Bicycle rear gears - sudden failure

[GeorgeB]

i can feel a george repair job coming on glue / fibreglass or something completely different go on george suprise us

You might be right after all. If Mr Mike is correct that this part is designed to fall apart when hit (and if true, I'm shocked to hear that) then perhaps it is worth trying to glue it back together again. I think some others have also suggested that the gear assembly is under relatively low stress in normal usage, so who's to say glue won't be strong enough?

 

[breezer]

Just buy a new one.

 

[chap]

If this component nearly sent you off the bike when it originally broke, bonding it back together is likely to leave it weaker and more likely to break in the future.. when you might be on the roads!
If i were you, i would look into buying a new rear mech. A cheap one might have all steel construction but be heavier.

As for the part that's broken, if you contact the manufacturer they may be interested in the mode of failure, but i personally would'nt be kicking up a fuss.

 

[Chickenjohn]

George, why don't you put the glued together derailier on the bike with the fibreglassed handle bars and maybe add another dangerously repaired component just for good measure.

Then post at regular intervals to a thread here so we know you are still alive (for know).

 

[GeorgeB]

From Campagnolo's web site:

"Campagnolo S.r.l. products are created using the most innovative technologies and production processes, with prime-quality materials from the aerospace industry: carbon fibre, titanium and aluminium alloys. And it is precisely in the carbon-fibre sector that Campagnolo, after dominating the aluminium world for decades, has now decided to make a name for itself with applications that were previously deemed unthinkable for the cycling market. It therefore comes as no surprise that the Composites Department, launched in 1998, currently employs one third of Campagnolo’s employees. Products in carbon fibre are constantly being created as a glance at the 2008 collection reveals: cranksets, front and rear derailleurs, integrated controls, headsets, seatposts, bottle cages and high and low-profile wheels all made from carbon fibre."

It's all very well publishing impressive sounding statements like the above, but if the products just snap up after a few years, how good are they really? Someone else said they prefer Shimano. If I'm looking to buy a replacement unit, should I be looking for a short, medium or long cage?

Could it be that the composite in my rear mech is really carbon fibre? I wouldn't expect carbon fibre to snap so readily.

 

[M4RKE]

George just get the same part as a replacment then the chain will not have to be shortened .chances of this happening agiang are zero if the rear gear is set up properly

 

[Barney1973]

Your mech wouldn't be carbon fibre if you go to an online bike shop and look at the price difference you will see why!

 

[tigler]

I would say that failed mech looks more Carbon Porridge than Carbon Fibre !!

Little tip for the future, don't believe the hype !!

 

[Barney1973]

Check out this one
http://http://www.wiggle.co.uk/p/cycle/7/Lightweight_RD_-_Rear_Derailleur/5360040339/

 

[GeorgeB]

I would say that failed mech looks more Carbon Porridge than Carbon Fibre !! Little tip for the future, don't believe the hype !!

I agree, and it will be the basis of my claim against the supplier. There's no way I'm going to use Campagnolo parts again, though. I'll replace it with Shimano but I need to know if it should be short, medium or long cage. How can one tell?

 

[GeorgeB]

Check out this one
http://http://www.wiggle.co.uk/p/cycle/7/Lightweight_RD_-_Rear_Derailleur/5360040339/

They also offer Shimano models at just over £20.

Anyone who pays £900 for a gear changer needs their head examining.

 

[Shox Dr]

Anyone who pays £900 for a gear changer needs their head examining.

Muuuuust resist, must resist. hhhhh... han.... hand (must resist) HANDLEBARS

 

[tigler]

I agree, and it will be the basis of my claim against the supplier. There's no way I'm going to use Campagnolo parts again, though. I'll replace it with Shimano but I need to know if it should be short, medium or long cage. How can one tell?

This should explain :-

Cage length
The distance between the upper and lower pulleys of a rear derailleur is known as the cage length. Cage length determines the capacity of a derailleur to take up chain slack. Cage length determines the total capacity of the derailleur, that is the size difference between the largest and smallest chainrings, and the size difference between the largest and smallest sprockets on the cogset added together. A larger sum requires a longer cage length. Typical cross country mountain bikes with three front chainrings will use a long cage rear derailleur. A road bike with only two front chainrings and close ratio sprockets can operate with either a short or long cage derailleur, but will work better with a short cage.

Manufacturer stated derailleur capacities are as follows: Shimano long = 45T; medium = 33T SRAM long = 43T; medium = 37T; short = 30T

Benefits of a shorter cage length:

more positive gear-changing due to less flex in the parallelogram
better gear-changing with good cable leverage
better obstruction clearance
less danger of catching spokes.
slight weight savings.

