How bad is this crack in my carbon frame?

That looks like it needs repair to me. As alluded to by others, you ought to get the seat post checked too.

Sorry that you've had to learn about using a torque wrench the hard way It's a pity that the retailer didn't warn you about this. It also applies to bolts on the stem if you even need to adjust those, as the steerer of the fork, which you can't see inside the (usually metal) stem and anything else that clamps something carbon.

Hope you can get it fixed for not too much money.

So like the others said get it checked, probably a cheap repair as its not 'structural' although granted it is keeping your saddle on.  

However, how you managed to get the seat tube to deform that much without crushing the seat post I'm not sure. The post in the photo looks to be carbon, I'd get that looked at too as there's a good chance it has crush damage. And if that fails you will notice it as you'll be sitting on the ground quite suddenly!

Robert - Understand that carbon is layered during manufacturing. What may not be noticeable are microscopic fractures in the underlying layer/s. At some point in time you may experience a complete failure. This is something you don't want happening while your toosh is planted on the saddle. As others have mentioned get it checked out not by your LBS but by a reputable carbon repair shop. Be safe rather than sorry.

Hi Robert

As others have said I would get it checked out... But don't worry, in all likelyhood it wouldn't be expensive to fix.

Over the summer I had quite a bad accident than resulted in the top tube of my bike being completely snapped through and cracked around in another place. At first I was horrified at the thought of having to buy a new frame, but after going to my local carbon repair place it turned out to only cost £150 for repairs, including painting.

The place I used (in North Yorkshire) is called Hansell Composites (http://www.fibre-lyte.co.uk/). If there isn't a repair place near you then perhaps you could post it to them. They also do re-painting, etc.

Richard

Whilst I don't own a carbon frame, from a purely materials science point of view any crack is bad news as they act as stress concentrators and propagate. Stress is proportional to the inverse of the radius of the "curve" - a crack is a very very tight curve, so stress gets very very high.

This is why the gap in the frame for the seatpost has a circular cutout bigger than the gap so that the stress in that area is kept to a minimum. A "square" notch would concentrate stress in the 90 degree corner.

I wouldn't want to ride it. I'd suggest an check and repair approach.

Any crack in carbon is a bad crack. Get it sent off to be checked and or repaired.

Doesn't look too bad to me, but it's hard to tell without seeing it in the flesh.

Could just be the paint that's cracked off. 

Can you see any evidence of a crack beneath the paint?

For future reference, use carbon paste, it helps increases friction and you can use less torque. 

And as a guide, I would tighten as hard as you can using the SHORT end of the allen key. That should be about 4 to 6Nm, which is plenty.