Carbon Frame Materials....the cons

Carbon Frame Materials for a new bike - the cons

I am hoping to meet some personal goals to "enable" myself to justify (hah!) a new bike in the late spring or early summer.  I am hoping to find the carbon bike and associated parts to complement my existing steel bike which is perfectly fine and will probably outlive me!   This is definitely not a "need" but a "want" - but it does meet the criteria for the answer to the question: "How many bikes do you need?"  The answer is of course "N+1" where N is the number of bikes you currently have - as opposed to the number of bikes your sig other thinks you have.   I am very experienced here in this area as the same dictum holds for fly fishing rods and reels - while I don't have many bikes yet, I do have a pretty good arsenal of high end fly fishing rods!  And they are all carbon!!

While carbon is the new "must have" material, I actually think things like gearing, shifters, brakes, wheels, tires, etc are actually equally if not more important.  But for now, let's focus on the frame material.  I bring up this discussion because my Cycle U coach, Colin, was able to show us the down side of carbon based on a recent experience with his racing team bike.   Another rider rode into a pavement groove, was unable to extricate herself, and went down and put her handle bars into his rear wheel spokes as they were riding along.  I don't know how fast they were going but I am presuming Colin never goes slow.  In any event, the rotation velocity of the spokes and front handle bar engagement actually fractured his seat stay in two places.  In the upper location, there was some sort of impact and delamination.  In the lower location, there was transfiber fracture and the seat stay actually separated into two pieces!  The latter is somewhat uncommon as it is a very high energy event.    While I could see conceptually how to repair it using some of the things we have done in the past, I am pretty sure the bike frame is economically scrap at this point. 

The bike rear wheel and seat stays

Here is a close-up of the lower transfiber fracture of the seat stay:

Now I don't know how steel would react to this since the experiment would need to be repeated to find out - which seems unlikely.  However, steel repair options are much easier to visualize.  Further, I am pretty sure aluminum repair would not be very easy compared to steel> As for bamboo.....well, there is always the next year's harvest I am guessing - although I think you would actually just rebuild the bike in that region using wet-layup fiberglass and bamboo.    So in looking ahead, while I still lust after carbon as it is the "forbidden fruit" (i.e., I don't have it  yet) for a bike frame, the  reality is to be sure you have adequate insurance to cover a frame loss of a carbon bike as this example would illustrate.  Lots of folks have carbon bikes now and there is apparently a burgeoning secondary market for composite repairs which would typically address a combination of impact zones and delaminations.  A full separation as seen here would challenge those methods in my mind (I can see a potential metallic doubler, bonded and maybe fastened to do the load transfer around the separated fracture surface) and probably lead to scrapping the bike.  At least, I think that is what I would want to do rather than ride the bike post-repair and wonder if the repair was going to hold!  So maybe I need to also be test riding some light steel bikes to complement the Carbon bike lust!??