[Closed] Failed frame after mech got jammed. Opinions sought.

I agree with you but...

https://singletrackmag.com/forum/topic/stiffening-derailleur-hangers/

Warranty job?

Marin warrantied a similar thing for me, ruined dropout after hanger didnt snap, whole new swingarm and bearings, and after the warranty period too! They just said 'that shouldn't happen, here's a new one'
Oddly enough ive now had three Marins and recomend them to everyone else

Did you buy the whole bike or just the frame? Either way you should try the warranty route, but the case might be stronger if you bought the whole bike. Still if just the frame I can see your point that the hanger should have failed first

I think its a warranty job Citizenlee but supplier doesn't...

IMO its user error / accident and nothing to do with the manufacturer unless in their literature they describe the bolts as "breakaway" or " built in failure point" or similar

You might get goodwill from the manufacturer but thats all

I would expect the CF frame to fail before the bolts. the mech hanger might have a deliberate weak point to fail built in but the bolts? Nope

Just a laymans opinion

edit : Not a chance under consumer law again IMO

Would it have made any odds if the had? Probably not.
If they were made such that they always fail that would be a much bigger issue and you and every other owner would be complaining that the mech falls off every time you change gear and trashes your wheels and frame.

It's protective but it's not infallible.

All that being said, a trashed chainstay off the back of it, I'd be a bit less accepting of I think. What do the mfr say?

Its the seat stay that's bent weirdly

markrh
Free Member

I think its a warranty job Citizenlee but supplier doesn’t…

What did the shop actually say "no claim because....?"

Its the seat stay that’s bent weirdly

I missed that bit! How the hell did the mech get anywhere near the SS without the hanger failing? That's about 200 degrees of rotation!

"Because the failure was caused by the mech jamming" masher, but my expectation is that the bolts on the mech hanger should fail first. I've been riding for 30 odd years and plenty of bikes have come and gone in that time and i've had the odd mech in the spokes before and its never resulted in a frame being written off.

Surprised a carbon frame has bent. Do you mean broken?

No, defiantly bent.

but my expectation is that the bolts on the mech hanger should fail first.

mech hanger maybe if it has a built in weak point. Bolts no

Would be interesting to see some pictures of the seat stay damage - thought carbon splintered before bending usually.

A 5 month old bike where a mech lunches itself yet the mech hanger doesn’t snap I’d want a warranty replacement frame or at least some money off a replacement one. No money towards the mech though as they take a lot of trail abuse.

If nothing from the manufacturer / retailer then I’d buy another brand and absolutely abuse the damaged frame one something chronic online every time a ‘what about this bike’ thread comes up.

Has the mech wrapped round the rear of the dropout and smashed into the carbon seat stay, subsequently bending it?

I've never know a carbon seat stay to bend to the point where it's written off, it'll snap, they're literally paper thin.

Do you have pictures?

My guess is the mech has come into contact with the spokes and then wrapped round the bike and smacked the seat stay, if as you say the hanger is intact and aligned then the mech has taken a battering at some point, probably right before it did this.

Chain-suck would drag the mech cage up into the chain-stay.

Sometimes they are an aluminium breakaway bolt TJ. My lads Norco has one, and they screw a second spare bolt in the frame near the bb in case it breaks on a ride.

Few things might need a bit more detail.

As above, bent or broken? Carbon on a bicycle isn't renowned for that sort of plastic deformation.

I wouldn't expect hanger bolts to fail as that would/could run the risk of taking the frame with it. I would expect the mech hanger itself to deform.

Having said that, even a sacrificial part like that is really difficult to design for a controlled failure in all circumstances.

Did the mech itself cause the failure or was it an overshift? What caused the overshift? Who set the mech up originally? Is there no offer of an assisted purchase for a new frame?

Sometimes they are an aluminium breakaway bolt TJ. My lads Norco has one, and they screw a second spare bolt in the frame near the bb in case it breaks on a ride.

Yeah, my Canyon had a breakaway bolt.

