Discussion in 'Bicycle Mechanics and Repairs' started by User, 11 Sep 2007.
You can get anodised alloy cap head screws in a variety of colours. S/S should be ok, depends what sort of torque settings you need.
I wouldn't of thought so, they would be made, I think, of a tough alloy (6082 ?) and "aged" (hardened), for a pannier no problem as they were initially manufactured for the custom car scene in the engine bay of the car.
Nip into Halfords and have a look, sure I've seen them in there, better still a custom car shop.
The S/S you wouldn't shear.
Unfortunately stainless steel won't be the end of your rusting trouble. In winter, the salt will still get it to 'bleed'.
Your local shop will probably have let you have some made of A2 (or 304) stainless, but if you live near a boat place, they will have a better grade which is A4 (or 316), and will probably still be cheaper than Wiggle!
If you really want to be as rust free as possible it helps if you dip them in lots of grease (cheap tub from Halfords) and use the allen key to force a bit into the hex recess. Then wipe all the excess off on a rag. Do the same for the threads on the frame.
Ironically people who like to keep their bikes looking good (and most bike shops when they build them up from new), keep them far too clean. Those degreaser sprays are the worse culprits. Basically the bits that need to shine should be polished and everywhere else should be greasy. All bare bits of steel will rust - stainless just does it slower when exposed to air. (Its propensity for anaerobic corrosion is another, quite frightening story).
As Tim said: hence my propensity for cleaning bikes with WD40 and an oily rag. An oily rag is your best friend.
Interesting pointers there folks, thanks.
Stainless steel is 'softer' than a bog standard carbon steel but you would have to be abusing the bolt to get it to shear. How about sticking on new bolts and and greasing them up to keep the water out?
Best to keep the bolt as similar as poss to the frame material.....limits the potential for galvanic corrosion. It's also best to select a bolt that will corrode in preference to your frame....coz it's a bit cheaper to replace a bolt than it is a frame, innit!
Re galvanic corrosion, you need an electrolyte (i.e. water) to get galvanic corrosion, so the best way to avod this is to make sure your bike is dried after getting it wet, or washing it. (Allen key heads tend to collect water though) - ensuring there is a film of oil on the surface as suggested above is very effective.
Softer? Have you ever tried cutting a Stainless bolt with a hacksaw? They're harder than 'standard steel', but not as strong. Stainless is also quite brittle so they'll tend to snap rather than bend if subjected to a large force. Having said that I've used stainless bolts in my stem, headset and brake calipers for years no problems and no rust.
Where do you get chrome bolts?
You need to define what you mean by "stainless" and "carbon steel". The former - 303/304 or 316? The latter, as drawn? How much carbon? Heat treated? And to what hardness?
A2 Stainless bolts (the most commonly found) are indeed "softer" than carbon steel equivalents. For example, the hexagon in stainless socket cap screws will wear out much quicker than their hi-tensile carbon steel equivalent (which are hardened), and for that reason don't find much favour in industry.
Having said that, I use them on my bikes wherever possible - bars/stem/mudguards/brake calipers and so on. I wouldn't use them for crank bolts, not sure they'd be strong enough.
As mentioned, stainless and aluminium is not too clever from a corrosion point of view, but I always use coppaslip or grease, and I've never had any problems.
May I recommend the use of sacrificial anodes?
Very useful - if you plan on immersing your bike in the sea!
As I said before, you need an electrolyte to get galvanic corrosion.
For what it is worth I have an MSc in Corrosion Science and Engineering (yes, such a subject really exists!) and I would happily use stainless or chrome plated screws on my steel bike.
Turbo Tim.....looks like you know a bit about materials too. I was going to respond to previous posts but could not be ar$ed arguing coz I do materials and corrosion for a living. Seems too much like work instead of fun ;-)
Chris James....do you use the MSc for work? I got my CEng on the back of materials and corrosion. The oil and gas industry are screaming for decent engineers!
No, I don't use either my Corrosion Science MSc or my BEng in Mech Eng. I am now doing process improvement stuff for a fastener distributor in the aerospace industry.
Having said that, I am starting to miss the problem solving aspect of engineering.
What do you do for a living then?
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