DeRosa Merak Rear Brake

[Tom Kunich]

I discovered why I got the DeRosa for nearly nothing. When it became time
to install the rear brake, there is an internally threaded aluminum bolt
in the hole. The outside of the (front facing) bolt has an allen head on
it but being aluminum, is stripped. The inside of the device is 5 mm and
threadding a screw in until it hits the end does not allow it to be
unscrewed and I don't want to force it since it is aluminum.

I have never seen a rear brake that attaches from the rear and an Ultegra
brake shaft is 5.75 mm. (thread depth on what's present) Now I could drill
a shaft size hole fron the back but this would leave about 28 mm on the
other side that needs a hole 8 mm in diameter with stop 10 mm in diameter.
I could also drill a hole 8 mm in diamerer and the normal connector would
hold it in the center if the present stop would allow me to tighten it
enough. Or I could use a steel washer 8 mm ID to spread the load of the
stop enough to allow me to tighten it enough to lock everything.

As I say, I've never seen anything like this before and it appears like
the this thing was either threaded in (unlikely into a carbon fiber rear B-
stay) or glued in (extremely poor judgement if so). It also could be
simply an slight interference fit into the original hole and that would
explain the reason the allen headed front facing fixture stripped. If this
were the case, I could thread this deep 5 mm bolt in to the rear id taping
with a hammer or pushing with a puller, pushing that thing out without any
damage to the original hole.

Now, has anyone else ever seen anything like this and do you have any
comments? Would you have any suggestions on what to do?

[AMuzi]

Post by Tom Kunich
I discovered why I got the DeRosa for nearly nothing. When it became time
to install the rear brake, there is an internally threaded aluminum bolt
in the hole. The outside of the (front facing) bolt has an allen head on
it but being aluminum, is stripped. The inside of the device is 5 mm and
threadding a screw in until it hits the end does not allow it to be
unscrewed and I don't want to force it since it is aluminum.
I have never seen a rear brake that attaches from the rear and an Ultegra
brake shaft is 5.75 mm. (thread depth on what's present) Now I could drill
a shaft size hole fron the back but this would leave about 28 mm on the
other side that needs a hole 8 mm in diameter with stop 10 mm in diameter.
I could also drill a hole 8 mm in diamerer and the normal connector would
hold it in the center if the present stop would allow me to tighten it
enough. Or I could use a steel washer 8 mm ID to spread the load of the
stop enough to allow me to tighten it enough to lock everything.
As I say, I've never seen anything like this before and it appears like
the this thing was either threaded in (unlikely into a carbon fiber rear B-
stay) or glued in (extremely poor judgement if so). It also could be
simply an slight interference fit into the original hole and that would
explain the reason the allen headed front facing fixture stripped. If this
were the case, I could thread this deep 5 mm bolt in to the rear id taping
with a hammer or pushing with a puller, pushing that thing out without any
damage to the original hole.
Now, has anyone else ever seen anything like this and do you have any
comments? Would you have any suggestions on what to do?

Your description sounds like a regular M6 brake mounting
sleeve installed backwards.

(guys do install calipers behind the seat stays. No
functional reason to do that. But no technical reason not to
either. Looks dorky to me. There are setups where the
slightly different brake reach matters, but that would be
very rare.)

Unless there's something I don't know about this, I'd screw
an M6 bolt into it, warm it with a heat gun (Not hot, warm.
Carbon adhesives don't like hot) and give it a sharp rap.

I agree that any drilling, reaming, assault with the dreaded
Dremel destruction device, or any material removal at all is
a bad idea until or unless you understand the problem better.

[Zen Cycle]

Post by Tom Kunich
I discovered why I got the DeRosa for nearly nothing. When it became time
to install the rear brake, there is an internally threaded aluminum bolt
in the hole. The outside of the (front facing) bolt has an allen head on
it but being aluminum, is stripped. The inside of the device is 5 mm and
threadding a screw in until it hits the end does not allow it to be
unscrewed and I don't want to force it since it is aluminum.
I have never seen a rear brake that attaches from the rear and an Ultegra
brake shaft is 5.75 mm. (thread depth on what's present) Now I could drill
a shaft size hole fron the back but this would leave about 28 mm on the
other side that needs a hole 8 mm in diameter with stop 10 mm in diameter.
I could also drill a hole 8 mm in diamerer and the normal connector would
hold it in the center if the present stop would allow me to tighten it
enough. Or I could use a steel washer 8 mm ID to spread the load of the
stop enough to allow me to tighten it enough to lock everything.
As I say, I've never seen anything like this before and it appears like
the this thing was either threaded in (unlikely into a carbon fiber rear B-
stay) or glued in (extremely poor judgement if so). It also could be
simply an slight interference fit into the original hole and that would
explain the reason the allen headed front facing fixture stripped. If this
were the case, I could thread this deep 5 mm bolt in to the rear id taping
with a hammer or pushing with a puller, pushing that thing out without any
damage to the original hole.
Now, has anyone else ever seen anything like this and do you have any
comments? Would you have any suggestions on what to do?

