"Actually you are the first person to bring up this issue"

Mark Hickey writes:

Does the industry have a duty to warn customers NOW? I don't
know... it all depends on how compelling the data they have is. I
have no problem at all believing the data they have right now
doesn't compel them to do an expensive recall / or to scare existing
customers.

"Compelling is in the eye of the beholder" seems to be what you're
suggesting. Fair enough, I think. In the case of the manufacturers,
I suspect that "compelling" is going to be equated with "massive
product liability if we don't immediately fix it" and they don't see
that yet. I think they're burying their heads, but that's between
themselves, their lawyers and their liability insurance carriers. In
the meantime, the users of these products are the ones assuming the
risk.

Mark Hickey writes:

Does the industry have a duty to warn customers NOW? I don't
know... it all depends on how compelling the data they have is. I
have no problem at all believing the data they have right now
doesn't compel them to do an expensive recall / or to scare existing
customers.

"Compelling is in the eye of the beholder" seems to be what you're
suggesting. Fair enough, I think. In the case of the manufacturers,
I suspect that "compelling" is going to be equated with "massive
product liability if we don't immediately fix it" and they don't see
that yet. I think they're burying their heads, but that's between
themselves, their lawyers and their liability insurance carriers. In
the meantime, the users of these products are the ones assuming the
risk.

Tim McNamara wrote:

"Compelling is in the eye of the beholder" seems to be what you're
suggesting. Fair enough, I think. In the case of the manufacturers,
I suspect that "compelling" is going to be equated with "massive
product liability if we don't immediately fix it" and they don't see
that yet. I think they're burying their heads, but that's between
themselves, their lawyers and their liability insurance carriers. In
the meantime, the users of these products are the ones assuming the
risk.

From the replys and lack of replies I had to the question I asked earlier
"Compelling" would seem to require at least having one person from the many
tens of thousand mountain bikers out there using discs reporting to a
manufacturer that they have experienced a problem of this nature with their
product. So far it looks as if no-one has done that in which case it would
not be unreasonable for them to assume that whatever the theory, across a
large population sample it is not happening in practice.

Have a look at the number of bicycle related CPSC actions and recalls
(http://www.cpsc.gov/cgi-bin/recalldb/prod.asp, choose Bicycles and
Accessories and click Find)and ask why on earth would they ignore this
particular problem when handlebars, forks, stems, helmets, whole bicycles,
disc brake rotors etc are being recalled all the time, sometimes at quite
considerable financial cost to the manufacturer. Either it is a massively
complex and coordinated conspiracy involving multiple companies across the
globe and the US government or there is a simpler answer.

Tony

Tim McNamara wrote:

"Compelling is in the eye of the beholder" seems to be what you're
suggesting. Fair enough, I think. In the case of the manufacturers,
I suspect that "compelling" is going to be equated with "massive
product liability if we don't immediately fix it" and they don't see
that yet. I think they're burying their heads, but that's between
themselves, their lawyers and their liability insurance carriers. In
the meantime, the users of these products are the ones assuming the
risk.

From the replys and lack of replies I had to the question I asked earlier
"Compelling" would seem to require at least having one person from the many
tens of thousand mountain bikers out there using discs reporting to a
manufacturer that they have experienced a problem of this nature with their
product. So far it looks as if no-one has done that in which case it would
not be unreasonable for them to assume that whatever the theory, across a
large population sample it is not happening in practice.

Have a look at the number of bicycle related CPSC actions and recalls
(http://www.cpsc.gov/cgi-bin/recalldb/prod.asp, choose Bicycles and
Accessories and click Find)and ask why on earth would they ignore this
particular problem when handlebars, forks, stems, helmets, whole bicycles,
disc brake rotors etc are being recalled all the time, sometimes at quite
considerable financial cost to the manufacturer. Either it is a massively
complex and coordinated conspiracy involving multiple companies across the
globe and the US government or there is a simpler answer.

Tony

wrote:


Let's get the caliper in the right place!


Right place for what? It might reverse the ejection force into a holding in
force but OTOH the caliper is out front where it is much more susceptible to
damage and to getting the mounting tabs bent/strained by hitting things. The
mounts would also be under tension under braking, rather than compression
which has an increased chance of failure. Specialized have already had a
recall for mounting tab failures. Don't simply replace one problem with
another and think through all the failure modes of a proposed solution before
implementing it - Design Control 101.

Tony

wrote:


Let's get the caliper in the right place!


Right place for what? It might reverse the ejection force into a holding in
force but OTOH the caliper is out front where it is much more susceptible to
damage and to getting the mounting tabs bent/strained by hitting things. The
mounts would also be under tension under braking, rather than compression
which has an increased chance of failure. Specialized have already had a
recall for mounting tab failures. Don't simply replace one problem with
another and think through all the failure modes of a proposed solution before
implementing it - Design Control 101.

