What is the Strongest Stem?- Mtbr.com
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  1. #1
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    What is the Strongest Stem?

    I've broken a few dozen over the years. Seems they only come in two varieties, the ones I've broken and the ones I haven't broken yet.

  2. #2
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    What stems have you broken and how are they breaking? That isnít a part many people break.


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    Truvativ Hussefelt any good?

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    Quote Originally Posted by austink26 View Post
    What stems have you broken and how are they breaking? That isnít a part many people break.

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    Basically all brands from budget to stupid expensive. Easily more than a dozen on road bikes. Only a few MTB (Race Face, Wake) and to be fair the Wake that just broke today was on my trials bike for 3 years. I'm fairly anal about greasing the threads and being careful about the torque. Usually it's stripped threads, but there have a been more than a few that just snapped off. Cinelli track stems and one that came with my bikes-direct bike are the only ones I never had a problem with.

  5. #5
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    ^yeah it's strong and stiff and also pretty cheap. if you break that you'll break anything really...
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  6. #6
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    Wow.. I've never broken a stem.... I expect I will on my ride tomorrow now.

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    Quote Originally Posted by 127.0.0.1 View Post
    ^yeah it's strong and stiff and also pretty cheap. if you break that you'll break anything really...
    The 500 gram stem from bikes direct?

  8. #8
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    Quote Originally Posted by sapva View Post
    Basically all brands from budget to stupid expensive. Easily more than a dozen on road bikes. Only a few MTB (Race Face, Wake) and to be fair the Wake that just broke today was on my trials bike for 3 years. I'm fairly anal about greasing the threads and being careful about the torque. Usually it's stripped threads, but there have a been more than a few that just snapped off. Cinelli track stems and one that came with my bikes-direct bike are the only ones I never had a problem with.
    You have broken over 12 stems on a road bike? Stripped threads? At the steerer tube or face plate? And what snapped off?
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  9. #9
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    Quote Originally Posted by Phillbo View Post
    Wow.. I've never broken a stem.... I expect I will on my ride tomorrow now.
    Yeah, don't ever say that

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    Quote Originally Posted by Vespasianus View Post
    You have broken over 12 stems on a road bike? Stripped threads? At the steerer tube or face plate? And what snapped off?
    Mostly stripped threads at the face plate, on the vintage road stuff stripped the single bar clamp bolt, and a few just snapped clean just in front of the steer tube. I've tried to be more gentle with bikes the past 10-15 years and it's helped, but I am fairly heavy and a natural masher. The ride today was both upper bolts on the face plate the second pedal stroke into the first climb.

  11. #11
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    Why don't you look for a stem that has addressed all the issues you have? You seem to have very specific demands on stems.

    How about a design like this Intend Grace FR?

    What is the Strongest Stem?-image.jpg
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    You are not breaking stems on your mountain bikes, you are breaking bolts. You are breaking bolts because the metal was stretched past it's fatigue point. The metal is past it's fatigue point because it's over torqued. They are over torqued because you are greasing the threads. Stop greasing the threads.
    Also, you should not have some insane body weight on the bars. Your primary weight should be on your pedals.

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    Quote Originally Posted by Varaxis View Post
    Why don't you look for a stem that has addressed all the issues you have? You seem to have very specific demands on stems.

    How about a design like this Intend Grace FR?

    Click image for larger version. 

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    That is crazy expensive. But interesting, and the same basic design of the old Cinelli stems. Pretty sure the failure on the Wake stem was a design failure of having the plane of the front plate rotated upwards so the torque is on the bolts and not the body.

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    Quote Originally Posted by Suns_PSD View Post
    You are not breaking stems on your mountain bikes, you are breaking bolts. You are breaking bolts because the metal was stretched past it's fatigue point. The metal is past it's fatigue point because it's over torqued. They are over torqued because you are greasing the threads. Stop greasing the threads.
    Also, you should not have some insane body weight on the bars. Your primary weight should be on your pedals.

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    Don't think it is realistic to change my riding habits after 50+ years. The grease is to prevent galling. Maybe that is wrong, but I've had much better luck since doing that.

    What I'm really interested in is a stem that is simply strong enough for anything, regardless of stem/rider weight.

