Hydraulic disc brakes and breakdowns (page 2 of 2)

Hi Hélène, All the best for 2017! Sorry if I’m partly to blame for your "spellbinding" question, but those brake "blowouts" were in the Alps and Laos—and the Atacama is yours whenever you want in 2018 for the Pasos Agua Negra and San Francisco, with or without disc brakes ;). Safe travels in the Balkans and Rroftë Shqipëri! Luc

Hi there,

Just a little tip.

I’m chiming in years later—sorry about that—I just read this today. But still a seasoned traveler!

I left without a bleed kit and had a real hassle.

Headed to a pharmacy, got 2 big syringes, needles, and catheters. Then used organic olive oil instead of some impossible-to-find liquid. I spilled some on the ground—no big deal, unlike the original oil, it doesn’t pollute.

Result: bleed went fine, braking was perfect (works in summer, but of course, if it’s really cold, don’t use olive oil). FYI, the boiling point is around 300°C—just as good as the best mineral oils (which are polluting). Min temp: -3°C.

Hi there.

That’s a great tip, thanks so much! Where I’m going, coconut oil is easier to find, so I’ll try it on an old brake to see how it works.

As for the bleed kit, I’ve got two updates.

Some older Shimano brakes, like the 2003 XT M755s—which still stop really well—have a small cover on the reservoir, so you don’t even need a bleed kit.

You can still find them cheaply on the second-hand market. The ergonomics are old-school (two or three fingers), but for travel, they’re usually perfect.

For other brakes, you can find a small aluminum reservoir with a screw-on lid on AliExpress, plus a rod that screws onto the brake, compatible with Shimano. It works as both an oil container and a bleed funnel.

Coconut oil operating temperatures aren’t ideal because its solidification point is 24°C~26°C, so not great.

FYI:

Comparison of emergency fluids (Mineral System only) FluidSolidification (Freezes)Boiling Point (Smoke Point)Verdict for MTB LHM Plus (Auto)-50°C~250°CThe best (reliable and stable) Rapeseed Oil-10°C~204°CBest emergency fluid Sunflower Oil-17°C~232°CVery good (heat-resistant) Olive Oil+6°C~190°CFair (risk of solidifying) Coconut Oil+24°C~177°C (Virgin)Avoid (solid in the shade) Water0°C100°CDanger (boils too quickly) for DOT systems only

A temporary fix should be very short-term, as there are long-term harmful effects.

A crucial point to watch out for:

Warning: This fix ONLY works if your brakes use mineral oil.

If your MTB uses DOT brake fluid (SRAM, Hope, Formula), putting olive oil in will swell and destroy your EPDM seals in just a few hours. DOT and oil are not chemically compatible at all.

Mineral System (Shimano): Seals made of NBR or Urethane (which like oil). => see vegetable oil table

DOT System (SRAM, Hope, Formula): Seals made of EPDM (Ethylene-Propylene-Diene Monomer). => Water or glycol (yuck)

In an emergency, use water—putting vegetable oil in a system designed for DOT is disastrous.