Trek top cap max torque... really ?
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    Trek top cap max torque... really ?

    So I just got a brand new Trek Emonda ALR Disc 5. I realized that the top cap screw has a "4nm max torque" written on it.

    Is it me or is this figure a good way to have a bunch of people ruin their headset bearings? By tightening by my usual rule of thumb (no play + 1/2 turn), I end up around 2.5 to 2.8 nM. 4nM does seems excessive.

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    Since they can't laser etch complete headset adjustment instructions on a top cap I guess they just figured a MAX value would be good enough for most people. Not all people mind you, but most. You can take that for what it's worth, or you can overthink it...
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    Quote Originally Posted by ToiletSiphon View Post
    So I just got a brand new Trek Emonda ALR Disc 5. I realized that the top cap screw has a "4nm max torque" written on it.

    Is it me or is this figure a good way to have a bunch of people ruin their headset bearings? By tightening by my usual rule of thumb (no play + 1/2 turn), I end up around 2.5 to 2.8 nM. 4nM does seems excessive.
    No different than max pressure written on the sidewalls of tires. It's not a torque spec, its the max.
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    Quote Originally Posted by ToiletSiphon View Post
    So I just got a brand new Trek Emonda ALR Disc 5. I realized that the top cap screw has a "4nm max torque" written on it.

    Is it me or is this figure a good way to have a bunch of people ruin their headset bearings? By tightening by my usual rule of thumb (no play + 1/2 turn), I end up around 2.5 to 2.8 nM. 4nM does seems excessive.
    I was just about to say I'd need to see it to believe it but I looked at one of my top cap screws and it does have some writing there too. Don't have a magnifying glass so don't know what it says though.

    Anyway, sure, I can see some people getting misled by that.

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    Quote Originally Posted by Srode View Post
    It's not a torque spec, its the max.
    BINGO

    Just because you 'can' doesn't mean you need to or should. What they're saying is if you get to 4nm and your headset isn't tight... something is wrong. Don't keep tightening.
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    Quote Originally Posted by tlg View Post
    BINGO

    Just because you 'can' doesn't mean you need to or should. What they're saying is if you get to 4nm and your headset isn't tight... something is wrong. Don't keep tightening.
    The thing I forgot to mention is when the saleseman installed me the new stem, he pulled out the torque wrench, set it to 4nM and tightened the cap without thinking. I'm not confrontational so I just said WTF in my head and just re-tightened everything properly back home.

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    Quote Originally Posted by ToiletSiphon View Post
    The thing I forgot to mention is when the saleseman installed me the new stem, he pulled out the torque wrench, set it to 4nM and tightened the cap without thinking. I'm not confrontational so I just said WTF in my head and just re-tightened everything properly back home.

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    That is wrong unless you have a Domane w/ front Iso Speed. That is the ONLY time you'd actually want to tighten a top cap to 4nm as there is a wave washer under the upper headset bearing. You are correct that is usually less than 3nm to get proper bearing preload on a headset.
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    Quote Originally Posted by cxwrench View Post
    That is wrong unless you have a Domane w/ front Iso Speed. That is the ONLY time you'd actually want to tighten a top cap to 4nm as there is a wave washer under the upper headset bearing. You are correct that is usually less than 3nm to get proper bearing preload on a headset.
    Didn't know why trek advised this for the Domane, I'll wake up smarter tomorrow.

    But I have an Emonda alr. Maybe the guy just developed a bad habit setting up too many Domanes

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    Quote Originally Posted by ToiletSiphon View Post
    Didn't know why trek advised this for the Domane, I'll wake up smarter tomorrow.