Your description sounds like a regular M6 brake mounting sleeve
installed backwards.
(guys do install calipers behind the seat stays. No functional reason to
do that. But no technical reason not to either. Looks dorky to me. There
are setups where the slightly different brake reach matters, but that
would be very rare.)
Unless there's something I don't know about this, I'd screw an M6 bolt
into it, warm it with a heat gun (Not hot, warm. Carbon adhesives don't
like hot) and give it a sharp rap.
I agree that any drilling, reaming, assault with the dreaded Dremel
destruction device, or any material removal at all is a bad idea until
or unless you understand the problem better.

"until or unless you understand the problem better."

That's a pretty tall request considering the intended recipient.

[cyclintom]

Post by Zen Cycle

Post by Tom Kunich
I discovered why I got the DeRosa for nearly nothing. When it became time
to install the rear brake, there is an internally threaded aluminum bolt
in the hole. The outside of the (front facing) bolt has an allen head on
it but being aluminum, is stripped. The inside of the device is 5 mm and
threadding a screw in until it hits the end does not allow it to be
unscrewed and I don't want to force it since it is aluminum.
I have never seen a rear brake that attaches from the rear and an Ultegra
brake shaft is 5.75 mm. (thread depth on what's present) Now I could drill
a shaft size hole fron the back but this would leave about 28 mm on the
other side that needs a hole 8 mm in diameter with stop 10 mm in diameter.
I could also drill a hole 8 mm in diamerer and the normal connector would
hold it in the center if the present stop would allow me to tighten it
enough. Or I could use a steel washer 8 mm ID to spread the load of the
stop enough to allow me to tighten it enough to lock everything.
As I say, I've never seen anything like this before and it appears like
the this thing was either threaded in (unlikely into a carbon fiber rear B-
stay) or glued in (extremely poor judgement if so). It also could be
simply an slight interference fit into the original hole and that would
explain the reason the allen headed front facing fixture stripped. If this
were the case, I could thread this deep 5 mm bolt in to the rear id taping
with a hammer or pushing with a puller, pushing that thing out without any
damage to the original hole.
Now, has anyone else ever seen anything like this and do you have any
comments? Would you have any suggestions on what to do?

Your description sounds like a regular M6 brake mounting sleeve
installed backwards.
(guys do install calipers behind the seat stays. No functional reason to
do that. But no technical reason not to either. Looks dorky to me. There
are setups where the slightly different brake reach matters, but that
would be very rare.)
Unless there's something I don't know about this, I'd screw an M6 bolt
into it, warm it with a heat gun (Not hot, warm. Carbon adhesives don't
like hot) and give it a sharp rap.
I agree that any drilling, reaming, assault with the dreaded Dremel
destruction device, or any material removal at all is a bad idea until
or unless you understand the problem better.

"until or unless you understand the problem better."
That's a pretty tall request considering the intended recipient.

The coward speaks again from the position of anonymity.

[AMuzi]

Post by Zen Cycle

Post by AMuzi

Post by Tom Kunich
I discovered why I got the DeRosa for nearly nothing.
When it became time
to install the rear brake, there is an internally
threaded aluminum bolt
in the hole. The outside of the (front facing) bolt has
an allen head on
it but being aluminum, is stripped. The inside of the
device is 5 mm and
threadding a screw in until it hits the end does not
allow it to be
unscrewed and I don't want to force it since it is aluminum.
I have never seen a rear brake that attaches from the
rear and an Ultegra
brake shaft is 5.75 mm. (thread depth on what's present)
Now I could drill
a shaft size hole fron the back but this would leave
about 28 mm on the
other side that needs a hole 8 mm in diameter with stop
10 mm in diameter.
I could also drill a hole 8 mm in diamerer and the normal
connector would
hold it in the center if the present stop would allow me
to tighten it
enough. Or I could use a steel washer 8 mm ID to spread
the load of the
stop enough to allow me to tighten it enough to lock
everything.
As I say, I've never seen anything like this before and
it appears like
the this thing was either threaded in (unlikely into a
carbon fiber rear B-
stay) or glued in (extremely poor judgement if so). It
also could be
simply an slight interference fit into the original hole
and that would
explain the reason the allen headed front facing fixture
stripped. If this
were the case, I could thread this deep 5 mm bolt in to
the rear id taping
with a hammer or pushing with a puller, pushing that
thing out without any
damage to the original hole.
Now, has anyone else ever seen anything like this and do
you have any
comments? Would you have any suggestions on what to do?

