Focus Paralane: Broken Seat Post Clamp Bolt

After the Focus Paralane was completed, I was still having some problems with the bike. One of the  area that still needs work was the seat post, where the setback seat post is not suitable for me.

While doing adjustments to the seat post height, I have to adjust the seat post clamp frequently. Unfortunately, during one of the adjustments, the seat post clamp broke. Luckily for me, it did not break during riding.

Stock seat post clamp on the Focus Paralane frame.

The maximum torque allowable on the clamp bolt is 6 N.m.

While tightening the clamp bolt, I heard a crack, and suddenly the clamp bolt was loose. I was quite surprised as the torque was nowhere near 6 N.m, probably 4-5 N.m.

Clamp bolt is broken! The clamp itself is OK, but the broken part is stuck inside.

I was surprised that the clamp bolt broke so easily, but also relieved that the carbon frame itself is OK. Now, to extract the broken clamp bolt from the clamp.

It was not too difficult to extract the broken part, as it was not seized in place. I was able to use a plier to loosen and turn it out carefully.

Clean break on the clamp bolt, from the minor diameter of the thread.

This is an aluminium clamp bolt, and the tensile stress from tightening the clamp was too high, causing the clamp bolt to break. Note that I did not exceed the 6 N.m torque stated on the clamp.

Obviously this is a manufacturer defect, where either the bolt was defective, or the design of the clamp bolt is an issue. 

Seat tube area, with the seat post clamp removed.

As the seat post clamp itself was OK, it is relatively simple to find a replacement clamp bolt to use temporarily. The thread on the clamp is not damaged, which is good.

Since the aluminium clamp bolt was too weak, I decided to use a stainless steel clamp bolt to replace it. It is a standard bolt, so it is easy to find.

Stainless steel bolt to replace the original broken aluminium clamp bolt.

Fits pretty well, as the clamp band design is quite standard.

Works well once the clamp bolt is replaced. Does not look so nice though.

I did inform the bike dealer about this issue, but did not seek a replacement. In my opinion, a replacement clamp band or clamp bolt of the same design will have the same issue, so no point getting a replacement.

In the long term, I will probably get a new third party clamp band to replace this stock clamp band. In the meantime, this stainless steel clamp bolt will do the job.