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  1. #1
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    got my torque wrenches to do it right. Now what?

    Hello,

    I finally caved in and bought two Park Tool torque wrenches to get the job done without guessing. Well, I'm still guessing. I'm finding recommended numbers and manuals for my parts to be harder to find than expected.

    Can anyone tell me the right torque for a for screw handlebar clamp? (Road bike, 3t Ergosum aluminum, Seven Stem). . Also, how tight should the singles steering screw be tightened to? (the cap on my threadless Chris King)

    If anyone knows of a good chart, please let me know !


    THANKS !

  2. #2
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    There is no reason to use a torque wrench on a top-cap bolt. As for stems and other small M5 bolts, 5Nm is almost always safe. Only use more if there is a slippage problem.

    Personally, I know what the necessary torques feels like by hand and never use a torque wrench for any M5 or M6 bolt. If you don't get a feel for this work by hand, how will you ever make an adjustment out on the road?

    Use the small torque wrench to tighten some bolts to 5Nm, then see how tight that feels with a short handled hex wrench or 4-5-6 Y-style wrench.

  3. #3
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    Quote Originally Posted by DaveSSS View Post
    There is no reason to use a torque wrench on a top-cap bolt. As for stems and other small M5 bolts, 5Nm is almost always safe. Only use more if there is a slippage problem.

    Personally, I know what the necessary torques feels like by hand and never use a torque wrench for any M5 or M6 bolt. If you don't get a feel for this work by hand, how will you ever make an adjustment out on the road?

    Use the small torque wrench to tighten some bolts to 5Nm, then see how tight that feels with a short handled hex wrench or 4-5-6 Y-style wrench.
    Thanks for the reply. Today I managed to SNAP the screw in my Seven stem (handle bar clamp) and it looks like no ride for me today.

    I think I'll toss the big Park tool torque wrench in the trash..

    Now back to hand tightening. I'll just stop when it feels reasonably tight. The Torque wrench went way beyond what my hand could do with a short allen wrench. I don't trust the readings at all now. I was going for 12 NM as the park tool guide shows.

    Side note: I carry tools on my rides for adjustments. I just thought a torque wrench would take all the "guess" work out of it.

  4. #4
    Senior Member BCRider's Avatar
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    The top cap screw isn't set by a torque meter. Instead it is set by the feel of your steering. You tighten the top cap screw in small increments and in between hold the stem at the top cap and turn the steering. When it's just barely taken up the slack the steering will feel super easy to turn. As you tighten the top cap screw it'll get a little stiff. Tighten some more and it'll get more stiff. You're looking for the point where it goes from totaly free to just a little bit of resistance. WHen you find that point it's good. If you go too far it's too much.

    Hint- despite what I just typed a good trick for a new headset installation is to over tighten at first so you can feel that it's more stiff than it should be. Rotate the forks a number of turns in each direction to bed in the headset components and then LOOSEN the top cap until you're down to just a slight noticable drag.

    You'll only feel the correct drag from this preload when you're feeling it from the stem right at the steerer tube. It's a subtle thing and if you have any sort of leverage like with handlebars you won't feel the right setting.

    As for tightening bicycle parts you can't go much wrong with the rules from the Park site.
    http://www.parktool.com/repair/readhowto.asp?id=88

    Note that in pretty much every case the smaller number in the range of torques they specify will be just fine. Going tighter will not aid anything at all if it's not required. Also when doing up parts with multiple screws such as stems and stem caps you need to tighten the screws in a back and forth or cross over manner so that the screws work up to the final even torque in small steps. If you try to tighten one screw to the final torque and then the other the parts will be overstressed in oddball ways and the end result could easily be a stripped out thread. Steel screw to alloy parts threads on your bicycle should always at least be oiled before threading in or better yet greased. This will avoid dissimilar metal corrosion and also make it less wearing on the alloy threads for parts that are tightened and loosened a lot. The lubrication also makes it easier to reach the final tension in the screw so again it's important to use no more than the lower level of torque unless you find the part is slipping or comes loose at some point. Things like stems, handlebars and seat post bolts should be done up evenly to the lower level or slightly lower and then test them by loading them hard in the manner you'll be using them when riding. If things don't slip then they are tight enough. If it does slip during the test or you find things like the seat post walks in the clamp while riding then tighten the screws a little more but not to the point you exceed the maximum torques given.
    Model airplanes are cool too!.....

  5. #5
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    Quote Originally Posted by BCRider View Post
    The top cap screw isn't set by a torque meter. Instead it is set by the feel of your steering. You tighten the top cap screw in small increments and in between hold the stem at the top cap and turn the steering. When it's just barely taken up the slack the steering will feel super easy to turn. As you tighten the top cap screw it'll get a little stiff. Tighten some more and it'll get more stiff. You're looking for the point where it goes from totaly free to just a little bit of resistance. WHen you find that point it's good. If you go too far it's too much.

