safest stem?

Damn, you are a load Chalo. You wrote before "I heard" and "I assumed".
You should do a commercial for them doing a jump or something.

I'm 240-250 and 6', so a more compact load. Lots of variables in
construction variables
and riding components/forces. I've dealt with materials in
manufacturing, job shops, and foundry's so I'm pretty comfortable with
different material specs. I have to admit, there's a lot of shabby
components, like the single nut AL seat post clamps and threadless
stems; so if you don't research for several hours at least on web, I
could see where you had failures. China material grades are [censored], so
that's another wild card right there.

Tried 6 different seats before I found SpiderFlex crotchless saddle. I
couldn't ride without it. But with it, constant spinning and no
problems.

I can see where you would rather not take chances and get the best
possible you can get. Post a link of you and your bike. I would be very
interested to see the combo. You sound like a professional football
player. I can't believe my Raleigh Supercourse rides so smooth with me
on it. I just feel sorry for your bike, lol. I used to engineer
man/machine interfaces in manufacturing. I'd always get the smallest
person and the biggest person to test my systems and make sure my
ranges were covered. That's why I'd like to see your setup and how you
are handling weight. Of course when I go to Walmart Groceries, I have a
hundred pounds on my Army duffle bag on my back. I'm planning to get a
front rack for additional reinforcment there, and when get new wheels,
will get the Phil Woods touring hubs.

Thanks,
Phil Bailey

Chalo said:

ddog said:

Oh yeah, Seat posts were what I was considering, but same difference
in all respects to stems.
Thompson makes high quality, high dollar reliable products that are
over marketed with verifiable evidence lacking: which I think is a
percentage of what you are paying for.

I haven't tuned in to any media featuring bike industry ads (except the
websites of bike manufacturers and retailers) since the mid-'90s. I
have never seen Thomson advertise or sponsor any of the bike-related
events I have attended during the same time. So I have to take your
word for it that Thomson products are heavily marketed. What I've
noted is that they have won the loyalty of many of the riders I know
who break stuff.

I can't speak from direct experience about Thomson stems, because I
haven't used one. I have used Thomson seatposts, though, and they have
a distinction: They are the only seatposts I've ever tried that I can
extend more than about 25cm without bending. I don't ride on harsh
surfaces, I don't jump my bike; but I do weigh about 375 lbs and
measure 6'8". I've had cause to try many a long seatpost, and I've
bent all of them except those of two manufacturers-- L. H. Thomson and
myself. Mine don't bend because I make them of very thick pieces of
the strongest materials I can get my hands on. Typically I use 7075
aluminum, and I use wall thicknesses from 5mm on up to solid rod.

I've bent SR Laprade posts, guaranteed IRD Racing posts, welded
chromoly posts, straight chromoly posts, even 3mm thick seamless
chromoly tubing I bought in the pursuit of a stronger, longer seatpost.
Thomson posts have never bent on me, even the 410mm length when
extended to near its limit.

Quoted message said:

They may be over specified materials in their 'steel alloy',

They don't use steel alloy except in their annoyingly proprietary
bolts. The posts and stems are made of 7075 aluminum. The seatposts
use a forging which is machined to net size. Since I have not seen
claims that the stems are machined from forgings, I assume that they
are machined from billet.

Quoted message said:

But it would have to be cost beneifted on known features I can verify:
not touchy feely descriptions.

http://lhthomson.com/elite_features.htm

You can believe these claims or not, but there are assertions here that
come with units attached, and that can be tested. The most specific
strength claim is as follows:

"The Thomson seatpost has a clamp, head, and upper tube strong enough
to withstand 350 foot-lbs of torque. The tube will start to yield and
bend at the seat tube clamp at about 250 foot-lbs of torque."

I've not performed any controlled tests on my Thomson seatposts, but
they have succeeded on a pass/fail basis where others have failed.

Chalo

In article <[email hidden]>,

jim beam said:

Quoted message said:

Paul Hobson said:

Dude was riding a Fuji track bike, geared at 53x13 (in Atlanta's
rolling terrain). He was sprinting up a hill (faster than anyone
around him, mind you) and then this happened:
http://tinyurl.com/ycdg73 http://tinyurl.com/ydlwa7

Looking at the first picture, the fracture surface that is closest
to the table, on both the quill and the extension, looks dark. If
you put the stem back together and looked at it from the front of
the bike, the area I'm talking about would be at 3 to 5 o'clock.
If this is not a trick of the light, it suggests there was already
a fairly substantial crack in the stem before the final separation.

that's the truth! it's most unlikely all that cracking happened
immediately - regular visual inspection should have caught it.