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    Quote Originally Posted by sapva View Post
    What I'm really interested in is a stem that is simply strong enough for anything, regardless of stem/rider weight.
    Mtb stems dont break as much as all other parts. You will be hard pressed to break even the cheap carbon fiber chiner stems.

    snapped a stem once and it was the bolt that snapped from jumping to high on a motoX bike, once I thought my stem let the bars slip, but the steel bars actually folded forward, and the stem didnt slip at all. that was a 10 foot high jump and I came down hard.

    most mtb bars will fold before the stem gives

  16. #16
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    Have you looked at the Syntace MegaForce2 stem yet?

  17. #17
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    https://www.profileracing.com/product/helm-mtb-stem/


    https://industrynine.com/stems/

    And as stated above, donít grease the treads. That could lead to over torquing and breaking them. Use blue loctite as per directed in most user manuals.


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    Quote Originally Posted by austink26 View Post
    https://www.profileracing.com/product/helm-mtb-stem/


    https://industrynine.com/stems/

    And as stated above, donít grease the treads. That could lead to over torquing and breaking them. Use blue loctite as per directed in most user manuals.


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    The Industrynine stems look nice. But also think that not having the bolts extend though the body reduces the thread length and thus strength.

    Pretty sure some stems come with greased threads, don't recall any having thread lock like brake bolts.

  19. #19
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    https://www.engineeringtoolbox.com/t...ts-d_1693.html

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    You are doing it wrong.
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  21. #21
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    The alloy is significant. 7050 is usually what you want.

    What is the Strongest Stem?-j01-moreaboutaluminumd1-gis.png
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  22. #22
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    Quote Originally Posted by ASiameseCat View Post
    Have you looked at the Syntace MegaForce2 stem yet?
    Agree

    or if you need 35mm https://chromagbikes.com/collections...tems-bza-clamp


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    Quote Originally Posted by DrDon View Post
    Those look nice. But guess they should for $170, may as well spend a couple more dollars and get full ti from ControlTech. Warranty is only one year, and specifically excludes stair sets of doom.

    Personally, I think it has little to do with any one magic material and more to do with certain design flaws like bolts that are too small or holes not tapped all the way through the body thus reducing the thread area.

  24. #24
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    Stem breakage is less common than I would have thought (230 out of 18k)...

    https://www.pinkbike.com/news/poll-w...hese-days.html

    Hard to find anything that resembles actual tests...

    Stem Review - Fairwheel Bikes Blog

  25. #25
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    sounds like you are over-tightening bolts and breaking them. that's not the stem's fault. no stem exists that is designed to handle over-torquing bolts. what kind of torque wrench are you using, and are you certain it's calibrated?

    treat the bolts with a light application of Loctite 242 to prevent galling. torque the bolts to spec with a calibrated torque wrench. that should be all you need. if you're worried about the stem slipping, apply a little "fiber grip" to the fork and handlebar interface.

    all that said, I think the Paul Boxcar stem looks like a beast, but you'll still need to adhere to good practices using a torque wrench.

  26. #26
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    Quote Originally Posted by mack_turtle View Post
    sounds like you are over-tightening bolts and breaking them. that's not the stem's fault. no stem exists that is designed to handle over-torquing bolts. what kind of torque wrench are you using, and are you certain it's calibrated?

    treat the bolts with a light application of Loctite 242 to prevent galling. torque the bolts to spec with a calibrated torque wrench. that should be all you need. if you're worried about the stem slipping, apply a little "fiber grip" to the fork and handlebar interface.

    all that said, I think the Paul Boxcar stem looks like a beast, but you'll still need to adhere to good practices using a torque wrench.
    I'm not anywhere near 3 ft-lbs on the torque. Carbon grease works on AL?

    That does look like a beefy stem, threaded all the way through, larger bolts. Let's see, $150 vs. 3 x $50 for realistically priced stems (one on bike, spare to carry, spare for shop). Wonder how many they sell at those prices, you could almost have a custom stem made for that.

  27. #27
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    most stems are 5-6 Nm for the small bolts, which is 44-53 inch pounds. it's not a lot of torque and easy to over-shoot it if you're not monitoring your torque. if you're regularly stripping out bolts, it's because you're over-torquing them.