 

[hotrodder]

From Campagnolo's web site:

"Campagnolo S.r.l. products are created using the most innovative technologies and production processes, with prime-quality materials from the aerospace industry: carbon fibre, titanium and aluminium alloys. And it is precisely in the carbon-fibre sector that Campagnolo, after dominating the aluminium world for decades, has now decided to make a name for itself with applications that were previously deemed unthinkable for the cycling market. It therefore comes as no surprise that the Composites Department, launched in 1998, currently employs one third of Campagnolo’s employees. Products in carbon fibre are constantly being created as a glance at the 2008 collection reveals: cranksets, front and rear derailleurs, integrated controls, headsets, seatposts, bottle cages and high and low-profile wheels all made from carbon fibre."

It's all very well publishing impressive sounding statements like the above, but if the products just snap up after a few years, how good are they really? Someone else said they prefer Shimano. If I'm looking to buy a replacement unit, should I be looking for a short, medium or long cage?

Could it be that the composite in my rear mech is really carbon fibre? I wouldn't expect carbon fibre to snap so readily.

From the xenon section of Campags website posted a day or two ago ...

Campagnolo made the part from 'technopolymer with glass fibre' aka some flavour of plastic with some chopped strand glass mixed in

 

[M4RKE]

I dont think the Shimano will work with your Campag changers Goerge

 

[GeorgeB]

I dont think the Shimano will work with your Campag changers Goerge

What aspect do you fear it won't work with:

- the fixing interface between the rear mech and my bike frame
- the rear cogs
- the ratchet based gear changer, mounted on the handelabers, near the brake levers, or
- something else?

I'm just so reluctant to give Campagnolo a second chance, given the low quality of their glass fibre (sold under a fancy marketing name "Technopolymer"). They should have used steel or aluminium. That's why I now want to replace the part with Shimano.

 

[M4RKE]

I belive it somthing to do with the spaceing as the only stuff I know that works 100% with both Shimano and Campag is Shram. The last thing you want is to fit a odd part for it to malfuntion agian due to incompatabillty of parts

 

[Wozzaaah]

I think you may find the indexing might not work properly George, normally manufacturers match the indexing of the shifters to the movement increments of the mech. Even a slight discrepancy between the two will result in poor shifting.
It may work to a fashion but I wouldn't be surprised if you'd be forever tweaking the cable tension as you're riding to compensate for the over or under-shifting.
Either get another campag or replace the mech and shifter with Shimano kit.

Oh, and I also think the failure was caused by something else rather than fatigue, as said, that part isn't under much stress, therefore I'd put a new good-quality chain on at the same time, just to be sure.

 

[GeorgeB]

I think you may find the indexing might not work properly George, normally manufacturers match the indexing of the shifters to the movement increments of the mech. Even a slight discrepancy between the two will result in poor shifting.
It may work to a fashion but I wouldn't be surprised if you'd be forever tweaking the cable tension as you're riding to compensate for the over or under-shifting.
Either get another campag or replace the mech and shifter with Shimano kit.

Oh, and I also think the failure was caused by something else rather than fatigue, as said, that part isn't under much stress, therefore I'd put a new good-quality chain on at the same time, just to be sure.

That's good advice, thanks to you and the others. I hate automation or over-fancy ways of doing things which can be more trouble than they're worth. The near-brake shifters are quite neat but changing the cables strikes me as a pain, too, so perhaps I'll ditch those and fit a simple manual lever like on vintage bikes.

As for stress, most people laugh here when it's suggested anything is made out of glassfibre, but that's what Campagnolo used under a fancy name. The pressure of the in-built rear mech springs is quite a lot, for a start. I say again - Campagnolo used a cheap skate material which even the Chinese would be unlikely to stoop to.

 

[mike os]

having read most of this thread... (quite honestly some parts were not worth the bother) personally I would suggest that the body failure is as likely the result of the mech ending up in the wheel as the other way round...... given that it looks like a clean break rather than a partial failure followed by repeated stressing enlarging the fault suggests very high "instant " load? rather that a "wear & tear" result of poor mech maintenance..

as suggested chain or impact would seem more likely than part failure at that point.

Given that campag are one of the worlds major component manufacturers and there is not a litany of failures if this component why would you not replace it with a similar unit..????Ah, I see why, its george........ no doubt we will see this "fixed" with blu tac or selotape in the near future.