2 broken hangers in 6 months

elbowloh

So, as in the title, i've now broken 2 hangers in 6 months.

The first time was going up a hill and a dropped down a gear, wham, hanger snaps, the derailleur goes into the wheel and the chain snaps. Derailleur is bent and the chain is twisted too. New hanger, derailleur and chain needed.

Then on yesterday, i've actually gotten to the top of a hill and our group stops at the top as to regather the stragglers. As we set off again, on the first pedal stroke (so not under great stress) the hanger snaps again. Luckllily this time the mechs ok and i only need a new hanger (i bought 2 last time just in case) and a new chain (twisted again).

Am I doing something wrong? I don't think it's the set up, as since the first occurrence, the wheels, cassette and derailleur have all been upgraded. Only the frame and the hanger (design) are the same. I know hangers are designed to break first, before anything else gets damaged, but it seems slighlty ridiculous. The hanger design is bad imo, there's a sharp 90 degree cut out in the design, where all the load goes and this is where it snaps.

Bike is a Felt Z6, with Ultegra groupset.

slowbike

There should never be any real load on the dérailleur - its there just to guide the chain to the right sprocket.

There will be a slight sideways load if it can't shift gear - but anything inline with the chain will be the pressure of the spring only... or should be!

bobones

More likely your derailleur went into the spokes and then the hanger broke.

desweller

Hangers are under very little load. You need to check your limit screws; it sounds like your derailleur is striking your spokes.

elbowloh

Cheers, I'll check, but this has happened twice now, with 2 different derailleurs. I wasn't in the lowest gear when it happened though?

desweller

How did you size your chain?

elbowloh

DesWeller wrote:

How did you size your chain?

When i get a new chain I generally just size it up against the one that was on before, so it's the same as when it was first set up.

dennisn

elbowloh wrote:

DesWeller wrote:

How did you size your chain?

When i get a new chain I generally just size it up against the one that was on before, so it's the same as when it was first set up.

This could be your issue. I suggest you read up on how to attain the optimal chain length.
Also wouldn't hurt to brush up on limit screw adjustment. Also a check of hanger alignment might be in order.
And even a check of your rear wheel dishing.

crankycrank

When installing a new hanger always have it's alignment checked. Just because it's new and doesn't have any visible defects doesn't mean it's aligned properly on your bike. Manufacturing discrepancies in the frame or hanger can be off a bit sometimes.

bobones

The broken hanger is more likely to be an effect than a cause. Could be your chain got kinked and jammed in the RD causing the hanger to break? The normal scenario though is for the RD to get caught in the spokes and ripped off, but that would normally only happen changing into the largest cog with badly adjusted limit screws or a super flexy wheel.

elbowloh

Thanks for all the advice people.

So to recap, i'll check:

chain length (and pins, stiff links)
hanger alignment
limit screws
wheel dishing

BTW, i have checked the spokes, there's no damage to them or anything. They're black anodised, so can see easilly if scratched and there are no marks on them. So looks like the derailleur probably didn't clash with the spokes.