Frame cracks, carbon fiber

[Tvcmd]

I have developed cracks in the horizontal tube of my carbon fiber e road bike. The bike store says I had a crash. That is untrue. Anyone else seen spontaneous cracking in the horizontal tube?

 

[HumanPerson]

Stress fractures?

 

[HumanPerson]

my friend has one of those carbon fibre analog bikes and his cracked by the head tube ....
Stress fractures/cracks from the vibration from the road he told me (shrugs)

 

["A"]

Post a few pictures.
Specify which frame you have, how old is the frame, how much have you ridden it, has the frame been exposed to extreme temperature?

 

[Tomm Williams]

I can’t help but believe that any type of material is subject to failure. For them to categorically state you crashed seems careless.

 

[fabbrisd]

Personally I have not been a fan of China Carbon Fiber either eBike or Bike frames. There is too much "hand work" as compared to Steel-Aluminum-Titanium.

Yes - what you describe can be reasonably caused by Impact Damage (where the fiber's shear) or by a "Hidden" Manufacturing Defect - by Hidden meaning not visible during production visual QC.

 

[m@Robertson]

Unfortunately, carbon fiber frame failures happen often enough on DIY mid drive builds that its common practice to warn people away from them when someone asks whether to go that route. Even if it involves a bespoke-to-the-motor frame and not something hanging off the bottom bracket like a BBSHD.

C/F also often fails spectacularly. An old adage when it comes to frame construction: "Steel bends. Aluminum snaps. Carbon fiber shatters." That may be a bit dramatic insofar as c/f is concerned, but not by much. Myself personally I've had a c/f seatpost split on me, which a) made me think in horror about the kind of bodily injury I could suffer if I came down on splinters and b) caused me to examine my priorities and remove c/f handlebars and stems on various bikes and switch back to alloy.

My favorite meme on the subject of bicycle frame material:

 

[Penfield E. Farthing]

Carbon Fibre...Why?

 

[fabbrisd]

Carbon Fiber had limited high end application in Road Bikes for Rigidity - Design Capability for AeroDynamic “Edge” Profile - and properly done can be Lighter than Titanium. Like anything knock off material is “Carbon Fiber Like” and just is a gimmick

 

["A"]

 

[HumanPerson]

I wonder if the harmonic vibration of a running electric motor would cause fractures/cracks

 

[fabbrisd]

The fact is this - "Carbon Fiber eBikes" - here in the U.S. Enthusiasts Carbon Fiber eBikes under $1500/as low as $899 have ZERO Genuine Carbon Fiber (think if it as a Plastic Frame with decorative fabric embedded in it) the Urtopia Carbon 1 does have non-functional "Carbon Fiber" matt material in it (where the embedded fabric is "a Carbon Fiber kleenex matrerial) - you have to be way beyound USD$6000 and up to have a Genuine Structural Carbon Fiber eBike Frame. ie: Trek Fuel Carbon - Cannondale etc. where the frame is contructed of structural cabon fiber matting - hand contructed One-Frame-At-A-Time

 

[Penfield E. Farthing]

The fact is this - "Carbon Fiber eBikes" - here in the U.S. Enthusiasts Carbon Fiber eBikes under $1500/as low as $899 have ZERO Genuine Carbon Fiber (think if it as a Plastic Frame with decorative fabric embedded in it) the Urtopia Carbon 1 does have non-functional "Carbon Fiber" matt material in it (where the embedded fabric is "a Carbon Fiber kleenex matrerial) - you have to be way beyound USD$6000 and up to have a Genuine Structural Carbon Fiber eBike Frame. ie: Trek Fuel Carbon - Cannondale etc. where the frame is contructed of structural cabon fiber matting - hand contructed One-Frame-At-A-Time

And you're dropping 6 large on an acoustic bike. Some folks just have more dollars than sense!