Broken sprocket

For discussions about bikes and equipment.
Steve
Posts: 203
Joined: 2 Apr 2007, 1:42pm

Broken sprocket

Postby Steve » 18 Jul 2012, 3:55pm

Can anyone suggest how I've managed to break this sprocket (10 speed, Veloce)? It's only about 4yrs/4500 miles old so am perplexed.
Image Attachments
IMGP2478.JPG

Brucey
Posts: 35952
Joined: 4 Jan 2012, 6:25pm

Re: Broken sprocket

Postby Brucey » 18 Jul 2012, 4:31pm

well my guess is that the break on the left goes through the (in a cod French accent) 'wafer-thin' region, and the break on the right was bound to happen once the other one was on its way. Maybe there was a small defect from the start.

If this hypothesis is correct you may find that the left break is slightly corroded (being older) and the right break isn't, but this could be masked by patchy chain lube so isn't to be relied upon 100%.

When regarding this design for the first time I was driven to remark that 'you wouldn't want to take any more material away' but having said this I don't recall seeing many other breakages.

cheers
-------------------------------------------------------------------------------
~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~

User avatar
cycleruk
Posts: 5209
Joined: 17 Jan 2009, 9:30pm
Location: Lancashire

Re: Broken sprocket

Postby cycleruk » 18 Jul 2012, 5:04pm

Other possibility, but unlikely, is a bad gear change or jammed chain trying to cross from one cog to the next.

The break, on the right is different to the one on the left. The left appears to be a clear crack whereas the right is a "twisting" break.
There's no such thing as a tailwind.
It's either a headwind, or you're going well.

thecycleclinic
Posts: 171
Joined: 20 Apr 2012, 8:58pm

Re: Broken sprocket

Postby thecycleclinic » 18 Jul 2012, 5:51pm

I have a part worn 19T Veloce 10 speed sproket if that helps.

User avatar
Mick F
Spambuster
Posts: 46802
Joined: 7 Jan 2007, 11:24am
Location: Tamar Valley, Cornwall

Re: Broken sprocket

Postby Mick F » 18 Jul 2012, 9:18pm

Steve wrote:........ so am perplexed.
Me too.

I had a Campag brake calliper break where the brake block fits, and I was perplexed too. Your sprocket damage is a strange defect. Do you have any thoughts on what happened, or how you found the breaks?

I have no idea about mine, I only found it whilst cleaning the bike. Was your sprocket still working?
Mick F. Cornwall

User avatar
meic
Posts: 19355
Joined: 1 Feb 2007, 9:37pm
Location: Caerfyrddin (Carmarthen)

Re: Broken sprocket

Postby meic » 18 Jul 2012, 9:22pm

Could it just be that Campagnolo make junk? :wink:
Yma o Hyd

rjb
Posts: 3466
Joined: 11 Jan 2007, 10:25am
Location: Somerset (originally 60/70's Plymouth)

Re: Broken sprocket

Postby rjb » 18 Jul 2012, 10:22pm

meic wrote:Could it just be that Campagnolo make junk? :wink:


You must be thinking of this quote from the 1970's

"Frank Berto caustically comments that the Campagnolo Nuovo Record rear derailleur shifted poorly, but was so well constructed that it would keep on shifting exactly as poorly - forever" (taken from here - http://www.disraeligears.co.uk/Site/Cam ... le%29.html)

:roll: :roll: :roll:
At the last count:- Focus Variado, Peugeot 531 pro, Dawes Discovery Tandem, Dawes Kingpin, Raleigh 20, Falcon K2 MTB dropped bar tourer, Longstaff trike conversion on a Falcon corsa. :D

User avatar
Mick F
Spambuster
Posts: 46802
Joined: 7 Jan 2007, 11:24am
Location: Tamar Valley, Cornwall

Re: Broken sprocket

Postby Mick F » 19 Jul 2012, 7:28am

I wonder if it's repairable - weldable?

Worth a go, but I note that "thecycleclinic" has a spare for you.
Mick F. Cornwall

Steve
Posts: 203
Joined: 2 Apr 2007, 1:42pm

Re: Broken sprocket

Postby Steve » 19 Jul 2012, 8:32am

No idea how it happened, though like many failures it started with a clicking which I didn't get round to investigating... until too late! So must have gone in the thinner part first then finally given up with the second tear when I was climbing.

The Mechanic
Posts: 1922
Joined: 23 Jul 2010, 1:38pm
Location: Scotland

Re: Broken sprocket

Postby The Mechanic » 19 Jul 2012, 11:24am

meic wrote:Could it just be that Campagnolo make junk? :wink:


+1 ^^^
Cancer changes your outlook on life. Change yours before it changes you.