bike brakes fluids(Alternatives) & Freezing prevention in winter

Cold weather below -10 degrees affects the rubber seals, calipers, and hydraulic brakes of bikes because of the moisture in the atmosphere which freezes the rubber brakes and also the salt-covered roads with snow slow down the working capacity of the hydraulic brakes mostly in a few days of winter when the temperature goes down from -10C degrees to -20C degrees. these days are mostly a headache for bike brakes because even the oil fluids of hydraulic brakes become useless and become dry on the surface of brake pads and rubber seals and water will go down deep within the holes which will affect the working power of brakes.

What are the different types of hydraulic brake fluids?

Mineral OilDOT 3 FluidDOT 4 FluidDOT 5 FluidDOT 5.1 Fluid
Hydrophobic FluidHygroscopic FluidHygroscopic FluidHydrophobic FluidHygroscopic Fluid
Heavy HydrocarbonGlycol Based FluidGlycol based FluidSilicone Based FluidGlycol Based Fluid
Colorless OilBluish Colour Mineral Yellowish Colour Purple Colour Amber Colour
Does Not Absorbs Moisture Absorbs Moisture Less Than DOT 4 FluidAbsorbs Moisture Does Not Absorbs Moisture Absorbs More Moisture
Viscosity (0.02 to 0.05 Pa. s at 40C)Viscosity( Max 1500mm/s) at -40CVisacosity(Max 1800mm/s) at -40CViscosity(Max 900mm/s at -40C)Viscosity(Max 900 mm/s)

Most commonly there are three types of brake fluids:

  • Mineral Oil
  • Shimano Mineral Oil
  • Dot Fluid

Dot fluid is further subdivided into 4 types of fluids

  • DOT 3
  • DOT 4
  • DOT 5
  • DOT 5.1

Properties of Mineral oil:

Mineral oil is used in homes for cooking, cleaning, and kitchen purposes and especially for skin and face but it is basically less used for hydraulic brakes because mineral oil is not a specific fluid for stopping bikes on terrains.

Actually, mineral oil is further classified into many types like baby oil, etc, which functions totally different for bike brakes.

These mineral oils contain thick fluid which usually has a bad effect on bike hydraulic brakes in winters.

if you are using mineral oil for your bike brakes, it definitely damages the brakes and does not works well.

The fluid of mineral oil is made of different chemicals, and perfumes which have a negative effect on bike brakes.

Properties of Shimano Mineral Oil:

Shimano mineral oil is a good and recommended brand for hydraulic bike brands.

Shimano oil protects rubber seals of brakes and increases the life span of brakes.

Shimano oil mixture does not contain any chemicals or bad stuff in its composition, a unique fluid comes with a warranty and is the most popular product of the Shimano brand for bike brakes.

Shimano mineral oil expels dust and mud through wet trails and does allow particles to stick on the surface of brakes.

Shimano Mineral oil lasts for many years and does not expire earlier as compared to other types of brake fluids and oils.

Fluid weight matters the most for bike brakes, Shimano oil has an appropriate and accurate weight for bike brakes and increases the quality and function of hydraulic brakes in working.

Oils you can use in winter :

There are 3 most prominent oils that have freezing point lower than mineral or shimano oil that you can use in winter.

  • Soya been oil (vegetable oil)
  • sun flower oil (vegetable oil)

The reason i mentioned these 2 oils only is due to there higher freezing point.

Soya been oil has -16°C

sun flower oil -17°C

These can be best alternatives for the people living in the area where temperature drops down to -10 or a little lower.

There is also Fish oil that’s more better than these two which comes down at -48°C

Now fish oil is for extreme cold areas where temperature drops below -20°C

NOTE :

Vegetable oils or Fish oils have lower boiling point meaning they might be best in the winter they are not good for summer while you can use these vegetable oils as mentioned above in your bikes in winter make sure you switch to shimao mineral oil or mineral oil in winter.

Properties of DOT Fluids:

Dot fluids are based on different types of minerals so it best that you check what type of fluid your brand or brakes have before filling them with anything.

DOT 3 Fluid:

DOT 3 is a glycol-based fluid, It is less reactive with a lower boiling point and is not an excellent result for hydraulic brakes because it is an older version it captures dirt and mud for bleeding purposes, it evaporates easily that’s why DOT 3 fluid is named hygroscopic fluid.