    I meant put some sort of carbon grip paste on the stem where the handlebar clamps to it if you're worried about it slipping. it's like gel sandpaper that increases friction between smooth surfaces. on bikes with carbon fiber seatposts, stems, fork steerer tubes, etc, it help prevent slipping. I've used it as a preventative measure on aluminum / aluminum interfaces (stem and bars, stem and fork steerer, etc) and had not problems.

    don't complain about the price if you want something "strong". I am not going to buy one, but I've never "broken" a stem. you'll strip out a Boxcar stem too, if you continue to over-torque the bolts on it.

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    That grip paste is a good idea. I use it on seat posts in carbon frames, but never thought about using for metal parts. Riser bars are a pain to keep in place and no doubt, unlike stems, I have way over torqued the microscopic bolts on my Oury grips that also seem to come loose all the time.

    Yeah, I'm not spending $150 either Those Paul components are a work of art. But short of a lifetime replacement warranty with no disclaimers, it just isn't cost effective. I don't need to save a few grams on a show bike, just want to save a few miles of pushing the bike back to the truck with my bars flopping around.

  29. #29
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    Syntace.

    And maybe buy a new torque wrench while you're at it.
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  30. #30
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    Quote Originally Posted by sapva View Post
    I'm not anywhere near 3 ft-lbs on the torque.
    how are you measuring this? if you're using your arm, it's obviously not calibrated correctly. you need a precision tool.

    a torque wrench costs a lot less than several stems. the $20 clicky wrench I bought at Harbor Freight is shockingly accurate and consistent. there are fancier ones that will do the job for less than $50. that will save you a lot of money in the long run. then buy a beefy stem designed for freeride for under $100 and you should be fine.

    and stop cranking down on the bolts until they strip, in case I have not made that part clear.

  31. #31
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    this all comes down to torque...measured torque


    torque a 4 bolt stem to 5.5nm for each bolt...dry...and evenly applied. the bolt won't break and the stem won't come apart or lose the handlebars

    recheck torque after the first few rides to verify staying put

    for my other post you asked hussefelt I meant yes it is strong and cheap
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    It's not the torque.

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    how are you certain of that if you're not measuring it in any way?

    no one else has the problem. the common denominator here is that you admitted you're not measuring your torque and you're stripping out bolts. what else could it be? believe what you want, but I guarantee you, unless you're riding like Marshall Taylor, the stem itself is not the problem.

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    Quote Originally Posted by mack_turtle View Post
    how are you certain of that if you're not measuring it in any way?

    no one else has the problem. the common denominator here is that you admitted you're not measuring your torque and you're stripping out bolts. what else could it be? believe what you want, but I guarantee you, unless you're riding like Marshall Taylor, the stem itself is not the problem.
    It's not the torque. Yes I have a torque wrench. Yes I know how to use it. If anything I'm paranoid and under torque, generally use only the small end of the wrench (1") between the thumb and forefinger. It would be really painful to over tighten that way. And yes, I've verified with the torque wrench. It is entirely possible that another 10% is added by lubing the threads (error noted), but should not be enough to strip the threads. So i think the torque thing has been covered and then some.

    Yes, I probably do ride like Major Taylor, with somewhat less elegance and subtlety. That's what I do for fun, chase cars, go down stair cases, mash in too big of a gear, just to name a few of the many sins. I'm not going to change. Just want some recommendations for moderately priced stems that are over built. Probably just as well they break from time to time, snapped bars are dangerous and I'd cry if I broke the steer tube on a $1,000 fork.

  35. #35
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    One reason why Syntace works stronger is that its body takes much of the loads, since the bar receptacle cradles more than half the bar.

    When the stem only cradles half, as if cut to make two almost-180 semi-circles between it and the faceplate, the bolts take the load. When someone weighing more than average puts a lot of impact-like loads on it from riding hard, the fasteners are loaded in tension even more, creating similar damage to overtorqueing.

    I'm guessing sapva is afraid that repetitive damage like this, and vibration in general, can cause the threads to get damaged, and used grease instead of medium strength threadlock (e.g. blue 243 loctite) because they don't want the threads to seize?

    Some other brands rely on interlocking faceplates, like Easton and RaceFace, which transfer loads to the body. They cost quite a bit more though ($50-100). Decent engineering costs $$$.

