Opinion needed

[Tin Pot]

I purchased a new road bike recently from Ribble with a Shimano Ultegra Groupset. I've done about 150 miles on it, then during a ride at weekend my chain snapped and when my local bike shop looked at it they said the front large ring had also bent - they had no idea why the circumstances of the chain incident would have caused such a result and suggested I contact my bike supplier. FYI I was pulling away on a slight incline and was on large ring on front and 4 or 5 on rear cassette, when this happened.

I was told by Ribble that cause of the failure was misuse of the equipment as I was in the wrong gear and had put the chain under too much strain.

This response feels completely ridiculous to me. I would be interested what more experienced cylists think about this?

It's a pretty unlikely scenario.

Have they examined the bike?

 

[Yellow Saddle]

At no point did the OP say he was shifting gear, where did your diagnosis come from?

Where did it come from?

A chainring cannot bend sideways from an in-plane force. For it to bend, the chain had to apply a lateral (sideways) force to it.
Further, the chainring can resist mild sideways forces such as when you are severely cross-chained in say big-big or small, small. That still won't do it.
The only plausible scenario where the chainring can bend is if the chain is halfway between big and small chainrings, making an acute angle, enough to bend the chainring if enough force is applied to the chain.

He said the chain snapped. We'll it didn't snap. "snap" suggests a tensile break, which it certainly wasn't. The chain broke open by popping a rivet. Then it broke when the sideplate was bent (again by a laterally-applied force). All of this happened underneath the front derailer where the botch-up started.

There is no other explanation. Perhaps you have one? The suggestion that he simply rode along and the chain snapped and chainring bent all by itself doesn't hold water.

The OP may not have been consciously shifting at the time but it is certain that the chain wasn't properly on the ring when he applied the force required to bend it.

 

[Yellow Saddle]

I agree, as does pretty much everyone else here. Yep, you're in the wrong gear for a hill start, but your chainring should be able to cope without bending. At worst, the chain breaks, or slips off the ring, or possibly the hanger on the rear derailleur snaps.

I'm a swine for being in the wrong gear at inopportune moments, and I've never bent a chainring yet. Sounds like yours is/was defective.

EDIT: just reread your OP and you say that you pulled away up a slight incline on the big ring and "4 or 5 on the rear cassette". I don't know exactly what your gearing is but I'm guessing that you were on something like 50/17, and that really shouldn't be an issue, apart from your grimace as you realise what gear you're in and have to stand up on the pedals.

What sort of defect do you suggest? Remember, in your scenario you have two defects to contend with and they have had to occur at the same spot at the same time - a defective chain and defective chainring.

 

[Yellow Saddle]

If that were true I would understand. It's not. They asked for a picture - clearly no accident damage. Understanding how the ring bent is exactly my point - it shouldn't and it did

Show us some pictures.

 

[Dec66]

The OP may not have been consciously shifting at the time but it is certain that the chain wasn't properly on the ring when he applied the force required to bend it.

Which should have resulted in one of three things; his chain slips across his cassette (if he's between two ratios on the cassette), or the chain slips off his big ring and probably gets jammed between that and his front mech (if he's shifted between his front rings, which is unlikely in the scenario he describes), or his chain breaks.

There is absolutely no way his chain ring should have bent, unless he was applying the sort of force you'd expect from an elephant.

 

[sight-pin]

I know i shouldn't, but regularly cross chain my Poggio 1.5 (50x32) and used to do the same with the triban 3, and then drop down to the 34 ring if i have to, never had any problems, yes it'll wear more rapidly as we all know.....just lately though i do use the 34 more often when i should.

 

[TheJDog]

There is absolutely no way his chain ring should have bent

I'd go so far as to say that if the chain was on the ring, and in gear 4 or 5 at the back there is no way the ring COULD have bent.

I'd say Yellow Saddle is almost certainly correct, the chain was coming off the big ring and OP was exerting full power.

 

[Milkfloat]

Even if the chain was coming off the big ring and putting it under lateral stress, I would expect a few of things:

1.) Ribble would look at the part and at least discuss it, not dismiss the customer without any investigation.
2.) Ribble would discuss it with their rep and at a minimum have this reported back to Shimano, they may be very interested in getting hold of this chainring.

In addition, I would not actually expect a supposed quality part to bend so easily - if Ribble were not playing ball I would work directly with Shimano.

 

[outlash]

I think some photos of the offending article would be in order here.

 

[Yellow Saddle]

Which should have resulted in one of three things; his chain slips across his cassette (if he's between two ratios on the cassette), or the chain slips off his big ring and probably gets jammed between that and his front mech (if he's shifted between his front rings, which is unlikely in the scenario he describes), or his chain breaks.

There is absolutely no way his chain ring should have bent, unless he was applying the sort of force you'd expect from an elephant.

The mess didn't start at the cassette. That had nothing to do with it. The problem was at the front. Had the mess started at the cassette and the chain popped a link open back there with an open plate facing forward, it would have ripped the front derailer off but not bent the chainring. Had the chain broken open with a forward-facing open plate and it had cleared the FD, it would have hooked on the RD cage and ripped that out.

A bent chainring is a sure sign of a chain jamming between the FD and chainring. Careful examination of the FD will show the necessary scarring.

Perfectly in-plane, chainrings are extremely rigid. This can be demonstrated by standing next to the bike, pulling the front brake and jumping down on a crank. This test is done by mechanics to identify a worn rear sprocket or worn hub pawls with no ill effects on the chain or chainring.

 

[Jody]

Had the chain broken open with a forward-facing open plate and it had cleared the FD, it would have hooked on the RD cage and ripped that out.

Perfectly in-plane, chainrings are extremely rigid.

I had this happen a few weeks ago when the plate popped off whist riding. It made it to the RD, twisted the cage and sent it into the back wheel. The chain was about 3 weeks old and the new mech was on its first ride #gutted

Front rings are extremely strong. I have hit mine on rocks/logs etc and only ever put the big ring slightly out of true.

 

[Jody]

This. I suggest you go back to Ribble quoting the Sale of Goods Act. Clearly the chainring was defective and not fit for purpose. If they still refuse, take it to Trading Standards.

Its £20 for a chain. Dip your hand in a pocket and put a new chain on.

 

[Tin Pot]

Wasn't there a fuss on here about changes to the law - retailers now have to take back any bike for any reason within a month or something?

 

[Yellow Saddle]

This. I suggest you go back to Ribble quoting the Sale of Goods Act. Clearly the chainring was defective and not fit for purpose. If they still refuse, take it to Trading Standards.

What makes you think it is so clear that the chainring is defective? The OP just gave more evidence that has previously botched a shift and popped a chain. For a chainring to be defective so that it bends it would have to have a very clear flaw in the material. I am 100% sure that photographic evidence will not show such a defect.

 

[Jody]

If you'd bothered reading the thread properly you'd have noticed that it wasn't just the chain that was the issue...

Iv'e read the OP. A slightly bent chainring won't cause a chain to pop and there is no way of proving it arrived bent from Ribble. Suck it up, put a chain on and get back riding.