Hygroscopic fluid:

Fluids on which dust particles, mud, and especially water stick easily decrease the working capacity of rubber pads and the components of the brake system. DOT 3 fluid allows water to mix and penetrates into the deeper parts of the brakes which reduces the working power of the brakes, especially in winters.

The weight of DOT 3 fluid is less than that of liquid water as it is hygroscopic, it easily allows water to mix within the fluid and settle at the bottom surface of the brakes which causes a difference between the boiling point of the brakes and as a result brakes does not perform well.

DOT 4 Fluid:

DOT 4 is a glycol-based fluid, It is an advanced version with a high boiling point as compared to DOT 3 fluid and performs much better than DOT 3 because it does not evaporate at any temperature due to which it does not allow water or any liquid to mix and penetrate within the DOT 4, these useful properties make DOT 4 more valuable product with increased performance as compared to the DOT 3. DOT 4 is hygroscopic and dry fluid.

DOT 5 Fluid:

DOT 5 is a silicon-based liquid and it is totally different from DOT 3 and 4 in function because it is a hydrophobic fluid. Water and other liquids do not mix with DOT 5 because it is strong enough to repel water as compared to other brake fluids. the boiling point of DOT 5 is more than both DOT 3 and 4.

DOT 5 sits stronger on brakes and performs better because it sticks thoroughly onto the brakes and penetrates deep within the holes and seals.DOT 5 usually needs to change after a few weeks, after some weeks it performs slower so changing and replacing is necessary.

DOT 5.1 Fluid:

DOT 5.1 is a glycol-based with high boiling point hygroscopic fluid, Absorbs water which affects the boiling temperature of the rubber seals of brakes because water penetrates and causes an effect on rubber seals, it is necessary to replace or rechange 5.1 fluid after 2 or 3 days if you are a regular rider or mountain biker.

How do I know what type of brake fluid I have?

It’s very important to know about the brake fluid which is currently in your bike brake because sometimes it happens by mistake you will mix silicon and glycol fluids into each other due to a lack of information, firstly you should ask the mechanic and if you want to do it by yourself then note the color of fluids, DOT 5 has a purple color and it does not make any mixture with the DOT 3, 4 and 5.1 fluids.

It’s not a safer method because sometimes the purple color of DOT 5 turns into yellowish color which is the genuine color of DOT 3 and it ever confusing to know about the fluid here is another method of knowing about fluids.

Take some water and fluid in an empty clean glass or bottle shake them well and after 10 to 15 minutes stop shaking and leave for 5 to 7 minutes, keep noticing if the fluid and water have been completely dissolved and it’s hard to differ both of them, the fluid is glycol-based.

But if fluid and water do not dissolve then fluid starts making bubbles and waves on the surface of the water and you can clearly identify water and fluid, this type of fluid is silicone-based.

Mineral oil and DOT fluid compatibility :

Mineral oil and DOT fluids are two different fluids used for bike brakes, both of these have different characteristics and features which differ in their function, if you use mineral oil in the DOT brake system you are ruining your hydraulic brakes with your hands because its risky step.

DOT 3, DOT 4, and DOT 5.1 are glycol-based fluids and DOT 5 is a silicone-based fluid that is totally different from the previous three DOT fluids so DOT 5 and DOT 3, 4, and DOT 5.1 are not compatible with each other.

You can also check out my post on Can you use car brake fluid(Dot fluids) in Mountain bikes for further questions about Dot and mineral oil fluids

 The freezing point of Mineral Oil:

-10C to -20C is the freezing point of mineral oil.

The freezing point of DOT 3 fluid:

-25C to -35C is the freezing point of DOT 3 fluid.

Freezing Point of DOT 4 fluid:

-35C to -40C is the freezing point of DOT 4 Fluid.

Freezing Point of DOT 5 fluid:

-40C is the freezing point of DOT 5 fluid.

Freezing Point of DOT 5.1 fluid:

-50C is the freezing point of DOT 5.1 fluid.

The freezing point of Shimano Mineral Oil:

-22C is the freezing point of Shimano mineral oil.

Dry And Wet Boiling Points Of DOT 3, DOT 4, DOT 5, DOT 5.1 Brake Fluids:

 DOT 3 DOT 4DOT 5 DOT 5.1
Dry Boiling Point 205C (401F)230C (446F)260C (500F)270C (518F)
Wet Boiling Point140C(284F)155C (311F)185C (356F)190C (374F)

 

Can you mix Mineral Oil with DOT fluid?

