Handlebar bolts

[Ajax Bay]

Be clear if they are M4 or M5, obviously.
From the images shared I'd say the gaps, top and bottom were dissimilar: should try to make them the same.
Think (again from images) that 18mm bolts would be secure.
You may have more joy searching for 'stem faceplate' bolts (rather than 'handlebar bolts').

 

[fossyant]

I wont do that, as tempting as it is to go rust-free. Stainless bolts don't have the required tensile strengthb for the job. However, I have no doubt that many people have replaced their stem bolts with stainless and lived to tell the tale. I don't want to deliver dire warnings, but there is a very good reason why these weren't stainless to start off with. After all, it is far cheaper to supply the stem with stainless bolts than going to the trouble of creating custom, heat-treaated bolts and coat them black or even chrome them.

I'll add the stem bolts were ordered from Ritchey. The none critical bolts were stainless from a pack. Sorry should have said that as stem bolts have higher strength needs.

 

[Profpointy]

Either Grade 5 or 8, IIRC. You are right that they are not torqued much, but they do undergo considerable cyclical strain (with strong athletes in anyway) and they are located in a critical place. Also, movement in the bolts results in erosion of the bar against the clamp edge. The brouhaha about stem bolts started when we moved from one M6 to four M4s in front-loader stems. There was an interimn period where the first front loaders either had a hook on the one end and a bolt at the other. These slipped and creaked. Then it went to two bolts, which still creaked and left gouges in the bar where the two parts work against each other. Today we have almost universal 4-bolt stems in quality stems with very few failures.

I doubt this is a problem for most of us. I'll confess that back in the day I experimented (without knowing I did it) on myself and a few of my mates with stainless steel capscrews. We had a statiscically significant number of failures. One female rider in our bunch was so freaked out by her seat bolt breaking frequently that she started developing a weight consciousness problem. I remember once she complained about her "jelly belly" having broken the bolt again. I was oblivious to the cause and kept on replacing them with standard stainless - probably A2, I can't remember. Later I looked into it, spoke to other engineers about it and eventually the penny dropped. We did a crude spark test on a bench grinder on a discarded bolt and the result showed high-carbon steel.

So yeah, I guess there is more to it.

By way of a comparison we tend to use 8mm stainless "stud-anchors" (guessing A2?) for caving purposes. Prior to that we used 10-8 non-stainless bolts into steel anchors. The latter had the disadvantage you had to drill a 13mm hole whilst the stud only needs an 8mm hole; a lot less work if hand-drilling and still easier on batteries with a power drill. cyclical loads -yup, safety-critical -hell yes, and desirability of corrosion resistance even if the old high tensile bolds might be "stronger" (casual use of the word). Needless to say I had a shared-anchor plus a back-up anchor also taking some load when working on my house. I did have some misgivingings

I guess the cyclical loading is is hundreds or thousands of "bounces" compared to the gazillions for cycling, even if the forces are much larger, mostly only shared between 1 -1/2 bolts albeit backed up

All way off topic but got me musing on fastener choices in a different and arguably more critical sporting activity. I'm not an engineer, but do read about such things. I'm generally right about forces and the physics side but merely vaguely aware of creep and stuff like that.

I have prussiked (ie gone back up) a 200m pitch onto the bolt into an anchor older style - load all on a single bolt (backed up to another). I was not keen on the experience having had a "natural" belay let go on me on an 80m drop earlier in the trip. The noise a television sized rock makes after falling 80m is quite something! I felt the draft as it just missed me. I dropped only 2m or so and the remaining single bolt (bolted into really shoot rock) held. The really scary part is we nearly did without the bolt as we couldn't find it. The whole experience still gives me the willies.

After that experience I whimped out of the last bit of Goufre Berger, the first discovered 1000m deep cave, as there was a section where the bolt achors were rusty and it seemed only 10 or 12 mm was actually in the rock. Got to nearly 900 I suppose, and it was mostly fantastic

i

 

[Yellow Saddle]

By way of a comparison we tend to use 8mm stainless "stud-anchors" (guessing A2?) for caving purposes. Prior to that we used 10-8 non-stainless bolts into steel anchors. The latter had the disadvantage you had to drill a 13mm hole whilst the stud only needs an 8mm hole; a lot less work if hand-drilling and still easier on batteries with a power drill. cyclical loads -yup, safety-critical -hell yes, and desirability of corrosion resistance even if the old high tensile bolds might be "stronger" (casual use of the word). Needless to say I had a shared-anchor plus a back-up anchor also taking some load when working on my house. I did have some misgivingings

I guess the cyclical loading is is hundreds or thousands of "bounces" compared to the gazillions for cycling, even if the forces are much larger, mostly only shared between 1 -1/2 bolts albeit backed up

All way off topic but got me musing on fastener choices in a different and arguably more critical sporting activity. I'm not an engineer, but do read about such things. I'm generally right about forces and the physics side but merely vaguely aware of creep and stuff like that.

