed??

And here i was earlier thinking those Triumph Brits were a little wonky. :lmao
the good to the single that splits is it is a tiny bit lighter, but its so little that i highly doubt anyone would ever notice the difference. also, like others have said, the little bit more fluid in two direct lines will last a tiny bit longer(doesnt matter if you are like me and change the brake fluid often), and be able to remove heat a little faster(again, wont be noticeable).

it is my belief that in the stock set-up i had, it presses the right caliper first, then the left and is slightly uneven in braking force between the two sides. i don't believe that the difference is much at all, tho.
even if it is grabbing the one side before the other, it would be such a miniscule time frame that it would be impossible to feel. also add in the fact that it doesnt matter if only one side grabs as far as making your bike pull to one side. in fact, look at most dirtbikes and many cruisers. i think every dirtbike i have seen and almost all cruisers only have it on one side(and may be wrong here, but i think even the buells that were in AMA only had a rotor on one side???)
 

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track junkie
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If the lines you put on were ss braided then they don't flex like the stock rubber lines. that's what you feel. Even then it's not a huge difference, but there is a difference by going to lines that don't flex. The largest thing people feel with aftermarket lines are the new pads they normally put on and fresh fluid and a good bleed job. Do it all at once though and it's normally a pretty drastic change.
the good to the single that splits is it is a tiny bit lighter, but its so little that i highly doubt anyone would ever notice the difference. also, like others have said, the little bit more fluid in two direct lines will last a tiny bit longer(doesnt matter if you are like me and change the brake fluid often), and be able to remove heat a little faster(again, wont be noticeable).



even if it is grabbing the one side before the other, it would be such a miniscule time frame that it would be impossible to feel. also add in the fact that it doesnt matter if only one side grabs as far as making your bike pull to one side. in fact, look at most dirtbikes and many cruisers. i think every dirtbike i have seen and almost all cruisers only have it on one side(and may be wrong here, but i think even the buells that were in AMA only had a rotor on one side???)
all of this is exactly what i was trying to say in my percocet-fueled post. i should really hash my thoughts out a little better when i'm on painkillers...


s3aturnr
 

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crashing aint so bad
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The main difference some people will notice when switching from a rubber hose system to a SS braided hose system is hose expansion. The rubber hoses will expand under heavy braking and can make the brakes feel spongy. The SS lines will not expand so the input into the brake lever feels more linear. That said there is not much of a difference between the routing. Or is there?

The largest difference can be made by using different line sizes. The master cylinder is 16mm on most stock sport bikes. As we all know if we get a bigger MC you get more braking power. You can accomplish somewhat the same thing if you use bigger lines and banjo bolts with larger orifices. Using direct lines that do not use Banjo bolts at all is also an improvement. Banjo bolts have small orifices in them that can only flow so much fluid. Direct flow lines will produce better braking power than lines that use Banjo bolts. Another part of fluid dynamics states that if you take a small piston and force fluid into a larger cylinder it will have mechanical advantage and compress more fluid. The opposite occurs when you take a large piston and try to compress it into a small cylinder. In our case with a smaller piston we can force fluid through a larger line and accomplish some more braking power, with a small trade off. The larger lines will increase the amount of lever movement required to create a large braking force. Since there is more fluid to flow and compress in the lines, the brake lever will travel further. The upside is that the increase in fluid compression will increase braking force and feel. This is the primary difference that is probably felt amongst different brands. This is also the only difference that may be noticed between different routing options.

The routing that has the least amount of fluid to compress and flow will have the most direct and linear feel. This is because the fluid is in more direct attachment to the brake lever. The routing option with the largest fluid area and flow will have a spongier and less direct feel. This shouldn't be confused with line size though. Both will have similar effects, but a larger line size with a shorter length will have more braking power than a small line size with a longer length. Since a bike will require at least some standard length of brake line. The direct difference in feel from line size and or routing difference is a direct result of those factors. If you were to keep the same routing and decrease or increase line size you would notice a difference.

