Broken rear hanger - what should I check?

[aferris2]

The hanger on my Dolomite bike broke in half the other day. It broke when I was just starting out down the flat drive, so little or no pressure on the pedals. Drivetrain just locked up then went ping. The edges of the break look clean so it looks like a sudden failure rather than a crack that has grown over time.

I've had the bike for just over 2 years and have clocked up just under 11000 miles (mainly commuting) so it's fairly well used. The only time that I can think that I could have damaged the hanger was at the end of January when I was pushed over (I was almost stationary and didn't end up landing on the bike). I did have a quick look once I picked myself up and didn't see anything odd, and gear changing was not affected - and has not been affected since.

Chain and cassette were both replaced at the beginning of January, so 1200 miles old. Previous chains did more than 3500 miles before they needed changing so this one should have plenty of life in it still.

So if the damage was due to the fall, all is good and I can just fit a new one, but I'm not convinced that the evidence matches the crime. Is there anything else that I should check?

Here are the two pieces:


and how it should be:


and how the two parts would like to fit together now (almost):

 

[si_c]

You'll need to get a replacement hanger, they're usually in the £10-£15 range. I'm presuming it's a Pinnacle Dolomite you have? If so Evans Cycles will be able to supply a replacement as the manufacturer. You could also look on ebay for 3rd party replacements.

You do need to make sure you get the right one though, otherwise it won't fit and there are thousands to choose from.

 

[lazyfatgit]

Could the bike have been bumped or knocked over without you knowing? Some hangers seem to be made of cheese.

 

[steveindenmark]

Someone posted a link on here a while back of a place where you could order all sorts of hangers.

Hangers can bend just by looking at them

 

[aferris2]

I've got a couple of hangers on order as my local Evans didn't have any in stock so that's not an issue. I wondered if there was anything else that I should check on the bike before fitting a new one.

 

[Milkfloat]

Check the package of odds and sods that came with bike, my Dolomite came with a spare hanger.

 

[Tim Hall]

I've got a couple of hangers on order as my local Evans didn't have any in stock so that's not an issue. I wondered if there was anything else that I should check on the bike before fitting a new one.

It's a bit of a puzzle as to why it snapped, given that you've been riding it for so long without a problem. However, when the new hanger is fitted make sure the chain is long enough when in a big-big combination, especially as you said the drive locked up. While you have it in bits check the spokes for damage, in case they got hit by the rear mech.

 

[si_c]

Yes, as @Tim Hall said you need to figure out what happened, otherwise it's going to happen again.

 

[I like Skol]

Things to check;

• Check that the rear mech isn't bent at the cage or parallelogram. Looking at the amount of twist in the hanger I would say there is a good chance it will be.
• Check chain for bent links.
• Check chain length is correct. As has been said, maybe you accidently ran a big/big gear combination and the chain just isn't long enough to allow it?
• Check rear wheel spokes for drive side damage.
• Check cassette for tooth damage. I had an incident like this a few years ago and one of the cassette sprocket was bent during the failure!
• Check stop limit screws are properly adjusted when the old/new mech is fitted.

 

[Racing roadkill]

Sounds like the rear mech got dragged into the spokes. The hangers tend to bend in over time, then they contact the spokes, then this happens. Get yourself a new hanger, and an alignment tool. When it’s all running again, check that the alignment is straight from time to time. If you hear a noise like having spokey dokeys on your wheel, the chances are, either you have spokey dokeys on your wheel, or your rear mech is getting close to the spokes. If it happens whilst your out on the bike, move the mech away from the spokes, by turning the screw marked ‘L’ on the rear mech, clockwise, by a quarter of a turn. When you get home, check the alignment of the hanger. In the mean time, a quick check of the spokes, and trueness of the wheel ( is it buckled) and check the cable, for fraying. That should be enough for now.

 

[Cycleops]

Probably a manufacturing fault. One reason I'd always favour a steel frame over an aluminium.

 

[I like Skol]

Probably a manufacturing fault. One reason I'd always favour a steel frame over an aluminium.

I doubt it, not after such a long time/distance and a few chains/cassettes. More likely a minor knock has caused the alignment to go out and the mech has hit the spokes or a chain that is too short has been fitted. The hanger has not fatigue failed but has been physically torn/twisted to the point of snapping.

 

[Tim Hall]

I see a new chain was fitted in January. I guess there's a slim chance it wasn't long enough and the OP managed to avoid, by chance, getting the wrong gear, until now.

 

[ianrauk]

Now, I do remember a thread about Pinnacle bikes being recalled because of dodgy rear mech hangers.
I remember this as I had a Pinnacle that was included in the recall, a couple of others on here too.

I'll try and find the thread.

 

[ianrauk]

Took a bit of searching but found it.
It was bikes from 2014, but it was more due to wheel slip rather then failure.

Hanger thread