Your description sounds like a regular M6 brake mounting
sleeve installed backwards.
(guys do install calipers behind the seat stays. No
functional reason to do that. But no technical reason not
to either. Looks dorky to me. There are setups where the
slightly different brake reach matters, but that would be
very rare.)
Unless there's something I don't know about this, I'd
screw an M6 bolt into it, warm it with a heat gun (Not
hot, warm. Carbon adhesives don't like hot) and give it a
sharp rap.
I agree that any drilling, reaming, assault with the
dreaded Dremel destruction device, or any material removal
at all is a bad idea until or unless you understand the
problem better.

"until or unless you understand the problem better."
That's a pretty tall request considering the intended
recipient.

Well, yes.
Hard to offer definitive advice when the problem is poorly
described.

[Frank Krygowski]

Post by AMuzi

Post by Zen Cycle

Post by Tom Kunich
I discovered why I got the DeRosa for nearly nothing. When it became time
to install the rear brake, there is an internally threaded aluminum bolt
in the hole. The outside of the (front facing) bolt has an allen head on
it but being aluminum, is stripped. The inside of the device is 5 mm and
threadding a screw in until it hits the end does not allow it to be
unscrewed and I don't want to force it since it is aluminum.
I have never seen a rear brake that attaches from the rear and an Ultegra
brake shaft is 5.75 mm. (thread depth on what's present) Now I could drill
a shaft size hole fron the back but this would leave about 28 mm on the
other side that needs a hole 8 mm in diameter with stop 10 mm in diameter.
I could also drill a hole 8 mm in diamerer and the normal connector would
hold it in the center if the present stop would allow me to tighten it
enough. Or I could use a steel washer 8 mm ID to spread the load of the
stop enough to allow me to tighten it enough to lock everything.
As I say, I've never seen anything like this before and it appears like
the this thing was either threaded in (unlikely into a carbon fiber rear B-
stay) or glued in (extremely poor judgement if so). It also could be
simply an slight interference fit into the original hole and that would
explain the reason the allen headed front facing fixture stripped. If this
were the case, I could thread this deep 5 mm bolt in to the rear id taping
with a hammer or pushing with a puller, pushing that thing out without any
damage to the original hole.
Now, has anyone else ever seen anything like this and do you have any
comments? Would you have any suggestions on what to do?

Your description sounds like a regular M6 brake mounting sleeve
installed backwards.
(guys do install calipers behind the seat stays. No functional reason
to do that. But no technical reason not to either. Looks dorky to me.
There are setups where the slightly different brake reach matters,
but that would be very rare.)
Unless there's something I don't know about this, I'd screw an M6
bolt into it, warm it with a heat gun (Not hot, warm. Carbon
adhesives don't like hot) and give it a sharp rap.
I agree that any drilling, reaming, assault with the dreaded Dremel
destruction device, or any material removal at all is a bad idea
until or unless you understand the problem better.

"until or unless you understand the problem better."
That's a pretty tall request considering the intended recipient.

Well, yes.
Hard to offer definitive advice when the problem is poorly described.

I too found the description to be poor. Again, I think if Tom gave some
close up photos from different angles, plus (say) a decent engineering
drawing or sketch of the troublesome insert, he'd have a better chance
of getting some good advice.