    But I have an Emonda alr. Maybe the guy just developed a bad habit setting up too many Domanes

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    Read my post again. There's a wave washer under the upper bearing on the SL and SLR. You need 4nm to properly compress the wave washer.
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    Quote Originally Posted by cxwrench View Post
    That is wrong unless you have a Domane w/ front Iso Speed. That is the ONLY time you'd actually want to tighten a top cap to 4nm as there is a wave washer under the upper headset bearing. You are correct that is usually less than 3nm to get proper bearing preload on a headset.
    Great information. I have a Domane SLR and have been tightening top cap just enough to remove play. Definitely not 4nm. Will have to get a 4nm wrench.
    thanks

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    Quote Originally Posted by cxwrench View Post
    Read my post again. There's a wave washer under the upper bearing on the SL and SLR. You need 4nm to properly compress the wave washer.
    I understood your post, just said I didn't know prior to reading it.

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    It's actually difficult to damage a modern angular contact cartridge headset bearing. If you tighten the top cap too much, the front wheel won't automatically return to a straight ahead position, after a turn. You'll notice that real quick. As long as that doesn't happen, the bearings won't be damaged.

    Traditional headsets are a different story. It takes a delicate touch to get no slop but no drag on those bearings and only a slight torque on the top cap can cause lots of drag and a major problem.

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    Quote Originally Posted by ToiletSiphon View Post
    So I just got a brand new Trek Emonda ALR Disc 5. I realized that the top cap screw has a "4nm max torque" written on it.

    Is it me or is this figure a good way to have a bunch of people ruin their headset bearings? By tightening by my usual rule of thumb (no play + 1/2 turn), I end up around 2.5 to 2.8 nM. 4nM does seems excessive.
    I had the same question when I was building my Emonda. I thought that was way too much as I usually set it to whatever keeps it from being loose and making noise. I contacted Trek and was told that rating is for the expander plug and not the actual top cap bolt. If that is truly true, then it's very misleading. Hell, once it's all set up you can actually remove the top cap and it won't affect the set up.
    Last edited by Methodical; 08-05-2019 at 08:15 PM.

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    Quote Originally Posted by Methodical View Post
    I had the same question when I was building my Emonda. I thought that was way too much as I usually set it to whatever keeps it from being loose and making noise. I contacted Trek and was told that rating is for the expander plug and not the actual top cap bolt. If that is truly true, then it's very misleading. Hell, once it's all set up you can actually remove the top cap and it won't affect the set up.
    Whomever you talked to at Trek was wrong...the torque for the expander is much higher than 4nm, it's actually more than double. Says so right on it. 9-10nm.

    4nm is the MAX...that doesn't mean you ever need to get it that tight anymore than a 120psi MAX pressure means you ever need to actually inflate your tire to that pressure.
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    Quote Originally Posted by cxwrench View Post
    Whomever you talked to at Trek was wrong...the torque for the expander is much higher than 4nm, it's actually more than double. Says so right on it. 9-10nm.

    4nm is the MAX...that doesn't mean you ever need to get it that tight anymore than a 120psi MAX pressure means you ever need to actually inflate your tire to that pressure.
    I fully understand what those torque ratings around the bike mean and I am not questioning that. I was just unsure whether the torque spec on the cap applied to the cap, the expander plug or both, since the expander plug nor the booklet that came with the frame had torque specifications for the expander plug.

    I did some checking online and all I could find were build manuals for the Domane and Madone, no luck with the Emonda. I found some videos where the person stated that if there were no torque specs to go with 5nm as a general rule. That's when I called Trek and was told what I was told.

    Do you have documentation that specifically states that the torque setting for the Emonda expander plug is 9-10nm because I have not been able to find any information online and Trek says it's only 4nm? I'd appreciate it. Thanks
    Last edited by Methodical; 08-06-2019 at 06:57 AM.

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    Quote Originally Posted by Methodical View Post
    I had the same question when I was building my Emonda. I thought that was way too much as I usually set it to whatever keeps it from being loose and making noise. I contacted Trek and was told that rating is for the expander plug and not the actual top cap bolt. If that is truly true, then it's very misleading. Hell, once it's all set up you can actually remove the top cap and it won't affect the set up.
    I'm guessing 'for the expander plug' is correct but you misunderstood what that meant or he did a poor job of explaining.

