Brake fluid life span

padams10003

Likes Dirt
I have had my Strive for almost 3 years and it that time have never touched the brakes (Guides) as they have always just kept working fine. They are still working fine, but I am thinking that the brake fluid must surely be starting to degrade by now.

Is there any issues that will be caused by leaving old fluid in them? I'll most likely bleed them soon anyway, but was just curious about it.
 

Haakon

Keeps on digging
Guides not needing a bleed for three years!? Send them back to SRAM so they can study them!

More seriously, bleeding them advisable is the short version. Longer version is depends on use and conditions.
 

rowdyflat

chez le médecin
I have 15 yo brakes and while I have bled and topped them up, have never flushed the fluid out completely.
Maybe I am just not hard enough on them to make them boil?
 

moorey

call me Mia
I have 15 yo brakes and while I have bled and topped them up, have never flushed the fluid out completely.
Maybe I am just not hard enough on them to make them boil?
If old Shimano, I used to go many years without issue. Later ones, metal must wear in the pistons, and turns the fluid metallic grey after a few months solid riding. It effects performance, cuss knows how, but makes them spongy.

OP, I’d be surprised if you don’t have a fair bit of water in there by now.
 

rowdyflat

chez le médecin
You mean free water or mixed w the DOT ?
I will bleed one dry tomorrow and see what the fluid is like .
 

Mr Crudley

Glock in your sock
I ran my Juicys for way too long without a bleed. They didn't feel bad either. Also felt teh same after a bleed. I guess that doesn't say much :)
 

padams10003

Likes Dirt
Guides not needing a bleed for three years!? Send them back to SRAM so they can study them!

More seriously, bleeding them advisable is the short version. Longer version is depends on use and conditions.
They did seem to be an exception. The guides on my dh bike need to be bled at least every 12 months and even then they never feel perfect..
 

creaky

XMAS Plumper
Just bled my Shimano roadie brakes for the first time. Nearly 4 years old and would have 15,000 km on them with some hot descents. Fluid coming out was mint. Don’t know why I bothered.

My DOT fluid brakes however, get an annual bleed.

Up to you @padams10003 as it could go horribly wrong given they’ve been flawless. However, technically you should get it done.
 

BT180

Max Pfaff
Didn't bleed the RSCs on my Strive for almost 3 years. They worked perfectly. Only did it when the whole bike got stripped down for a major service.
 

Calvin27

Eats Squid
I rode on deores for about 5 years without a bleed. Finally bled it due to some brake issues, turned out the pad was just worn.
 

T-Rex

Template denier
The dot fluid is hygroscopic (sp?) and attracts water into the system over time
Correct young man.

The water that gets absorbed by glycol based brake fluid has a much lower boiling point so when the brakes get properly hot on a long descent the fluid boils and the brake levers use a lot of their stroke trying to compress the vapor, so they go soft.

Or the mildly entertaining alternative many years go I left my bike in the January sunshine at Eagle Park in ‘Radelaide, that was hot enough to expand the fluid and lock both the brakes on.
 

moorey

call me Mia
Or the mildly entertaining alternative many years go I left my bike in the January sunshine at Eagle Park in ‘Radelaide, that was hot enough to expand the fluid and lock both the brakes on.
AKA, every set of early guides ever.
 

mark22

Likes Dirt
Geez this Shimano oil sounds good it's a wonder every car and motorcycle manufacturer hasn't ditched DOT brake fluid and got onto it.
 
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