Threadless stems and carbon steerers in crashes

This is a repost because the other news server seems to be no longer
propagating messages very far.

Email to me is just like email to my son, or talking to him for that
matter: messages are not monitored or answered.

In article ,
(George Herbert Walker) wrote:

Witnessing a crash this weekend, and reading the threadless vs. quills
thread with this passage,

---------------
the quill
stem isn't nearly as secure as a threadless system. I didn't have the
quality of bikes then that I do now, but it was common for the quill to
go out of kilter, especially after a small accident. Compared to a
threadless stem, quill stems are held together by a wing and a prayer.
You get one bolt and a tenuous, zero area friction interface between the
stem and steerer.
----------------

prompts the following question:

In a crash with a regular stem, the bars turn easily, pretty well
eliminating or markedly reducing the damage to the brake levers and bars,
and to the rider too. Additionally, there is no damage to the stem or the
steel steerer. But the threadless setup is much tighter on the steerer as
pointed out above, and then if the steerer is aluminum, or worse carbon...
what happens? Are you and/or the bike hosed?

I guess a similar question applies to carbon seatposts that get forcefully
turned around while clamped. And what if you have something clamped to the
seatpost, like a rack or fender or KlikFix, and it gets forcefully turned
around?

--
TO WHOM IT MAY CONCERN

Please excuse the inconvenience allegedly caused by our son. Send
us the bill for all the damages, and we can settle this to your
satisfaction, without any need for a public record of the incident.

Most Sincerely, George and Bar

George Herbert Walker said...

prompts the following question:

In a crash with a regular stem, the bars turn easily, pretty well
eliminating or markedly reducing the damage to the brake levers and bars,
and to the rider too. Additionally, there is no damage to the stem or the
steel steerer. But the threadless setup is much tighter on the steerer as
pointed out above, and then if the steerer is aluminum, or worse carbon...
what happens? Are you and/or the bike hosed?

I guess a similar question applies to carbon seatposts that get forcefully
turned around while clamped. And what if you have something clamped to the
seatpost, like a rack or fender or KlikFix, and it gets forcefully turned
around?

You must not have read my full post. I was in a crash where my carbon
fork and steerer should have been smashed to pieces, but after
rebuilding the headset and a careful inspection by two very experienced
bike wrenches, nobody can find a thing wrong with it.

George Herbert Walker said...

prompts the following question:

In a crash with a regular stem, the bars turn easily, pretty well
eliminating or markedly reducing the damage to the brake levers and bars,
and to the rider too. Additionally, there is no damage to the stem or the
steel steerer. But the threadless setup is much tighter on the steerer as
pointed out above, and then if the steerer is aluminum, or worse carbon...
what happens? Are you and/or the bike hosed?

I guess a similar question applies to carbon seatposts that get forcefully
turned around while clamped. And what if you have something clamped to the
seatpost, like a rack or fender or KlikFix, and it gets forcefully turned
around?

You must not have read my full post. I was in a crash where my carbon
fork and steerer should have been smashed to pieces, but after
rebuilding the headset and a careful inspection by two very experienced
bike wrenches, nobody can find a thing wrong with it.

SuperSlinky wrote in message t...
George Herbert Walker said...

prompts the following question:

In a crash with a regular stem, the bars turn easily, pretty well
eliminating or markedly reducing the damage to the brake levers and bars,
and to the rider too. Additionally, there is no damage to the stem or the
steel steerer. But the threadless setup is much tighter on the steerer as
pointed out above, and then if the steerer is aluminum, or worse carbon...
what happens? Are you and/or the bike hosed?

I guess a similar question applies to carbon seatposts that get forcefully
turned around while clamped. And what if you have something clamped to the
seatpost, like a rack or fender or KlikFix, and it gets forcefully turned
around?

You must not have read my full post. I was in a crash where my carbon
fork and steerer should have been smashed to pieces, but after
rebuilding the headset and a careful inspection by two very experienced
bike wrenches, nobody can find a thing wrong with it.

What you described didn't seem to be an accident of the type I was
referring to. You are talking about brute strength in response to a
smash, I'm talking about twisting and possibly scoring or otherwise
damaging through rotation against the tube, or damaging the rider.

SuperSlinky wrote in message t...
George Herbert Walker said...

prompts the following question:

In a crash with a regular stem, the bars turn easily, pretty well
eliminating or markedly reducing the damage to the brake levers and bars,
and to the rider too. Additionally, there is no damage to the stem or the
steel steerer. But the threadless setup is much tighter on the steerer as
pointed out above, and then if the steerer is aluminum, or worse carbon...
what happens? Are you and/or the bike hosed?

