Any reason not to use stainless steel fasteners?

deadwax
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Any reason not to use stainless steel fasteners?

Postby deadwax » Wed Jan 31, 2018 4:17 pm

In putting some old brakes on a bike I'm building up I discovered I was missing one of the fasteners to hold them to their mounts. In poking around in the parts bin I've found a couple of stainless (316 I think) fasteners that will fit fine and look the part. Is there any reason this is not a common thing? I know they'll corrode eventually, being in contact with ferrous metal in the bosses, but my thinking is that they may last longer than the bright zinc plated fasteners normally used.

westab
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Re: Any reason not to use stainless steel fasteners?

Postby westab » Wed Jan 31, 2018 6:05 pm

Personally I would use them without a worry. The only issue that I would be concerned about would be "Galling". This is where the threads of the bolt and nut "cold weld" together - stainless is often the worst material for doing this.

To assist in preventing this the steps are:
1. Clean both the bolt & frame
2. Apply an anti seize lubricant
3. Bolts and nuts are there to hold things together not bring them together so put the brakes where they need to got and move the bolt in.
4. don't tighten fast as it increases heat increasing the risk of galling.

One of the reasons for not using stainless screwing it into your frame is it limits the options of getting it out without damaging the frame. the other reason is that generally Stainless manufactured parts are 3 times the price.

Hope that helps.
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deadwax
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Re: Any reason not to use stainless steel fasteners?

Postby deadwax » Wed Jan 31, 2018 6:34 pm

That makes sense, ta. I would like them to be able to come out again. Stainless is expensive and I don't know if I'd buy them if I didn't already have them but the cost is often not that bad.

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RonK
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Re: Any reason not to use stainless steel fasteners?

Postby RonK » Wed Jan 31, 2018 6:51 pm

Stainless cap steel screws are low tensile so don't overtighten them.
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Duck!
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Re: Any reason not to use stainless steel fasteners?

Postby Duck! » Wed Jan 31, 2018 7:26 pm

Stainless steel work hardens and becomes brittle, potentially leading to breakage when subjected to cyclic stress. However the only place you really need to be wary of this on a bike is the saddle clamp, although discretion should be used if you suspect there may be such stress imposed elsewhere.
I had a thought, but it got run over as it crossed my mind.

deadwax
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Re: Any reason not to use stainless steel fasteners?

Postby deadwax » Wed Jan 31, 2018 8:17 pm

I've just looked it up and found unmarked stainless fasteners are probably a little better than grade 4.6 (i.e. low tensile) steel fasteners, which is about what I would have guessed. Are the cap screws used generally on bikes normally of a better grade?

Mike Ayling
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Re: Any reason not to use stainless steel fasteners?

Postby Mike Ayling » Wed Jan 31, 2018 9:47 pm

Duck! wrote:Stainless steel work hardens and becomes brittle, potentially leading to breakage when subjected to cyclic stress. However the only place you really need to be wary of this on a bike is the saddle clamp, although discretion should be used if you suspect there may be such stress imposed elsewhere.


I experienced a saddle clamp bolt break just before Christmas. Could have been a nasty experience but fortunately I managed to stand on the pedals and kept away from the seatpost sans saddle.

I had been riding over a lot of corrugations in the previous few week.

The bike is a Thorn Mercury flat bar.

Mike

westab
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Re: Any reason not to use stainless steel fasteners?

Postby westab » Thu Feb 01, 2018 3:00 pm

Duck! wrote:Stainless steel work hardens and becomes brittle, potentially leading to breakage when subjected to cyclic stress. However the only place you really need to be wary of this on a bike is the saddle clamp, although discretion should be used if you suspect there may be such stress imposed elsewhere.


Discretion is not using them on Pannier racks for the commuters in our midst - ask me how I know :wink:

I had no issue getting the fatigued thread left out - prudence is to leave 3-4 thread lengths out the back of the lug on the frame near the rear wheel drop out :mrgreen:
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deadwax
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Re: Any reason not to use stainless steel fasteners?

Postby deadwax » Thu Feb 01, 2018 5:08 pm

Hah, that was my thinking for the next place they may get used, ta.

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