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Selecting An Appropriate Bolt



 
 
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  #1  
Old April 14th 17, 04:07 AM posted to rec.bicycles.tech
Art Shapiro
external usenet poster
 
Posts: 14
Default Selecting An Appropriate Bolt

I had a bit of an adventure when one of the two handlebar-fixing bolts
on my Deda Murex quilled stem decided to snap with a rather impressive
cracking noise. I somehow didn't crash and happened to be only about
seven miles from home. I got slowly home holding the stem with one hand
and one of the brake levers on the dangling handlebars with the other
hand. (This is not recommended to the reader.)

I see that the bolt is a M6x18 tapered cone head Allen cap screw with
pressed-on washer.

The stem is two months shy of 15 years old, but I don't want to have
this happen again. Looking on eBay, I see quite a few appropriate
bolts, but I'm not sure what is optimal. Can anyone help?

Everything seems to be Grade 5. Is that safe enough, or do I really
want to (somehow) find Grade 8?

Many are titanium. Is that a better choice than the more-common steel?
Or should I look for stainless steel? I am always happy to save a few
grams, but not if that's a significant risk.

Advice welcome!

Art

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  #2  
Old April 14th 17, 12:15 PM posted to rec.bicycles.tech
John B Slocomb
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Posts: 268
Default Selecting An Appropriate Bolt

On Thu, 13 Apr 2017 20:07:48 -0700, Art Shapiro
wrote:

I had a bit of an adventure when one of the two handlebar-fixing bolts
on my Deda Murex quilled stem decided to snap with a rather impressive
cracking noise. I somehow didn't crash and happened to be only about
seven miles from home. I got slowly home holding the stem with one hand
and one of the brake levers on the dangling handlebars with the other
hand. (This is not recommended to the reader.)

I see that the bolt is a M6x18 tapered cone head Allen cap screw with
pressed-on washer.

The stem is two months shy of 15 years old, but I don't want to have
this happen again. Looking on eBay, I see quite a few appropriate
bolts, but I'm not sure what is optimal. Can anyone help?

Everything seems to be Grade 5. Is that safe enough, or do I really
want to (somehow) find Grade 8?

Many are titanium. Is that a better choice than the more-common steel?
Or should I look for stainless steel? I am always happy to save a few
grams, but not if that's a significant risk.

Advice welcome!

Art


Grade 5 bolts should certainly be strong enough to hold the handle
bars on. But there are grades 8 or 9 that are stronger.

As an aside your description is incorrect. It might be an U.S. size
which might be 8-32 or it might be metric in which case it would be
M8-1.25 or maybe M8-1.0. A U.S. #8 bolt is about half the thickness
of a 8mm bolt.

Generally speaking stainless is no stronger than mild steel and
Titanium is about the same strength as steel of the same hardness.
stainless, of course doesn't corrode much and titanium is about half
the weight of steel.

Your description of snapping sounds seems more like something that was
under great tension.... like over torqued?

Again an aside. The bolt(s) broke once in 15 years.....
  #3  
Old April 14th 17, 01:35 PM posted to rec.bicycles.tech
AMuzi
external usenet poster
 
Posts: 8,269
Default Selecting An Appropriate Bolt

On 4/13/2017 10:07 PM, Art Shapiro wrote:
I had a bit of an adventure when one of the two
handlebar-fixing bolts on my Deda Murex quilled stem decided
to snap with a rather impressive cracking noise. I somehow
didn't crash and happened to be only about seven miles from
home. I got slowly home holding the stem with one hand and
one of the brake levers on the dangling handlebars with the
other hand. (This is not recommended to the reader.)

I see that the bolt is a M6x18 tapered cone head Allen cap
screw with pressed-on washer.

The stem is two months shy of 15 years old, but I don't want
to have this happen again. Looking on eBay, I see quite a
few appropriate bolts, but I'm not sure what is optimal.
Can anyone help?

Everything seems to be Grade 5. Is that safe enough, or do
I really want to (somehow) find Grade 8?

Many are titanium. Is that a better choice than the
more-common steel? Or should I look for stainless steel? I
am always happy to save a few grams, but not if that's a
significant risk.

Advice welcome!


Original handlebar clamp bolts are Grade 8; readily
available and cheap. Grade 5 may be strong enough but for
pennies difference I suggest an 8. I wouldn't use Ti
fasteners in a stem but some guys do and many don't die.

Clean your handlebar, stem and and stem plate. Inspect for
damage/cracks. Clean threads in the stem, inspect for
damage, replace both bolts, lubricate at assembly, ensure
the gap of the handlebar plate is even on both ends. Deda
says torque to 10nm.