Tony

Tony Raven writes:

If you consider forks without offset at the dropout end, as they
are commonly made today, where offset is achieved at the fork
crown, No change other than placing the mounting lugs for the
disc brake caliper on the front side is required. I think the
same caliper would be adequate for most brands with the distance
between caliper and fork leg remaining as it is today. This
requires a new fork strut anyway.

It might even be possible to simply swap the left and right fork
lowers. Sometimes one sees bikes where the forks have been
installed backwards... usually on eBay.

How long will it take to get the disc caliper ahead of the fork leg?

I wouldn't be surprised to see different wheel attachment instead.
There are already various quick(ish) release 20mm systems that
seem little more trouble than a QR with retention lips. That can
also be sold as an upgrade rather than merely a bug-fix. And you
get to buy a new shiny hub too!

Well that won't do as I already mentioned. The reversing load from
braking and bouncing on the road makes anything but a conical "lug
nut" ineffective to reliably prevent loosening.

Let's get the caliper in the right place!

Right place for what?

The right place to resolve the hazards that have been under discussion
in this thread for more than 500 replies.

It might reverse the ejection force into a holding in force but OTOH
the caliper is out front where it is much more susceptible to damage
and to getting the mounting tabs bent/strained by hitting things.

Yes, and the moon may yet be made of green cheese. This is grasping
at straws to obscure the issue when all else fails. What sort of
damage do you foresee for a metal brake caliper that is far behind the
leading edge of an adjacent wheel? This sounds like the bicycle is
being tossed into a rock crusher. Ejection forces from a rear mounted
caliper are real and undeniable, bending parts of the fork "from
hitting things" is unreal conjecture as is apparent from aluminum
parts of suspension forks that are not full of scrapes and gouges on
their front side "from hitting things".

The mounts would also be under tension under braking, rather than
compression which has an increased chance of failure. Specialized
have already had a recall for mounting tab failures. Don't simply
replace one problem with another and think through all the failure
modes of a proposed solution before implementing it - Design Control
101.

There is nothing wrong with tension. If it were we couldn't ride
spoked wheels that have plenty of tension. In fact, no matter how you
make it, the bicycle (and n=most machines) are full of tension and
compression stresses. That is what bending is.

Jobst Brandt

Tony Raven writes:

If you consider forks without offset at the dropout end, as they
are commonly made today, where offset is achieved at the fork
crown, No change other than placing the mounting lugs for the
disc brake caliper on the front side is required. I think the
same caliper would be adequate for most brands with the distance
between caliper and fork leg remaining as it is today. This
requires a new fork strut anyway.

It might even be possible to simply swap the left and right fork
lowers. Sometimes one sees bikes where the forks have been
installed backwards... usually on eBay.

How long will it take to get the disc caliper ahead of the fork leg?

I wouldn't be surprised to see different wheel attachment instead.
There are already various quick(ish) release 20mm systems that
seem little more trouble than a QR with retention lips. That can
also be sold as an upgrade rather than merely a bug-fix. And you
get to buy a new shiny hub too!

Well that won't do as I already mentioned. The reversing load from
braking and bouncing on the road makes anything but a conical "lug
nut" ineffective to reliably prevent loosening.

Let's get the caliper in the right place!

Right place for what?

The right place to resolve the hazards that have been under discussion
in this thread for more than 500 replies.

It might reverse the ejection force into a holding in force but OTOH
the caliper is out front where it is much more susceptible to damage
and to getting the mounting tabs bent/strained by hitting things.

Yes, and the moon may yet be made of green cheese. This is grasping
at straws to obscure the issue when all else fails. What sort of
damage do you foresee for a metal brake caliper that is far behind the
leading edge of an adjacent wheel? This sounds like the bicycle is
being tossed into a rock crusher. Ejection forces from a rear mounted
caliper are real and undeniable, bending parts of the fork "from
hitting things" is unreal conjecture as is apparent from aluminum
parts of suspension forks that are not full of scrapes and gouges on
their front side "from hitting things".

The mounts would also be under tension under braking, rather than
compression which has an increased chance of failure. Specialized
have already had a recall for mounting tab failures. Don't simply
replace one problem with another and think through all the failure
modes of a proposed solution before implementing it - Design Control
101.

There is nothing wrong with tension. If it were we couldn't ride
spoked wheels that have plenty of tension. In fact, no matter how you
make it, the bicycle (and n=most machines) are full of tension and
compression stresses. That is what bending is.

Jobst Brandt

Simon Brooke wrote:
I think one of the things that's going on here is that people who ride
road bikes a lot are speculating about what it's like to ride off-road.

This is not entirely fair. The laws of physics are not changed off-road;
and specifically bicycle geometry still can constrain maximum braking in
exactly the same way.
--
David Damerell flcl?

Simon Brooke wrote:
I think one of the things that's going on here is that people who ride
road bikes a lot are speculating about what it's like to ride off-road.

This is not entirely fair. The laws of physics are not changed off-road;
and specifically bicycle geometry still can constrain maximum braking in
exactly the same way.
--
David Damerell flcl?