BrazAd

I bought a 2011 Bianchi Sempre a year ago. The metal cable stop on the chain stay fell off a couple of nights ago... the pop rivets were sheared and the epoxy joint failed. I found the cable stay in the road and my bike mechanic and me are trying to figure out the best way to reinstall it.

Ideally I want to put new rivets and new epoxy when he puts it back. The problem we're having is finding a rivet tool that is small enough to go through the hole in the bottom of the cable stay in order to put the rear rivet in. (The front rivet isn't covered by the round tube of the cable stay like the rear one is)

Thoughts? Input? Some have told me that the rivets don't matter - just epoxy it back on. Another said that epoxy alone will ultimately fail.

Thanks in advance,

Gary

AnkleWork

Careful prep by someone who knows how glued joints work, maybe with steel screws or rivets (unpeened) to locate the stop and provide some structure, along with high strength epoxy suitable for the application. And/or add a composite wrap around the stop and stay for extra structure.

One wonders what Bianchi might say if contacted.

BrazAd

I talked to Bianchi directly on Friday afternoon. I was told that my frame is out of warranty and that my "best hope" would be to ship my frame to a carbon repair shop. When I asked if they had one they recommended, the answer was "No."

It was a dead end call.

One of my friends had the same thing happen to his Trek bike. He lives in Va. Beach and there happens to be a carbon repair shop in Portsmouth, just 20 miles from his house. Unfortunately for me, there is nothing similar close by as I live near Albany, GA, a small town.

Gary

dedhed

https://www.google.com/search?client....0.lDNK8HnE020

WizardOfBoz

IT strikes me as weird that the pop rivets sheared AND the epoxy failed. I guess if the rivets failed and then the thing pulled out of the frame?

One key element regarding pop rivets is that there are the type you get at Ace Hardware which are most often tubular (hollow), and then there are structural pop rivets in which the mandrel that is left in the rivet is solid and will resist shear. In an aerospace application, you'd definitely want (you'd be required to use) structural rivets as they resist shear better. Here, you have a cable stop, a CF frame, and a rivet. It may be that the original design used tubular rivets with the intention that if a shear failure occured, you'd shear the rivet and not the CF. That didn't work out I guess.

In any case, I'd hope that folks here can recommend a qualified shop. Worth shipping the frame to someone who won't mork it up.

The point is, find out which rivet Bianchi used - you probably want to mimic their approach. Or... have the shop reinforce the chainstay and fill it with CF epoxy and then drill through and use a backing washer and use a long structural rivet through the reinforced section. My 2 cents. Good luck.

TimothyH

Kinetix in Chamblee claims to be able to repair carbon.
Kinetix Cycling

SE Composites claims the same. They are in Hoschton, GA, near Road Atlanta Intl Raceway and do service on race cars too.
Carbon Bike Frame Repair

You could ship the frame to any of these but there may be someone in Tallahassee, FL which seems closer.

Kontact 

I don't see why you need to send the frame off, unless you want someone to redesign the cable stop so it can't fail the same way in the future. Clean it, lightly sand it, degrease with acetone, coat both part's mating surfaces with 2 hour Devcon and rivet the stop in place. It will likely last another 7 years.

The rivets are aluminum, so I wouldn't be shocked if they galvanically corroded from contact with the carbon frame.

AnkleWork

OK, not sure why it is so difficult to get out of the rut. There must be many capable boat repair shops near Albany, GA, any of which could produce an effective repair. In the end, it does not matter if you have a million reasons for not fixing your bike, it only matters if you actually fix it. You want to ride, right?

Some people study the snake that crawled into the tent; some people kill it.

Kontact 

This isn't a "carbon repair". The carbon is fine.

fietsbob

run full length housing, past the broken stop

G et a few self adhesive zip tie guides,
if strips of Gorilla or gaffers tape to hold it down, is not aesthetically pleasing ..

BrazAd

Boat repair? You're kidding, right? They wouldn't have a clue on what to do with this.

You're right about the snake analogy. Some people use a shotgun right away and blow a hole through their tent. Others are more judicious and figure out a way to kill the snake and still preserve their property.

My mechanic was able to successfully reinstall the cable stop last night. It took a trip to a fastener store here in our small town to find the right rivets to use. He was able to use his experience to figure out how to install BOTH rivets (not just the one in front) and get a proper installation.

So yeah, I'll be riding tonight... :-)

Gary

BrazAd

Perzackly.

Gary

AnkleWork

No doubt, you know best.

BrazAd

Be sarcastic if you want. This was never a carbon repair issue. Nothing is wrong with the frame in the least.

My mechanic was able to get it fixed the right way. The original epoxy was applied over the FINISH, not directly to the carbon frame. He got it riveted back and he lightly sanded through the finish so the new epoxy is bonded directly to the frame.

It could last a long time... or it could break again in 7 years, like the original did. For the $50 repair, I'll take my chances.

Thanks for all sincere replies!

Gary

Kontact 

Tiny rivets are used a lot in boat repair?

TimothyH

Why did the OP mention carbon in the title of the thread if this isn't about carbon?

Kontact 

Because it is true and it affects what kind of repair can be made. Otherwise, some people would advise a welder. But the repair itself doesn't require working with carbon fiber, but understanding how cable stops are attached to carbon tubing.