*Scuba 

Hi all,

I snagged a pair of vintage stainless steel fenders off of my local CL, they had been posted for a long time, didn't need them. But when then I saw the poster lower the price and after a couple of months, the price finally dropped down to $15CDN, so I decided to pick them up.

The fenders are in great shape, however the original fender stays are really beat up, there is heavy corrosion and some pretty deep pitting from rust. They were chrome plated, but I guess, over the years the chrome has either flaked or bubbled off and has allowed the underlying steel to corrode.

I want to restore the fenders (even though I don't have a bike for them at the moment). One idea that was suggested to me, was to polish up the current stays with steel wool and sandpaper and get them rechromed or nickle plated. But, I think that would take a lot of elbow grease and the finished results would not look that nice, since there would be pits from the rust giving it a dimpled surface. My idea was to fabricate some new fender stays to replace the originals.

I know that I can order some three feet lengths of stainless steel round stock from McMaster Carr in 4mm diameter. But there are quite a few options, they have 303, 304 and 316 stainless to choose from. 316 stainless steel has the best corrosion resistance, but it is also three times the cost of the 303. When I emailed both SKS and Planet Bike to ask them what type of stainless steel they use in their fender stays, since they hold up well to the weather in the Pacific Northwest, neither of their service reps could tell me the type of material used, except to confirm that it is a stainless steel material.

There are chemical tests that can be performed on stainless steel to grade them, but I don't have ready access to either sulphuric acid or hydrocloric acid. Neither do I want to purchase an expensive steel test kit from a metal supply company. So, I was hoping that some one here with some industry connection or knowledge would be able to tell me the type of stainless steel that are normally used for bicycle fender manufacturing.

Don't have pictures right now, but will share some pictures of my project at the earliest opportunity.

dsbrantjr

You are fabbing fender stays, not building an airplane engine, get the cheap stuff. Any of them will be so much better than the original chrome-plated mild steel that they will probably outlive you.

Bill Kapaun

Any 300 series should work fine.
3X as much as what. If it's $1 vs $.33, shipping cost is probably a bigger concern.

HillRider

Any of the 300-series will be fine. 303 or 304 are more than adequate and 316 is overkill. You are putting them on a bike, not building chemical plant equipment.

TGT1

Yep!

303 is just an easier to machine version of 304. No need for 316 on a bike.

WizardOfBoz

If you can, set up a customer account with McMaster-Carr. It may get you better prices/terms/shipping. I think it matters a lot with MSC, and with Grainger.

I'm a PhD Chemical Engineer who's worked in chemical plants. The other guys are spot on. The cheapest austenitic (300 grade) SS will avoid corrosion sufficiently. Please take heed to the caution about machinability. 300 SS exhibits EXTREME work hardening, and this is especially the case in stuff that's already been cold-formed or drawn (cold-drawn bar or wire). Push down on the drill press handle too slowly with too fast a spindle speed, and you will have a dull drill rubbing against very hard steel very quicly. If you are going to machine the stuff, make sure you get annealed bar, and not cold drawn wire.

If you think you're gonna drill it or tap it, be prepared for a significant learning curve and have spare bits and taps. Unless this isn't your first stainless rodeo. Good luck.

FBinNY 

304 is the most common and readily available as wire. It also has good workability, which is important to you.

*Scuba 

For the various three feet lengths, the prices are as follow (all funds in USD).

303 is $5.14
304 is $6.45
316 is $15.87

Therefore, if I was to use 316 4mm diameter round bar for the fenders to make my fender stays, they would cost over $30 USD for me.

*Scuba 

The vintage fenders that I am refurbishing have stays like the Honjo style fender stays, U shaped that wrap around the back of the fenders. So no need to drill or machine anything. Just going to bend a piece of straight 4mm stainless steel into a U shape. I will probably need to cut the ends, as I only need a 800mm to make the fender stays.

