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Selecting An Appropriate Bolt



 
 
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  #11  
Old April 14th 17, 07:11 PM posted to rec.bicycles.tech
Frank Krygowski[_4_]
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Posts: 4,425
Default Selecting An Appropriate Bolt

On 4/14/2017 12:33 PM, 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 metric fine pitch threads
https://mdmetric.com/tech/thddat3.htm
like 5mm-0.5 instead of 5mm-0.8 but I've hardly ever come across them
in real life.

Fine thread fasteners are a bit stronger and more resistant to vibrating
loose. But in most cases, you can solve both problems by other means -
perhaps "next size up" and Loctite.

--
- Frank Krygowski
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  #13  
Old April 15th 17, 12:44 AM posted to rec.bicycles.tech
JBeattie
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Posts: 2,288
Default Selecting An Appropriate Bolt

On Friday, April 14, 2017 at 11:11:18 AM UTC-7, Frank Krygowski wrote:
On 4/14/2017 12:33 PM, 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 metric fine pitch threads
https://mdmetric.com/tech/thddat3.htm
like 5mm-0.5 instead of 5mm-0.8 but I've hardly ever come across them
in real life.

Fine thread fasteners are a bit stronger and more resistant to vibrating
loose. But in most cases, you can solve both problems by other means -
perhaps "next size up" and Loctite.


My concern was matching the pitch on threaded bosses -- and most recently wondering whether the 4mm button-head bolts I picked up at the hardware store had the right pitch. For some reason, Specialized decided to use 4mm bolts for the BB/bridge fender mounts on the Roubaix. Very odd. I didn't have any 4mm bolts lying around.

-- Jay Beattie.

  #14  
Old April 15th 17, 12:50 AM posted to rec.bicycles.tech
Frank Krygowski[_4_]
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Posts: 4,425
Default Selecting An Appropriate Bolt

On 4/14/2017 7:44 PM, jbeattie wrote:
For some reason, Specialized decided to use 4mm bolts for the BB/bridge fender mounts on the Roubaix. Very odd. I didn't have any 4mm bolts lying around.


That does seem like an odd decision. M5x0.8 has been so normal for so
long. What, were they hoping to save half a gram??

It's like the bicycle industry employs specialists whose job it is to
destroy standardization.


--
- Frank Krygowski
  #15  
Old April 15th 17, 04:03 AM posted to rec.bicycles.tech
John B Slocomb
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Posts: 268
Default Selecting An Appropriate Bolt

On Fri, 14 Apr 2017 07:14:19 -0700, 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?

Art


There are a great number of mail order companies who can supply the
bolts you need. The taper head is a matter of "what looks pretty" and
no not strength. I'm not necessarily recommending them but peruse the
McMaster-Carr web site for available bolts.

Or you could probably contact Andrew Muzi, our resident bicycle parts
specialist :-)

  #16  
Old April 15th 17, 04:03 AM posted to rec.bicycles.tech
John B Slocomb
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Posts: 268
Default Selecting An Appropriate Bolt

On Fri, 14 Apr 2017 19:50:58 -0400, Frank Krygowski
wrote:

On 4/14/2017 7:44 PM, jbeattie wrote:
For some reason, Specialized decided to use 4mm bolts for the BB/bridge fender mounts on the Roubaix. Very odd. I didn't have any 4mm bolts lying around.


That does seem like an odd decision. M5x0.8 has been so normal for so
long. What, were they hoping to save half a gram??

It's like the bicycle industry employs specialists whose job it is to
destroy standardization.


Or maybe their procurement department got a really, really, great deal
on 4mm bolts -)

What's the old theory? ""Never attribute to malice that which is
adequately explained by stupidity"?

  #17  
Old April 17th 17, 01:29 AM posted to rec.bicycles.tech
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Posts: 1,659
Default Selecting An Appropriate Bolt

On Friday, April 14, 2017 at 2:40:22 PM UTC-7, Art Shapiro wrote:
On 4/14/2017 10:24 AM, wrote:

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.


You assume wrong. My Habanero is most assuredly a road bike. And it's
a one-bolt quill stem; I find those cost-reduced threadless stems to be
an ugly atrocity.