    A brand like Wake, which I saw on ebay and ali shipped from China at rock bottom prices, are mere copy cats that I'm afraid don't even meet, let alone surpass standards. I'm surprised you got that much use out of it. Standard stuff that shows up on budget bikes have stems that are maybe in the $20 range too, but seem better made. I'd look for 3D forged and shot peened or bead blasted over any cheap ano CNC stem, especially if it had 4 widely spaced bolts for the faceplate and girthy external dimensions. Having closely spaced bolts, not any wider spaced than the steerer clamp part is a no-go for me. Welded is also a no-go. Being short in height is a no-go, unless I was slamming the stem to be as close to the upper bearing as possible, with the star nut or expansion plug directly under it.

    Attached pic of interlocking faceplate, with a body that supports more than half the bar, that's an improvement over the usual straight edge cut-in-half style.

    Here's my recommendation:

    https://northwestbicycle.com/product...e-black-sm8467
    Attached Thumbnails Attached Thumbnails What is the Strongest Stem?-dsc00628.jpg  

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  36. #36
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    Quote Originally Posted by Varaxis View Post
    One reason why Syntace works stronger is that its body takes much of the loads, since the bar receptacle cradles more than half the bar.
    Yes, that design makes a lot more sense. For me, it's not so much about the impact and general abuse, it is pulling up hard on the bars while mashing down on the pedals that kills them. And long MTB bars just generate all that much more force.

  37. #37
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    Quote Originally Posted by sapva View Post
    It's not the torque. Yes I have a torque wrench. Yes I know how to use it. If anything I'm paranoid and under torque, generally use only the small end of the wrench (1") between the thumb and forefinger.
    thank you for clarifying. I've met many, many people who think their wrist is a suitable substitute for a torque wrench. this kind of numbskullery leaves me jaded and skeptical of most people's abilities, so I had to ask specifics in order to believe that you know what you're doing. sometimes that works out for them, other times, they strip and break things. forgive me for concluding that you're one of those.

    I don't think that is the right way to use a torque wrench though. if you're not applying force at the part of the tool where it's designed to measure torque, it's bound to be imprecise. a tool like that is designed to measure force at a specific place on the handle. holding the wrench that lose to the head is giving you imprecise measurements. however, it sounds like you're not just pounding on the bolts like a gorilla. so it's still possible that you're not just stripping out the bolts like a novice. I can't tell remotely what you're doing, but I recommend that you start holding the wrench in the right place to avoid this. make that change and at least you can cancel out user error on the tool.

    not to insult your intelligence further, but are you tightening all four bolts evenly?

    unfortunately, as a mere waif of 160 pounds, I rarely break parts, so I have nothing more to add. There are some stronger stems out there but I've never needed to look for them.

    some of the context found later in this discussion was helpful, but your weight and riding style make a difference. let me get this straight: you're at least 55 or 60 years old and you're riding so hard that you're breaking stems? damn.

    I would recommend posing this in the clydesdale forum as well.

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    I'll get right on making you a $20 unobtanium stem which needs dimondium bits to machine it from a solid block to your specifications.

    Buck up for top quality components or keep dealing with your stem breaking habit. Up to you.

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    Quote Originally Posted by mack_turtle View Post
    not to insult your intelligence further, but are you tightening all four bolts evenly?
    Yes of course, crisscross just like lug nuts.

    Quote Originally Posted by mack_turtle View Post
    some of the context found later in this discussion was helpful, but your weight and riding style make a difference. let me get this straight: you're at least 55 or 60 years old and you're riding so hard that you're breaking stems? damn.
    Yes, and no broken bones or surgeries so far this year [knock on wood]. Being an aerobic specimen floating effortlessly up hills on a light breeze was never in the cards for me.

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    Quote Originally Posted by Fajita Dave View Post
    I'll get right on making you a $20 unobtanium stem which needs dimondium bits to machine it from a solid block to your specifications.
    Lol. Honestly, I'd be happy with plain old stainless steel w/ grade 8 bolts.

  42. #42
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    Quote Originally Posted by sapva View Post
    It's not the torque. Yes I have a torque wrench. Yes I know how to use it. If anything I'm paranoid and under torque, generally use only the small end of the wrench (1") between the thumb and forefinger. It would be really painful to over tighten that way. And yes, I've verified with the torque wrench. It is entirely possible that another 10% is added by lubing the threads (error noted), but should not be enough to strip the threads. So i think the torque thing has been covered and then some.

