A Cycling & bikes forum. CycleBanter.com

Go Back   Home » CycleBanter.com forum » rec.bicycles » Techniques
Site Map Home Register Authors List Search Today's Posts Mark Forums Read Web Partners

Selecting An Appropriate Bolt



 
 
Thread Tools Display Modes
  #1  
Old April 14th 17, 04:07 AM posted to rec.bicycles.tech
Art Shapiro
external usenet poster
 
Posts: 17
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

  #2  
Old April 14th 17, 12:15 PM posted to rec.bicycles.tech
John B Slocomb
external usenet poster
 
Posts: 356
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, 05:26 PM posted to rec.bicycles.tech
[email protected]
external usenet poster
 
Posts: 445
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.
  #4  
Old April 17th 17, 09:52 PM posted to rec.bicycles.tech
Doug Landau
external usenet poster
 
Posts: 1,424
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


  #5  
Old April 17th 17, 10:51 PM posted to rec.bicycles.tech
[email protected]
external usenet poster
 
Posts: 445
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



  #7  
Old April 18th 17, 04:29 AM posted to rec.bicycles.tech
John B Slocomb
external usenet poster
 
Posts: 356
Default Selecting An Appropriate Bolt

On Mon, 17 Apr 2017 17:51:39 -0400, wrote:

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 right. I'll change my reply to read "It might be an U.S. size
which might be 6-32 or it might be metric in which case it would be
M6-1.0. A U.S. #6 bolt is about half the thickness
of a 6mm bolt." Happy now?

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.


Nope. A thread is described by two things diameter and number of
threads per unit. One can easily buy, for example, a 1/4" thread any
where from a quarter of an inch long, or so, to three feet, or more.

If you want to talk length then yes. A bolt should be long enough that
one complete thread will be extend past the nut. but there is not
maximum length, un less, or course it hits the other side of the
automobile.



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


If you wish to be picky then let us be picky. There is no such thing
as a M6X10 thread, and even if it existed it would hardly be
equivalent to a 1/4-20 bolt. After all a 1 inch 1/4" bolt would have
20 threads on it while your imaginary M6X10 bolt would have only
(roughly) 4. Probably have to tighten the nut real tight to get it to
hold. I wonder can one even cut a 60 degree 10mm thread on a 6 mm rod?
  #8  
Old April 18th 17, 05:08 AM posted to rec.bicycles.tech
[email protected]
external usenet poster
 
Posts: 445
Default Selecting An Appropriate Bolt

On Tue, 18 Apr 2017 10:29:32 +0700, John B Slocomb
wrote:


If you want to talk length then yes. A bolt should be long enough that
one complete thread will be extend past the nut. but there is not
maximum length, un less, or course it hits the other side of the
automobile.



This is not true with AN hardware.AN hardware is spec'd by it's
diameter and grip length -and there is a stringent spec as to how much
thread must/may extend beyond the nut. You NEVER have threads within
the "grip"


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


If you wish to be picky then let us be picky. There is no such thing
as a M6X10 thread, and even if it existed it would hardly be
equivalent to a 1/4-20 bolt. After all a 1 inch 1/4" bolt would have
20 threads on it while your imaginary M6X10 bolt would have only
(roughly) 4. Probably have to tighten the nut real tight to get it to
hold. I wonder can one even cut a 60 degree 10mm thread on a 6 mm rod?


Who's being picky??
  #9  
Old April 18th 17, 10:15 PM posted to rec.bicycles.tech
Doug Landau
external usenet poster
 
Posts: 1,424
Default Selecting An Appropriate Bolt

On Monday, April 17, 2017 at 8:29:53 PM UTC-7, John B Slocomb wrote:
On Mon, 17 Apr 2017 17:51:39 -0400, wrote:

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 right. I'll change my reply to read "It might be an U.S. size
which might be 6-32 or it might be metric in which case it would be
M6-1.0. A U.S. #6 bolt is about half the thickness
of a 6mm bolt." Happy now?

Nope. Please return to the subject, and change your reply to answer the OP's question, which was "Everything seems to be Grade 5. Is that safe enough, or do I really want to (somehow) find Grade 8?"

This will require first identifying the most extreme condition that the bolt will experience as long as the rider can hold on and stay upright. The goal is to determine safe enough, and one is not going to be safe after riding at cruising speed into a wall or curb anyway. Hitting a pothole seems reasonable to me, but whatever. Then calculate the tension on the bolt in that situation, and then compare that to specification for grade 8.

But what is the value in stating "Grade 5 should certainly be strong enough to hold the bars on." ? So will a rubber band or some scotch tape, as long as one rides slow on smooth road.

But there are grades 8 or 9 that are stronger

Yes, the OP knows that, and had to to pose the question "Do I need grade 8?" in the first place.

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.


Nope. A thread is described by two things diameter and number of
threads per unit. One can easily buy, for example, a 1/4" thread any
where from a quarter of an inch long, or so, to three feet, or more.


We are not talking about a thread.

If you want to talk length then yes.

Again the OP was talking about grade; you faulted him for the way he described the bolt, and I am saying that a)he described it in the same way we all do most of the time, which is not flawed, and b)the quality of this method which you say is a flaw also exists in your claim of what is correct.

The fact is that a bolt has three identifying characteristics, and all must be expressed in order to avoid being incomplete, and at times, insufficient.
  #10  
Old April 19th 17, 05:06 PM posted to rec.bicycles.tech
[email protected]
external usenet poster
 
Posts: 3,345
Default Selecting An Appropriate Bolt

On Monday, April 17, 2017 at 1:52:58 PM UTC-7, Doug Landau wrote:

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


Doug - a stem should NOT be designed in such a manner that it is being held from failing by a bolt. These should be only there to put the parts together and the forces should be held in check by the design of the stem.

Yes, most stems are not so designed but most stems come from China where they don't have to worry about lawsuits from Americans.

A stem should have TWO bolts to tighten it to a steerer only to tighten it from rotating. And two bolts so that one breaking does not disable this capacity. Why on Earth would anyone question that? The handlebar mount likewise should have four bolts on it and the mount should be angled and a step placed in it so that the stem itself is carrying the load of a handlebar and not the bolts that are only there to assemble it.

Old fashioned threaded-head style stems were vastly overbuilt precisely because they were afraid of aluminum. We have more experience and better alloys today and don't have one single angle of stem to pretend racer with.

And those old stems had way oversized stem bolts and still failed because of bolts being given sidewise forces in most of them other than Cinelli who were real engineers.
 




Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Converting Brake mounting bolt to recessed bolt? Sir Ridesalot Techniques 18 August 23rd 09 12:49 PM
Selecting a Bike Katuzo General 46 July 26th 08 03:11 PM
selecting a BB [email protected] Techniques 5 September 12th 07 03:10 AM
Selecting the right chain heedcase Techniques 10 August 28th 04 02:32 AM
Selecting a new saddle Nick Kew UK 18 December 25th 03 11:47 PM


All times are GMT +1. The time now is 03:04 PM.


Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Copyright ©2004-2024 CycleBanter.com.
The comments are property of their posters.