I have prussiked (ie gone back up) a 200m pitch onto the bolt into an anchor older style - load all on a single bolt (backed up to another). I was not keen on the experience having had a "natural" belay let go on me on an 80m drop earlier in the trip. The noise a television sized rock makes after falling 80m is quite something! I felt the draft as it just missed me. I dropped only 2m or so and the remaining single bolt (bolted into really shoot rock) held. The really scary part is we nearly did without the bolt as we couldn't find it. The whole experience still gives me the willies.

After that experience I whimped out of the last bit of Goufre Berger, the first discovered 1000m deep cave, as there was a section where the bolt achors were rusty and it seemed only 10 or 12 mm was actually in the rock. Got to nearly 900 I suppose, and it was mostly fantastic
View attachment 761892



i

Heights, caves, bolts, faith....nope. Give me a 13-spoke front wheel on a sprint any day over your nutty persuits.

 

[lostinthought]

By way of a comparison we tend to use 8mm stainless "stud-anchors" (guessing A2?) for caving purposes. Prior to that we used 10-8 non-stainless bolts into steel anchors. The latter had the disadvantage you had to drill a 13mm hole whilst the stud only needs an 8mm hole; a lot less work if hand-drilling and still easier on batteries with a power drill. cyclical loads -yup, safety-critical -hell yes, and desirability of corrosion resistance even if the old high tensile bolds might be "stronger" (casual use of the word). Needless to say I had a shared-anchor plus a back-up anchor also taking some load when working on my house. I did have some misgivingings

I guess the cyclical loading is is hundreds or thousands of "bounces" compared to the gazillions for cycling, even if the forces are much larger, mostly only shared between 1 -1/2 bolts albeit backed up

All way off topic but got me musing on fastener choices in a different and arguably more critical sporting activity. I'm not an engineer, but do read about such things. I'm generally right about forces and the physics side but merely vaguely aware of creep and stuff like that.

I have prussiked (ie gone back up) a 200m pitch onto the bolt into an anchor older style - load all on a single bolt (backed up to another). I was not keen on the experience having had a "natural" belay let go on me on an 80m drop earlier in the trip. The noise a television sized rock makes after falling 80m is quite something! I felt the draft as it just missed me. I dropped only 2m or so and the remaining single bolt (bolted into really shoot rock) held. The really scary part is we nearly did without the bolt as we couldn't find it. The whole experience still gives me the willies.

After that experience I whimped out of the last bit of Goufre Berger, the first discovered 1000m deep cave, as there was a section where the bolt achors were rusty and it seemed only 10 or 12 mm was actually in the rock. Got to nearly 900 I suppose, and it was mostly fantastic
View attachment 761892



i

I’m a climber, not a caver, but I think I recognise your perspective on bolts (or similar devices), and the degree to which you literally attach your life to them. Climbing -apart from the physical efforts- is a constant exercise in risk-assessment, because mortal risk is literally everywhere.


However I don’t quite agree with the thrust of your musings, that it is somehow a more challenging environment for a bolt to be fixed into a rock, per se, than to attach parts to a bicycle. For a couple of reasons:


One, specific: the loads that bike components endure is cyclical and repetitive. (I note that you did refer to this, but I think it’s worth expanding on, as we’re talking about it!) Nearly everything that ever breaks on a bike, does so as fatigue failure. I think there are multiple reasons for this, which could become a digression- briefly I’d say there is significant cultural pressure for bike components to be lightweight, but the cost of that lightness might take years to manifest in failure, by which time the horse has bolted, the company has sold their fancy thing, and everyone’s moved on to something else. Ad nauseam.

