TacomaSailor

Hayes Stroker Ryde hydraulic disk brakes

The brakes work fine for hours of fast riding on rolling trails. I carefully adjust the lever pull to have exactly the feel I want. At that setting I can easily and accurately lock up or modulate the braking on front and rear. I test the brakes on very steep downhills and they work just as I wish.

However, the required lever pull becomes longer and longer to get the same stopping power when I do long steep descents with a lot of braking. The brakes do retain the same stopping power but eventually I have to pull the levers almost to the grips to get that power. The front brake lever travel increases much more quickly than the rear brake.

A five mile 2000’ descent will result in me eventually pulling the levers all the way to the grips. At that point - the master cylinders, the brake lines, and the calipers are only slightly warm to the touch but the discs are very hot.

If I ride for 30 minutes on level ground after the descent, and never touch the brakes – they still require a lever pull to the grip. The brake levers do not return to their normal amount of travel until the next day but at that time the lever travel is just as I set it when I last bled the brakes. This problem may not occur the first couple times I ride after I bleed the brakes but within 100 miles or so the problem returns.

I have a fair amount of experience with high end automotive hydraulic brake systems but I guess I don’t understand something about bicycle hydraulics.

I have bled the brakes many times. I use fresh DOT 4 fluid each time. Each time I bleed the brakes I find NO (NO!) bubbles in the fluid. I carefully follow the instructions shown in the YouTube video made by Hayes. I rotate the master cylinder to ensure all the bubbles come out of the tiny channels. When I bleed the brakes I pump 2 – 3 ounces of new fluid thru each brake system to ensure any contaminants are flushed out.

I thought the trick was to ensure no bubbles, tap and rotate the MC and caliper to free the trapped bubbles, and ensure clean fluid is being forced out of the MC.

The pads are stock Hayes but look clean and unglazed.

What am I doing wrong?

AEO

well, it certainly seems like you are doing everything correctly.

I would guess brake fade, but it's puzzling that the fade will last that long.


Maybe you have a mostly invisible hairline crack in the line?

Zef

You are overheating your brakes/brake fluid. Since the amount of fluid is small the temperature of it can rise quickly.

Overheated brake fluid can boil in the caliper. Boiling produces gas bubbles within any boiling fluid. While brake fluid in liquid form is not compressible, the gas produce from boiling/overheating is compressible. The boiling brake fluid leads to a “soft” brake lever pull with longer travel.

The caliper then becomes a heat-sink that could keep the brake fluid at an elevated temp for awhile after your descent is complete.

Try pumping your brakes or alternating a couple seconds front and then a couple of seconds rear to keep temps from spiking so much.

If your rotors drag on the pads this will also exacerbate the problem after the fluid is heated to its boiling point by possibly adding enough friction to keep the fluid at an elevated temp after the descent is done with. If this is the case, adjust pad clearance if you can or true the rotor(s) to prevent them from dragging.

-j

fietsbob

Bigger disc with an aluminum core as a Heat sink ,

if there were a machine shop that would do it,

a finned tube right out of the caliper would also dissipate

some more heat back out of the brake fluid.