Brake hose discussion. (So as not to clutter up another thread.)

[thetable]

It started out like this, from me:

Also HEL lines are 32 strand where Galfer is 24, Spiegler is 24 I think, Russell is 16 strands. So the HEL lines have more braided strands and to me that results in better braking than the others. The HEL does not flex as much as the lower strand lines.

That is an interesting note. Everything I have read, and all the research I have done, has said that the SS is there to protect from abrasion, cutting, and kinking. The PTFE is what contains the brake fluid and the pressure.

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And then Tmod offered this:

That is an interesting note. Everything I have read, and all the research I have done, has said that the SS is there to protect from abrasion, cutting, and kinking. The PTFE is what contains the brake fluid and the pressure.

You are correct but the SS braid also holds the pressure as the PTFE liner is thin and would easily expand under pressure. If you look at specs for different line manufacturers you will notice that most if not all have a line expansion of >1% with 3000+ psi applied, So basically there is zero difference between a HEL line and any other as far as expansion goes unless your finger can sense a >1% expansion rate. What is better about the HEL is the flexibility that it has, And in this regards it is very flexible and can have a tighter bend radius. This really isn't a factor unless the lines are way too long and have a big bow that when the forks compress the lines will pinch or way too short where the line will be trying to pull itself out of the fitting. The thicker the PTFE liner the more kink resistant and better bend radius you will have as well as less permeation of gases.

There have been what I thought were some misconceptions about brake hose and what makes one any better than the rest and while visiting the HEL site I happened across some interesting reading and here are a few clips from their tech section.

Brake Doctor - Do -02 lines give more pressure than -03 lines?

No - the fitting of the smaller dash 2 hoses sold by some manufacturers makes NO difference to the pressure produced at the caliper as is commonly believed. There are no substantial benefits associated with the use of dash 2 hoses except that the manufacturer can charge you more for them. The only way to increase pressure coming out of the system is to increase the pressure going into the system. 500 psi in equals 500 psi out - Fluid cannot be compressed to a lesser volume, no matter how high the pressure and Pressure is equal over all surfaces of the containing system.

Brake Doctor - What is the difference in performance between two full length front lines and an over the mudguard line kit?

Nothing except for the way the system looks. Both systems operate in exactly the same way and give you the same performance. As the system is a closed hydraulic system without air in it when the fluid moves at one end the same movement takes place at the other end. Because they have different lengths doesn't mean that the system will work slower at one end than the other. Imagine pushing two sticks away from you which are both 6" long - the ends both move at the same time. Now imagine pushing two sticks - one is 6" and the other is 36" - the ends still both move at exactly the same time. So the over the mudguard gives the same performance as the 2 full length - it's just which you prefer.

Brake Doctor - What's better - three front lines using the oem splitter, 2 full length fronts or 2 fronts with one over the mudguard?

As we have said above the three systems give the same performance but the three line front has an additional 2 possible leak points in the system, is heavier and harder to bleed than 2 front lines. It is easier to fit though as you follow the oem setup. Another thing to remember is do you race or use the bike on track days? If so go for the 2 full length front as in the UK one of the ACU rules states that you are not allowed an over the mudguard system unless it is an original system.

Anyway I hope that sheds a little light on your research of brake lines.

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And very soon I shall offer my counters.

[thetable]

You are correct but the SS braid also holds the pressure as the PTFE liner is thin and would easily expand under pressure.

The Teflon in all the hoses I have seen is quite thick. I'll have to look in my stash of old hoses ans see if I have one that I can sacrifice to the Dremmel for pics. Earl's, for instance, uses a PTFE liner with a wall thickness of .040"

Upon going to the Earl's site I learned this:

In the mid-1960s, Earl's pioneered the use of armored flex hose of extruded Teflon to solve this problem. The stiffness of the Teflon liner combined with the tightly woven high tensile stainless steel outer braid solved the pedal travel problem. By eliminating the line swell it also dramatically increased the firmness and feel of the brake pedal which allowed the drivers to modulate the brakes more efficiently. Improved abrasion resistance and increased temperature capacity are secondary advantages.

There have been what I thought were some misconceptions about brake hose and what makes one any better than the rest and while visiting the HEL site I happened across some interesting reading and here are a few clips from their tech section.

Brake Doctor - Do -02 lines give more pressure than -03 lines?

No - the fitting of the smaller dash 2 hoses sold by some manufacturers makes NO difference to the pressure produced at the caliper as is commonly believed. There are no substantial benefits associated with the use of dash 2 hoses except that the manufacturer can charge you more for them. The only way to increase pressure coming out of the system is to increase the pressure going into the system. 500 psi in equals 500 psi out - Fluid cannot be compressed to a lesser volume, no matter how high the pressure and Pressure is equal over all surfaces of the containing system.

Now perhaps my issue with this statement is it's wording more than it's intent, but the way they have worded it is fundamentaly untrue. If they were to have worded it that it makes "effictively no difference" or the "difference is negligable" then I would have no issues. From what little I remember of the fluid dynamics courses I took in college, even if we say that the flow of the fluid in the hose itself is laminar, there will still be turbulence generated at the fittings, and the size of the fitting will affect the turbulence. The volume of fluid is low and the pressure is high, so the end result may be negligable, but definitely not nonexistant.

Doing the math on the actual pressure drop is giving me a headache, so I'm going to leave it alone for the moment, and I kind of doubt anyone cares about the math.

The only possible advantage to the -02 hose would be that the fluid has less surface area onto which it can impart pressure, so their would be less possibility for expansion.

Brake Doctor - What's better - three front lines using the oem splitter, 2 full length fronts or 2 fronts with one over the mudguard?

As we have said above the three systems give the same performance but the three line front has an additional 2 possible leak points in the system, is heavier and harder to bleed than 2 front lines. It is easier to fit though as you follow the oem setup. Another thing to remember is do you race or use the bike on track days? If so go for the 2 full length front as in the UK one of the ACU rules states that you are not allowed an over the mudguard system unless it is an original system.

Same as above, more fittings equal more turbulence equals more pressure drop.

[Black_peter]

The only possible advantage to the -02 hose would be that the fluid has less surface area onto which it can impart pressure, so their would be less possibility for expansion.

Yeppers..

Reducing the surface area where flow is basically negligible is always a good idea. However reducing the volume of the fluid in the line also reduces the overall hygroscopic volume. You will reach saturation quicker..