DOT Fluid

Someone cautioned that DOT brake fluid, in bicycle disk brakes, should
be changed annually.
Is this correct? A requirement of the disk makers? Or ?
--
cheers,

John B.

On Thursday, June 18, 2020 at 6:48:38 AM UTC+2, John B. wrote:
Someone cautioned that DOT brake fluid, in bicycle disk brakes, should
be changed annually.
Is this correct? A requirement of the disk makers? Or ?
--
cheers,

John B.

Never heard of that requirement. In my car is is changed every 2 years.

Lou

Lou

On Wed, 17 Jun 2020 23:07:14 -0700 (PDT), wrote:

On Thursday, June 18, 2020 at 6:48:38 AM UTC+2, John B. wrote:
Someone cautioned that DOT brake fluid, in bicycle disk brakes, should
be changed annually.
Is this correct? A requirement of the disk makers? Or ?
--
cheers,

John B.

Never heard of that requirement. In my car is is changed every 2 years.

Lou

Somebody here, talking about bicycle disk brakes mentioned that DOT
liquid must be changed annually while mineral oil did not require
this.

As the DOT brake oil in my pickup truck has been there for probably 20
years without being changed I asked the question.
--
cheers,

John B.

Am 18.06.2020 um 08:32 schrieb John B.:
On Wed, 17 Jun 2020 23:07:14 -0700 (PDT), wrote:

On Thursday, June 18, 2020 at 6:48:38 AM UTC+2, John B. wrote:
Someone cautioned that DOT brake fluid, in bicycle disk brakes, should
be changed annually.
Is this correct? A requirement of the disk makers? Or ?

Never heard of that requirement. In my car is is changed every 2 years.

Somebody here, talking about bicycle disk brakes mentioned that DOT
liquid must be changed annually while mineral oil did not require
this.

As the DOT brake oil in my pickup truck has been there for probably 20
years without being changed I asked the question.

Outch. DOT brake fluid (as opposed to mineral oil) is strongly
hygroscopic, i.e. it absorbs water, changing it properties
significantly. Therefore, DOT brake fluid must be changed regularly; in
Europe, the age of brake fluid is one of the safety checks that need to
be documented every 2 years, or the car will be taken out of service.
If your truck was 40 years old instead of 20, it might still have the
old mineral oil that doesn't need changing

In cars and motorbikes, the exchange interval is every two years
irrespective of mileage. Possibly, in bicycles it has to be changed
more often due to the smaller brake fluid container, or possibly the
bike manufacturers are just more cautios if they stipulate annual change.

Given that bicycles have significantly lower problems with overheating,
mineral oil seems more appropriate than DOT fluid for bicycle brakes.

Rolf

On 18/06/2020 06:48, John B. wrote:

Someone cautioned that DOT brake fluid, in bicycle disk brakes,
should be changed annually. Is this correct? A requirement of the
disk makers? Or ?

That was me, and istr it from my Hope brakes. Which use DOT 5.1, again
iirc.

On 18/06/2020 08:32, John B. wrote:
On Wed, 17 Jun 2020 23:07:14 -0700 (PDT), wrote:

On Thursday, June 18, 2020 at 6:48:38 AM UTC+2, John B. wrote:
Someone cautioned that DOT brake fluid, in bicycle disk brakes, should
be changed annually.
Is this correct? A requirement of the disk makers? Or ?
--
cheers,

John B.

Never heard of that requirement. In my car is is changed every 2 years.

Lou

Somebody here, talking about bicycle disk brakes mentioned that DOT
liquid must be changed annually while mineral oil did not require
this.

As the DOT brake oil in my pickup truck has been there for probably 20
years without being changed I asked the question.

Reading, after I posted up there--^ DOT 3,4 and 5.1 are hygroscopic
polyputtheketteon, DOT 5 is silicone and isn't.

Soo...hygroscopic ones need replacing, silicone ones last a lot longer.

So if it has silicone it will probably be ok, the issue is moisture
pools at the bottom of the system potentially causing rot.

On 18/06/2020 08:32, John B. wrote:
On Wed, 17 Jun 2020 23:07:14 -0700 (PDT), wrote:

On Thursday, June 18, 2020 at 6:48:38 AM UTC+2, John B. wrote:
Someone cautioned that DOT brake fluid, in bicycle disk brakes, should
be changed annually.
Is this correct? A requirement of the disk makers? Or ?
--
cheers,

John B.

Never heard of that requirement. In my car is is changed every 2 years.

Lou

Somebody here, talking about bicycle disk brakes mentioned that DOT
liquid must be changed annually while mineral oil did not require
this.

As the DOT brake oil in my pickup truck has been there for probably 20
years without being changed I asked the question.

Errmmm...might be ok. If it's DOT 5.1

On 6/17/2020 11:07 PM, wrote:
On Thursday, June 18, 2020 at 6:48:38 AM UTC+2, John B. wrote:
Someone cautioned that DOT brake fluid, in bicycle disk brakes, should
be changed annually.
Is this correct? A requirement of the disk makers? Or ?
--
cheers,

John B.

Never heard of that requirement. In my car is is changed every 2 years.

Lou

Lou

I can't imagine changing bicycle brake fluid annually. In a motor
vehicle you're supposed to change it every couple of years because you
get some water in there, especially in humid climates.

Do they also advise you to change the air in your tires?

On 18/06/2020 15:09, sms wrote:
On 6/17/2020 11:07 PM, wrote:
On Thursday, June 18, 2020 at 6:48:38 AM UTC+2, John B. wrote:
Someone cautioned that DOT brake fluid, in bicycle disk brakes, should
be changed annually.
Is this correct? A requirement of the disk makers? Or ?
--
cheers,

John B.

Never heard of that requirement. In my car is is changed every 2 years.

Lou

Lou

I can't imagine changing bicycle brake fluid annually. In a motor
vehicle you're supposed to change it every couple of years because you
get some water in there, especially in humid climates.

Do they also advise you to change the air in your tires?

No you can keep the same air as long as you want, if I was you I'd do
exactly that and not waste time adding any.

sms wrote:
On 6/17/2020 11:07 PM, wrote:
On Thursday, June 18, 2020 at 6:48:38 AM UTC+2, John B. wrote:
Someone cautioned that DOT brake fluid, in bicycle disk brakes, should
be changed annually.
Is this correct? A requirement of the disk makers? Or ?
--
cheers,

John B.

Never heard of that requirement. In my car is is changed every 2 years.

Lou

Lou

I can't imagine changing bicycle brake fluid annually. In a motor
vehicle you're supposed to change it every couple of years because you
get some water in there, especially in humid climates.

Do they also advise you to change the air in your tires?


Bicycle disk brake system probably have a higher ratio of surface area to
volume than automotive systems, and therefore might accumulate water at a
faster rate (in much the same way that bike tires go flat faster than car
tires).