Threadless stems and carbon steerers in crashes

George Herbert Walker said...

Quoted message said:

Quoted message 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 <[email hidden]> wrote in message news:<[email hidden]>...

Quoted message said:

George Herbert Walker said...

Quoted message said:

Quoted message 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...

Quoted message 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 said:

George Herbert Walker said...

Quoted message 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" <[email hidden]> wrote in message
news:lct7d.285556$4o.115901@fed1read01...

Quoted message 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've got 60,000 miles out of my front Spinergy with no failures.

I've had a few Spinergies which have ridden just fine after having one to
three 'spokes' removed by a pedal while racing - in both cases I didn't even
crash but kept riding. The wheels did wobble but they still worked fine.

So perhaps your fear of new technology leads to over stating the risk.

Bruce

Quoted message said:

--
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.

On Sat, 02 Oct 2004 09:51:34 GMT, "Bruce Frech"

bfrech@no_spam_verizon.net said:

"Mark Wolfe" <[email hidden]> wrote in message
news:lct7d.285556$4o.115901@fed1read01...

Quoted message 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've got 60,000 miles out of my front Spinergy with no failures.

I've had a few Spinergies which have ridden just fine after having one to
three 'spokes' removed by a pedal while racing - in both cases I didn't even
crash but kept riding. The wheels did wobble but they still worked fine.

So perhaps your fear of new technology leads to over stating the risk.

Are you talking of the Rev-X's, which is what I think Mark meant? I
am not so sure that I believe that a Rev-X could lose 3 of the 8
'spokes' on a wheel and not fail. There were a lot of folks who
crashed when 1 'spoke' on those things collapsed, which is shy
Spinergy took them off the market.

- rick

Mark Wolfe said...

Quoted message 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.

"Rick Warner" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

On Sat, 02 Oct 2004 09:51:34 GMT, "Bruce Frech"

bfrech@no_spam_verizon.net said:

"Mark Wolfe" <[email hidden]> wrote in message
news:lct7d.285556$4o.115901@fed1read01...

Quoted message 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

Quoted message said:

Quoted message said:

Quoted message said:

go with no warning.

I've got 60,000 miles out of my front Spinergy with no failures.

I've had a few Spinergies which have ridden just fine after having one to
three 'spokes' removed by a pedal while racing - in both cases I didn't

even

Quoted message said:

Quoted message said:

crash but kept riding. The wheels did wobble but they still worked fine.

So perhaps your fear of new technology leads to over stating the risk.

Are you talking of the Rev-X's, which is what I think Mark meant? I
am not so sure that I believe that a Rev-X could lose 3 of the 8
'spokes' on a wheel and not fail. There were a lot of folks who
crashed when 1 'spoke' on those things collapsed, which is shy
Spinergy took them off the market.

- rick

Yes, I am talking about the Rev-X wheels. I have had one spoke ripped out
of the front wheel and kept riding, and three spokes out of the rear wheel
and kept riding. The rim does not bend, and the wheel just wobbles. It is
still attached to the hub but rubs against the brakes and any other contact
points. That is not a collapse and should not cause a crash. Would a
spoked wheel with insufficient tension so the rim wobbles cause an instant
crash? Or would it be good enough to ride carefully to finish the ride? I
found the 2nd to be true, regardless of what the spokes were made of.

Bruce