[Closed] Brake fluid

Different strengths and weaknesses to the two but shimano are the outlier.  the vast majority of braking systems on all vehicles are dot 4 or 5.1 fluid

Be grateful there are only two 🙂 I've got a shelf full of various suspension fluids and grease.

Real answer, Pros and cons of both but mineral is the better solution for bikes but you are fighting the history of how its always been done

the vast majority of braking systems on all vehicles are dot 4 or 5.1 fluid

A daresay that brakes can get a lot hotter on cars than on hybrid bikes 😀 hence the need for glycol based.

It's probably the least annoying non-standard thing in the industry, IMO.

I'd rather have standard pads and rotors, though again that's nothing like as annoying as the various axle, chainring, shock mount and rear mech hangers.

Can't even agree on a single correct wheelsize (29er obvs), so what chance do you think of agreeing on something like brake fluid is?

Real answer, Pros and cons of both but mineral is the better solution for bikes but you are fighting the history of how its always been done

This basically.

A daresay that brakes can get a lot hotter on cars than on hybrid bikes

My heat discoloured discs would say otherwise 🙂

Actually to some extent I think you are right.  IMO a lot of the issues that folk have with bicycle brakes is because they never get up to operating temperature meaning mainly abrasive friction not adherent friction thus rapid wear and squeal.

Living in a hilly city I tend to deliberately do hard stops regularly which IMO / IME improves the brakes hugely

Does the use of mineral oil not give rise to issues in low temps when the oil thickens which glycol based stuff does not?????

DOT fluid is designed for high temperatures, the only real drawback to it is that it strips paint. Would have been much simpler if Shimano and Magura just stuck with DOT.

Not just Shimano. Magura, Clarks, Tectro off the top of my head.

Just AVID/SRAM and Hope using DOT?

Just AVID/SRAM and Hope using DOT?

+ Formula & Hayes I believe

Mineral is my preference though. Nicer to work with and performs great in all but substantially sub-zero temps.

the only real drawback to it is that it strips paint.

And it is worse for the environment
and it has a limited shelf life
and it is harder to handle and deal with spillages

it would be much simpler if Hope and Sham moved to mineral, like everybody else 🙂

So mineral oil for the fair weather mincers and dot for the gnarly all year round folk?
*runs away*  🙂

And it is worse for the environment
and it has a limited shelf life
and it is harder to handle and deal with spillages

Mineral oil is extremely environmentally harmful.
DOT fluid can be stored for years if it's in a sealed container. It's only unsealed containers that are a problem.
It's no harder to handle. If you spill either, you need to clean it up.

The drawback to DOT fluid is that you need to wash it off fairly quickly or it will peel paint.

Also, DOT fluid has the benefit that, if moisture does get into the system, it disperses through the fluid. If moisture gets into a mineral oil system, it will gravitate to the lowest point, which is the caliper. The caliper is the hottest part so water will cause much more severe problems in a mineral oil system than a DOT system. However, the only ways water can get in are if you blast the calipers and levers with a pressure washer or the master cylinder seals are totally knackered. More of a theoretical problem than a real one.

Oh, and mineral oil is an irritant too, I always have to use gloves when handling it, as it plays hell with my skin.

Oh, and mineral oil is an irritant too, I always have to use gloves when handling it, as it plays hell with my skin.

That's interesting (and unfortunate). It is dot that is generally considered a skin irritant and not mineral for most people.

Ahem, you left out water...

https://singletrackmag.com/wp-content/uploads/2015/10/why-not-water-asks-brake-force-one/

Oh, and mineral oil is an irritant too, I always have to use gloves when handling it, as it plays hell with my skin.

You can get contact dermatitis from minerals oils but they aren't toxic like glycol is.

You can get contact dermatitis from minerals oils but they aren’t toxic like glycol is.

Mineral oil's not toxic? Are you sure about that?

So mineral oil for the fair weather mincers and dot for the gnarly all year round folk?
*runs away*

For some of us the gnarly all year round folk means a minimum temperature of 5 and a maximum of 40 😛 Pretty sure I don't need to worry about mineral oil getting too thick!

DOT fluid should absolutely not be kept in a container that's had its seal broken! It's hygroscopic - if you live anywhere with a bit of humidity you're asking for trouble.