Shipping should not cost too much, I have a friend that lives in White Rock, British Columbia, just on the other side of the US border of Blaine, Washington. He uses a freight fowarding company to save on shipping costs and he lets me ship stuff there for him to pick up. It is not an issue or inconvenience, since he go over the border to fill up on cheaper gas for his car in the US at least once a week.

*Scuba 

Thanks for all the replies and suggestions, I think I have made up my mind.

Since 304 has slightly better corrosion resistance than 303 and is only cost slightly more, I am going to go ahead and order two lengths of that.

Like I said, shipping won't be across the border into Canada, so it should be pretty reasonable.

WizardOfBoz

That sounds like a nice, simple, functional and elegant design. You may want to consider using a wire bending tool (pretty cheap: about 8 bucks US) to get the "eyes" right. Or make your own. They look like this:

HillRider

Good suggestion. If you bend the wire freehand you are likely to kink it or get a bend of the wrong radius that will be hard to correct. Use (or make) a wire bending tool as shown or use a piece of pipe of the correct diameter to bend the wire around.

fietsbob

FWIW Thicker Aluminum rod is also used .. P clips used at the frame eyelets to mount them ..


(order a Brompton with the Ti parts and the mudguard struts are Ti, too..)


I'd go dig around in the LBS basement and just get struts from old mudguards that died in the line of duty..





....

AnkleWork

+1, as others have also said: any 300. But, for real corrosion protection it will need to be fully passivated after bending/cutting. Maybe try some aluminum solid wire as used by chain link fencing to tie the fabric to the posts. It's very stiff due to work hardening and no passivation needed.

Ghrumpy

Right, so break out the nitric acid!

j/k apparently citric acid can do the job well enough. You should be able to find that in the canning section of the grocery store.

FBinNY 

Passivation is simply about removing surfae contamination that can serve as a gateway for ions to penetrate the chromium oxide skin that makes stainless rustproof. Acids are used in industry because they're cheap, fast and effective, but those are not the only options.

You can use a mild acid, even vinegar or lemon juice or oxalic acid (sold for household cleaning purposes) and one of those green "Scotchbrite" pads to polish the surface, removing a thin layer, and letting it naturally form the protective skin. The one thing you cannot use is a steel wool pad, since iron transfer is exactly what you're trying to avoid.

WizardOfBoz

The comments on passivation are all true, but they all depend upon a scrupulously cleaned, degreased part. Industrially, they wash and degrease, then soak in 5% sodium hydroxide for 30 minutes (at 170°F), then 10% citric acid for 30 minutes (at 150° F), then another 30 minutes in the hydroxide. That's overkill.

Wash the bracket with dish soap or TSP, water rinse, soak in 10% citric for the 30 minutes at 150, rinse, and you should be good to go. If you ride a lot in winter in Pittsburgh, with road salt, or you live on an island near the ocean and get the salt mist, you could do the hydroxide pre and post treatment, but I wouldn't.

dwmckee

I'd judt buy premade ones. Most LBS have unused ones for sale as surplus.

rumrunn6

you would have enjoyed my nightmare when I broke a bolt that holds my car's hatchback door on & while trying to extract the broken bolt, broke a hardened steel threaded extractor into the hole I had drilled in the bolt. then I had to drill out the hardened steel tool to insert a new fluted extractor, which did the trick. did indeed go thru many bits, including left hand bits

WizardOfBoz

Holy cow, my condolences. Typically you need a carbide burr on a flexible shaft tool or a die grinder to get a thread extractor or drill out. That you got it out with drill bits is impressive as hell. You must be one persistent individual.

rumrunn6

thanks, it took weeks & several Amazon orders. when it finally came out I was so overjoyed I showed it to my new neighbors walking by. gosh only knows what they were thinking "um ok wutz the big deal, but whatevs ..." I'd share a pic or three but the images I posted on other forums were on photobucket so I'd have to dig up the originals & haven't been able to justify that yet