What clear tube to use for remote brake/clutch reservoir?

[mangocrazy]

No matter what clear tube I use to connect the remote brake/clutch reservoirs to the master cylinder(s), they all seem to 'sweat' after a while. Has anyone found a particular type of clear hose that is resistant to this happening when used for brake fluid? I've tried using Ariete fuel hose for this, as it works really well when holding petrol, but the dreaded 'sweaty Betty' returns after a few weeks when it's used for brake fluid. I'd prefer if possible to use clear/translucent hose, but if not what is best for brake lines that are not under pressure?

[Rockburner]

Couldn't you buy a spare part from some 90s bike that had a remote reservoir? I seen to remember they were all clear?

[KungFooBob]

How long does it need to be?

HRC must sell more of these kits than anything else, I've seen them fitted on everything from GSXR's to Ducati track bikes. I guess your local HRC dealer might just be able to get you the pipe without the bung and clips.

https://www.ebay.co.uk/itm/385446204108

EDIT:

I've just found some 3rd party versions that boast they use Tygon 2375, so I guess that's what you need.

[Skub]

How long does it need to be?

HRC must sell more of these kits than anything else, I've seen them fitted on everything from GSXR's to Ducati track bikes. I guess your local HRC dealer might just be able to get you the pipe without the bung and clips.

https://www.ebay.co.uk/itm/385446204108

EDIT:

I've just found some 3rd party versions that boast they use Tygon 2375, so I guess that's what you need.

The HRC ones go sweaty too. Because they are changed regularly on a race bike,it isn't an issue,like on road bikes. I haven't tried the Tygon jobbies.

Eventually I gave up and fitted a little Brembo reservoir.

[mangocrazy]

I've just found some 3rd party versions that boast they use Tygon 2375, so I guess that's what you need.

Cheers KFB. I've just bought some of this - looks like it should do the job:

https://www.ebay.co.uk/itm/111215279138

Interestingly it says it's not suitable for fuel hose, which indicates that brake fluid and fuel have very different hose requirements. So my use of fuel hose for brake line wasn't the smartest thing to do.

[mangocrazy]

Tygon 2375 tubing arrived on Friday and fitted yesterday. I'll report back longer term on whether it cures the sweating problem or not.

[mangocrazy]

The Tygon 2375 tubing has been fitted to the Falco's remote clutch and brake reservoirs for nearly 4 weeks now and has seen some fairly elevated temperatures, whether in a sweltering van on the way down to France or parked up in the sun in the south of France. In that time there has been no hint of any sweating or moisture transmission through the tubing, so I can only say that it gets a thumbs up from me and will be my go-to tubing of choice for this application in future.

[millemille]

Just to be clear, the moisture you see beading on the outside of many aftermarket reservoir hoses isn't the fluid inside the hose leaking out. It's moisture in the air condensing on the hose because the hose is permeable enough to allow the aggressively hygroscopic nature of brake fluid to permeate the material.

[mangocrazy]

Just to be clear, the moisture you see beading on the outside of many aftermarket reservoir hoses isn't the fluid inside the hose leaking out. It's moisture in the air condensing on the hose because the hose is permeable enough to allow the aggressively hygroscopic nature of brake fluid to permeate the material.

Thanks - I'd always wondered how that worked! So the permeability of the hose isn't sufficient to allow brake fluid to leak out, but is enough to attract water vapour? I guess it's a question of molecule size, or am I over-thinking this?

[cheb]

You'll need to a do a full on radioactive tracking molecule test to be certain.

[Mr. Dazzle]

Most polymers will let water in/through...in fact nearly anything will let water in/through It's the universal solvent, can dissolve almost anything given enough time! Mostly down to how small a molecule it is, but also other chemistry things I've long since forgotten.

But yeah, polymers in particular. Not really any such thing as a 'fully waterproof' polymer.

[Count Steer]

Most polymers will let water in/through...in fact nearly anything will let water in/through It's the universal solvent, can dissolve almost anything given enough time! Mostly down to how small a molecule it is, but also other chemistry things I've long since forgotten.

But yeah, polymers in particular. Not really any such thing as a 'fully waterproof' polymer.

Something to do with 'electrical polarity'. I did lots of experiments on sealants for gas mains years ago looking at what caused them to fail. Thought the glycol stuff they use for 'fogging' was going to be prime candidate. Nope. Good old aitchtwoo.