How to repair a carbon fibre frame

[phillb]

I broke my frame. It's a red '05 Specialized Tarmac.

I was run over in Flinders St. on Friday afternoon riding home (so actually, I didn't break it, the driver of a white falcon wagon broke it).

I repaired the frame. I'm posting a "how to" here because I "CBF" writing up a web page or doing the blog thing. So I'm simply going to reply to my own post, complete with photos of the various steps needed to repair that much loved frame.

The attached photos (need to register - easy as - to see) show the frame (stripped down) with the outer clear coat and red paint removed from the cracked areas. The black bits are the original carbon.

Phillb.

[phillb]

My lovely red frame sat broken in the corner for months. 0ne day in Shepparton, my brother says, "why don't you buy one of those carbon repair kits off the Internet".

Oh yeah right!, why not? Well I did.

The kit arrived. It just sat there for almost a year (which is close to the use by date - goes off quickly). I just thought, "this'll never work, I don't why I bought this thing".

Then... I just had time to kill. I'll give it a go.

The attached photos show the NASTY chemicals. These things really really stick. And they are carcinogenic. Let me say that last bit again. The NASTY chemicals can give you *CANCER* (this is a real WARNING). Essentially, from my extremely limited knowledge of chemistry, this epoxy goo goes off at a relatively low temperature. That means you don't have to own a baking oven like the big frame factories. The downside is the chemicals are NASTY.

The carbon microfibre powder thingies are really bad for you if you breath them in. I don't think they are as bad as asbestos, but you'd better check before you take off the supplied breathing mask.

Phillb

[phillb]

Once you have your frame's naked carbon exposed, you mix up some nasty chemical's adding various fillers to the epoxy goo.

The instructions recommend that you mix it 'til it's like peanut butter.

The first step is to seal the tubes so that subsequent layers don't just squish into the tube. For me that meant that the entire frame went from a floppy sorry mess to a rigid structure so strong I thought "why even bother with all that carbon weave stuff".

The only thing I missed at this point, as I later found out - after finishing almost everything, was that you *must* insert the wheel back in. This ensures that the frame goes back to the original design position before the nasty goo sticks hard. The width across my rear dropouts is about 25mm too wide, because I didn't think of it at the time. I can just get the wheel in by stressing the frame. I don't like doing it, but there's no option.

Once the tubes are sealed you can get to laying up the carbon weave. The layers are saturated with even more goo and various fillers.

As each step progresses, a heat shrink tape is wrapped around the job (see pic). You get the heat gun out and then shrink the tape. This applies the force that you'd get from a mold in a factory. Really simple and really effective. See the pictures of step 2 of my repair.

[phillb]

Once all the steps are complete and you have carbon weave running in all directions and sacrificial layers ready for sanding, you're ready to sand and paint.

Amazingly, I have discovered that Specialized paint technicians have been down to the Bunnings Hardware store to get some cheap cans of paint. It turns out they selected Flame Red epoxy spray paint cans for the '05 and '06 range. So I had no trouble matching the colour for only $12 a can. I have heaps left if anyone needs it.

This pic show the completed repair.

The bike is now a single speed commuter complete with mud guards. The original Dura Ace 7800 stuff migrated over to a replacement frame (Giant TCR Advanced ISP - but it's black )

I get heaps of comments about how my SS is way over the top. I'm forever explaining that it's actually worthless and broken in two places.  Anyway, it's really good fun to ride to work every day!

I even had fun repairing it too. I occassionally ride it on the North rd. ride.

Phillb

[phillb]

Took the old girl out to Sandown race track last night for the CCCC crits.

My old work bike has red Fulcrum Racing 7 wheels now (and no mud guards) so it's become even redder.

It's amazing how well you can keep up in C grade with single speed (53/16) gearing. Even managed a couple of attacks on the bunch (no one came with me though  there must be a credibility issue). The going got tough on the down wind sections of the course with the cadence creeping past 115 once the speed got up. I had absolutely no hope in the sprint (I'd have to master a cadence of 130+), so a breakaway was the only chance.

Great fun.