Stem bolt failure

Have a Cinelli Solido/Solado stem/bar combination. On Saturday the stem
bolts went on me while riding, now a pretty sight. The stem is about 2
years old and maybe 20,000km on it, no previous crashes.

It has been suggested by several people that light weight stuff should
be replaced every couple of years at least. I don't race, so the weight
issue is a non event for me. I weigh about 200lbs, and want/need
something sturdy. About 3 years ago I broke a set of Deda handlebars,
cracked right through while riding, getting pretty concerned with the
lifespan of some of these things... I ride a Litespeed Siena, about 1
year old.

Any recommendations for something sturdy, 120 stem and 44 bars.

Thanks

Are you being careful about torque ? If you overtighten stem bolts,
they'll break off and you can stress your bars leading to failure. Step
one - buy a torque wrench. That being said, there's a lot of
lightweight crap out there. I'm about to change a set of Deda bars
pre-emptively after 5 seasons/23,000 miles.
I also went through a couple of stems with my last bike purchase -
slipping bars, bending (luckily, not breaking) titanium stem bolts,
retorquing after every few rides, etc. I had picked these all based on
what was new and light at the time. Finally got smart and went to LBS
for the 411.

Hands down, the unbeatable stem for reliability is Thomson. Both of
their stems (Elite and X-2) are milled from solid blocks of aluminum,
no welds. The Elite weighs 190 g and has a 4 bolt faceplate (sturdy
steel bolts). Only comes as 26.0. I can vouch for this one as I're
ridden it for 3 1/2 years and never given it a second thought (other
than to admire it). Their new one, the X-2, has a hollowed out area on
the 2 bolt faceplate and a hollowed out area on the steerer clamp -
about 155 g, I think, and available in 31.8. Here's website:

http://www.lhthomson.com/

Good luck..........Lou D'Amelio

Colin Marshall wrote:

Have a Cinelli Solido/Solado stem/bar combination. On Saturday the stem
bolts went on me while riding, now a pretty sight. The stem is about 2
years old and maybe 20,000km on it, no previous crashes.

It has been suggested by several people that light weight stuff should
be replaced every couple of years at least. I don't race, so the weight
issue is a non event for me. I weigh about 200lbs, and want/need
something sturdy. About 3 years ago I broke a set of Deda handlebars,
cracked right through while riding, getting pretty concerned with the
lifespan of some of these things... I ride a Litespeed Siena, about 1
year old.

Any recommendations for something sturdy, 120 stem and 44 bars.

You could just replace the bolts if the stem isn't stripped.

Lou D'Amelio wrote:
Hands down, the unbeatable stem for reliability is Thomson. Both of
their stems (Elite and X-2) are milled from solid blocks of aluminum,
no welds.

Based on what? Forging is superior to milling from a solid block... the
best stems are all forged these days.

Some test data on stems can be found he
http://www.biketechreview.com/stems/summary.htm

Ron Ruff wrote:

Lou D'Amelio wrote:

Hands down, the unbeatable stem for reliability is Thomson. Both of
their stems (Elite and X-2) are milled from solid blocks of aluminum,
no welds.

Based on what? Forging is superior to milling from a solid block... the
best stems are all forged these days.

Somebody better tell Boeing that they're making all their airplanes
using inferior techniques!

Forging *can* make a stronger, more durable part than machining.
However, machining often allows the use of a stronger material, better
part geometry, or better finish and tolerances than forging, at the
same or lower cost. Any of these other factors can have a bigger
effect on strength and durability than the relatively small property
differences between forgings and wrought bars.

Chalo Colina

"Ron Ruff" wrote in message
Some test data on stems can be found he
http://www.biketechreview.com/stems/summary.htm


I looked at the link but couldn't get past the fact that they have the
equation wrong. Cantilever beam deflection is PL^3/3EI not PL^3/16EI. I
assume the rest is also unreliable.

Colin Marshall wrote:
Have a Cinelli Solido/Solado stem/bar combination. On Saturday the stem
bolts went on me while riding, now a pretty sight. The stem is about 2
years old and maybe 20,000km on it, no previous crashes.

