Forum: bicycles.stackexchange.com
Tags: <full-suspension>
Title: Inside of my full suspension bike pivots is cracked!
Question: Is this normal? I just noticed it when I was cleaning my bike after a long day downhill mtb. Are those screws? Thanks for any replies.

Answers:
sents: text: Are you sure those hex bolts are cracked?
text: They could instead just have peeling chrome.
text: Hex bolts tend to accumulate water and grime and thus corrosion.
text: It could just be surface peeling of the chrome.
text: I'd poke at them with a sharp ice pick and see if it's just surface peeling of chrome or if the bolts are actually cracked.
text: If it's the former you can ignore.
text: If it's the latter, follow @criggie's suggestion.
answer_details: author: bicycles.stackexchange.com/users/11160/RoboKaren
score: 26
sents: text: The good news is those bolts aren't load bearing parts directly.
text: The bad news is those are holding the load-bearing parts in place, so a failure of the bolt will allow the pivots to fail very quickly.
text: I'd strongly recommend taking them out and getting replacements from the maker of your frame.
text: Have a look at the answers to this question about shearing rotor bolts notice how little beef there is between the head and the shaft?
text: Damage
text: to bolt heads needs to be fixed.
answer_details: author: bicycles.stackexchange.com/users/19705/Criggie
score: 13
sents: text: Take them out and check if they are hollow, it might be that those are only the burrs from machining the hex.
answer_details: author: bicycles.stackexchange.com/users/32464/imp
score: 5
sents: text: That's left over material from the broaching of the hex head in the bolt.
text: broaching is a machining process in which material is removed.
text: In this case the inside of the hex is formed with a broaching tool
answer_details: author: bicycles.stackexchange.com/users/32472/emoney
score: 3
sents: text: Those are artifacts or chips resulting from broaching the hex into the bolt head.
text: Should be nothing to worry about but ask a mechanic if you want to be sure.
answer_details: author: bicycles.stackexchange.com/users/29921/YoJoe
score: 3
sents: text: Broaching in this reference: Hammering a hex shaped tool into the round hole in the bolt (maybe done when the bolt is red hot) to produce the hex profile for the allen wrench.
text: Pushes the material from the sides of the hole down and leaves the strange looking ragged chips you see when the tool is pulled out.
text: The aluminum surrounding such a hi-tensile bolt would probably fail long before the bolt fails.
answer_details: author: bicycles.stackexchange.com/users/32488/JSacks
score: 2

Summary of the answers:
Poking the bolts with a sharp ice pick and will show if it's just surface peeling of chrome or if the bolts are actually cracked. Taking them out and checking if they are hollow is another way, it might be that what can be seen is only the burrs from machining the hex. This issue should be nothing to worry about but it is always worth checking with a mechanic to be sure. The good news is those bolts aren't load bearing parts directly.  It would be better to take them out and get replacements from the frame manufacturer.
This could be peeling of the surface coating, but is probably just chips left over from machining the hex. These bolts are not load bearing and are stronger than the surrounding metal, so they are unlikely to fail but can be replaced by the maker of the frame.