All about bicycles, electric-assisted bikes, technology and safety in the press

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.

For many years now the Eurobike Show Daily accompanying the annual international Eurobike Show has given us the opportunity to publish our perspective on major developments in the cycle industry in full-page articles.

We also speak regularly in independent lectures about all topics relating to bicycle technology and bicycle market. In addition, we are regularly cited by further special-interest magazines or trade journals as well as more and more by radio and television and in their media reports, which shows us that we are completely right with our information. The section NEWS informs you about the latest news from our specialist fields. The reports and publications of this section are listed chronologically or according to topics of interest.

TOUR 11/2004
Reading time 1:20 minutes

Controlling authority

The wrench as the symbol of anything mechanical - not only as an indicator of the TOUR-workshop's degree of difficulty - suggests: Any child knows bolts and nuts.

Nuts and bolts are part of almost every toy building set - either in form of easy-to-grap wooden toys or in form of small brass parts. Also on a roadbike, bolts and nuts are everywhere - but did you know that a normal roadbike has around 120 to 130 bolted connections with completely different functions?

The bolts at the bottle cage are typical fixation bolts, with the nuts on the wheels' axes you can fine-tune and fix the bearing play; end stop bolts at front and rear derailleur limit the pivot range of the bicycle gearing, but except from this only have to hold themselves. The one commonality they have is that the way they are assembled decides if they can accomplish their task.

The wheels' spokes and nipples are just as well a bolt-and-nut-system - and a good example of how forces develop in bolts and what influence they have. (...)

This resilience of bolts is also taken advantage of with handlebar and stem, for example. In order to fix the handlebar firmly, the stem bolts' resilience has to be high enough to build up sufficient friction between handlebar and clamping area. If the bolt is overtightened, however, the stem constricts the handlebar and dents it. Other problems: Too much force applied can cause bolt heads to be pulled of or threads being torn out of the stem. (...)

Such failures are caused because you cannot directly determine the bolt's resilience. Therefore, the torque is used as controlling authority. This is the force a bolt is tightened with multiplied with the moment arm. (...)

(...) Unfortunately, most torque wrenches are quite expensive - but, considering the possibility of a broken part or a material failure, they are worth the money.

Author: Dirk Zedler

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