Mech Hangers on a £500 road bike

Usually the failure of a derailleur tab is the victim of what went wrong, not the cause. Often the cause is jamming the chain between the cassette and the frame or spokes, or breaking the derailleur, or a foreign object becoming caught in the drivetrain. If you have a replaceable derailleur tab, then you thank your lucky stars and buy a replacement. If your frame is toast then you may want to spend more effort trying to get help from the merchant. When I worked in bike shops, if I sold someone a bike and they had a hard-luck story like that, I would usually try to fix it regardless of what happened.

Last month I went through two rear mechs in the space of a week on two different bikes. No crashes involved, just pure bad luck.

Original equipment hangers are often cast ally and they can indeed just fracture with no abuse, it's not like they x-ray each one.

Goldtech do CNC machined replacements made from T6 ally plate, same as their chainrings.

Something similar happened to me too but it was due to a fall onto the mech side, that caused damage to the mech hanger, which I could not replace in a hurry, so I used the damaged hanger, which failed later braking the chain (but fortunately not the rear deraileur).

If you have never dropped your bike onto the mech, fallen onto that side, or bent it putting it into a car say, then it should not have failed.

You should have noticed the fall since the gears would have been out of trim and gnashing a bit after the damage (bend). The gears would have had to have been adjusted after the hanger was damaged for there to have been no noises from the rear mech in all gears. Did you notice any noises from the back ever?

The hanger is designed to fail before the deraileur does, hopefully thereby protecting the deraileur (but alas not in your case).

It would be difficult to prove that you did not take a fall onto your mech, and difficult for a place like Wiggle to take your word for it. I guess this is one of the drawbacks of purchasing online. An LBS might know the bike's history and trust you.

So I suppose you are going to have to bite the bullet. A new Sora chain 8UKP a new rear deraileur 15UKP and perhaps another 15UKP for the hanger. These are online prices. Labour costs will depend a lot on where you are but it should be no more than 120UKP all in, at a local bike shop I guess. Painful, but this may be less than the discount you got at Wiggle.

Which bit died? any photos? was the break from a manufacturing defect or your ineptitude?

I ride a C12… kind of hope its neither tbh.

it's correct that the replacealbe hanger is "expendable", but they don't normally
just fail. The only times any of mine have gone is post crash. If it's not taken a
hit of any sort then I'd pursue Wiggle .....