All about bicycles, pedelecs, 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.

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.

RadMarkt 08/2006

Success or setback

Working with carbon is difficult – real life problems

Ludwigsburg-based "Zedler – engineering and consulting" concentrates, among other things, on carbon parts (...). At the "Fahrrad.Markt.Zukunft" conference, Dirk Zedler once again gave a lecture on the problems caused by improper handling of this material. Zedler pointed out what he considers the worst mistakes causing problems in everyday life.

Seatpost – frame
Failure: Seatposts are crushed in the frame and finally break. Carbon seatposts are usually varnished and the material generally is pressure sensitive. The frame’s seatpost clamp, however, has to be tightened forcefully to fix the smooth seatpost. By doing so, the material is stressed improperly, the tube is damaged.

Remedy: Enhance friction between seatpost and frame, so lower torques are necessary. Never use grease, the frame has to be carefully degreased. Use dynamic assembly paste.


 

Wheel and rim material – brake pads
Problem: The braking performance of carbon rims is often stuttering and from time to time very aggressive. Under wet conditions, friction decreases considerably. On long downhill rides the developing heat can lead to dissolution of the brake pads’ suface. The surface is not smooth and cannot conduct away heat as it is the case with aluminium. Under wet conditions there is no friction, the brake pads skid over the resin surface.

Remedy: The varnished or resin surfaces need special carbon brake pads. They have to be matched and chosen very carefully. Concerning problems with wet and heat development manufacturers have to do their homework.

Handlebar – stem
Failure: Drop bars are crushed in the stem and finally break. Carbon handlebars usually are varnished. Because of this, the stem clamp has to be tightened forcefully to fix the smooth handlebar. By doing so the pressure sensitive material is stressed improperly, the tube is damaged.

Remedy: Diameters must be accurate to a tenth of a millimetre. Therefore it is sensible to buy handlebar and stem of the same manufacurer. Assemble without grease, apply Dynamic assembly paste to handlebar and stem. Assemble with a torque wrench starting with very low torques – control if the handlebar still moves in the stem. Tighten bolts very carefully until the handlebar is fixed.


 

Mountain bike handlebars – levers and bar ends
Problem: Handlebars break in the areas where levers and bar ends are fixed. Besides the facts cited above this is often caused by assembly parts not fixed at the reinforced parts of the handlebar.

Remedy: Only put bar ends on carbon handlebars with special reinforcements or such which can be reinforced with cases. Use Dynamic assembly paste in order to lower the torque necessary. Do not shorten carbon mountainbike handlebars as they often have integraed reinforcements for brake levers or bar ends. Manufacturers have to indicate where parts can be fixed.

Author: jk/dz
Photos: Zedler