Although I don't see any obvious polishing of any part of the edges,
which I'd expect to see if the crack had been there a while. OTOH it
seems like it'd take a really bit hit to just snap it off in on shot.

Quoted message said:

Quoted message said:

Something about the way the exposed crack surface on the quill
doesn't touch the quill tube makes me wonder if the extension was
mitered carefully to fit onto the quill, although maybe it was and
the mitered surface is all hidden under the weld.

that may be true, but one of the obvious issues is very poor melt
depth - the weld pool is largely cosmetic. but even /that/ is
academic - the cracking is not in the weld, but the heat affected
zone of the extension, and well beyond.

It sure looks like the extension was just barely attached.

Quoted message said:

cheap cheesy garbage. i don't have any welded stems.

I share your opinion. I don't have any welded aluminum stems for this
very reason. I've had one welded aluminum stem that started to crack
(3ttt as I recall), and I have had some Salsa and a couple of
Ritchey/Nitto welded steel stems that never showed any signs of failure.

In article <[email hidden]>,

Peter Cole said:

jim beam wrote: the ultimate in old quill stems was nitto, imo.
beautiful cold forging

Quoted message said:

of the very highest quality.

I thought so too until mine broke. It is the only stem I've ever had
break...

How'd it break? And which Nitto model?

Quoted message said:

Quoted message said:

Quoted message said:

which is why i say stick to single-piece cold forged stems! [apart from
the clamp of course.]

You mean like the one I had fail? It was a Mavic forged aluminum stem,
and the bottom part of the handlebar clamp, where the tightening bolt
threaded into, simply pulled away from the rest of the stem.

got a pic? not many people cold forge - it costs more. i've not seen
this mavic stem, but if the material was good, theres still no guarantee
the design was right - need design /and/ material.

Nope, happened before I became camera-crazy. Which means sometime before
1998, I'm thinking. The stem was very similar in appearance to a 3TTT model
at the time.

--Mike Jacoubowsky
Chain Reaction Bicycles
www.ChainReaction.com
Redwood City & Los Altos, CA USA

"jim beam" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Mike Jacoubowsky said:

Quoted message said:

>> Seems to me that a stem is a good place to use some steel that's less
>> brittle than aluminum. Salsa makes a steel threadless stem that costs
>> about $40USD. Very nice stuff. Then again, I've got a stupid amount of
>> miles on aluminum stems without failure. Maybe I'm just not man enough
>> to wrench it apart. :sigh:
> Dude was riding a Fuji track bike, geared at 53x13 (in Atlanta's
> rolling terrain). He was sprinting up a hill (faster than anyone
> around him, mind you) and then this happened:
> http://tinyurl.com/ycdg73
> http://tinyurl.com/ydlwa7
>
which is why i say stick to single-piece cold forged stems! [apart from
the clamp of course.]

You mean like the one I had fail? It was a Mavic forged aluminum stem,
and the bottom part of the handlebar clamp, where the tightening bolt
threaded into, simply pulled away from the rest of the stem.

got a pic? not many people cold forge - it costs more. i've not seen
this mavic stem, but if the material was good, theres still no guarantee
the design was right - need design /and/ material.

Quoted message said:

The threads didn't strip, but rather the section the threads were in just
separated. I replaced that with an Ibis titanium stem; the handlebar
pinch bolt broke on that one (and during a sprint, no less... why I
didn't go down is completely beyond me).

Now I've got a massively-big & sorta ugly Bontrager carbon stem, which
would probably take a chainsaw to kill. 140 grams, which is about 40
grams heavier than some of the modern ultralight aluminum stems these
days. Yeah, it would be nicer if they'd engineer something a bit lighter,
but it's also nice that I don't worry about stem failures anymore.

actually, carbon can be great in that respect - much less fatigue. the
issue with a stem is whether it's one of the on-piece items and built
appropriately or whether it's bonded to aluminum ends like some of the
poor designs are. i'd not bother with the latter.

the ultimate in old quill stems was nitto, imo. beautiful cold forging of
the very highest quality.