    I'd have to imagine 'for the expander plug" means the expander plug won't hold if you put 4nm of pull on it with the top cap screw. Not that the expander plug needs 4nm for installation.

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    Quote Originally Posted by Jay Strongbow View Post
    I'm guessing 'for the expander plug' is correct but you misunderstood what that meant or he did a poor job of explaining.

    I'd have to imagine 'for the expander plug" means the expander plug won't hold if you put 4nm of pull on it with the top cap screw. Not that the expander plug needs 4nm for installation.
    No miscommunication or understanding on my part. I was very clear with my questions to Trek and that is what I was told. To be sure what I was told, I always repeat back to the rep what was stated to make sure I understood exactly what was stated. Maybe the rep was wrong, he did have to ask someone, so who knows.

    I torqued the expander plug to 4nm as Trek suggested without issues. And as always, I just tighten the cap to the point where there's no movement at the fork.
    Last edited by Methodical; 08-06-2019 at 06:50 AM.

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    Quote Originally Posted by Methodical View Post
    No miscommunication or understanding on my part. I was very clear with my questions to Trek and that is what I was told. To be sure what I was told, I always repeat back to the rep what was stated to make sure I understood exactly what was stated. Maybe the rep was wrong, he did have to ask someone, so who knows.

    I torqued the expander plug to 4nm as Trek suggested without issues. And as always, I just tighten the cap to the point where there's no movement at the fork.

    The expander will most likely pull out of the fork if you only tighten it to 4nm. Generally the top part of the expander will be laser etched w/ the torque range, the ones Trek use (as I posted previously) are supposed to be tightened to 9-10nm. Here's the one on my Crockett...

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    Quote Originally Posted by cxwrench View Post
    The expander will most likely pull out of the fork if you only tighten it to 4nm. Generally the top part of the expander will be laser etched w/ the torque range, the ones Trek use (as I posted previously) are supposed to be tightened to 9-10nm. Here's the one on my Crockett...

    Man, I wish it were stamped on mine like that. When I was assembling the bike, I looked all over that plug and nothing. That's why I called Trek. I will take the cap off and look one more time, but I'm not hopeful though. Thanks...

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    Just noticed today that the top cap on my Fuel EX8+ also says 4Nm max torque.

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    4Nm is what I always suggest using, but you can bring it under if you have it tight where there is no play in the headset or spacers.
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    CX, here's the photo of the top of the expander plug on my Emonda. Unlike yours, Trek doesn't provide any torque specifications for the expander plug. I searched around the web and found nothing on it.

    Emond expander plug.jpg

    Not sure why the image did not post in my response as a thumbnail.
    Last edited by Methodical; 08-08-2019 at 08:18 AM.

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    Quote Originally Posted by Methodical View Post
    CX, here's the photo of the top of the expander plug on my Emonda. Unlike yours, Trek doesn't provide any torque specifications for the expander plug. I searched around the web and found nothing on it.

    Emond expander plug.jpg

    Not sure why the image did not post in my response as a thumbnail.
    Interesting. I'm sure I've seen them like yours but just never really noticed because I've seen so many w/ the torque spec on them and just know how tight to make them. That's definitely a part that should have the spec in a visible spot.
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    Quote Originally Posted by cxwrench View Post
    Interesting. I'm sure I've seen them like yours but just never really noticed because I've seen so many w/ the torque spec on them and just know how tight to make them. That's definitely a part that should have the spec in a visible spot.
    Yeah, that's what I thought, too. Hopefully, Mitch will come back and clear the air on this. Below is the video where the guy said to use 5nm if there were no torque specs for the plug (see 1:38). That's why I just called Trek because I kept reading horror stories about this part needing to be done correctly.

    https://www.youtube.com/watch?v=aBjJ35B-Og0

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    Not sure what Mitch does at Trek but I've never tightened a normal threadless headset to 4nm. With the Domane SL/SLR you need to comperess the spring washer so 4nm is needed. It's definitely more than a normal headset. I'll have to try it sometime w/ a torque wrench to see just what happens.
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