After a ride last week my Dad noticed a dark line forming on my Cannondale Six13’s seatstay near the dropout. He had a aluminum Cannondale Synapse that snapped apart at the same location and I’ve heard that it’s common for CAAD9s to break there. I was a bit worried about it so I rolled out the CAAD 9 for some riding, including last Sunday’s Assault on Williams Hill.Dad, with his endless supply of spare parts and such hooked me up with a compact crank and a better fork for the hill climbing challenge. It’s amazing when you switch bikes how different little things like that can seem. The CAAD9 with open pro rims and a synapse carbon fork rides incredibly smoother then the Six13 I’ve been riding, bumps have just lost their bite. Of course the downside is the bike doesn’t feel quite as springy fast as Six13.
With a Thursday off I got in a morning training ride of about 20 miles and some good hard efforts, then I checked out the crack. The white paint Cannondale used for this particular frame seems to be weak, the Six13 has a downtube made of carbon and glued into lugs, around both lugs the paint is cracked, it’s been like this for years and I’m very certain it’s just the paint and not the tube’s coming apart. The carbon and aluminum have different characteristics and stressed the paint.
I removed the paint from the area around the crack with a dremel grinder. Not exactly the most elegant way but I didn’t want to spent 30 minutes sanding away paint. With the paint gone I can see no indication of a crack. I’m almost certain the crack was just in the paint. If there was a crack I would have attempted reinforcing the juncture with carbon wrap, but that doesn’t look necessary now. Looks like I’ll be back on the Six13 soon.