Stand in front of your bike and put your full weight on the
brake levers. Handlebar should not move. If it does or if
anything seems awry in any way, replace the stem.


--
Andrew Muzi
www.yellowjersey.org/
Open every day since 1 April, 1971


  #4  
Old April 14th 17, 03:14 PM posted to rec.bicycles.tech
Art Shapiro
external usenet poster
 
Posts: 14
Default Selecting An Appropriate Bolt

On 4/14/2017 5:35 AM, AMuzi wrote:

Original handlebar clamp bolts are Grade 8; readily available and cheap.
Grade 5 may be strong enough but for pennies difference I suggest an 8.


How does one get these "readily available" Grade 8 guys? Deda doesn't
seem to have much of a web presence outside of Italy. Is this a generic
item stocked by a good LBS?

Art

  #5  
Old April 14th 17, 03:27 PM posted to rec.bicycles.tech
AMuzi
external usenet poster
 
Posts: 8,269
Default Selecting An Appropriate Bolt

On 4/14/2017 9:14 AM, Art Shapiro wrote:
On 4/14/2017 5:35 AM, AMuzi wrote:

Original handlebar clamp bolts are Grade 8; readily
available and cheap.
Grade 5 may be strong enough but for pennies difference I
suggest an 8.


How does one get these "readily available" Grade 8 guys?
Deda doesn't seem to have much of a web presence outside of
Italy. Is this a generic item stocked by a good LBS?



Any metric fastener supplier if not your local hardware store.

https://duckduckgo.com/?q=DIN+912+grade+8&t=ha&ia=web

--
Andrew Muzi
www.yellowjersey.org/
Open every day since 1 April, 1971


  #6  
Old April 14th 17, 04:37 PM posted to rec.bicycles.tech
Art Shapiro
external usenet poster
 
Posts: 14
Default Selecting An Appropriate Bolt

On 4/14/2017 7:27 AM, AMuzi wrote:

Any metric fastener supplier if not your local hardware store.

https://duckduckgo.com/?q=DIN+912+grade+8&t=ha&ia=web

Thanks. That search engine link appears to be for traditional cap head
bolts rather than the original tapered cone head bolts. But I'll hit
the drawers at a couple of the area hardware stores or big box stores
and see what they have. Appreciated the input.

Art
  #7  
Old April 14th 17, 05:26 PM posted to rec.bicycles.tech
external usenet poster
 
Posts: 354
Default Selecting An Appropriate Bolt

On Fri, 14 Apr 2017 18:15:25 +0700, John B Slocomb
wrote:

On Thu, 13 Apr 2017 20:07:48 -0700, Art Shapiro
wrote:

I had a bit of an adventure when one of the two handlebar-fixing bolts
on my Deda Murex quilled stem decided to snap with a rather impressive
cracking noise. I somehow didn't crash and happened to be only about
seven miles from home. I got slowly home holding the stem with one hand
and one of the brake levers on the dangling handlebars with the other
hand. (This is not recommended to the reader.)

I see that the bolt is a M6x18 tapered cone head Allen cap screw with
pressed-on washer.

The stem is two months shy of 15 years old, but I don't want to have
this happen again. Looking on eBay, I see quite a few appropriate
bolts, but I'm not sure what is optimal. Can anyone help?

Everything seems to be Grade 5. Is that safe enough, or do I really
want to (somehow) find Grade 8?

Many are titanium. Is that a better choice than the more-common steel?
Or should I look for stainless steel? I am always happy to save a few
grams, but not if that's a significant risk.

Advice welcome!

Art


Grade 5 bolts should certainly be strong enough to hold the handle
bars on. But there are grades 8 or 9 that are stronger.

As an aside your description is incorrect. It might be an U.S. size
which might be 8-32 or it might be metric in which case it would be
M8-1.25 or maybe M8-1.0. A U.S. #8 bolt is about half the thickness
of a 8mm bolt.

Generally speaking stainless is no stronger than mild steel and
Titanium is about the same strength as steel of the same hardness.
stainless, of course doesn't corrode much and titanium is about half
the weight of steel.

Your description of snapping sounds seems more like something that was
under great tension.... like over torqued?

Again an aside. The bolt(s) broke once in 15 years.....

The steel bolt may have been "necked down" by rust. Stainless doesn't
do that - but often "welds" itself to the nut - particularly in high
torque installations.
  #8  
Old April 14th 17, 05:33 PM posted to rec.bicycles.tech
JBeattie
external usenet poster
 
Posts: 2,288
Default Selecting An Appropriate Bolt

On Friday, April 14, 2017 at 7:27:06 AM UTC-7, AMuzi wrote:
On 4/14/2017 9:14 AM, Art Shapiro wrote:
On 4/14/2017 5:35 AM, AMuzi wrote:

Original handlebar clamp bolts are Grade 8; readily
available and cheap.
Grade 5 may be strong enough but for pennies difference I
suggest an 8.


