Weird hydraulic disc brake issue...

I have a set of magura marta disc brakes and had the oddest experience
that I figured I'd share...

The symptom was after installing new pads, the grip strength of the
rear caliper was insufficient to lock up the rear wheel. Lever travel
and feel was normal, the only difference was braking force.

Long story short, after endless futzing with pads, rotors, and bedding-
in techniques, the problem was ultimately fixed with a bleed. I
figure that pressing in the pistons before installing the pads must
have allowed some air intrusion.

What's odd to me is that when I've had air bubbles in the brake lines
in the past, pumping the lever would enable me to get sufficient
power. This makes sense to me. With enough pressure, the air will
compress enough to transmit braking force. That wasn't the case this
time.

Its not at all clear to me how a bleed could fix the issue I was
experiencing, but it did.

Dave wrote:
I have a set of magura marta disc brakes and had the oddest experience
that I figured I'd share...

The symptom was after installing new pads, the grip strength of the
rear caliper was insufficient to lock up the rear wheel. Lever travel
and feel was normal, the only difference was braking force.

Long story short, after endless futzing with pads, rotors, and bedding-
in techniques, the problem was ultimately fixed with a bleed. I
figure that pressing in the pistons before installing the pads must
have allowed some air intrusion.

more likely the result of putting the bike in a non-operating position
thus allowing air in the master cylinder fluid chamber to intrude.


What's odd to me is that when I've had air bubbles in the brake lines
in the past, pumping the lever would enable me to get sufficient
power. This makes sense to me. With enough pressure, the air will
compress enough to transmit braking force. That wasn't the case this
time.

Its not at all clear to me how a bleed could fix the issue I was
experiencing, but it did.

if there's air, of course it will.