Mech was trapped in the spokes below the chain stay. I was off the power as soon as I felt it lock. I'd been riding through a field with a Barley growing in it. Some of the Barley got wrapped around the mech and cassette and caused the problem.
And yes its bent not broken. Can't be arsed to do pics, just imagine what was a straight tube now having an (approx) 5 % bend in it. Chainstay must be affected to but harder to see, back wheel now sits at an angle in the frame 🙁

Interesting that anyone, never mind several people, consider this kind of thing a warranty issue. Replaceable mech hangers are great, because if bent from a side impact, the chances are both the frame and mech will survive the immediate problem. If the mech ends up in the rear wheel all sorts of damage can occur though… and none of it due to defects. The chain, spokes, stays… all can easily be a written off as secondary casualties from the mech being bashed if it ends up in the spokes.

My experience of most modern frames is that mech hangers and bolts breaking away first is a bit of a thing of the past. Of the current frames I have the CF hanger is one piece with the dropout/ stays, one is a meaty bit of aluminium as one piece with the SS sliders and the other has the hanger as part of the thru axle dropout which in turn bolt in to the frame. All are very rigid and definitely not made to breakaway. Not a given the hanger is designed to snap off beautifully saving the frame and pics definitely needed.

Edit: also good point by another here that mech in the wheels is a recipe for a whole host of non warranty damage

If you don't get anywhere with warranty - is it worth looking at repair? I would have thought someone like https://www.carboncyclerepairs.co.uk/ would be able to give you an opinion.

I wouldn't say it's a warranty job. Cirtainly not without photos etc. Possibly an insurance claim of your with Bikmo or similar (accident damage claim), but definitely not warranty.

If you drive over a  large stone and damage your exhaust, would you go to the dealership and claim warranty?

Sometimes they are an aluminium breakaway bolt TJ.

indeed - and if this frame is supposed to have such a bolt then yes its a warrenty issue but as far as we know it did not

Replaceable mech hangers are great, because if bent from a side impact, the chances are both the frame and mech will survive the immediate problem.

This is exactly the situation I've seen where the mech hanger saved both the frame and the mech from needing replacement, and in my opinion that's the sort of situation it's there for. I wouldn't have thought it's a warranty job personally, unless the bolt(s) it's sold with are designed to do that.

Any chance of a crash replacement reduced frame price?

nope

I've never broken a mech hanger but broken a few mechs, in my experience mech hangers are not a sacrificial part to save the mech and are actually more likely to bend and put the mech into your spokes to also ruin the wheel

I’ve never broken a mech hanger but broken a few mechs, in my experience mech hangers are not a sacrificial part to save the mech and are actually more likely to bend and put the mech into your spokes to also ruin the wheel

Frames are expensive to replace. Spokes are cheap. Hangers are cheap. Derailleurs are generally cheaper than frames. The point is to sacrifice the cheap parts to protect the expensive parts.

Not a warranty. Unfortunate accident, but in no way the manufacturer's responsibility.

Some of the Barley got wrapped around the mech and cassette and caused the problem.

In fairness if that's the case I'm afraid it really does sound like dumb luck. Stuff, no matter how flimsy, jammed in and around is way outside of "normal use" despite the fact it might be very common.

It could easily be the barley wrapped round the the frame preventing the hanger falling.

It's a pita but it sounds like you're looking for goodwill rather than a warranty to me.

I didn’t realise carbon tubes would bend, always thought they’d crack/ break.

thanks for all the opinions, really interesting thanks.

Irrespective of cause, a lot of (some?) manufactures/importers offer frames under a "crash replacement" policy, not free but usually with a significant discount of RRP.
Have you tried that route?

If that manufacturer doesn't do crash replacement or does but refused you, then you'd be doing the cycling community a service by naming names so we can all avoid them in the future...😉

“Mech was trapped in the spokes below the chain stay. I was off the power as soon as I felt it lock. I’d been riding through a field with a Barley growing in it. Some of the Barley got wrapped around the mech and cassette and caused the problem.”

This precludes a warranty claim. The damage to the frame was caused by an external force, rather than by a failure of any of the components due to a manufacturing or material defect. Sucks to be you in this position but it’s the truth.

The damage to the frame was caused by an external force, rather than by a failure of any of the components due to a manufacturing or material defect.

You missed failure of design. It's difficult to argue that a mech hanger shouldn't snap before other components are overloaded, because that's what they're designed to do.

You could try it as a fit for purpose argument, a bike for riding off road should survive being ridden off road.

OTOH it'd be like driving your car into a kerb and expecting the wheels to survive.

It'll probably be repairable, I know a couple of people who've had similar incidents and the mechs gone straight through the seatstay who've had them repaired good as new.

I destroyed a ti frame on its first ride. Mashed the non replaceable mech hanger. Got it fixed but never the same.