Quoted message said:

--Mike-- Chain Reaction Bicycles
www.ChainReactionBicycles.com

"jim beam" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Paul Hobson wrote:
> landotter wrote:
>> Callistus Valerius wrote:
>>> What would be the safest threadless road stem out there, with a face
>>> plate
>>> so you don't have to remove the shifters etc? Of all the bike
>>> components, I
>>> always look at the stem as the most scary, as a failure would be
>>> catastrophic. I've seen lots of metal [censored] break that looked a hell
>>> of a
>>> lot stronger than a bicycle stem, thus the paranoia. I've ridden
>>> around a
>>> 100,000 miles and never had a failure, and I have had two bolt and 4
>>> bolt
>>> stems, and never a failure or a crack in any of them. But is there
>>> such a
>>> thing as a fail-safe one, with the specs I listed?
>> Seems to me that a stem is a good place to use some steel that's less
>> brittle than aluminum. Salsa makes a steel threadless stem that costs
>> about $40USD. Very nice stuff. Then again, I've got a stupid amount of
>> miles on aluminum stems without failure. Maybe I'm just not man enough
>> to wrench it apart. :sigh:
> Dude was riding a Fuji track bike, geared at 53x13 (in Atlanta's
> rolling terrain). He was sprinting up a hill (faster than anyone
> around him, mind you) and then this happened:
> http://tinyurl.com/ycdg73
> http://tinyurl.com/ydlwa7
>
which is why i say stick to single-piece cold forged stems! [apart from
the clamp of course.]

Chalo said:

Callistus Valerius said:

What would be the safest threadless road stem out there, with a face
plate
so you don't have to remove the shifters etc?

Thomson Elite is the strongest, most proven stem for its weight that I
know of.

Do you remember this thread?

http://tinyurl.com/uusuu

In article
<[email hidden]>
,

Qui si parla Campagnolo said:

Callistus Valerius said:

What would be the safest threadless road stem out there, with a face plate
so you don't have to remove the shifters etc? Of all the bike components, I
always look at the stem as the most scary, as a failure would be
catastrophic. I've seen lots of metal [censored] break that looked a hell of a
lot stronger than a bicycle stem, thus the paranoia. I've ridden around a
100,000 miles and never had a failure, and I have had two bolt and 4 bolt
stems, and never a failure or a crack in any of them. But is there such a
thing as a fail-safe one, with the specs I listed?

Ritchey Comp or Salsa steel one.

Copy says the face plate is Al.
What about the single bolt steering tube clamp?
<http://xoomgear.com/manufacturer/Salsa/stems//Salsa_S_U_L_/368/>

--
Michael Press

Chalo said:

Matt O'Toole said:

Quoted message said:

Thomson Elite is the strongest, most proven stem for its weight that I
know of.

Proven how? It looks good to me too, but...

I've heard it has been proof tested to over 3000 lbs. of vertical load.

As far as I can tell, it is the long-term favorite stem among
downhillers, whose other long-term favorite parts tend to be strong but
heavy.

The problem with stems isn't ultimate strength, but fatigue.
Downhillers do not put anywhere near the number of fatigue cycles on stems
that road riders do. What downhill MTB accumulates tens of thousands of
miles?

Matt O.

Tim McNamara said:

In article <[email hidden]>,

Peter Cole said:

jim beam wrote: the ultimate in old quill stems was nitto, imo.
beautiful cold forging

Quoted message said:

of the very highest quality.

I thought so too until mine broke. It is the only stem I've ever had
break...

How'd it break? And which Nitto model?

"Technomic". It broke right in the middle of the vertical part. These
are tall stems, but I didn't have it anywhere near maximum extension.

It was a benign break, other than being out a $40 stem, in that the
binder bolt held things together, much like a QR will hold a broken axle.

Matt O'Toole said:

Chalo said:

Matt O'Toole said:

> Thomson Elite is the strongest, most proven stem for its weight that I
> know of.
Proven how? It looks good to me too, but...

I've heard it has been proof tested to over 3000 lbs. of vertical load.

