Gear hangers – What are they – And why do they break?

We have a few emails regarding gear hangers breaking/snapping a year, sometimes within weeks of receiving the bike usually after a few months/years of riding. Gear hangers are not a part that is usually covered under warranty and unless this the result of a crash then having them snap on you can generally be avoided. So for those people who are not sure what these are, or those who are buying their first bike and want to avoid the inconvenience of this, and a gear hanger breaking mid ride is pretty inconvenient, here is all the information I have on them and how to preserve their life as long as possible.

How they fit and what they do!

Gear hangers, or replaceable dropouts as they are otherwise known, are designed to be replaceable. They are usually made of alloy and will break under extreme stress in order to save your frame from being damaged. This can be the result of a crash, mis-shift or most usually simply being in the wrong gear when the chain and derailleur are under the most load either when the road goes upwards sharply or setting off from a standing/stationary start.

All the hangers for our bikes are of the cast alloy type and attach to the frame using either one, two or in some cases three countersunk bolts. The mech itself then attaches to the hanger. There are many different types of hangers and you usually find that each model of frame will have a specific one unique to it. This can sometimes change year by year, which doesn’t make things easy when trying to source a replacement.

 Ribble Cycles Gear HangerHere is a gear hanger in action – blink and you’ll miss it!

Why do they break and how to avoid it! (Overshifting)

As previously mentioned hangers are made from a soft metal designed to break under extreme stress, this may sound a bit strange, but the reasons for this are to protect the more expensive parts of the bike firstly the rear derailleur and then frame, they are if you like the ‘weakest link’ on a bike’s drivetrain. A broken rear mech, although dependent on which one, can be relatively expensive and a bit annoying. It is nothing however compared to the cost of replacing the frame.

There are a few reasons why they break aside from crashes, which are usually pretty much unavoidable. The most common on new bikes is usually however down to rider error. Either being in the wrong gear combination for the terrain or when starting off, i.e. the big ring on the chainset paired with the biggest sprocket on the cassette, or trying to change gear when the load on the chain and gears is at its greatest on steep inclines.

Other reasons can be an incorrectly fitted or worn chain, a chain that is too short for the chainset/cassette combination fitted, debris in the chain or derailleur and incorrectly set up gears can also cause undue stress on the hangers.

Dos and Don’ts!

Do keep your chain well maintained. Clean and lube regularly. The same goes for your derailleur, cassette and chainset.

Do check your chain regularly for stiff links or possible bent links.

Do ensure that after fitting any new parts to the bikes drivetrain that you check the gears are correctly set up – reset and adjust if necessary.

And lastly Do make sure that you are in the right gear for starting off and climbing, always start off in the small/inner ring at the front, and ensure you are in a suitable gear combination before the road ramps up on a steep climb.

Hopefully then your hanger will last as long as you have the frame and you won’t have to try and limp home if one does snap on you!

5 Comments
  1. Thank you this really helped me understand what happened to me a few days ago half way up a hill when I changed gear, then my chain jammed i thought it had fallen off but when i looked the whole back derailleur had come off and this particular part had clean snapped ( i now know it’s a gear hanger ) so it all makes sense to me as to why this would happen and possibly why!

  2. Do they hanger can break because a low speed cassette? My bike is 11 speed gear. I took my bike to change the speed cassette. They person said that is 10 speed cassette and change the cassette. Two days ago the hanger broke. I took it the bike shop and they said that my bike is 11 speed no 10 than why I have a 10 speed cassette. The tech person told me that one of the reasons that got broke is that cassette, another that got hit with something or somebody made a bad chain change or repair and bend the hanger and tried to make it straithgt. My question is the low speed cassette is a reason to broke the hanger?

  3. I wish my hanger broker when under stress. I moved slightly off trail to let someone pass. My derailer hit a stump hidden in grass and got shoved up into the rim. The hanger bent slightly, however managed to destroy the carbon rear triangle where it sits. So my question is should there be a more breakable hanger to avoid this? This little courtesy is going to cost over 1000 to replace rim which was not able to be repaired, and new section of rear triangle and derailer and of course the tough hanger which unfortunately stood the rest of time.

  4. Really useful.

    I ride a recumbent trike, and my chain came off and jammed between the spokes and cassette (no spoke protector fitted!) on a VERY steep hill. When I eventually got it unjammed the gears kept skipping and changing gear on their own and occasionally the derailleur would jam into the cassette stopping any movement. On close inspection everything looked “normal” and I couldn’t see any reason for the problem so I limped it home.

    On the phone to the dealer he seemed to know the cause without even seeing the trike, which at the time made me a bit suspicious. However now I understand that, after I explained how the issue happened, he seemed confident that it will be “an easy fix”. [Hopefully the bent hanger WILL be the cause.]

    I’ve not had the trike long and it was supplied new. I have not hit the derailleur on anything and, being a trike, it cannot fall over onto the derailleur. Was the sheer strain of the chain coming off and jamming between spokes and cassette whilst in a low crawler gear enough to bend the hanger?
    Perhaps this is why the manufacturers website lists the hanger as one of very few “spares” in the accessories list !!!

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