I know auto mechanics that are really anal about this.

DOT fluid should absolutely not be kept in a container that’s had its seal broken! It’s hygroscopic – if you live anywhere with a bit of humidity you’re asking for trouble.

If it's in a sealed container, it's fine. The absorbing water from the atmosphere thing is a bit exaggerated. Sure, if you leave it in an open container, it'll deteriorate after a couple of years, but if you screw the cap back on the bottle, it'll be fine. If you're really worried, put the bottle into a Ziplock bag for peace of mind.

DOT fluid can be stored for years if it’s in a sealed container. It’s only unsealed containers that are a problem.

Yes, but it needs to be filled to the brim and sealed. No point in tightening up the lid of a half full bottle, as the fluid will absorb the moisture in the air part

Mineral oil’s not toxic? Are you sure about that?

Not to the same extent as glycol.

as the fluid will absorb the moisture in the air part

Which is an insignificant amount especially given very few folk get bicycle brakes properly hot

For some of us the gnarly all year round folk means a minimum temperature of 5 and a maximum of 40

The coldest air temperature I've ridden in is minus 14, last Winter. I regularly ride in sub-zero. My Shimano brakes work just fine. How much colder does it have to be before mineral oil affects performance?

I think Shimano state <-20°c which is a bit vague but I doubt that'll effect me. One issue with mineral oil is that there isn't a standard so some may be better others worse.

Shimano takes mineral oil

SRAM & Avid takes DOT 5.1

Why can’t these clowns agree on a common fluid?!

???

Cycle industry? All working to the same standards? Ridiculous notion

😀

The coldest air temperature I’ve ridden in is minus 14, last Winter. I regularly ride in sub-zero. My Shimano brakes work just fine. How much colder does it have to be before mineral oil affects performance?

The only time I've had an issue was on top of Skiddaw in snow and a very cold wind, so I don't know the effective temperature - but it was bloody freezing and my brakes went all wooden and useless.

Fortunately the snowdrifts slowed my progress descending and the brakes (original SLX I think) returned to life lower down.

I'm still a Shimano man, so that didn't put me off.

I think Shimano state <-20°c which is a bit vague but I doubt that’ll effect me. One issue with mineral oil is that there isn’t a standard so some may be better others worse.

Cool. I only use genuine Shimano oil so I'll assume I'll never experience the issue.

The only time I’ve had an issue was on top of Skiddaw in snow and a very cold wind, so I don’t know the effective temperature – but it was bloody freezing and my brakes went all wooden and useless.

Fortunately the snowdrifts slowed my progress descending and the brakes (original SLX I think) returned to life lower down.

More likely frozen ice around the caliper and pads?

Don't think so, it was a dry kind of cold and both ends felt the same.

Why can’t these clowns agree on a common fluid?!

Not really an issue though is it? I mean even if you have bikes with Shimano or "other" brakes, just get the appropriate fluid, that fact that you've got two bottles rather than just one of the shelf is hardly world-ending is it?

No point in tightening up the lid of a half full bottle, as the fluid will absorb the moisture in the air part

To absorb a significant amount of water, the fluid would have to be stored in an open container. If the container is sealed, there will be a tiny amount of moisture in the air at the top. This is not enough to be a problem. Once that has been absorbed, there's no more moisture to absorb. The only way it can absorb enough moisture to be a problem is if the container is open and the moisture content of the air is constantly being equalized with the atmosphere.

If I was racing DH, I'd flush my brake fluid at least every six months and use an unopened bottle each time just to eliminate any remote chance of a problem. For most people, if you screw the cap back on the bottle, you aren't going to have boiling brake fluid. The absorbing water thing is massively exaggerated.

Not really an issue though is it?

This too. I have Avids on a couple of bikes and Shimano on others. They all work fine. Minor hassle of needing two bleed kits and bottles of fluid. Keeping track of the different brake pads is a much worse hassle.

You have also left out silicon based brake fluids. Very good in little used/retro/old bikes as the self lubing properties keeps the pistons moving freely. Best but expensive, tends to be compatible with your existing seals.

You have also left out silicon based brake fluids.

I didn't want to bring it up, it's kinda like Betamax, if you mention it, crazy people appear out of the woodwork and won't stop ranting on about it.