How does one get these "readily available" Grade 8 guys?
Deda doesn't seem to have much of a web presence outside of
Italy. Is this a generic item stocked by a good LBS?



Any metric fastener supplier if not your local hardware store.

https://duckduckgo.com/?q=DIN+912+grade+8&t=ha&ia=web


My neighborhood hardware store has them: http://aboysupply.com/wp-content/upl...1024x415_c.png They have a crazy selection of fasteners.

By the way, what's the deal with thread pitch? I always worry I'm getting the wrong pitch, but I guess that the whole "standard/fine/extra fine" thread pitch only kicks in with fasteners over 8mm(?). Otherwise, it's a pre-set. Right?

-- Jay Beattie.
  #9  
Old April 14th 17, 06:07 PM posted to rec.bicycles.tech
AMuzi
external usenet poster
 
Posts: 8,269
Default Selecting An Appropriate Bolt

On 4/14/2017 11:33 AM, jbeattie wrote:
On Friday, April 14, 2017 at 7:27:06 AM UTC-7, AMuzi wrote:
On 4/14/2017 9:14 AM, Art Shapiro wrote:
On 4/14/2017 5:35 AM, AMuzi wrote:

Original handlebar clamp bolts are Grade 8; readily
available and cheap.
Grade 5 may be strong enough but for pennies difference I
suggest an 8.

How does one get these "readily available" Grade 8 guys?
Deda doesn't seem to have much of a web presence outside of
Italy. Is this a generic item stocked by a good LBS?



Any metric fastener supplier if not your local hardware store.

https://duckduckgo.com/?q=DIN+912+grade+8&t=ha&ia=web


My neighborhood hardware store has them: http://aboysupply.com/wp-content/upl...1024x415_c.png They have a crazy selection of fasteners.

By the way, what's the deal with thread pitch? I always worry I'm getting the wrong pitch, but I guess that the whole "standard/fine/extra fine" thread pitch only kicks in with fasteners over 8mm(?). Otherwise, it's a pre-set. Right?



There are/were indeed other pitches available (the French
metric m5x0.9 for example) but the DIN standard (m5x0.8,
m6x1 etc) is well established now.

In my experience that's more of a problem with SAE fasteners
(1/4-20, 1/4-28 etc). Prior systems such as AC/AF, UNC/UNF,
Whitworth have become rare and unusual.

--
Andrew Muzi
www.yellowjersey.org/
Open every day since 1 April, 1971


  #10  
Old April 14th 17, 06:24 PM posted to rec.bicycles.tech
external usenet poster
 
Posts: 1,659
Default Selecting An Appropriate Bolt

On Friday, April 14, 2017 at 10:07:57 AM UTC-7, AMuzi wrote:
On 4/14/2017 11:33 AM, jbeattie wrote:
On Friday, April 14, 2017 at 7:27:06 AM UTC-7, AMuzi wrote:
On 4/14/2017 9:14 AM, Art Shapiro wrote:
On 4/14/2017 5:35 AM, AMuzi wrote:

Original handlebar clamp bolts are Grade 8; readily
available and cheap.
Grade 5 may be strong enough but for pennies difference I
suggest an 8.

How does one get these "readily available" Grade 8 guys?
Deda doesn't seem to have much of a web presence outside of
Italy. Is this a generic item stocked by a good LBS?


Any metric fastener supplier if not your local hardware store.

https://duckduckgo.com/?q=DIN+912+grade+8&t=ha&ia=web


My neighborhood hardware store has them: http://aboysupply.com/wp-content/upl...1024x415_c.png They have a crazy selection of fasteners.

By the way, what's the deal with thread pitch? I always worry I'm getting the wrong pitch, but I guess that the whole "standard/fine/extra fine" thread pitch only kicks in with fasteners over 8mm(?). Otherwise, it's a pre-set. Right?



There are/were indeed other pitches available (the French
metric m5x0.9 for example) but the DIN standard (m5x0.8,
m6x1 etc) is well established now.

In my experience that's more of a problem with SAE fasteners
(1/4-20, 1/4-28 etc). Prior systems such as AC/AF, UNC/UNF,
Whitworth have become rare and unusual.

--
Andrew Muzi
www.yellowjersey.org/
Open every day since 1 April, 1971


I am horrified that anyone would need a Grade 8 bolt for a stem. I would get a stem that uses two stainless bolts to clamp to the steerer and four to clamp to the bar. I would assume that he is discussing an MTB because I can't imagine conditions bad enough on a road to pop a grade 8 bolt under any forces there.
 




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