For a long time I’ve been looking for a possibility to fit my road bike with pannier bags for a trip. Two years ago I found such a possibility and mounted a Tubus-Fly-pannier rack to my aluminium racer originating from the beginning 2000 years with respective quick-release hub holder. Loaded with about ten kilos of luggage I made a trip with friends to the south of France. Everything worked perfectly, the riding behaviour of the road bike was great: no wobbling, no vibration, just like I had wished.
Some time after I had returned home I noticed creaking noises on my road bike when I was cycling out of the saddle. After a long search I found out that the frame was broken. Right under the front derailleur clamp the seat tube was broken over three quarters of its circumference. Did I overload the frame with the use of the pannier bags? Is it possible that due to the pannier bags’ inertia increased bending torques possibly bundled due to the front derailleur clamp (2-3 Newton metres) occur in particular when riding out of the saddle. Can you imagine that these may be the reason for the frame to break? Until my frame broke I had warmly recommended this road bike fly solution to anyone who wanted it to know.
Reply by Dirk Zedler, TOUR technology expert and bicycle expert
The fact that your aluminium frame broke is unfortunate, but not so much astonishing. The frame is meanwhile ten years old and has certainly experienced a lot. In the case of aluminium as well as steel frames a docile breakage is again and again a signal that the useful life has come to its end. Especially very low weight frames made of metal bear the risk of being affected by cracks. In my opinion there is no direct connection with your Tubus Fly. As long as you had mounted it to the brake calliper and to the drop-out/quick-releases, its load had been introduced into the rear frame, which has nothing to do with the seat tube.
Meanwhile, all bicycle manufacturers have become clearly more professional. With many of their frames it is normal that the frames are checked for operational strength. My tip for a multifunctional bicycles, as you may like it: a cross bike. Its geometry often allows more space for your legs and feet towards the rear, thus avoiding a collision with the pannier bags. Some cross bikes also have mudguard eyelets allowing the mounting of pannier racks.