    Yes, I probably do ride like Major Taylor, with somewhat less elegance and subtlety. That's what I do for fun, chase cars, go down stair cases, mash in too big of a gear, just to name a few of the many sins. I'm not going to change. Just want some recommendations for moderately priced stems that are over built. Probably just as well they break from time to time, snapped bars are dangerous and I'd cry if I broke the steer tube on a $1,000 fork.
    If you checked that engineering study I attached above you will see that adding grease to threads results in 50-55% less torque required to reach the same axial loading. So if you are setting your torque wrench at the same number, you are essentially doubling the stretch on the bolt, putting it well past it's ability to recover.

    The grease is causing you to over torque the bolts, stressing them, and breaking them. This has nothing to do with your riding style and everything to do with your mechanic skills.

    Buy any stem that you like the way it looks/ color/ price, use ONLY a dab of blue locktite on the threads (no grease!), and you'll never have a problem with your stems again.

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    I appreciate your tolerance for my relentless probing questions! I hope you find a stem that holds up better. in the meanwhile, I think you can derive some better practices from this thread that will give your next stem a better chance.

    I sounds like a GG shill these days, but I'll bet they have some bruisers in their customer base who break stuff. ask them what they recommend to those customers.

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    Quote Originally Posted by sapva View Post
    Lol. Honestly, I'd be happy with plain old stainless steel w/ grade 8 bolts.
    If you can find a stem with enough material around the bolt holes it might be worth a shot to install a helicoil. Drill out the original holes and install the helicoil with red threadlock. You'll have a stem with steel threaded inserts.

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  46. #46
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    Quote Originally Posted by Suns_PSD View Post
    You are not breaking stems on your mountain bikes, you are breaking bolts. You are breaking bolts because the metal was stretched past it's fatigue point. The metal is past it's fatigue point because it's over torqued. They are over torqued because you are greasing the threads. Stop greasing the threads.
    this advice may be useful for some industrial applications where very large bolts are used, but in general, manufacturers list the torque specs on stems with greased threads. read carefully, all of the support docs below say that their bolts are pre-greased, or that you should check for grease if re-installing.

    Hope
    Chromag
    Thomson
    Renthal

    I think it's safe to assume that the torque specs presume lubricated threads.

    in short, OP is not stripping bolts because he is greasing threads. he may still be over-torquing bolts, but it's not because of the grease.

    funny story: I owned a Thomson stem years ago and it came with bolts for a 3mm hex. tiny! I was used to using a torque key with a glued-in 4mm hex driver. I called Thomson to ask about it and the person on the phone told me "we use 3mm hex on our stems now because people strip out our bolts and break our stems by over-tightening the 4mm hex we used to use. a 3mm is more likely to round out before it does any damage to the stem. it sounds like you know what you're doing, so what's your address?" then he mailed me some nicer bolts with a 4mm hex.

  47. #47
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    I've broken everything on a bike except the stem. I'm honestly impressed. I've seen 3 broken stems in my life- 2 overtorqued thomsons, and a truvativ that i bolted to a pipe and twisted the bars, just to see what would happen. It was an XC stem and took all my strength to break.
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    Not by itself but its a contributor. It sounds like youre applying unequal amounts of torque to the bolts as you tighten the interface between the face plate and stem. I mean this really easy to over tighten the top bolts of a 4 bolt face then the lower two. And when you cant see the lower bolts you cant notice that the faceplate isnt square to the stem.

  49. #49
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    Quote Originally Posted by Fajita Dave View Post
    Now that is different. May try that one.

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    Quote Originally Posted by Fajita Dave View Post
    that's pretty close to a direct ripoff of an Odyssey Elementary stem. I wonder fi George French has seen that.

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    Quote Originally Posted by scottzg View Post
    I've broken everything on a bike except the stem. I'm honestly impressed. I've seen 3 broken stems in my life- 2 overtorqued thomsons, and a truvativ that i bolted to a pipe and twisted the bars, just to see what would happen. It was an XC stem and took all my strength to break.
    Guess everyone is different. I've always had issues with stems, cranks, chains and bb's. Even had one folded chain ring. And yet have bikes that I've ridden for 20 years without so much as a scratch on the frame. Always expect to have problems with wheels, but the worst that has ever happened is a popped spoke and normal truing of the wheels. There were a couple of broken frames, but suspect internal rust was more of a factor.

