However, in our first production run in early 2020 we had some issue with the covering and we only had little number of saddles in the market. We then took our time (several months) to find a new process for covering and slightly changed the layer composition on our covering.
When we then did the first bigger production batch of the SAGMAs (in early 2021, if I remeber correctly out of the top of my head), we found out (after a few weeks after delivery), that sometimes bolts needed to be re-tightened, although we had used properly calibrated torque tools and blue loctite during installation on all of them.
So after thinking and evaluating we figured what happened was following:
The bumpers are made of carbon reinforced Nylon. Now when you apply pressure on this material (or on any material for that matter) for a longer period of time, it will creep.
[https://en.wikipedia.org/wiki/Creep_](https://en.wikipedia.org/wiki/Creep_)(deformation)
So lets say you torque the bumper bolts to spec with 2Nm. The bumper material, however will slightly deform/compress under the pressure of the bolt head over several days, thus losing pre-tension on the bolted connection - et voilà, the bolt will not be at 2Nm anymore, although it did not move. You can not really measure this deformation as it is too little, but the result remains, nevertheless.
July 23, 2021, 5:51 a.m. - sacki
However, in our first production run in early 2020 we had some issue with the covering and we only had little number of saddles in the market. We then took our time (several months) to find a new process for covering and slightly changed the layer composition on our covering. When we then did the first bigger production batch of the SAGMAs (in early 2021, if I remeber correctly out of the top of my head), we found out (after a few weeks after delivery), that sometimes bolts needed to be re-tightened, although we had used properly calibrated torque tools and blue loctite during installation on all of them. So after thinking and evaluating we figured what happened was following: The bumpers are made of carbon reinforced Nylon. Now when you apply pressure on this material (or on any material for that matter) for a longer period of time, it will creep. [https://en.wikipedia.org/wiki/Creep_](https://en.wikipedia.org/wiki/Creep_)(deformation) So lets say you torque the bumper bolts to spec with 2Nm. The bumper material, however will slightly deform/compress under the pressure of the bolt head over several days, thus losing pre-tension on the bolted connection - et voilà, the bolt will not be at 2Nm anymore, although it did not move. You can not really measure this deformation as it is too little, but the result remains, nevertheless.