What is the torque needed for chainring bolts?











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I have a bike that is no longer in production, but it has a standard drivetrain (FSA). I had some shifting issues the past couple days, and to my surprise when I did a clean/inspect, three of the 5 chainring bolts had dropped out and the other two were finger loose.



I salvaged some bolts from my donor bike. I needed a breaker attachment to my 5mm hex to get them off. There was no residual threadlock on the threads. Now I'm unsure how hard I should tighten them onto the first bike.



Why would they have come loose in the first place? How hard should I tighten them to prevent this from happening again? Would a dab of threadlock be good insurance?










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    I have a bike that is no longer in production, but it has a standard drivetrain (FSA). I had some shifting issues the past couple days, and to my surprise when I did a clean/inspect, three of the 5 chainring bolts had dropped out and the other two were finger loose.



    I salvaged some bolts from my donor bike. I needed a breaker attachment to my 5mm hex to get them off. There was no residual threadlock on the threads. Now I'm unsure how hard I should tighten them onto the first bike.



    Why would they have come loose in the first place? How hard should I tighten them to prevent this from happening again? Would a dab of threadlock be good insurance?










    share|improve this question
























      up vote
      4
      down vote

      favorite
      1









      up vote
      4
      down vote

      favorite
      1






      1





      I have a bike that is no longer in production, but it has a standard drivetrain (FSA). I had some shifting issues the past couple days, and to my surprise when I did a clean/inspect, three of the 5 chainring bolts had dropped out and the other two were finger loose.



      I salvaged some bolts from my donor bike. I needed a breaker attachment to my 5mm hex to get them off. There was no residual threadlock on the threads. Now I'm unsure how hard I should tighten them onto the first bike.



      Why would they have come loose in the first place? How hard should I tighten them to prevent this from happening again? Would a dab of threadlock be good insurance?










      share|improve this question













      I have a bike that is no longer in production, but it has a standard drivetrain (FSA). I had some shifting issues the past couple days, and to my surprise when I did a clean/inspect, three of the 5 chainring bolts had dropped out and the other two were finger loose.



      I salvaged some bolts from my donor bike. I needed a breaker attachment to my 5mm hex to get them off. There was no residual threadlock on the threads. Now I'm unsure how hard I should tighten them onto the first bike.



      Why would they have come loose in the first place? How hard should I tighten them to prevent this from happening again? Would a dab of threadlock be good insurance?







      chainring






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      asked Nov 28 at 4:08









      AdamO

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          A Shimano "General Operations" manual states the tightening torque for road chainwheels is 12-14 N-m. For mountain bike chainwheels it's upped to 14-16 N-m for large and middle ring and 16-17 N-m for the smallest ring of a triple.
          The website: http://si.shimano.com/#/
          The manual number I'm referring to: DM-GN0001-20-ENG.pdf
          Blue loctite or equivalent threadlocker is indicated here as well.
          I can't accurately surmise the cause of the loose and lost bolts in this specific case. However my experience with situations of loosening bolts or part failure due to "coming apart" in various mechanical settings often comes down to incorrect or incomplete tightening of the fastener (bolt, nut, etc). Part of this process is rechecking and re-torqueing after a break-in period of normal use.






          share|improve this answer




























            up vote
            4
            down vote













            Park tool has a great reference Here
            (all inch-pound)
            Chainring bolt- steel



            Shimano 70-95



            Campagnolo® 84-120



            Race Face&erg; 100



            Truvativ® 107-124



            Jury is out on thread lock on chain ring bolts. A do not believe a light thread lock will hurt ( until you need to remove them), but also believe correctly tightened bolts should not need it. The problem is the little two prong thing used to hold the nut is unlikely to allow a decent torque.