We are compressing fluid in the calipers first and the lines second. The calipers have the largest fluid capacity and with the pistons having the largest area for expansion, the compression of fluid will place force there first. Once the pistons are compressed we start working on the amount of force applied into the lines. The larger lines will allow more fluid flow and this allows the MC to compress more fluid into the lines and direct the energy down into the calipers where the pistons are forced out with more force. Since the calipers have the largest area for fluid to be compressed the more fluid we can squeeze in there, the more braking force there will be. The calipers are like a cylinder that we are trying to force a piston down. If we have a small pump on one end, it takes more pumps to get fluid to push the piston down. If we can increase the amount of fluid in each pump we still have mechanical advantage and are moving more fluid into the cylinder area. We can go backwards though too. If we make the lines too big, the pump ( MC ) may not be able to fill the area enough and instead of creating compression throughout the brake stroke we are only pushing the pistons a very little bit. So line size is important for great braking power. Too small and the braking power will be a lot less but have more linear and direct feel. Too large and the lever movement may be too great to produce any real braking force.

This is where different MC sizes come into play. The larger MC moves a larger volume of fluid. This increase in fluid movement at the pump source allows for braking energy to be applied sooner in the braking stroke. This basically means that more energy is spent in actual braking than in trying to move fluid. So a larger MC will allow you to start compressing fluid sooner and get more braking force earlier in the stroke. A smaller MC will have similar effect in a system of smaller sizes. Those of you who have used a 16mm MC for the rear brake know that it takes almost no energy at all to lock up the rear brake with that set up. This is why using larger MC's on the standard bike brake set up works so well.

Another difference between braking systems is the lever ratio. Many of you have heard of Brembo's new RCS system that has several piston sizes to choose from and has a switchable lever system that can go from 18mm to 20mm pivot distance. The lever ratio ( created by the lever pivot point ) can be used to increase brake energy or reduce it. By having the longer ratio ( 20mm ) you increase mechanical leverage on the lever. This make for a longer lever travel and increased power, but you can get more finesse and control with better brake feel. The shorter 18mm setting will allow for a more firm brake lever with less travel, but it will take more effort to have aggressive braking inputs and brake feel will be reduced. This doesn't really apply to stock brake systems since most don't have the adjustable lever ratio. But different brands may have a different ratio which could be why some bikes have brakes that feel better than others.

In either case the major difference that is noticed when switching from rubber hose to SS lines, is hose expansion. The SS lines don't expand and more energy is put towards braking effort. This increase in braking power is what is felt. As for other routing options the difference that would be felt would be a combination of line size and line length. The shorter more direct lines such as would be found is a crossover system ( like the 675 Triumph ) would be technically the best, followed by the Y system ( found on the stock R6 machines ) then by the individual lines ran to each caliper. This is assuming that line size is the same for each system. The reason that the individual lines is most popular is that there is not much advantage to the other systems and bleeding and maintenance is much easier. Also it is easier to manufacture standard lengths of line vs. that of making a different one for each bike model or brand in the other line styles. The different manufacturers will all have a pretty standard line size that is used. So line size may not be advertised. Goodridge claims openly that there smaller lines will yield better brake feel. Which I have already outlined.

Some links:

http://www.indysuperbike.com/customer/product.php?productid=118812

http://indysuperbike.com/customer/product.php?productid=3174&cat=0&page=3

Notice how each shows a different line size. The Goodridge a -2 and the Galfer a 2.8 line size. These are the only two that I see openly explaining their line sizes. Galfer also has a new GP line that is a T or Y style that is very similar to the stock R1 and R6 bikes.

As seen here:

http://indysuperbike.com/customer/product.php?productid=3140&cat=35116&page=1

So does different routing options change brake performance. The answer is yes, assuming that all line sizes are the same. Is there a definite advantage over one system to the other. The answer to that is yes and no. The performance of each system and it's results will be rider dependent. If a rider likes a firm and direct feel then he may have to give up overall braking power to get that feel. A rider can also add braking power at the cost of feel, or exaggerated lever movement. The individual line system is easier to maintain, whereas the crossover system ( like on the 675 ) is the most difficult to maintain. The T, or Y style is as easy as the individual line system in terms of maintenance, but is more expensive to produce. In general however, the individual line system is an improvement over any of the stock systems on just about any bike. Not by much, but enough to make notice. Money is the only other part that will make any real changes. Better brake lines with direct fittings ( not Banjo Bolts ) and MC's with adjustable lever ratio's, in combination with different routing options can yield any type of brake feel you should desire.
 

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iRun
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Holy mother of christ, there's entirely too much writing here...


