In our daily work as we deal with bicycle safety, technology and user manuals we come across lots of safety risks. The most frequent ones are published in articles of the leading German special-interest magazines TOUR – Europas Rennrad-Magazin Nr. 1, BIKE – Das Mountainbike Magazin Europas Nr. 1 and E-Bike – Das Pedelec-Magazin to make this information important for the sector accessible to a wider public.
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With regard to the issue "Screwing chainrings" I would like to know whether or not I have to grease the bolts and to which torque the bolts must be tightened. Cranks are not necessarily supplied with manufacturers’ information. Many cranks are supplied ex works without assembly grease on the chainring bolts. In addition, there are indications on torque values circulating on the internet, such as "aluminium chainring bolts 8-9 Nm, steel 12-14 Nm". How do I do it properly?
Reply by Dirk Zedler, TOUR technology expert and bicycle expert
Personally speaking I would always liberally apply grease to the bolts and/or nuts of chainrings. This prevents noises as well as corrosion. As to the torque values: The torques indicated by Shimano in their documentation for chainring fastening are 8-11 Newton metres, the torques indicated by SRAM are 8-9 Newton metres for aluminium and 12-14 Newton metres for steel. Campagnolo do not indicate a range, but the precise torque value of 8 Newton metres. These values are taken from the original manufacturer documentation. For my part, I would recommend that you always go to the bottom limit of the indicated torque values. According to our experience, this always worked well in the past. If bolts come loose, you can increase moderately; however never exceed the upper limit of the indicated torque value.