As far as I can tell, it is the long-term favorite stem among
downhillers, whose other long-term favorite parts tend to be strong but
heavy.

The problem with stems isn't ultimate strength, but fatigue.
Downhillers do not put anywhere near the number of fatigue cycles on stems
that road riders do. What downhill MTB accumulates tens of thousands of
miles?

other way around. downhillers experience much greater stress and are
therefore subject to much more fatigue. the cycles may have a lower
count, but with a higher stress, that is to be expected. check out an
s-n graph.

jim beam said:

Matt O'Toole wrote:

Quoted message said:

Quoted message said:

The problem with stems isn't ultimate strength, but fatigue.
Downhillers do not put anywhere near the number of fatigue cycles on stems
that road riders do. What downhill MTB accumulates tens of thousands of
miles?

other way around. downhillers experience much greater stress and are
therefore subject to much more fatigue. the cycles may have a lower
count, but with a higher stress, that is to be expected. check out an
s-n graph.

I'm betting (and think I recall reading) that this simply isn't true.

The ultimate stress on a stem isn't simply a matter of the size of the
bump. On a downhill racing bike, when the front wheel slams into a
three inch rock, the fat, low-pressure tire absorbs a great deal of
the impact, and any remaining impact that reaches the stem has to be
transmitted through a VERY cushy fork (one that probably has 5-6
inches of travel). The result is that the stem is loaded for a longer
period (as the tire and fork "soak up the bump"😉, but at a lower
magnitude.

OTOH, when a road bike hits a 1/2" rock, the 100psi (or more) tire can
only absorb so much of the impact, and the fork doesn't help a bit (at
least in a vertical sense - flexing fore/aft does help extend the
period). The period of the impact's effects is much shorter, but also
or a much greater amplitude.

Think of it this way - imagine trying to drive a nail using a bicycle
stem on an upside-down bicycle as the contact point with the nail, and
hammering on the front tire. You'd certainly have to work to get the
road bike's nail driven, but you'd never, ever get the nail driven
using the downhill bike as a buffer.

Mark "don't try that at home, kids" Hickey
Habanero Cycles
http://www.habcycles.com
Home of the $795 ti frame

Mark Hickey said:

Quoted message said:

Quoted message said:

The problem with stems isn't ultimate strength, but fatigue.
Downhillers do not put anywhere near the number of fatigue cycles
on stems that road riders do. What downhill MTB accumulates tens
of thousands of miles?

Quoted message said:

Quoted message said:

other way around. downhillers experience much greater stress and
are therefore subject to much more fatigue. the cycles may have a
lower count, but with a higher stress, that is to be expected.
check out an s-n graph.

Quoted message said:

I'm betting (and think I recall reading) that this simply isn't
true.

Quoted message said:

The ultimate stress on a stem isn't simply a matter of the size of
the bump. On a downhill racing bike, when the front wheel slams
into a three inch rock, the fat, low-pressure tire absorbs a great
deal of the impact, and any remaining impact that reaches the stem
has to be transmitted through a VERY cushy fork (one that probably
has 5-6 inches of travel). The result is that the stem is loaded
for a longer period (as the tire and fork "soak up the bump"😉, but
at a lower magnitude.

Quoted message said:

OTOH, when a road bike hits a 1/2" rock, the 100psi (or more) tire
can only absorb so much of the impact, and the fork doesn't help a
bit (at least in a vertical sense - flexing fore/aft does help
extend the period). The period of the impact's effects is much
shorter, but also or a much greater amplitude.

Quoted message said:

Think of it this way - imagine trying to drive a nail using a
bicycle stem on an upside-down bicycle as the contact point with the
nail, and hammering on the front tire. You'd certainly have to work
to get the road bike's nail driven, but you'd never, ever get the
nail driven using the downhill bike as a buffer.

Hey! That's my model for Brinelled head bearings. Its that (chip
seal) road impact on the tire that indents bearing balls into their
races.

Jobst Brandt

Mark Hickey said:

jim beam said:

Matt O'Toole wrote:

Quoted message said:

Quoted message said:

The problem with stems isn't ultimate strength, but fatigue.
Downhillers do not put anywhere near the number of fatigue cycles on stems
that road riders do. What downhill MTB accumulates tens of thousands of
miles?

other way around. downhillers experience much greater stress and are
therefore subject to much more fatigue. the cycles may have a lower
count, but with a higher stress, that is to be expected. check out an
s-n graph.

