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Discussion Starter · #1 ·
Got a new Orbea Orca M30 Pro (2016 leftover) last weekend, and neither of the brake calipers (105) will stay centered. 3 or 4 times now I've taken the bolts loose and centered the calipers (then fine tuned with the adjuster screw), after 15-20 miles they are both off center, usually to the opposite of the cable side. Have to loosen the adjuster screw to recenter them, but usually run out of travel on the adjuster before they're back like they should be. The one pad is almost touching the rim and the other has a good size gap between it and the rim. It's enough that when the bike is on the stand I can see the rim move to the side when I squeeze the lever. I'm tightening the mount bolt pretty tight with a normal long Allen wrench, but hesitant to get too midieval on it for fear of breaking the carbon frame or fork.
Never had this problem before, what am I missing here?
 

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cable housing length
 

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Discussion Starter · #4 ·
Went back and had another look at it. Found that I could move the brake arms with my fingers, so believe they just weren't tight enough. I took a deep breath and twisted the mount bolts on down some more. They're for sure tight now (nothing broke), so I'll see if they stay put now.
Wish bicycles had more torque specs like motorcycles do. Occasional Nm spec on stem bolts or a seat post clamp, but I've never really found much else.
 

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Discussion Starter · #5 ·
Cable housing lengths look to be good. Long enough to still have a bit of slack when I apply the brakes, but not an excessive amount. What exactly would I be looking for with the housing lengths? I've never given it much thought actually. Dealership built this one, but in the past I've always just cut them to where there was "enough" and went with it. While the subject is here, is there a set formula or way to go about making sure they're the right length?
 

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sheldon covers this.

this one is too long and pushes the caliper to the opposite side:



this one is just right:

 
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Discussion Starter · #8 ·
Housing should be as short as possible.

The spec you're looking for is 8 newton meters.
Ok, worked up to 70 in lbs (8 Nm converts to 70.83 in lbs) on both bolts. Was a bit tighter than i had it by hand. Once again, nothing creaked, cracked, or broke (sigh of relief :D).


sheldon covers this.

this one is too long and pushes the caliper to the opposite side:



this one is just right:

It looks like my rear housing might be a hair on the long side. It's about in the middle between the two photos. Front should be good as there's no real excess there either.
See if getting the mount bolts tightened does the trick. If they still move, I'll take it back to the shop where I got it and tell them to deal with it.
Thank you both for all your input and help. i learned a couple things here. :thumbsup:
 

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sheldon covers this.

this one is too long and pushes the caliper to the opposite side:



this one is just right:

Like much of Sheldon's stuff those photos are really outdated. That's a single pivot caliper which does need to have the housing the proper length. On all modern brakes (SRAM Red being the exception) housing length doesn't make the brake move if it's properly tightened, just as the OP discovered.
 

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Found that I could move the brake arms with my fingers
You need to be actually moving the brake body - think of pivoting the entire brake around the center mounting bolt. Not sure from your description if this is what you are doing. Lots of people just push on the brake arms, they move to "proper" position relative to the rim, and then as soon as you operate the brakes they are off center relative to the rim because the body of the brake is not centered.

I typically tighten my brake mounting bolts so that I can move the body of the brake with firm finger pressure. I can adjust the brake centering if it gets knocked out of line for some reason, but the brake will not go off center just through usage.
 

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My centering technique is to sight directly down onto the center of the tire as I actuate the brake. If the brake is centered there will be no rim movement either way. Adjust as necessary.
 
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