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 |
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..... |
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 |
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 |
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 |
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 |
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. |
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. |
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 |
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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