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Brake calipers with least center depth?

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Scott Gordo

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May 21, 2012, 1:00:16 PM5/21/12
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I have a buddy who drilled his fork and now finds that the single
pivot brakes he's tried rub against the top of the tire. Anyone else
run into this, and have a brake to recommend with minimal material
below the bolt?

I was thinking about recommending he find an old Weinmann and file it
down until the tire clears, but that sounds like a Very Bad Idea.

Thanks ;)
Scott

DirtRoadie

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May 21, 2012, 2:39:06 PM5/21/12
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I don't have a brake recommendation but the other thought that comes
to mind is seeing whether it might be possible to use an old brake
"drop bolt" turned upside down. I don't have any idea whether such
things are still available but I'm sure Andrew and Chalo know.

DR

AMuzi

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May 21, 2012, 3:42:23 PM5/21/12
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It will not and moreover there are no such products for DP
calipers. Campagnolo made the 2012/2 for the rear brake in
1968 when many otherwise nice bicycles from the 1950s and
1960s were still around but built for a 610 front with 750
rear CP and could not otherwise use Campagnolo's new 500
length sidepull caliper.

Those among us who deduced that he drilled a track fork with
insufficient clearance for a standard brake caliper have
otherwise not commented.

--
Andrew Muzi
<www.yellowjersey.org/>
Open every day since 1 April, 1971

DirtRoadie

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May 21, 2012, 4:38:41 PM5/21/12
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On May 21, 1:42 pm, AMuzi <a...@yellowjersey.org> wrote:
> DirtRoadie wrote:
> > On May 21, 11:00 am, Scott Gordo <blubberp...@gmail.com> wrote:
> >> I have a buddy who drilled his fork and now finds that the single
> >> pivot brakes he's tried rub against the top of the tire. Anyone else
> >> run into this, and have a brake to recommend with minimal material
> >> below the bolt?
>
> >> I was thinking about recommending he find an old Weinmann and file it
> >> down until the tire clears, but that sounds like a Very Bad Idea.
>
> > I don't have a brake recommendation but the other thought that comes
> > to mind is seeing whether it might be possible to use an old brake
> > "drop bolt" turned upside down. I don't have any idea whether such
> > things are still available but I'm sure Andrew and Chalo know.
>
> It will not and moreover there are no such products for DP
> calipers.

Well the OP did say "...the single pivot brakes he's tried rub..."
In looking at a drop bolt I have I now see that its specific
incarnation would not work properly if inverted because there is a
groove to retain the return spring which is above the brake mounting
bolt. If nothing else, that would be out of place.
But there is enough bulk in the connector portion of the bolt itself
(it's pretty beefy) that its clearance is probably no more than an
additional mm or
two better than the caliper arms.

Another potential kludge, but might the brake be repositioned or
placed behind the fork to get a little more clearance?
DR

Frank Krygowski

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May 21, 2012, 4:51:03 PM5/21/12
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Not necessarily a _very_ bad idea. It depends how much material you
have to remove. I did that once to a rear Shimano Tiagra (IIRC) dual
pivot brake. It's still working fine, thousands of miles and ten years
later. But I didn't remove very much material at all.

So how much would the clearance need to be increased?


--
- Frank Krygowski

James

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May 21, 2012, 5:33:09 PM5/21/12
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On 22/05/12 03:00, Scott Gordo wrote:
> I have a buddy who drilled his fork and now finds that the single
> pivot brakes he's tried rub against the top of the tire.

Use a smaller tyre?

--
JS.

datakoll

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May 21, 2012, 6:31:36 PM5/21/12
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Shaping adapters, filed/ground bolt/rod/red loctite shapes and aluminum backer blocks hold the unit farther out, finding a unit with longer pad holder arms ? for filing out, elongating with a new round file ?

ask Jenson and Nashbar: callum

The Ivan Basso unit ?

filing out a wee bit produces a lotta drop.

James

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May 21, 2012, 7:52:36 PM5/21/12
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Drill a second hole?

--
JS.

AMuzi

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May 21, 2012, 8:36:57 PM5/21/12
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You're right, sorry.

Maybe possible with a single pivot and a new spring slot. I
wouldn't, but he could try that.

DirtRoadie

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May 21, 2012, 9:49:44 PM5/21/12
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Or move the wheel slightly in the dropouts?
I have adjusted custom dropouts made from flat plate by both filing
and filling (how's that for contrasting words?) in order to achieve
correct wheel alignment, so it's certainly a possibility.
DR

datakoll

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May 21, 2012, 10:57:30 PM5/21/12
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yeah I don't follow. an aluminum strip with two holes....thickness brings the unit forward with more rub but the second hole below the first corrects.
the block can be threaded and bolted from behind. an aluminumm or prob steel strip bolted to fork then lead forward durved or stepped dopwnward to position adjustabole pad slots....the unit has pad bolt slots right ?

datakoll

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May 22, 2012, 1:48:25 AM5/22/12
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iow THE PROB ISN'T cd (FILE AWAY) BUT POSITION. ANY RUBY G RIG LOOKING ELEGANT WILL DO.BLOCK ON FRAME, S STRIO ON BLOCK, BLOCK ON S STRIO THERE MOUNT UNIT.
UGHPEOPLE WILL SCREAM "JESUS LOOKIT THAT URA GENIUS"

datakoll

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May 22, 2012, 11:06:57 AM5/22/12
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On Monday, May 21, 2012 11:48:25 PM UTC-6, datakoll wrote:
> iow THE PROB ISN'T cd (FILE AWAY) BUT POSITION. ANY RUBY G RIG LOOKING ELEGANT WILL DO.BLOCK ON FRAME, S STRIO ON BLOCK, BLOCK ON S STRIO THERE MOUNT UNIT.
> UGHPEOPLE WILL SCREAM "JESUS LOOKIT THAT URA GENIUS"

typed that at 12AM on top of mountain in the dark. looks it. Your description of the prob as least center depth not longer pad arms suggests trying moving the pieces around manually several more times then drawing the problem. The available geometries for prob solution may not be immediately evident.

a look at past brake systems timeline, possibly available online...there's a rear deray collection...and experience tryiong to cope with adjustment and maint. is revealing as the inventors seam to share the problem.

xpzzzz

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May 24, 2012, 10:26:18 AM5/24/12
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Most of the 60's/70's era brakes were about 9mm bolt-centre-to-bridge/
boss edge. Side-pulls were usually on the big side, 10mm-ish, and
Weinmans generally smaller (*not* the 570 Top) at 8.5mm; their Symetric
is about 8mm. The smallest in the parts box was a Mafac Competition at a
bit under 7mm, which has a slot where most center-pull bridges have a
hole. This bridge has a drop-section (in the vertical plane) to allow
for the slot; and I don't think he should file a plain old bridge down to
mimic it - they don't have any more material and the slot in the
Competition is forged.

If 9mm is enough there are plenty of old Weinmann centre-pulls around,
and they'll work fine. Their levers are wobbly, a bit of fiddling to
remove side-play at the body will improve feel.

He may have an added difficulty finding arms short enough to contact the
rims.
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