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The Street => The Bike Shop => Topic started by: dude... on March 21, 2015, 12:10:07 AM

Title: zinc coated stem bolts yay or nay
Post by: dude... on March 21, 2015, 12:10:07 AM
probably the nerdiest query since q factor was an issue, but are there any positives or negatives to having zinc coated stem bolts? (aside from them not rusting)

the head of one from my stem was seized in recently and i had to cut the bolt in half to get the stem off, the rest of the bolt unthreads fine so im guessing the sticking point was the head, and i was wondering if it was worth tracking down some non zinc coated m8s (ive already got some more zincy ones but i dont want them to get stuck again)
Title: Re: zinc coated stem bolts yay or nay
Post by: Prodigal Son on March 21, 2015, 12:20:02 AM
Oh man, do you remember building galvanic cells in chemistry? The reduction potential of Zn vs Fe vs Al and their respective oxidation states.
Title: Re: zinc coated stem bolts yay or nay
Post by: metalbmxer on March 21, 2015, 08:23:39 AM
I got the bluesix Ti bolts to prevent rusting and premature snappage
Title: Re: zinc coated stem bolts yay or nay
Post by: blueee on March 21, 2015, 08:59:14 AM
i got the b6 ti bolts to shave fractions of an ounce

just grease your parts, dude...
Title: Re: zinc coated stem bolts yay or nay
Post by: JFax on March 21, 2015, 09:58:36 AM
Use copper paste on everything. works wonders for my bike
Title: Re: zinc coated stem bolts yay or nay
Post by: couch on March 21, 2015, 02:56:57 PM
If you're concerned with corrosion, you can always switch entirely to stainless hardware, but the typical black oxide fasteners are fine as long as you use some antisieze/grease on the threads.
Title: Re: zinc coated stem bolts yay or nay
Post by: dude... on March 21, 2015, 09:46:20 PM
im not really that bothered about, i was just wondering if zinc was more prone to cold forging to the aluminium in the stem (or something like that), than the regular black oxide coating. the stem came with zinc coated bolts is all

i grease the shit out of all the bolts on my bike but this thing was not budging at all, i guess i must have overtightened cos it launched out of there when i sawed through the bolt (the head is still in my lounge somewhere, i dont know where it ended up it shot off that fast).
Title: Re: zinc coated stem bolts yay or nay
Post by: Prodigal Son on March 21, 2015, 11:12:12 PM
One of these

(http://wps.prenhall.com/wps/media/objects/3311/3390507/imag0404/TB04_005.JPG)

Stick a piece of sacrificial metal on it? I wonder if you had a Magnesium stem plate if it would prevent it?
Title: Re: zinc coated stem bolts yay or nay
Post by: tecnic1 on March 22, 2015, 06:07:35 AM
If you're concerned with corrosion, you can always switch entirely to stainless hardware, but the typical black oxide fasteners are fine as long as you use some antisieze/grease on the threads.
this is where its at.

I've tried to switch to all stainless steel fasteners anywhere I'm contacting aluminum on my bike.  They just look good and don't gall as readily.

The Navy uses stainless in aluminum anywhere things are exposed to seawater. I don't usually resort to "it works for XX, so it must be good" arguments, but seawater and aluminum is a motherfucker, and of the numerous problems crossing my desk, stainless fasteners are not that common, so I'm buying it.