  52. #52
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    Wow.
    I'm 225 lb, and I have never ever broken a stem. Snapped many frames, folded wheels, but never a bar or stem. The bolt thing really seems strange though.

  53. #53
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    Quote Originally Posted by mack_turtle View Post
    that's pretty close to a direct ripoff of an Odyssey Elementary stem. I wonder fi George French has seen that.
    If it is anything like the elementary, your bars are going to move way too often.....


    Sent from my iPhone using Tapatalk

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    Properly installed MTB stems can withstand huge amounts of abuse: 250lb guys coming up short on massive doubles and step downs over and over again. WC DH riders or pro freeriders do not break stems/stem bolts typically (only the rare case where they are using m4 Ti bolts or something). It is unlikely that this is an equipment problem.

  55. #55
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    Quote Originally Posted by Gemini2k05 View Post
    Properly installed MTB stems can withstand huge amounts of abuse: 250lb guys coming up short on massive doubles and step downs over and over again. WC DH riders or pro freeriders do not break stems/stem bolts typically (only the rare case where they are using m4 Ti bolts or something). It is unlikely that this is an equipment problem.
    Yes, that idea has been posted about a dozen times. And it matters little about other people's stems if my stem breaks.

    I don't think the stress from jumps is much of a factor, impacts from stem striking the ground maybe. Invariably it happens while standing and pulling up on the bars.

    One thing seems to be in common with stems that have failed at the threads is having only around 5mm of bolt covered in a stem that is tapped all the way through at 15mm. Guess they do that to keep it looking clean. Ordered a Hussefelt as a replacement, along with a collection of longer M5 bolts.

  56. #56
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    Quote Originally Posted by sapva View Post
    Don't think it is realistic to change my riding habits after 50+ years. The grease is to prevent galling. Maybe that is wrong, but I've had much better luck since doing that.

    What I'm really interested in is a stem that is simply strong enough for anything, regardless of stem/rider weight.
    Dude, he's right. You need to adjust torque down if you lubricate the threads with grease.

  57. #57
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    Race Face Atlas is strong, not super heavy and not overly expensive:

    https://www.raceface.com/products/atlas-35-stem

    I have the Atlas stem and cranks on my enduro bike, they work and are very stiff.

    Technically, a forged 7000 series Al downhill/e-bike rated stem will be strongest, so you could look for that.

    I assemble using carbon grip paste, you're better off slightly under vs overtorquing the stem and checking to make sure bolts are tight occasionally. If you look at a stress/strain curve staying on the left allows more force to be applied while riding before the material hits the plastic region, which seems to be the case.

    Another thing you can do is buy strong bolts, this is often done in automotive applications, ARP is a famous bolt maker, maybe some tiny con rod bolts will fit an Atlas Stem?

    https://arp-bolts.com/

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    Quote Originally Posted by sapva View Post
    I don't think the stress from jumps is much of a factor, impacts from stem striking the ground maybe. Invariably it happens while standing and pulling up on the bars.
    But functionally that's the same type of force. Just in the opposite direction, which is all the same to the stem and bolts. And you definitely cannot pull up as hard as someone can push down when the case a jump. This is all just very confusing. 🤷*♂️

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    You're about an order of magnitude less force bouncing on the ground than you are landing a jump with your upper body locked. 2-3G on the ground and you can be 10-20G shock loading from a bottom-out.

    There's no need to grease SS/CRES bolts on aluminum bodies. The torque knockdown is also over 100% by greasing threads intended to be torqued dry. You're likely yielding the aluminum threads and beginning a stress fracture inside the body of the stem.

    The fact that it's a chronic issue and that it's isolated points squarely to a configuration problem. Don't grease the bolts, ignore the torque entirely, make sure the gaps are about equal on either side of the handlebar, and bring them all to about 1/4 turn past finger tight.

    You are also very lucky to have experienced >0 stem failures and be here to write about it.

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    Alternatively, if you are a REALLY big dude, and outside of the average rider stature, you can probably get some stems machined that take M8x1.25 hardware and just suck up the weight penalty. They're not complicated to machine or design, especially if you're not going to obsess about weight or aesthetics. Expect to pay about double what a high end stem costs for a one-off.