    Hint- despite what I just typed a good trick for a new headset installation is to over tighten at first so you can feel that it's more stiff than it should be. Rotate the forks a number of turns in each direction to bed in the headset components and then LOOSEN the top cap until you're down to just a slight noticable drag.

    You'll only feel the correct drag from this preload when you're feeling it from the stem right at the steerer tube. It's a subtle thing and if you have any sort of leverage like with handlebars you won't feel the right setting.

    As for tightening bicycle parts you can't go much wrong with the rules from the Park site.
    http://www.parktool.com/repair/readhowto.asp?id=88

    Note that in pretty much every case the smaller number in the range of torques they specify will be just fine. Going tighter will not aid anything at all if it's not required. Also when doing up parts with multiple screws such as stems and stem caps you need to tighten the screws in a back and forth or cross over manner so that the screws work up to the final even torque in small steps. If you try to tighten one screw to the final torque and then the other the parts will be overstressed in oddball ways and the end result could easily be a stripped out thread. Steel screw to alloy parts threads on your bicycle should always at least be oiled before threading in or better yet greased. This will avoid dissimilar metal corrosion and also make it less wearing on the alloy threads for parts that are tightened and loosened a lot. The lubrication also makes it easier to reach the final tension in the screw so again it's important to use no more than the lower level of torque unless you find the part is slipping or comes loose at some point. Things like stems, handlebars and seat post bolts should be done up evenly to the lower level or slightly lower and then test them by loading them hard in the manner you'll be using them when riding. If things don't slip then they are tight enough. If it does slip during the test or you find things like the seat post walks in the clamp while riding then tighten the screws a little more but not to the point you exceed the maximum torques given.


    Thanks, that is where I got my numbers that broke the Screw. (thanks for your explanation of the headset tightening, I am using it now)


    I am looking to tighten the four screws that hold the handle bar to the stem. (clamp). This is where I broke my screw.

    Park tool numbers have me confused. For the torque of a four screw clamp, there are many different numbers.??? See below

    Stem handlebar binder
    4 binder bolts Control Tech® 120-144
    Deda magnesium 71
    Thomson® 48
    FSA® OS-115 carbon 78
    Time® Monolink 53

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    It's better to know the size of the bolt and use that as a guide. 12Nm would be far too much for an M5 bolt and and would rarely be suggested for most M6.


    http://www.cncexpo.com/MetricBoltTorque.aspx

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    Thanks much for the help all. I just got a mechanic to remove the broken screw ($25 dollar tip) and I'm now off to ride.

    I've greased (finish line teflon grease) and tightened all four bolts gradually in a criss cross fashion until all felt "snug" by hand. I then used the big torque wrench and find the torque to be around 8 NM

    I'll take it easy today and hopefully I wont kill myself. I'm off for a ride now.

  8. #8
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    Quote Originally Posted by DaveSSS View Post
    It's better to know the size of the bolt and use that as a guide. 12Nm would be far too much for an M5 bolt and and would rarely be suggested for most M6.


    http://www.cncexpo.com/MetricBoltTorque.aspx

    Thanks, great chart. This explains the broken magnesium screw. Now I've noticed that all the other screws are bent as well. (I got replacement stainless steel)

    You gotta love being a newb..... At least I'm careful and ask if unsure. (the reason I'm here)

  9. #9
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    Now you see why I'm saying that these are a maximum torque. If the Thompon 4 screw stem cap can hold the bars just fine at 48 inch-lbs per screw or even less then why would a Control Tech 4 screw cap need 120 to 144 inch-lbs? Simple, it doesn't. But the torque given is the maximum torque that the stem and screws will withstand without breaking something. Hence my suggestion to start evenly tightened in stages and sneak up on a much lower setting and try to twist the parts in the stem.

    Try this on your four bolt stem cap. Using a regular allen key and only two fingers tighten the screws in the correct crossing pattern and bring them up to a firm pinch on the allen key using your thumb at the elbow and your forefinger about 2 inches up from the elbow. Tighten so that you feel it in your finger but not so much that it leaves a serious pressure mark. With all four tight try to twist the bar. I'll bet that the bar pretty much feels welded in place. Or if you do manage to twist it try torqueing with the allen key to the same feel level but with your forefinger out to 3 inches from the elbow. At that point the bar WILL feel welded when you try to twist it in the clamp. Now put your torque meter on there and see what the meter says for torque when the bolts just start to move. I'm assuming that you have the needle type guages. If you got click type guages than you'd need to start with a really low setting. If it clicks without turning the screw then up the setting in 5 in-lb increments until the screw just starts to turn without the wrench clicking. Your true torque value is then somewhere between the last two settings where it didn't and then did move.