[cyclintom]

Post by Frank Krygowski

Post by AMuzi

Post by Zen Cycle

Post by Tom Kunich
I discovered why I got the DeRosa for nearly nothing. When it became time
to install the rear brake, there is an internally threaded aluminum bolt
in the hole. The outside of the (front facing) bolt has an allen head on
it but being aluminum, is stripped. The inside of the device is 5 mm and
threadding a screw in until it hits the end does not allow it to be
unscrewed and I don't want to force it since it is aluminum.
I have never seen a rear brake that attaches from the rear and an Ultegra
brake shaft is 5.75 mm. (thread depth on what's present) Now I could drill
a shaft size hole fron the back but this would leave about 28 mm on the
other side that needs a hole 8 mm in diameter with stop 10 mm in diameter.
I could also drill a hole 8 mm in diamerer and the normal connector would
hold it in the center if the present stop would allow me to tighten it
enough. Or I could use a steel washer 8 mm ID to spread the load of the
stop enough to allow me to tighten it enough to lock everything.
As I say, I've never seen anything like this before and it appears like
the this thing was either threaded in (unlikely into a carbon fiber rear B-
stay) or glued in (extremely poor judgement if so). It also could be
simply an slight interference fit into the original hole and that would
explain the reason the allen headed front facing fixture stripped. If this
were the case, I could thread this deep 5 mm bolt in to the rear id taping
with a hammer or pushing with a puller, pushing that thing out without any
damage to the original hole.
Now, has anyone else ever seen anything like this and do you have any
comments? Would you have any suggestions on what to do?

Your description sounds like a regular M6 brake mounting sleeve
installed backwards.
(guys do install calipers behind the seat stays. No functional reason
to do that. But no technical reason not to either. Looks dorky to me.
There are setups where the slightly different brake reach matters,
but that would be very rare.)
Unless there's something I don't know about this, I'd screw an M6
bolt into it, warm it with a heat gun (Not hot, warm. Carbon
adhesives don't like hot) and give it a sharp rap.
I agree that any drilling, reaming, assault with the dreaded Dremel
destruction device, or any material removal at all is a bad idea
until or unless you understand the problem better.

"until or unless you understand the problem better."
That's a pretty tall request considering the intended recipient.

Well, yes.
Hard to offer definitive advice when the problem is poorly described.

I too found the description to be poor. Again, I think if Tom gave some
close up photos from different angles, plus (say) a decent engineering
drawing or sketch of the troublesome insert, he'd have a better chance
of getting some good advice.

After all, no one and especially you knows what a B-Stay is and although there are at least three different names for what is presently called a pivot screw, it is impossible to understand "brake locking screw".

You need an engineering drawing, but then you needed and engineering drawing of a splined hollow crankset. without an engineering drawing (when you could look on Ebay and see the actual thing.) You think that the crankset should "wobble" before it falls off.

I managed without a degree in mechanical engineering or a PE to figure out a way to repair it but sinxe no on can understand my terminology there is no use in explaining it.

[AMuzi]

Post by Tom Kunich
I discovered why I got the DeRosa for nearly nothing. When it became time
to install the rear brake, there is an internally threaded aluminum bolt
in the hole. The outside of the (front facing) bolt has an allen head on
it but being aluminum, is stripped. The inside of the device is 5 mm and
threadding a screw in until it hits the end does not allow it to be
unscrewed and I don't want to force it since it is aluminum.
I have never seen a rear brake that attaches from the rear and an Ultegra
brake shaft is 5.75 mm. (thread depth on what's present) Now I could drill
a shaft size hole fron the back but this would leave about 28 mm on the
other side that needs a hole 8 mm in diameter with stop 10 mm in diameter.
I could also drill a hole 8 mm in diamerer and the normal connector would
hold it in the center if the present stop would allow me to tighten it
enough. Or I could use a steel washer 8 mm ID to spread the load of the
stop enough to allow me to tighten it enough to lock everything.
As I say, I've never seen anything like this before and it appears like
the this thing was either threaded in (unlikely into a carbon fiber rear B-
stay) or glued in (extremely poor judgement if so). It also could be
simply an slight interference fit into the original hole and that would
explain the reason the allen headed front facing fixture stripped. If this
were the case, I could thread this deep 5 mm bolt in to the rear id taping
with a hammer or pushing with a puller, pushing that thing out without any
damage to the original hole.
Now, has anyone else ever seen anything like this and do you have any
comments? Would you have any suggestions on what to do?

Your description sounds like a regular M6 brake mounting
sleeve installed backwards.

(guys do install calipers behind the seat stays. No
functional reason to do that. But no technical reason not to
either. Looks dorky to me. There are setups where the
slightly different brake reach matters, but that would be
very rare.)

Unless there's something I don't know about this, I'd screw
an M6 bolt into it, warm it with a heat gun (Not hot, warm.
Carbon adhesives don't like hot) and give it a sharp rap.

I agree that any drilling, reaming, assault with the dreaded
Dremel destruction device, or any material removal at all is
a bad idea until or unless you understand the problem better.