The Saga of the Broken Derailleur

Guest poster Don Blount has been dealing with a frustrating situation.

It is never comforting to show a mechanic or an experienced cyclist a broken bike part and hear them respond: “Oh wow, I have never seen that one before.”

I received that response several times when I told people of my bike’s broken front derailleur. (Click photos to enlarge.)

It did not make any unusual noises before it broke. Nor did it go out with a clang. It just went. One moment I was pedaling and attempting to shift into the big ring and there was no shift. I looked down and saw the now oddly shaped derailleur.

I could not fully assess the damage on the road, so I cut my ride short and returned home. I called a few bike shops and found one that said they had the part in stock.

The next day, Saturday, I stopped by that shop only to discover they did not have the style of derailleur I needed. My Scattante CFR Comp uses a clamp-on derailleur, like the name indicates the derailleur clamps onto the seat tube of the bike.

There is also the braze-on derailleur, which attaches by fasteners directly to the frame. They too would have to order the part or I could pay an additional $15 or so to buy an adapter to fit the braze on derailleur to my bike. Nah, I passed on that.

At home I removed the chain, removed the derailleur and cleaned my bike. After everything was reassembled I realized there was no reason I couldn’t continue to ride the bike provided the course was relatively flat as I could not shift from the small ring to the big ring.

Sunday night I ordered the replacement part ($60), upgrading from a Shimano 105 to a Shimano Ultegra. That same day, I rode 22 miles and the bike handled just fine. Until the new one is installed I will continue to get in rides as long as I remember to not attempt to shift the front rings.

The new derailleur is here.

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6 thoughts on “The Saga of the Broken Derailleur

  1. I had this happen to my 105 front mech this morning. I’d like to know what causes a break like this (in the hopes it can be avoided again).

  2. This has just happened to my 105 front mech as well, somehow the warranty wont cover i reckon. had the nike less than 2 years.

  3. I have had the same failure… 1st time back in October, I bought another derailleur off of Ebay and installed it. While I was waiting for the new one to arrive I welded the broken one back together to use on a ride the next morning. The new one (both Tiagra) is having a similar issue. They don’t break shifting from little to big, they break shifting from big to little and then it is noticed the next time a shift is made from little to big. This is what happens, I don’t know why.
    1. Riding in the big ring.
    2. Shift is needed to the little ring.
    3. Shift is actuated and derailleur moves.
    4. Chain hesitates in the big ring.
    a. this would appear to just be a noisy shift.
    5. Front derailleur is distorted sometimes breaking, sometimes just bending,

    No idea what causes this. I chalked up the first one to inexperience or damaged by the previous owner. I had just came around a right hand corner and attempted to shift when it failed.

    2nd time. Climbing and tried to shift under a load. (just bent, did not break). I bent the mechanism back into place and it continued to work. I didn’t trust that it would continue to work and replaced it with my crappy looking welded spare.

    3rd time. My welds don’t give. Shifting at a low cadence at the bottom of a descent just before starting the next climb.

    For the sake of argument lets just assume that if I have the skill set required to weld one back together, that it is likely that I can install it properly also.

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