    Bottom line is that I think you'll find that for many cases there is no need to do everything up to the torque levels given. Now I'm not saying that you should only do things up until they barely don't quite move. That would be too much the other way and would not allow for special circumstances. But this is a good excercise to do in a few spots to understand that not all fasteners need to be done to the max possible torque to function. Meanwhile there's other parts where you WANT them done up close to the max. For example crank arm bolts for almost any sort of style should be pretty much right at the limit. There's a lot of pressure in this area and the tension from the bolt must be well above the expected loads in order to retain the parts in place. And you're only going to get this if you torque that puppy down to a nice middle setting given in the maker's specs or from the Park table. Meanwhile the LAST place you want to dial a fastener to the max would be a brake lever clamping bolt. This is one spot where you want just enough torque to avoid the lever slipping around during use but you want it to be loose enough to allow the lever to pivot during a crash so you have a better chance of the lever surviving with nothing more than some scuffs. If you tighten enough to "weld" it in place then something has to give. And that something would typically be the lever.

    I hate to say it but knowing where to use less and where to dial it to the proper limit is a subjective thing that comes with some analysis backed up with experience. It's hard to get this from a torque chart. But the wrenches and the chart will certainly aid in keeping you out of trouble until you get the experience to develop your sense of judgement. And trying some simple experiments like the stem clamp thing I just gave you can help you to figure out and better understand where you can temper the torque back a little and where you should not.
    Model airplanes are cool too!.....

  10. #10
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    Quote Originally Posted by BCRider View Post
    Now you see why I'm saying that these are a maximum torque. If the Thompon 4 screw stem cap can hold the bars just fine at 48 inch-lbs per screw or even less then why would a Control Tech 4 screw cap need 120 to 144 inch-lbs? Simple, it doesn't. But the torque given is the maximum torque that the stem and screws will withstand without breaking something. Hence my suggestion to start evenly tightened in stages and sneak up on a much lower setting and try to twist the parts in the stem.

    Try this on your four bolt stem cap. Using a regular allen key and only two fingers tighten the screws in the correct crossing pattern and bring them up to a firm pinch on the allen key using your thumb at the elbow and your forefinger about 2 inches up from the elbow. Tighten so that you feel it in your finger but not so much that it leaves a serious pressure mark. With all four tight try to twist the bar. I'll bet that the bar pretty much feels welded in place. Or if you do manage to twist it try torqueing with the allen key to the same feel level but with your forefinger out to 3 inches from the elbow. At that point the bar WILL feel welded when you try to twist it in the clamp. Now put your torque meter on there and see what the meter says for torque when the bolts just start to move. I'm assuming that you have the needle type guages. If you got click type guages than you'd need to start with a really low setting. If it clicks without turning the screw then up the setting in 5 in-lb increments until the screw just starts to turn without the wrench clicking. Your true torque value is then somewhere between the last two settings where it didn't and then did move.

    Bottom line is that I think you'll find that for many cases there is no need to do everything up to the torque levels given. Now I'm not saying that you should only do things up until they barely don't quite move. That would be too much the other way and would not allow for special circumstances. But this is a good excercise to do in a few spots to understand that not all fasteners need to be done to the max possible torque to function. Meanwhile there's other parts where you WANT them done up close to the max. For example crank arm bolts for almost any sort of style should be pretty much right at the limit. There's a lot of pressure in this area and the tension from the bolt must be well above the expected loads in order to retain the parts in place. And you're only going to get this if you torque that puppy down to a nice middle setting given in the maker's specs or from the Park table. Meanwhile the LAST place you want to dial a fastener to the max would be a brake lever clamping bolt. This is one spot where you want just enough torque to avoid the lever slipping around during use but you want it to be loose enough to allow the lever to pivot during a crash so you have a better chance of the lever surviving with nothing more than some scuffs. If you tighten enough to "weld" it in place then something has to give. And that something would typically be the lever.

    I hate to say it but knowing where to use less and where to dial it to the proper limit is a subjective thing that comes with some analysis backed up with experience. It's hard to get this from a torque chart. But the wrenches and the chart will certainly aid in keeping you out of trouble until you get the experience to develop your sense of judgement. And trying some simple experiments like the stem clamp thing I just gave you can help you to figure out and better understand where you can temper the torque back a little and where you should not.

    Thanks much. I think you can understand my confusion looking at those charts. I had hoped it would be a simple matter of dialing in numbers. Not so at all.

    I followed your tips and went with my old way of tightening, which is mainly by feel. I have been building and rebuilding bikes for a while and always felt fairly confident all was safely adjusted. Funny that a torque wrench added more confusion. I thought it would take all the "Guess work" out, but it proved to be the opposite.

    Thanks much for your great right up. I really appreciate it. Now off for a 50 mile ride before I let the whole day slip away !

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