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Formula brakes and Carbon fibre handlebars - DOT Fluid issue

iain1775iain1775 Posts: 98
edited June 2008 in MTB workshop & tech
Anybody experienced any problems with Formula Oro brakes on carbon handlebars?
There is a small hole on the inside of the clamp to let air in/out of the expansion reservoir
Apparently DOT Fluid can occasionally leak out and comes into direct contact with the handlebar.
As you probably know DOT fluid and carbon is not a good combo.
I originally heard of this problem on an old mtbr forum from 2006 and it came up again elsewhere so decided to investigate and having removed my brakes yesterday I have noticed that the laquer is eaten away and the carbon isnt looking too clever.

Emailed Formula and got this response -

"Tucked away beneath that hole is a small rubber bladder gasket that is the
expansion reservoir of your brake system. Fluid sits below this bladder.
Under normal operation of the brake the fluid in the system becomes hot
(heat being a by product of the friction between pads and disc). It is usual
that under normal operation of the brake system that condensation will build
up in this area. The small hole is there to allow the passage of air in and
out of the system as the bladder expands and contracts with the fluid and
also to allow condensation to weep free.

It is possible to find trace residue of brake fluid in this condensation and
as DOT brake fluid is a corrosive and can damage some plastics and paints we
suggest regular cleaning with isopropyl alcohol, this is easily obtained in
the form of zero residue electrical contact cleaner that can be purchased
from any good automotive retailer. It is suitable for many cleaning
applications associated with disc brake systems. I would also suggest that
you contact the manufacturer of the bar and ask them about the suitability
of this material for exposure to traces of DOT fluid. Many carbon products
are covered with a protective lacquer that should be enough to protect the
bar however it is impossible for me to comment as we handle no products of
this nature. When kept clean and correctly maintained there should be no
reason to find any brake fluid in this area.

I hope this is some help, if you need any further information you can call
us during office hours on the number below."


[email protected]
Tel: 01726 825038 Fax: 01726 825041
Unit 3, Mid Cornwall Business Centre, St Austell Bay Business Park, Par Moor
Road, St Austell, Cornwall, PL25 3RF.

Seems plausable but I do feel that the damage starting on my bar is caused by more than just "trace elements", and I don't fancy removing brake levers and cleaning underneath after every ride, surely this is a bad design if you have to go to those extremes!

I plan to send a photo of the bar off to Formula and to FSA and get both opinions.

In the mean time I am going to make a shim out of a coke can and place that between the brakes and the bar to offer some protection (hopefully any trace elements of diet Coke won't affect the carbon )


  • nicklousenicklouse Posts: 50,675 Lives Here
    so you now want to put the bar under greater forces by introducing a shim?

    if you are concerned i would remove the cap and clean the rubber bladder so there is zero fluid on the out side and then re-bleed they system.
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • iain1775iain1775 Posts: 98
    how does putting a very thin shim under create greater forces?
    It is not loads on the bar I am concerned about but fluid coming into contact with the bar

    Obviously I will clean everything, but the fluid is obviously leaking under general use and from what I read elsewhere will leak after the brakes are bled also. How often do you intend I strip, clean and then have to re-bleed my brakes, after every ride???

    I forgot to mention these brakes are only a few months old

    what cap? how do I remove it?
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