Ask a Mechanic | Tubeless Road Tire Installation & Braze-On Front Derailleur Setup

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Shimano Pro Torque WrenchQuestion: When I put my 9070 front derailleur on, I set things up and get the cage parallel to the chain ring. As soon as I tighten the bolt to the braze-on, the back of the cage angles out (away from the frame) and the set screw is not even touching the little metal stick on plate they give you for a carbon frame. What am I doing wrong? From: Gerry

Answer: You may be over torqueing the braze-on bolt. Front derailleur braze-on mounts are often very flexible and when the braze-on bolt is tightened down; this mount will cause the derailleur to angle outward. Try to compensate for this flex by setting up the derailleur angled in toward the frame before tightening it down.

If you have a torque wrench, torque the braze-on anchor bolt to 5nm. Shimano gives a torque range of 5-7nm, but start at the bottom of the range since your frame doesn’t seem to like higher torque. Of course it is always a good idea to use as little torque as possible to get the job done reliably. At any rate, because 9070 derailleurs have that set screw to help maintain their angle position, the bolt doesn’t need to be super tight in order for it to stay in place.

Daniel Slusser is a professional bicycle mechanic with over ten years of experience. He holds a bachelor’s degree in business administration from HSU and a master’s degree in history from Cal Poly. When he is not riding, wrenching, or writing he enjoys spending time with his wife and two children.

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