Simple answer: Pascal's Law of fluid mechanics. As thinkmoto said, it doesn't matter how the hoses are routed-- if it's all connected there's no difference.
 

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crashing aint so bad
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There is a difference though. If each line size was the same in each style of system. The crossover system ( like the 675 ) would technically be the best and the individual lines would be the worst. This is dependent on what a rider actually wants though. The crossover system would yield more direct power and feel, while the individual line system would be spongier and have less feel. The Y system would be somewhere in between.

The reason I brought up all those points is to express that different brands have different line sizes and that changing from the stock system to one brand or another may or may not change the actual feel at the lever. It is dependent upon all the factors. My experience with the R6 is that going with the individual line system feels about the same as the stock system. Some notice a change and some don't. Those that feel a change will probably find it has to do with brand choice. I went with Goodridge and I felt no difference from the stock system except under really hard braking. That difference has to do with line expansion at that point. The stock rubber lines expand under heavy braking, pulling power and feel away from the lever.

If I had a choice knowing what I do now, I would probably choose the Galfer Superbike lines with the direct fittings. This is a larger line than the Goodridge and the direct fittings at the caliper will help with braking a little more. If they could figure out a way to do that at booth ends of the brake line, it would be even better. Perhaps I will sell my Goodridge lines and get the Galfer set anyway. The Goodridge lines are better for braking feel and linear effort but what they don't mention is the small loss in braking power that is the result of the smaller lines.

I did a fair amount of research on line size effects in a a braking system and found no definite answer. The Pascal's theory on fluid dynamics account for everything but the actual effect of the size of a transfer line in a system. The basic arguments are that line size makes no difference. Many do agree that a line that is too small in contrast to the system design will still work, but it will have increased braking effort with better feel. A line that is too large in contrast to the brake system will work like normal but will have a spongier feel. I agree that this is true, but the limited number of options for purchase will reduce the extremes. I feel that the market of brake lines available to us range in enough sizes from slightly too small, to slightly too large. The actual size of the line may be very minimal, but the effect is noticeable.

What is true and makes sense is system volume. The more fluid in the system to compress, the spongier and less direct the systems feel is. Again according to Pascal there is no clear answer, but this seems to be a common conclusion. A system with more fluid volume will also be less likely to have brake fade or boiling of brake fluid. This is because there is more fluid to transfer heat to.

My statements about larger lines equaling larger force at the pistons is wrong in science according to my research. It does seem however that using lines with a larger I.D do yield better braking power, or at least power that comes on quicker. What this may actually mean is that several companies use lines that are under sized. I was working on the principal that a line that is small will reduce immediate lever inputs, increasing lever effort and feel. It would make sense that a larger line would have easy lever effort with reduced feel. This may only mean that a larger line is actually properly sized for that system. The smaller lines are undersized enough to create the effect of better feel and more linear brake action. These effects may have nothing to do at all with line size but the choice in Banjo bolts. The Banjo bolts have small orifices in them. If there is limited flow in the Banjo bolts this would have the same effect as a small brake line.

After reading claims from the different companies it would seem to me that I am correct in assuming line size for brake power and effort. Galfer claims that the direct fitting lines they have improve lever feel and offer quicker stopping power. Goodridge claims that there smaller lines create a more improved lever feel and more linear braking effort. My experience with different machines seems to conclude the same. The ones that have aftermarket lines do seem to have better stopping power. The difference from that power is probably brand specific. For example: My friend owned an 07 R6V ( identical braking system to the 05 R6 which I own ) and he installed Galfer lines. I felt that his system had a firmer lever and that braking effort was a little bit less. It had good feel, but was a little less linear than mine. My bike has Goodridge lines and seems to have a light braking onset that is very linear once the pads are biting. The brake lever feel isn't as firm early in it's stroke, but once the pads bite the lever feels good and feedback is great. I also had a chance to ride a new 09 R6 at the track recently and it still had the stock brakes and lines. I noticed that the brakes had a firm lever feel, but the feel wasn't as linear further in the stroke. The initial bite was ok, it just seemed as if the brakes got more aggressive as you squeezed them more. The pads perhaps had a later bite to them than the HH compounds I'm used to which have a stronger initial bite. The major difference between each system was the brand of brake parts. This also seems to be the factor that has the largest impact on overall brake feel.
 
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