Mixing mineral oil and DOT fluid is like ruining your brake system because both of these are two different mixtures with different properties and working principles. although DOT fluids are mixable as I have discussed in the above paragraph these can be mixed without DOT 5 fluid.

At the bleeding time, it’s important to check the brakes which fluid has been used before actually for Shimano brakes, Shimano mineral oil is used. never fill random fluid in your brakes because it damages the whole brake system and hydraulic brakes become useless if you fill mineral oil in place of DOT fluid.

What happens if you mix Mineral Oil and DOT fluid?

After mixing two different fluids, your brake rubbers and seals will get damaged and destroy because the gel-like mixture blocks the working power of hydraulic brakes, and brake systems become useless, calipers lose their4 function because both these fluids work on the basis of different volumes.

Shimano brakes need mineral oil and the SRAM brake has DOT fluid but if you replace their fluids inversely, these brakes will not work and damage your brake system.

Does Shimano mineral oil freeze?

below -30C Shimano mineral oil freezes, always use Shimano mineral oil for Shimano brakes. more than 2 hours in winter and snow bike brakes will start freezing and become hard and stiff.

Bike Hydraulic brakes in snow:

There are many areas where it’s cold for almost 6 months in a year, so hydraulic brakes start to freeze and they stop working if you will stay in the snow with your bike for more than 1 hour, the reason is that when you push the pedals wheels start rotating which is dragging snow and hitting rapidly within the hydraulic brakes and the wheel is repeating the same process many times in one hour. continuous rotation of wheel affects the function of hydraulic brakes very badly and after some time you will notice your bike brakes will block the wheel and unable to rotate.

Downhill terrains in winters where it snows all around on bike trail when you pedal your bike, wheels start sinking within the snow and hydraulic brakes are made of rubber, this situation creates a negative effect on bike brakes.

Bike Brake Pads and levers in winters:

Hydraulic brake pads start shrinking in cold weather and they become rigid and lose their function, and rotors become less responsive. the best way to make these pads more responsive is never to stay much more within the snow and cold weather. ride your bike in a limited range when the degree is -12 and never leave your bike outside open to the atmosphere. After the evening, bring your bike to your room in a warm place where the pads start melting and become normal as usual.

Hydraulic brake levers even stop working in winters because of too cold, apply the same trick as above and stay the levers warm for better working which increases their power capacity.

Do all hydraulic brakes fail in winters?

Absolutely not, Shimano hydraulic brakes are the top quality brand that can survive -15 degrees of cold and work properly, mountain bikers have Shimano hydraulic brakes because they would not fail in any season, no matter how many miles you will ride in the snow but sometimes they might end up failing and you can use vegetable oils (as mentioned above).

Deore hydraulic brakes can also have excellent performance in the winter season, they do not shrink, they can tolerate even -20 degrees of cold, and do not freeze in winters. but sometimes they might end up failing and you can use vegetable oils (as mentioned above)

Fluids and mineral oil performance for bike hydraulic brakes in winters?

In cold weather, Dot fluids and other bleeding mineral oils for hydraulic brakes stop working and they become dry and do not stick with the brake pads because of the moisture in the atmosphere, but it lasts temporarily a week or 10 days when the weather is too cold, the best option is that upgrade your hydraulic brakes to Shimano and Deore brakes, both these brakes fully give response of fluids and mineral oils in freezing cold and does not become dry in the winter season, while the other hydraulic brakes do not give response so much better in freezing temperature.

What is the reason bike hydraulic brakes do not work better in winters?

  • Bleeding too much to your brakes in cold weather is the main reason that these oils become dry and make a surface layer above the brakes which increases the thickness, due to which hydraulic brakes do not perform fully in winter seasons.
  • In cold weather, moisture increases within the brake pads and inner parts of the hydraulic brakes, this moisture causes the fluid particles to become dry and stop the whole working system of brakes. the liquid particles like water, fluid, and mineral oils do not perform their work, but in such an irritating moment if your hydraulic brakes are the best quality product then those brakes will survive every condition.

 

  • Another reason is that the contacting points of the hydraulic brakes have a lot of friction because of the freezing cold, it is risky for your bike because sometimes brakes will stick with the rim and block the rotation of the wheel, and this happens just because of the freezing temperature.

 

  • And the final point is that in the starting days of the winter season, clean your cable thoroughly with Mucc Off spray and other lubes and make the cable waterproof to increase the functioning power of the hydraulic brakes.
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