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    Quote Originally Posted by GH28 View Post
    Alternatively, if you are a REALLY big dude, and outside of the average rider stature, you can probably get some stems machined that take M8x1.25 hardware and just suck up the weight penalty. They're not complicated to machine or design, especially if you're not going to obsess about weight or aesthetics. Expect to pay about double what a high end stem costs for a one-off.
    Yes, probably just a bit outside what they design for. Checked a half dozen stems from bikes in the garage. Most have M5 bolts with only 5mm of engagement. Think that is just not enough. The Hussefelt stem just arrived. It has M6 bolts with at least 12mm of engagement. Didn't weight it, but feels like about 3 typical stems. I don't expect to have a problem with this one.

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    Quote Originally Posted by Gemini2k05 View Post
    And you definitely cannot pull up as hard as someone can push down when the case a jump. This is all just very confusing. 🤷*♂️
    Send me your stem and I'll test that theory for you

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    Quote Originally Posted by sapva View Post
    Send me your stem and I'll test that theory for you
    Only if I can install it.

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    Quote Originally Posted by sapva View Post
    Yes, probably just a bit outside what they design for. Checked a half dozen stems from bikes in the garage. Most have M5 bolts with only 5mm of engagement. Think that is just not enough. The Hussefelt stem just arrived. It has M6 bolts with at least 12mm of engagement. Didn't weight it, but feels like about 3 typical stems. I don't expect to have a problem with this one.
    To your credit, 1D of thread engagement is not enough for aluminum. 1.5D - 2D is a good rule of thumb. Generally 6 full threads of engagement (meaning not the tapered threads at the end) is a good minimum. Normal bolt stretch (well within the elastic range) will stretch the first 4 threads, and the next two threads are just there in case there are irregularities in the first 4 threads. There is a LOT of non-engineering in the bike industry, and it shows with stuff like that. An M6 like you have now with 8-12 clean DRY threads (emphasis on DRY) should be fine.

    Just remember, you can hang a car from a single #10 bolt or an M5 (basically the same cross section). You've got at least a 20% increase going to an M6. Then you've got 4 of those. So you've got the fastener capacity of a fvcking dump truck in that new stem (~25,000lb). If you've got a ~2" x 2" cross section in the stem, it's got a yield strength of about 160,000lb. That's roughly 5.5 dump trucks (40,000 psi yield for 6061). Knockdown from there if there are draft angles or whatever, but it won't be much.

    The other number that's important for aluminum is the 45,000psi ultimate strength. It's not a big zone for yield to failure. So if you grease the threads and cause a 100% change in the torque reading versus bolt strain, you WILL fail the material.

    If that one breaks, the problem is between the seat and grips. Do not grease the threads.

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    Quote Originally Posted by GH28 View Post
    To your credit, 1D of thread engagement is not enough for aluminum. 1.5D - 2D is a good rule of thumb. Generally 6 full threads of engagement (meaning not the tapered threads at the end) is a good minimum.
    Yes, they couldn't save enough to be worth using the shorter bolts. Has to be a purely aesthetic decision to hide the bolt ends. But then if engineers ruled the world and everything simply worked, there'd be no excitement.

    Quote Originally Posted by GH28 View Post
    If that one breaks, the problem is between the seat and grips. Do not grease the threads.
    https://www.servicearchive.sram.com/...stems-e-r2.pdf

    "Figure 3 - use grease or titanium anti-seize on all bolts before assembly"

  66. #66
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    Quote Originally Posted by sapva View Post
    Yes, they couldn't save enough to be worth using the shorter bolts. Has to be a purely aesthetic decision to hide the bolt ends. But then if engineers ruled the world and everything simply worked, there'd be no excitement.



    https://www.servicearchive.sram.com/...stems-e-r2.pdf

    "Figure 3 - use grease or titanium anti-seize on all bolts before assembly"
    Is this a titanium stem or titanium fasteners? Or is it steel bolts on aluminum?

    Also, this is a 2005 document. 15 years ago in the bike industry.

    From the track record we have today, what's the likelihood of the bike industry engineering their fasteners properly at that time? Knowing people who worked in engineering at SRAM/Truvativ and how much weed they smoked during that time period, I have my answer.

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