I destroyed a ti frame on its first ride. Mashed the non replaceable mech hanger. Got it fixed but never the same.

Was that a 456?

because that’s what they’re designed to do.

Not necessarily, they're designed to hold the mech. They're commonly replaceable because they often get damaged. Sometimes they're intended to fail before other stuff but not always and the line between simply falling apart and not failing when you want it to is a fine one. Clutched mechs put a lot more force through those hangers than mechs of old and beyond as received wisdom I don't think I've heard anymore refer to a mech hanger as sacrificial since the days of 9 speed. (Otherwise known as when we moaned about them breaking too often compared to non replaceable but easily bent back ones on steel frames.)

I'm suprised by what some (not the OP) think a mech hanger could prevent - think of the force created by a jammed/wrapped up chain driven by a wheel rotating with your momentum behind it. May not matter if the hanger is intact or not by that stage, it'll be a mess.

This happened to me
I think it happened when the mech hit the spokes and the rearward force through the mech cracked the dropout rather than the hanger. You could argue it was my fault for putting the mech in the spokes. I made the point it was poor design.
I received a full refund for the cost of the whole bike, 18 months old (warranty was 12 months). A new chainstay would have sorted the problem but they have no stock.
I’ve just ordered a replacement frame- I paid more attention to the design of the dropout and hanger when ordering….

I'd expect a mech hanger to fail if twisted but pulled round parallel to the axle not a chance.

Best I'd hope for here is a crash replacement discount.

And I'll second the hows it bent carbon...

Have you had the wheel out? To see if its just preloaded up?

Yes, wheel out, still bent. Think i'll just have to chalk it up to experience. But I do wonder about the carbon lay up, it seems very plastic...

What bike is this ? I'd be curious to see pictures of the bent stays as well

in docrobsters case it does look like a design / manufacturing fault to this amateur. Very little metal around where it has cracked. However the result he got is purely a goodwill measure

OP - can we have pictures as then we will have more information for our armchair engineering ( unfair - we probably have some real engineers here)

I tend to think of modern mech hangers as a bit of a "mechanical fuse" an engineered, preferable failure point.

The trouble is what the failing mech does next. If you're lucky it wraps itself up in the chain and cassette and misses the spokes and stays. But it's not a predictable failure, and as often as not it will end up getting fired into the frame with a few KN behind it...

The 'bent' carbon tube is an odd one OP, are you certain that's what has happened? Composites down tend to do much plastic deformation, plus it will have been a point impact, are there any signs of damage through the laminate? Surface chipping, softer spots, a duller tone when tapped? I think it might be worth your while getting it inspected by someone qualified...

I’m suprised by what some (not the OP) think a mech hanger could prevent – think of the force created by a jammed/wrapped up chain driven by a wheel rotating with your momentum behind it. May not matter if the hanger is intact or not by that stage, it’ll be a mess.

yeah, had a few people saying to me the hanger should of failed when the chain got jammed between the cassette and spokes(wasn't shifting at the time, dropped the chain on very rough ground and it bounced over), ripped the mech back and destoyed the bottom of the seatstay where the hanger locates on my rallon.

orbea must have had a few similar issues as they updated the hangers but then they where so weak they where just breaking in normal riding so they have now gone back to stronger ones.

i got a crash replacement stay from them.

“Mech was trapped in the spokes below the chain stay. I was off the power as soon as I felt it lock.

Even if you were off the power instantly unless you slammed the brakes on your momentum is still going to pull the mech round and do damage . Unlucky but not warranty , best you can hope for is a goodwill gesture so my advice would be tell the shop or manufacturer what happened and don't go in with all guns blazing .

On the Warranty point, I doubt you'll make a claim stick.
The question to answer is What was the material defect with the bike that caused your issue?

From what I can tell, you were riding through a field of Barley, and your mech got jammed up with barley? Which sent it sideways into your wheel and then it got wrapped round into the stay...
what you've typed so far would suggest to me that the cause of your problem was riding through Barley, not shoddy bike manufacture.

I've done something very similar myself recently, but with ferns and bushes in my local woods, the hanger failed as intended (the jockeys were choc full of plant material).
I was lucky and the speed was low enough that I only tore the mech off, no wheel or frame damage... But the basic cause was my own enthusiastic ploughing into some undergrowth, I can't really claim otherwise...