Carbon Fiber Seatpost Failure

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Non-branded carbon fiber seatpost. 27.2mm post diameter, approximately 205g weight. Failed at or near transition from tube to seat clamp. The failure goes around the full circumference of the post.

Rider noticed light-color crack during routine inspection.

It appears to be at or near junction between carbon tube and aluminum head. It may be a glue separation. The light color may be aluminum exposed under cracking paint.

Note the seatpost narrows at the clamp, thus raising stresses. Also, seat clamp bolt tension tends to bend the post head, which may also stress the post near the fracture.

Rider weight is about 62 kg. Post was bought new and used about 10,000 km of road riding.

The post is non-branded; the head shape may be a clue, it is also painted with height marks and "27.2". The post "should" be of good quality, as it came on a bicycle with new price about US$4,000.

See also FAIL-126.html