Hi All,

Whilst installing a new BB on the GF’s road bike. I noticed a crack like mark on the BB shell and running around the edge.

I reckon it’s a crack and I was if any you could cast an eye over the pictures to confirm or reinforce.

She has just told me it’s creaking alot in the area of the BB for a while.

Also, if it is cracked… would you ride it ?. I’d err towards to no.

Found out Giant has a lifetime frame warranty and the receipt has been found 🙂

Many thanks,

RT

Album of possible crack photos.
https://www.flickr.com/photos/58162507@N07/albums/72157664118203288

[url=https://flic.kr/p/21UCYn5]P1510003[/url] by SGMTB, on Flickr

That looks like damage caused by a dropped chain, not a crack

Looks like the chain has sawn through the shell!

They might warranty it but they might argue some form of misuse.

@JoeG

We just chatted about chain drop and could be likely candidate. After looking at the pic above again I have noticed similar parallel marks.

A crack would of followed the weld, more than likely.

I’d agree with Joe – looks like dropped chain damage, but would be impossible to tell for certain if it’s gone through without the x-ray machines etc they use to determine cracks.

Also, due to the nature of it, Giant might just come back to you and say the warranties void – damage caused by the chain dropping rather than a welding defect 🙁

Have you tried shining a torch through it to see if it goes through?

The marking (if not the actual ‘crack’) crosses a weld and goes into the BB shell whilst staying perfectly parallel to the edge of the shell as it wraps around.

-Looks like damage from a dropped chain (lots of dropped chain action from the look of the close-ups)?

Agree, it looks like the chain has caused that. Never seen a frame crack there either. If it was a crack, I’d expect it to be at the weld.

Running with Joe’s diagnose. Thanks.

I might rub it back a bit with some sandpaper and repaint paint with some AirFix white enamel.

Many thanks, guys.

chain thing: possible. Chain drop was an issue as well.
and yes – would be a strange crack.

But interested in the outcome…

If the crack was growing from the inside out – the crack might run “in line” with machining features. Cracks like to start at edges / corners / threads.

And directly “under” this mark there are a lot of features which cracks like to start…
Additional it needs a “changing load peak”. It’s there as well…

Never seen a frame crack there either

me too. But this is interesting.

creaking alot in the area of the BB for a while

mmmmhhh

not typical for a crack moving from the inside out: such a crack would be hardly visible.

Here it appears like the crack is wider to the top. Would reinforce the chain theory.

I would say 50/50
😥

me too. But this is interesting.

creaking alot in the area of the BB for a while

Surely this is why the OP was installing a new BB. Shagged BBs creak

If there was a crack, I’d expect to be at the root of the tube weld. Also, the fact that the mark appears to ‘stop’ most cracks propogate along a line of weakness.

Is it a BB30? They creak for fun. Look for signs of fretting where the axle sits inside the inner bearing races. Smear bearing fit compound on the axle at the drive end and inside the bearing inner race at the LH end then refit the chainset and enjoy the silence.

I’ll rub it back gently. Have a good inspection, if OK I’ll paint over.

Once again many thanks, guys