            Better to give the threads a good clean and lightly grease the threads.






            share|improve this answer





















            • I use low strength loctite 222 on the bolts and always carry a spare chainring bolt
              – Vorsprung
              Nov 28 at 13:01










            • If tightened to the correct torque, I have never had a chainring bolt come loose with the application of light grease. I agree that thread lock could cause more problems than help.
              – Rider_X
              Nov 28 at 14:27










            • @Rider_X Do you mean to grease the inner threads so as to prevent crossthreading or grease the outside of the female part so that it plays more freely in the chainring recesses? Also what grease do you use? I will cinche down to bolts to the specified torques without chain lock and look after them for a week to see how they fair.
              – AdamO
              Nov 28 at 15:04




















            up vote
            1
            down vote













            On my race BMX's I put cable ties through the chain ring bolts once they are correctly tightened as this prevents them falling out if they come loose. You need to still check them regularly to ensure that they have not come loose.



            Cable ties are a good insurance policy to stop them dropping out.






            share|improve this answer





















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              3 Answers
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              active

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              3 Answers
              3






              active

              oldest

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              active

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              active

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              up vote
              6
              down vote



              accepted










              A Shimano "General Operations" manual states the tightening torque for road chainwheels is 12-14 N-m. For mountain bike chainwheels it's upped to 14-16 N-m for large and middle ring and 16-17 N-m for the smallest ring of a triple.
              The website: http://si.shimano.com/#/
              The manual number I'm referring to: DM-GN0001-20-ENG.pdf
              Blue loctite or equivalent threadlocker is indicated here as well.
              I can't accurately surmise the cause of the loose and lost bolts in this specific case. However my experience with situations of loosening bolts or part failure due to "coming apart" in various mechanical settings often comes down to incorrect or incomplete tightening of the fastener (bolt, nut, etc). Part of this process is rechecking and re-torqueing after a break-in period of normal use.






              share|improve this answer

























                up vote
                6
                down vote



                accepted










                A Shimano "General Operations" manual states the tightening torque for road chainwheels is 12-14 N-m. For mountain bike chainwheels it's upped to 14-16 N-m for large and middle ring and 16-17 N-m for the smallest ring of a triple.
                The website: http://si.shimano.com/#/
                The manual number I'm referring to: DM-GN0001-20-ENG.pdf
                Blue loctite or equivalent threadlocker is indicated here as well.
                I can't accurately surmise the cause of the loose and lost bolts in this specific case. However my experience with situations of loosening bolts or part failure due to "coming apart" in various mechanical settings often comes down to incorrect or incomplete tightening of the fastener (bolt, nut, etc). Part of this process is rechecking and re-torqueing after a break-in period of normal use.






                share|improve this answer























                  up vote
                  6
                  down vote



                  accepted







                  up vote
                  6
                  down vote



                  accepted






                  A Shimano "General Operations" manual states the tightening torque for road chainwheels is 12-14 N-m. For mountain bike chainwheels it's upped to 14-16 N-m for large and middle ring and 16-17 N-m for the smallest ring of a triple.
                  The website: http://si.shimano.com/#/
                  The manual number I'm referring to: DM-GN0001-20-ENG.pdf
                  Blue loctite or equivalent threadlocker is indicated here as well.
                  I can't accurately surmise the cause of the loose and lost bolts in this specific case. However my experience with situations of loosening bolts or part failure due to "coming apart" in various mechanical settings often comes down to incorrect or incomplete tightening of the fastener (bolt, nut, etc). Part of this process is rechecking and re-torqueing after a break-in period of normal use.






                  share|improve this answer












                  A Shimano "General Operations" manual states the tightening torque for road chainwheels is 12-14 N-m. For mountain bike chainwheels it's upped to 14-16 N-m for large and middle ring and 16-17 N-m for the smallest ring of a triple.
                  The website: http://si.shimano.com/#/
                  The manual number I'm referring to: DM-GN0001-20-ENG.pdf
                  Blue loctite or equivalent threadlocker is indicated here as well.
                  I can't accurately surmise the cause of the loose and lost bolts in this specific case. However my experience with situations of loosening bolts or part failure due to "coming apart" in various mechanical settings often comes down to incorrect or incomplete tightening of the fastener (bolt, nut, etc). Part of this process is rechecking and re-torqueing after a break-in period of normal use.