I guess a similar question applies to carbon seatposts that get forcefully
turned around while clamped. And what if you have something clamped to the
seatpost, like a rack or fender or KlikFix, and it gets forcefully turned
around?

You must not have read my full post. I was in a crash where my carbon
fork and steerer should have been smashed to pieces, but after
rebuilding the headset and a careful inspection by two very experienced
bike wrenches, nobody can find a thing wrong with it.

What you described didn't seem to be an accident of the type I was
referring to. You are talking about brute strength in response to a
smash, I'm talking about twisting and possibly scoring or otherwise
damaging through rotation against the tube, or damaging the rider.

George Herbert Walker said...

What you described didn't seem to be an accident of the type I was
referring to. You are talking about brute strength in response to a
smash, I'm talking about twisting and possibly scoring or otherwise
damaging through rotation against the tube, or damaging the rider.

Stem pushed up and rotated on the carbon steerer. Some marking that
doesn't quite qualify as scoring. I think you are worrying too much. The
scoring needs to be worse than what you will get by twisting a seatpost
for it to be a problem. Bigger problems for CF are hidden damage caused
by bending or crushing.

George Herbert Walker said...

What you described didn't seem to be an accident of the type I was
referring to. You are talking about brute strength in response to a
smash, I'm talking about twisting and possibly scoring or otherwise
damaging through rotation against the tube, or damaging the rider.

Stem pushed up and rotated on the carbon steerer. Some marking that
doesn't quite qualify as scoring. I think you are worrying too much. The
scoring needs to be worse than what you will get by twisting a seatpost
for it to be a problem. Bigger problems for CF are hidden damage caused
by bending or crushing.

SuperSlinky wrote:
George Herbert Walker said...


What you described didn't seem to be an accident of the type I was
referring to. You are talking about brute strength in response to a
smash, I'm talking about twisting and possibly scoring or otherwise
damaging through rotation against the tube, or damaging the rider.


Stem pushed up and rotated on the carbon steerer. Some marking that
doesn't quite qualify as scoring. I think you are worrying too much. The
scoring needs to be worse than what you will get by twisting a seatpost
for it to be a problem. Bigger problems for CF are hidden damage caused
by bending or crushing.

The catastrophic failure mode of carbon is scary. Ask someone who's
done a face plant on a set of Spynergy (sp) 4 spoke carbon wheels.
Personnaly, I'd be X-raying it, or replacing it. That's the thing that
bothers me about carbon, extrodinarily strong and light, but it will let
go with no warning.


--
Mark Wolfe Lakeside, ca http://www.wolfenet.org
gpg fingerprint = 42B6 EFEB 5414 AA18 01B7 64AC EF46 F7E6 82F6 8C71
evilPetey I often think I'd get better throughput yelling at the modem.

SuperSlinky wrote:
George Herbert Walker said...


What you described didn't seem to be an accident of the type I was
referring to. You are talking about brute strength in response to a
smash, I'm talking about twisting and possibly scoring or otherwise
damaging through rotation against the tube, or damaging the rider.


Stem pushed up and rotated on the carbon steerer. Some marking that
doesn't quite qualify as scoring. I think you are worrying too much. The
scoring needs to be worse than what you will get by twisting a seatpost
for it to be a problem. Bigger problems for CF are hidden damage caused
by bending or crushing.

The catastrophic failure mode of carbon is scary. Ask someone who's
done a face plant on a set of Spynergy (sp) 4 spoke carbon wheels.
Personnaly, I'd be X-raying it, or replacing it. That's the thing that
bothers me about carbon, extrodinarily strong and light, but it will let
go with no warning.


--
Mark Wolfe Lakeside, ca http://www.wolfenet.org
gpg fingerprint = 42B6 EFEB 5414 AA18 01B7 64AC EF46 F7E6 82F6 8C71
evilPetey I often think I'd get better throughput yelling at the modem.

Mark Wolfe said...

The catastrophic failure mode of carbon is scary. Ask someone who's
done a face plant on a set of Spynergy (sp) 4 spoke carbon wheels.
Personnaly, I'd be X-raying it, or replacing it. That's the thing that
bothers me about carbon, extrodinarily strong and light, but it will let
go with no warning.

I paid to have the bike fixed up to make it ridable. I really admire the
fork's apparent indestructibility, but I do wonder if one day it will
disintegrate under me. It is a backup bike now, and I'm a little too
scared to do anything high speed on it.