In contrast, climbing equipment to my knowledge tends to fail for other reasons: Fixed bolts corrode or the adhesive fails, or the substrate changes (moisture, etc), such is nature. Gear wears out through abrasion. Fatigue failure isn’t really something you see much of, because there just isn’t that same regular, cyclical loading. I can only guess that caving equipment is similar in this regard, though I stress that is only a guess.

Two, general: I think there is a prevailing sense- even amongst enthusiastic cyclists- that bicycles are harmless and innocuous contraptions. We can forget that it is easy enough to get on a bike and ride 50mph, which is most of the national speed limit in a car. I sometimes have to remind myself that I’m probably far more likely to die riding my bike than run-out on an exposed rock climbing pitch, even though I’ll feel way more scared on the rock face, than cruising down a sleek descent. A stem bolt failure at high speed really does not bear thinking about!

Regardless of all that, I absolutely love that you stuck a bolt in your house to do some work on it 😂 I had a harness on this summer, tied off to a cast iron bed inside while I was cleaning the gutter, looked a sight, didn't die though🤘

 

[Profpointy]

I’m a climber, not a caver, but I think I recognise your perspective on bolts (or similar devices), and the degree to which you literally attach your life to them. Climbing -apart from the physical efforts- is a constant exercise in risk-assessment, because mortal risk is literally everywhere.


However I don’t quite agree with the thrust of your musings, that it is somehow a more challenging environment for a bolt to be fixed into a rock, per se, than to attach parts to a bicycle. For a couple of reasons:


One, specific: the loads that bike components endure is cyclical and repetitive. (I note that you did refer to this, but I think it’s worth expanding on, as we’re talking about it!) Nearly everything that ever breaks on a bike, does so as fatigue failure. I think there are multiple reasons for this, which could become a digression- briefly I’d say there is significant cultural pressure for bike components to be lightweight, but the cost of that lightness might take years to manifest in failure, by which time the horse has bolted, the company has sold their fancy thing, and everyone’s moved on to something else. Ad nauseam.

In contrast, climbing equipment to my knowledge tends to fail for other reasons: Fixed bolts corrode or the adhesive fails, or the substrate changes (moisture, etc), such is nature. Gear wears out through abrasion. Fatigue failure isn’t really something you see much of, because there just isn’t that same regular, cyclical loading. I can only guess that caving equipment is similar in this regard, though I stress that is only a guess.

Two, general: I think there is a prevailing sense- even amongst enthusiastic cyclists- that bicycles are harmless and innocuous contraptions. We can forget that it is easy enough to get on a bike and ride 50mph, which is most of the national speed limit in a car. I sometimes have to remind myself that I’m probably far more likely to die riding my bike than run-out on an exposed rock climbing pitch, even though I’ll feel way more scared on the rock face, than cruising down a sleek descent. A stem bolt failure at high speed really does not bear thinking about!

Regardless of all that, I absolutely love that you stuck a bolt in your house to do some work on it 😂 I had a harness on this summer, tied off to a cast iron bed inside while I was cleaning the gutter, looked a sight, didn't die though🤘

I didn't mean to suggest that there weren't critical bolts, or components generally, on bikes, though concede I did imply most bolts did not fall into this category. Handlebars falling off at high speed, or a snapped seat post could easily be in the "Jesus bolt" category of failure - though I think one of the four grippy bolts fatigue failing would be more in the nuisance category. Doubt you'd lose them all at once (based on opinion only) even if a chain reaction, such is with spokes could be envisaged for some components

 

[lostinthought]

I didn't mean to suggest that there weren't critical bolts, or components generally, on bikes, though concede I did imply most bolts did not fall into this category. Handlebars falling off at high speed, or a snapped seat post could easily be in the "Jesus bolt" category of failure - though I think one of the four grippy bolts fatigue failing would be more in the nuisance category. Doubt you'd lose them all at once (based on opinion only) even if a chain reaction, such is with spokes could be envisaged for some components

I don't think you really did suggest that, I just saw and took the chance to riff on about it..!

Reminds me that I actually caught a fatigue failure in the faceplate of the Thomson stem I still use- it was a developing crack right across the thinnest point, which is the front face. Challenged, they replaced it- but I still check the replacement assiduously. Probably, I should take my own advice and just get a more substantial stem...