I'm betting (and think I recall reading) that this simply isn't true.

The ultimate stress on a stem isn't simply a matter of the size of the
bump. On a downhill racing bike, when the front wheel slams into a
three inch rock, the fat, low-pressure tire absorbs a great deal of
the impact, and any remaining impact that reaches the stem has to be
transmitted through a VERY cushy fork (one that probably has 5-6
inches of travel). The result is that the stem is loaded for a longer
period (as the tire and fork "soak up the bump"😉, but at a lower
magnitude.

OTOH, when a road bike hits a 1/2" rock, the 100psi (or more) tire can
only absorb so much of the impact, and the fork doesn't help a bit (at
least in a vertical sense - flexing fore/aft does help extend the
period). The period of the impact's effects is much shorter, but also
or a much greater amplitude.

Think of it this way - imagine trying to drive a nail using a bicycle
stem on an upside-down bicycle as the contact point with the nail, and
hammering on the front tire. You'd certainly have to work to get the
road bike's nail driven, but you'd never, ever get the nail driven
using the downhill bike as a buffer.

the flights of imaginative fantasy people spew on this group to justify
their prejudice is sometimes quite amazing! there /is/ a reason
downhill bikes are made of strong fatigue resistant componentry you know....

Quoted message said:

Mark Hickey writes:

Quoted message said:

Quoted message said:

Think of it this way - imagine trying to drive a nail using a
bicycle stem on an upside-down bicycle as the contact point with the
nail, and hammering on the front tire. You'd certainly have to work
to get the road bike's nail driven, but you'd never, ever get the
nail driven using the downhill bike as a buffer.

Hey! That's my model for Brinelled head bearings. Its that (chip
seal) road impact on the tire that indents bearing balls into their
races.

Next time I'll put an attribution... ;-)

Thing is, I wish you hadn't commented... now Jim Beam is going to feel
obligated to explain how "it can't be so if Jobst agrees"... sigh.

Mark Hickey
Habanero Cycles
http://www.habcycles.com
Home of the $795 ti frame

Mark Hickey said:

Quoted message said:

Mark Hickey writes:

Quoted message said:

Quoted message said:

Think of it this way - imagine trying to drive a nail using a
bicycle stem on an upside-down bicycle as the contact point with the
nail, and hammering on the front tire. You'd certainly have to work
to get the road bike's nail driven, but you'd never, ever get the
nail driven using the downhill bike as a buffer.

Hey! That's my model for Brinelled head bearings. Its that (chip
seal) road impact on the tire that indents bearing balls into their
races.

Next time I'll put an attribution... ;-)

Thing is, I wish you hadn't commented... now Jim Beam is going to feel
obligated to explain how "it can't be so if Jobst agrees"... sigh.

you don't pay much attention do you? even jobst gets some things right,
and i say so. but he keeps lecturing on materials applications and
theory and getting it badly wrong. now, you may not have areas of
expertise where intrusion of misinformation is a problem, but in
technical applications, it is.

Wild Turkey said:

Quoted message said:

Quoted message said:

> Think of it this way - imagine trying to drive a nail using a
> bicycle stem on an upside-down bicycle as the contact point with
> the nail, and hammering on the front tire. You'd certainly have
> to work to get the road bike's nail driven, but you'd never, ever
> get the nail driven using the downhill bike as a buffer.

Quoted message said:

Quoted message said:

Quoted message said:

Hey! That's my model for Brinelled head bearings. Its that (chip
seal) road impact on the tire that indents bearing balls into
their races.

Quoted message said:

Quoted message said:

Next time I'll put an attribution... ;-)

Quoted message said:

Quoted message said:

Thing is, I wish you hadn't commented... now Jim Beam is going to
feel obligated to explain how "it can't be so if Jobst agrees"...
sigh.

Quoted message said:

you don't pay much attention do you? even jobst gets some things
right, and i say so. but he keeps lecturing on materials
applications and theory and getting it badly wrong. now, you may
not have areas of expertise where intrusion of misinformation is a
problem, but in technical applications, it is.

What did he say tangentially???

Jobst Brandt