Bicycle Mechanics - Professionally and permanently corrosion proofing a steel bike (any engineers?)
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Hello, I have been here a while but just registered. I am an engineer who works in a plating shop and loves to ride in the winter. The last few years I kept my bike on the back of the car for the whole winter and the salt spray was not kind to it at all. The bike is a 1995 Specialized stumpjumper that has been converted to a hybrid.
My plan for finishing the bike is as followed:
1)20 micron electrogalvanized (zinc plate)
2)iron phosphating to prep for painting and coat the inside of the tubes
3)2 coats Polyester powder coat
4)1 coat clear Polyester powder coat
5)Oil the inside of the tubes with rust prevention oil
Now this will take care of the frame, but there are several other weak areas:
1)Replace all hardware with type 316 stainless steel, we use that in the shop for heavy duty chloride resistance, a test coupon on the back of my car showed no rust
2)Fill all brazing holes in frame with Lab-metal before powder coating
3)Black or yellow zinc plate the chain (worked well last year), all zinc gone but no red rust
Any experiences with stainless brake cables? I dont know what alloy they are
What about corrosion resistant rims? After two years they always develop stress cracks from chloride pitting near the spokes and I need new rims.
Please don't say keep my bike inside, this is also partially a game, to see if I can beat the elements.
07-01-11, 10:49 AM
You can still purchase stainless rims, and they make stainless bicycle chains. Google is your friend. Leaving your bicycle on the back of a car all winter is stupid.
07-01-11, 11:04 AM
If your going to leave your steel bicycle on the back of the car all winter the best way to corrosion proof it is to remove all hardware from the frame and replace the steel frame with a titanium frame and reassemble using only rust resistant fittings.
07-01-11, 11:14 AM
Treat the frame, fork blades and all stays internally with Weigels Frame Saver or Amsoil HDMP. These inhibited wax based "undercoatings" are far more effective and durable than any "rust prevention oil".
Stainless streel rims, even if you can find them, will likely give very poor braking performance. If they 400-series stainless for strength they won't be completely corrosion resistance and if 300series stainless, will be prone to chloride cracking.
The best external rust preventative I've found after a salty road ride is a hose and warm water followed by a dry rag.
Are those wax coatings applied by hot dipping, spray on, or drip on
07-01-11, 12:00 PM
You spray framesaver inside the tubes of the frame. External wax is any car wax such a turtle.
I would be wary of zinc-plating in case you want to make additional braze-ons or repairs. Once you coat in zinc, then heating it up (as you should know) vapourises (http://www.ehow.com/about_5306156_effects-welding-galvanized-metals.html) the zinc which can condense in your lungs.
Boats use a sacrificial zinc (anode) plate or block to prevent corrosion. Ive never heard of cyclist bolting on on but in a severe salt environment, its worth a try.
Most winter riders find that a normal, quality paint job with a couple of wax coats is more than sufficient.
Sealing a frame is impossible, water always gets in. A useful option is a drain hole at the bottom bracket.
Zinc plating provides a sacrificial coating to prevent the spread of under-film corrosion- "bubbles" that happen like on trailer hitches when there is a pinhole/scratch in the coating. Most exterior metal we coat in the powder coating shop is electrogalv/hot dip galv then phosphated then powder coated.
Sacrifical zincs, like on boats, work by inducing a current in the hull. This requires an electrolyte, and is slightly different.
I do not plan on doing more braze-ons. Leaving a hole in the frame is a good idea.
07-01-11, 12:46 PM
I had a Trek 400 that was phosphated and it showed no rust at all when it got dinged. More steel frames should get treated to a phosphate dip. I have a feeling it was zinc phosphate as it looked just like the parts I ran through my Zinc line back in the day.
You'll have to do something with the cogs as they're pretty much all steel except some cogsets have some cogs in Ti and way back in the day there were some Al cogsets made. If your hybrid conversion included use of a road crankset then you're probably OK there, if you're running a MTB set then your small chainring has a good likelihood of being steel. Some have steel mid rings too. Typically only really cheep ones have all 3 in steel.
While certainly not the sensible way to go about things it would be an interesting experiment. I'd probably just get a decent station wagon and keep the bike nice and dry. Headset, BB, hubs. Maybe just annually for freehub body.
I'd keep on a regular bearing repack schedule of twice per year. Once in September and once in April or May.
07-01-11, 04:04 PM
Are those wax coatings applied by hot dipping, spray on, or drip on
Frame Saver and HDMP are aerosols and come in spray cans. The cans contain the wax dissolved in a volatile solvent that evaporates after the material is sprayed into the interior of the tubes and vent holes of the stays and fork blades. They are best applied to a completely stripped frame and fork.