                  share|improve this answer












                  share|improve this answer



                  share|improve this answer










                  answered Nov 28 at 8:05









                  Jeff

                  3144




                  3144






















                      up vote
                      4
                      down vote













                      Park tool has a great reference Here
                      (all inch-pound)
                      Chainring bolt- steel



                      Shimano 70-95



                      Campagnolo® 84-120



                      Race Face&erg; 100



                      Truvativ® 107-124



                      Jury is out on thread lock on chain ring bolts. A do not believe a light thread lock will hurt ( until you need to remove them), but also believe correctly tightened bolts should not need it. The problem is the little two prong thing used to hold the nut is unlikely to allow a decent torque.



                      Better to give the threads a good clean and lightly grease the threads.






                      share|improve this answer





















                      • I use low strength loctite 222 on the bolts and always carry a spare chainring bolt
                        – Vorsprung
                        Nov 28 at 13:01










                      • If tightened to the correct torque, I have never had a chainring bolt come loose with the application of light grease. I agree that thread lock could cause more problems than help.
                        – Rider_X
                        Nov 28 at 14:27










                      • @Rider_X Do you mean to grease the inner threads so as to prevent crossthreading or grease the outside of the female part so that it plays more freely in the chainring recesses? Also what grease do you use? I will cinche down to bolts to the specified torques without chain lock and look after them for a week to see how they fair.
                        – AdamO
                        Nov 28 at 15:04

















                      up vote
                      4
                      down vote













                      Park tool has a great reference Here
                      (all inch-pound)
                      Chainring bolt- steel



                      Shimano 70-95



                      Campagnolo® 84-120



                      Race Face&erg; 100



                      Truvativ® 107-124



                      Jury is out on thread lock on chain ring bolts. A do not believe a light thread lock will hurt ( until you need to remove them), but also believe correctly tightened bolts should not need it. The problem is the little two prong thing used to hold the nut is unlikely to allow a decent torque.



                      Better to give the threads a good clean and lightly grease the threads.






                      share|improve this answer





















                      • I use low strength loctite 222 on the bolts and always carry a spare chainring bolt
                        – Vorsprung
                        Nov 28 at 13:01










                      • If tightened to the correct torque, I have never had a chainring bolt come loose with the application of light grease. I agree that thread lock could cause more problems than help.
                        – Rider_X
                        Nov 28 at 14:27










                      • @Rider_X Do you mean to grease the inner threads so as to prevent crossthreading or grease the outside of the female part so that it plays more freely in the chainring recesses? Also what grease do you use? I will cinche down to bolts to the specified torques without chain lock and look after them for a week to see how they fair.
                        – AdamO
                        Nov 28 at 15:04















                      up vote
                      4
                      down vote










                      up vote
                      4
                      down vote









                      Park tool has a great reference Here
                      (all inch-pound)
                      Chainring bolt- steel



                      Shimano 70-95



                      Campagnolo® 84-120



                      Race Face&erg; 100



                      Truvativ® 107-124



                      Jury is out on thread lock on chain ring bolts. A do not believe a light thread lock will hurt ( until you need to remove them), but also believe correctly tightened bolts should not need it. The problem is the little two prong thing used to hold the nut is unlikely to allow a decent torque.



                      Better to give the threads a good clean and lightly grease the threads.






                      share|improve this answer












                      Park tool has a great reference Here
                      (all inch-pound)
                      Chainring bolt- steel



                      Shimano 70-95



                      Campagnolo® 84-120



                      Race Face&erg; 100



                      Truvativ® 107-124



                      Jury is out on thread lock on chain ring bolts. A do not believe a light thread lock will hurt ( until you need to remove them), but also believe correctly tightened bolts should not need it. The problem is the little two prong thing used to hold the nut is unlikely to allow a decent torque.