 

[Dadam]

Usual disclaimers, I am not an engineer etc

I understand the points about material strength and rolled threads etc, and can certainly see the logic for seatpost bolts, but I need more convincing that four m5* stainless bolts, correctly torqued, are a safety risk in that application. I would imagine the threads cut into the alloy stem body are at much greater risk of failure. In the OP's picture there looks to be about 7 threads of engagement into the stem holes.

Also, trying to find OEM stem bolts online is surprisingly difficult. Most hits seem to be aftermarket ones! Ironically, I did a couple of searches for stem bolts for big bike brands and the top link for Trek was OEM from their own website, titanium M5x20 cone head bolts. And they have the threads all the way up to the head. £8.99 a piece too!

* Pretty sure without checking that all my bikes are m5

 

[Jameshow]

Hello

My son has just bought a Calibre Bossnut (great bike!) to cut a long story short the handlebar bolts seem to be rounded off and I can’t get them torqued up properly (using a torque wrench) plus worry about loosening in future so I think the best thing is to replace them.

Any advice on good replacements? I’m pretty sure they’re M4 x20mm (pic attached). Does the material matter (steel / alloy) - don’t want them seizing in!

Why would they be rounding off?
I cannot see why you cannot torque them up unless you strip the alu stem threads. If they are coming loose then perhaps some locktite?

 

[C R]

Usual disclaimers, I am not an engineer etc

I understand the points about material strength and rolled threads etc, and can certainly see the logic for seatpost bolts, but I need more convincing that four m5* stainless bolts, correctly torqued, are a safety risk in that application. I would imagine the threads cut into the alloy stem body are at much greater risk of failure. In the OP's picture there looks to be about 7 threads of engagement into the stem holes.

Also, trying to find OEM stem bolts online is surprisingly difficult. Most hits seem to be aftermarket ones! Ironically, I did a couple of searches for stem bolts for big bike brands and the top link for Trek was OEM from their own website, titanium M5x20 cone head bolts. And they have the threads all the way up to the head. £8.99 a piece too!

* Pretty sure without checking that all my bikes are m5

I think you are correct about M5 rather than M4. I also agree that the female thread in the aluminium stem is more likely to fail than the male threads in the steel part.

 

[silva]

There is another concern: stainless bolts in aluminium + a fluid that conducts electricity, dissolves aluminium.
That is, the thread in the aluminium becomes loose powder, and with it, the connection strenght goes - the bolt feels loose.

One thinks oh bolt got loose, and tensions it further.
Until thread material dissolved to the point that tensioning = stripping the remainder and then it's hum replacement time for bicycle parts.

 

[Fastpedaller]

This talk of failure caused by repetitive strain reminds me of my old kit car....... I don't know how many thousands of miles it had 'under its belt' as a Ford Escort before becoming a Rickman Ranger, anyway, a few years ago I was driving slowly over a speed hump on the driveway into a bowls club. The car stopped - my immediate thought was 'clutch or gearbox faulty', and then (with it still in gear and the engine running) I looked underneath and saw the propshaft still spinning! RAC came to the rescue, and when I got home I jacked up one side and moved the wheel by hand - the propshaft moved.....hmm a bit mysterious, so I did the same on the other side with the same result. When I removed the cover off the diff I expected to be greeted by a 'chink, chink, chink' of broken parts, but that didn't happen either. When the diff was removed I found the ring gear had sheared all 6 bolts off where it bolted to the carrier. These are the same bolts used to attach the flywheel to the crankshaft of the engine - very strong beasts!. One of the bolt holes was ovalised, apart from that there was no lasting damage which would prevent it from being kept as a spare (the new owner of the car has it now). I sourced a replacement diff from a local classic motorsport restorer, who said he'd never seen one do it even though they ran almost 300BHP engines on their cars. It must have been 'hanging on' with the last bolt for some time. The oil viscosity led to the prop being able to turn when the wheel was turned by hand. How many million turns had that part made during the last 40+ years?

 

[pfm401]

Got it sorted. A lot of googling and measuring led me to Trek Speed Concept faceplate bolts M5 x 18 at £2 each which are identical - weird considering the difference in the unit (MTB stem v triathlon bike stem) but works so I’m happy enough!!

 

[Yellow Saddle]

Got it sorted. A lot of googling and measuring led me to Trek Speed Concept faceplate bolts M5 x 18 at £2 each which are identical - weird considering the difference in the unit (MTB stem v triathlon bike stem) but works so I’m happy enough!!

A like a result.