It has been suggested by several people that light weight stuff should
be replaced every couple of years at least. I don't race, so the weight
issue is a non event for me. I weigh about 200lbs, and want/need
something sturdy. About 3 years ago I broke a set of Deda handlebars,
cracked right through while riding, getting pretty concerned with the
lifespan of some of these things... I ride a Litespeed Siena, about 1
year old.

Any recommendations for something sturdy, 120 stem and 44 bars.

Thanks

yes. you should pre-emptively replace this stuff. disregard the
"racing" definition - you're riding and putting on the miles. that's
fatigue loading.

as mentioned by lou, use a torque wrench. buy quality gear. make sure
the stem clamp at the handlebar has slightly rounded edges - reduces
stress risers. forged stems are best.

Lou D'Amelio wrote:
Are you being careful about torque ? If you overtighten stem bolts,
they'll break off and you can stress your bars leading to failure. Step
one - buy a torque wrench. That being said, there's a lot of
lightweight crap out there. I'm about to change a set of Deda bars
pre-emptively after 5 seasons/23,000 miles.
I also went through a couple of stems with my last bike purchase -
slipping bars, bending (luckily, not breaking) titanium stem bolts,
retorquing after every few rides, etc. I had picked these all based on
what was new and light at the time. Finally got smart and went to LBS
for the 411.

Hands down, the unbeatable stem for reliability is Thomson. Both of
their stems (Elite and X-2) are milled from solid blocks of aluminum,
no welds.

no welds is good, but forged is much better. attention to detail like
making sure the stem clamp has no sharp edges is paramount.

The Elite weighs 190 g and has a 4 bolt faceplate (sturdy
steel bolts). Only comes as 26.0. I can vouch for this one as I're
ridden it for 3 1/2 years and never given it a second thought (other
than to admire it). Their new one, the X-2, has a hollowed out area on
the 2 bolt faceplate and a hollowed out area on the steerer clamp -
about 155 g, I think, and available in 31.8. Here's website:

http://www.lhthomson.com/

Good luck..........Lou D'Amelio

Colin Marshall wrote:
Have a Cinelli Solido/Solado stem/bar combination. On Saturday the stem
bolts went on me while riding, now a pretty sight. The stem is about 2
years old and maybe 20,000km on it, no previous crashes.

It has been suggested by several people that light weight stuff should
be replaced every couple of years at least. I don't race, so the weight
issue is a non event for me. I weigh about 200lbs, and want/need
something sturdy. About 3 years ago I broke a set of Deda handlebars,
cracked right through while riding, getting pretty concerned with the
lifespan of some of these things... I ride a Litespeed Siena, about 1
year old.


Don't use titanium stem bolts.
..stlob mets miunatit esu t'noD

Chalo wrote:
Ron Ruff wrote:

Lou D'Amelio wrote:

Hands down, the unbeatable stem for reliability is Thomson. Both of
their stems (Elite and X-2) are milled from solid blocks of
aluminum, no welds.

Based on what? Forging is superior to milling from a solid block...
the best stems are all forged these days.

Somebody better tell Boeing that they're making all their airplanes
using inferior techniques!

Forging *can* make a stronger, more durable part than machining.
However, machining often allows the use of a stronger material, better
part geometry, or better finish and tolerances than forging, at the
same or lower cost.

This can't possibly be true across all economies of scale. If you were to
mill 10,000 stems versus forge 10,000 stems, I'm sure that the forging
process would save a whole heck of a lot of material. Sure, you need molds
and all that stuff, but you can recoup initial investment after X number of
stems.

Then again, I saw an amazing video of a CNC machine (with a bajillion
automatic tools) making aircraft wing ribs and holy crap, it taps threads
while feeding and spinning at full speed (probably 3krpm)! Not to mention
the stopping and reversing to unthread the tap before tapping more holes.
The time investment may not be all that high, but I'll bet one goes through
tools quickly on those things.

Maybe I can get that video from my teacher...

--
Phil, Squid-in-Training