                      Better to give the threads a good clean and lightly grease the threads.







                      share|improve this answer












                      share|improve this answer



                      share|improve this answer










                      answered Nov 28 at 8:09









                      mattnz

                      23.9k23375




                      23.9k23375












                      • I use low strength loctite 222 on the bolts and always carry a spare chainring bolt
                        – Vorsprung
                        Nov 28 at 13:01










                      • If tightened to the correct torque, I have never had a chainring bolt come loose with the application of light grease. I agree that thread lock could cause more problems than help.
                        – Rider_X
                        Nov 28 at 14:27










                      • @Rider_X Do you mean to grease the inner threads so as to prevent crossthreading or grease the outside of the female part so that it plays more freely in the chainring recesses? Also what grease do you use? I will cinche down to bolts to the specified torques without chain lock and look after them for a week to see how they fair.
                        – AdamO
                        Nov 28 at 15:04




















                      • I use low strength loctite 222 on the bolts and always carry a spare chainring bolt
                        – Vorsprung
                        Nov 28 at 13:01










                      • If tightened to the correct torque, I have never had a chainring bolt come loose with the application of light grease. I agree that thread lock could cause more problems than help.
                        – Rider_X
                        Nov 28 at 14:27










                      • @Rider_X Do you mean to grease the inner threads so as to prevent crossthreading or grease the outside of the female part so that it plays more freely in the chainring recesses? Also what grease do you use? I will cinche down to bolts to the specified torques without chain lock and look after them for a week to see how they fair.
                        – AdamO
                        Nov 28 at 15:04


















                      I use low strength loctite 222 on the bolts and always carry a spare chainring bolt
                      – Vorsprung
                      Nov 28 at 13:01




                      I use low strength loctite 222 on the bolts and always carry a spare chainring bolt
                      – Vorsprung
                      Nov 28 at 13:01












                      If tightened to the correct torque, I have never had a chainring bolt come loose with the application of light grease. I agree that thread lock could cause more problems than help.
                      – Rider_X
                      Nov 28 at 14:27




                      If tightened to the correct torque, I have never had a chainring bolt come loose with the application of light grease. I agree that thread lock could cause more problems than help.
                      – Rider_X
                      Nov 28 at 14:27












                      @Rider_X Do you mean to grease the inner threads so as to prevent crossthreading or grease the outside of the female part so that it plays more freely in the chainring recesses? Also what grease do you use? I will cinche down to bolts to the specified torques without chain lock and look after them for a week to see how they fair.
                      – AdamO
                      Nov 28 at 15:04






                      @Rider_X Do you mean to grease the inner threads so as to prevent crossthreading or grease the outside of the female part so that it plays more freely in the chainring recesses? Also what grease do you use? I will cinche down to bolts to the specified torques without chain lock and look after them for a week to see how they fair.
                      – AdamO
                      Nov 28 at 15:04












                      up vote
                      1
                      down vote













                      On my race BMX's I put cable ties through the chain ring bolts once they are correctly tightened as this prevents them falling out if they come loose. You need to still check them regularly to ensure that they have not come loose.



                      Cable ties are a good insurance policy to stop them dropping out.






                      share|improve this answer

























                        up vote
                        1
                        down vote













                        On my race BMX's I put cable ties through the chain ring bolts once they are correctly tightened as this prevents them falling out if they come loose. You need to still check them regularly to ensure that they have not come loose.



                        Cable ties are a good insurance policy to stop them dropping out.






                        share|improve this answer























                          up vote
                          1
                          down vote










                          up vote
                          1
                          down vote









                          On my race BMX's I put cable ties through the chain ring bolts once they are correctly tightened as this prevents them falling out if they come loose. You need to still check them regularly to ensure that they have not come loose.



                          Cable ties are a good insurance policy to stop them dropping out.






                          share|improve this answer












                          On my race BMX's I put cable ties through the chain ring bolts once they are correctly tightened as this prevents them falling out if they come loose. You need to still check them regularly to ensure that they have not come loose.



                          Cable ties are a good insurance policy to stop them dropping out.







                          share|improve this answer












                          share|improve this answer



                          share|improve this answer










                          answered Nov 28 at 10:36









                          fcbsd

                          16616




                          16616






























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