I sprayed a generous amount into each vent hole and frame tube and rotated the frame frequently to distribute the liquid evenly as it dried. I repeated the process after 24 hours to assure everything got a good coating. Work outdoors, with good ventilation and spread plenty of newspaper under where you are working. The stuff is hazardous to breathe and messy until it dries. Kerosene will clean up any overspray or leakage.
Permanent and corrosion proof don't really exist. Bad news, while 316 does better against chloride attack than lower grades, the chlorides in salt eventually attack 316SS.
"Chloride attack of austenitic stainless steels, like 316, occur in three ways: stress corrosion cracking (SCC), pitting corrosion, and crevice corrosion. SCC is usually not a problem in the temperature range you have described. Pitting corrosion is associated with stagnant conditions and usually not an issue where continuous flow is occurring. Crevice corrosion can be minimized by eliminating crevices through proper design."
Unfortunately, a bike can have both stagnant conditions and crevices.
You also will eventually get corrosion of the aluminum parts, and of course, steel such as the cassette, steel axles, bearings, etc.
07-01-11, 04:16 PM
If it was mine and I worked at a plating shop and I was worried about corrosion,my bicycle would be nickle colored.
07-01-11, 04:29 PM
Hello, I have been here a while but just registered. I am an engineer who works in a plating shop and loves to ride in the winter. The last few years I kept my bike on the back of the car for the whole winter and the salt spray was not kind to it at all. The bike is a 1995 Specialized stumpjumper that has been converted to a hybrid.................Please don't say keep my bike inside, this is also partially a game, to see if I can beat the elements.
The last statement proves you are indeed an engineer.
All I can say is report back. Stumpys are great bikes. Please don't experiment this one to death!
07-01-11, 04:58 PM
What about Parkerising for all the steel components (eg the frame)? Seems to me like it would last the season at least.
As for wheels, I've seen titanium rims; there's a bike in the WA museum of sport which has Araya titanium rims on it, if these are no longer available what about carbon?
I know you can get titanium nipples and spokes.
07-01-11, 05:05 PM
As for wheels, I've seen titanium rims; there's a bike in the WA museum of sport which has Araya titanium rims on it, if these are no longer available......
AFAIK, these haven't been available for many years and they were fringe items even then. There has to be a reason. :)
07-01-11, 05:56 PM
Yeah, I would have thought that Ti rims were a complete waste of money - no stiffer than aluminium rims of equivalent width and weight and only marginally stronger (the strength of a wheel is mostly due to the spokes).
Friction seems roughly comparable - I just did a rough test in my shed of dry friction between Koolstop salmon pads and a block of 6-4 Ti and it came out about 0.5, same result with a block of Al (unknown alloy, probably 2XXX series).
Last winter I plated the cogs with 40 microns electroless nickel and baked 4 hours and they held up without a scratch.
I have a feeling no matter what the hubs will be maintaince items along with the ball bearings
I could try to plate the inside of the fork if I set up auxillary pumps for the electroless nickel but can't steal production line capacity for that. I could zinc plate it if there was a way i could build an auxillary anode without touching the fork tubes for the inside.
316 is not immune to chloride attack but we make plating racks out of 316L and they will hold up for about two years on the average line, and the pre-plate process includes a 2 minute dip in 30% HCL many times a day. Bolts on the fixtures in HCL tanks, yes those are Ti or alloy C276 but way too expensive and unrequired for bikes.
Are the ball bearings for bikes usually 440C ss or carbon steel?
About crevice corrosion, when bolting joints on the pumping mounts in the shop, we use an anti-sieze behind the washers and on all threaded connections. Maybe this would work on the bike.
07-01-11, 08:43 PM
Bll bearings for bikes are usually "chrome steel", i.e. not stainless as the Cr content isn't that high. 440C bearing balls are usually specified for corrosive service and bikes don't ordinally qualify.
BTW, this whole project seems to be technical overkill and a very elaborate way of accomplishing what a small amount of prevention would do at much less cost and trouble. I'm an engineer too and always thought simple was better (and cheaper) than complex.
simple is better almost always, I agree with that.
I am also the type of designer who likes to avoid maintenance items, as no one ever seems to perform it in the shop I work in. I prefer to design for the set-and-forget mentality. It is just ingrained in me now.
Probably just as easy to pick up another '90's steel Mt. bike off C/L every year.
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