I hope to keep the Habanero for a long time; almost everything on it has
been upgraded over the years to full Campy record. The Deda stem, which
I originally sent them to use when constructing the machine, continues
to be a non-Campy exception.

The unexpected failure mode, which could have been catastrophic, was the
reason I posted.

Jay, that's one hell of a hardware store! I've rarely seen that many
specialty drawers.

Art


And I have always found quill stems to be an atrocity.
  #18  
Old April 17th 17, 09:52 PM posted to rec.bicycles.tech
Doug Landau
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Posts: 818
Default Selecting An Appropriate Bolt

On Friday, April 14, 2017 at 4:15:34 AM UTC-7, 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.


What makes you say this? Do you have some #s to back this statement up, or is it just your wild guess? Have you calculated the load on this part when when a rider of a given weight hits a pothole at a given speed, or ??? And more importantly, why skimp here?

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.


Huh?!? What are you on about? It is you who is incorrect not he. He said it was an M6x18. The x is pronounced "by". Put M6x18 in google and click images. You will see M6 bolts in an 18mm length. He chose to identify the bolt by it's diameter and length, just like the rest of the world does most of the time.

You are describing bolts using diameter and pitch. This is incomplete, as it does not specify the length. Further is is irrelevant since the JIS and ISO standards both specify 1.0 as the standard pitch for 6mm bolts.

It is not an 8-32, nor is it an 8mm. Both of these suggestions are ridiculous. It is an M6x18 and while fine m6 bolts do exist in 1.10 pitch they are not common and it is safe to say it is, in this application, almost undoubtedly a 1.0. You seem to have latched on the number 8 for some reason.


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.


Steel has or can have greater strength for a given diameter. Why skimp here?

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


Looking at it the other way, it already broke once. Furthermore some possible reasons e.g. (e.g. over-tightening) might have also affected the threads that the bolt went into.

The stem is two months shy of 15 years old, but I don't want to have

this happen again.


Get a new stem. This one is a flawed design. There is built-in problem with the shape of the part, and that is a lack of remaining metal around the bolt hole. The stem has been made bigger around the front bolt hole to overcome this, but it still has the 2-bolt-1-failure problem. The traditional shape does not make this concession to ease-of-handlebar-change, and carefully places the single bolt in the rear where there is plenty of metal surrounding the threads.
The traditional design is both less likely to experience a bolt failure, and - in the wild guess dept., be more likely to hold on to the bars and remain usable in the event that one does.

Deda Murex 2-bolt:
https://www.google.com/search?q=deda...f3AGoQ_AUIBygC

3ttt traditional:
https://www.google.com/search?q=3ttt...w=1306&bih=724


  #19  
Old April 17th 17, 10:51 PM posted to rec.bicycles.tech
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Posts: 354
Default Selecting An Appropriate Bolt

On Mon, 17 Apr 2017 13:52:56 -0700 (PDT), Doug Landau
wrote:

On Friday, April 14, 2017 at 4:15:34 AM UTC-7, 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.


What makes you say this? Do you have some #s to back this statement up, or is it just your wild guess? Have you calculated the load on this part when when a rider of a given weight hits a pothole at a given speed, or ??? And more importantly, why skimp here?

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.


Huh?!? What are you on about? It is you who is incorrect not he. He said it was an M6x18. The x is pronounced "by". Put M6x18 in google and click images. You will see M6 bolts in an 18mm length. He chose to identify the bolt by it's diameter and length, just like the rest of the world does most of the time.

You are describing bolts using diameter and pitch. This is incomplete, as it does not specify the length. Further is is irrelevant since the JIS and ISO standards both specify 1.0 as the standard pitch for 6mm bolts.

It is not an 8-32, nor is it an 8mm. Both of these suggestions are ridiculous. It is an M6x18 and while fine m6 bolts do exist in 1.10 pitch they are not common and it is safe to say it is, in this application, almost undoubtedly a 1.0. You seem to have latched on the number 8 for some reason.

An M6X10 is the metric "functional equivalent" of a 1/4" UNC bolt.
It's dimensions and strength are very close. Being a metric bolt it
will be neither a Grade 5 nor a Grade 8. - it will be a class 8.8 or
10.9 or 12.9 An 8.8 is the metric "functional equivalent" to a grade 5



 




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