531Aussie

I just stole this off the Serotta forum
https://www.serotta.com/forum/showthread.php?t=11510



"Independent Fabrications have been quietly making road and track frames out of a brand new Reynolds tubeset - 953. It's super hard, very strong (and this track bike had 0.3mm wall thickness tubes. And it doesn't corrode (or so they reckon...) We'll be interested to see what the uptake is on it. Apparently no other framebuilder had even heard of the tubeset, so it was quite a coup for Indy Fab.

sunninho

Wow, an interesting development

ivan_yulaev

Mmm, I don't think that stainless has the right properties for a bike frame, it's not "tough" enough. But, this reynold's stuff could be nice.

.3mm thickness? OUCH! I though my 1.1mm titanium was getting thin...

Drayko

.3mm? Seems a little low. That's like most paper.

nova

Pure stainless would be near worthless but depending on the alloy it can be very tuff and strong. Take knife blade steel for example so many grades and alloys with various properties. Then theres stainless steel spring steel thats got a fairly high carbon content. Strong tuff and well springy. Pure unhardened stainless is soft and will bend if you look at it wrong pure stainless thats been hardened is very brittle (often called surgical steel as its used in scaple blades) Even this stainless isnt 100% pure and has some carbon added. This is probably some alloy that will be strong light and will be able to flex a fair bit with out cracking or breaking.

psuaero

Sounds like heavy duty aluminum foil!

2manybikes

Bridgestone made prodution stainless bikes many years ago, they fell from popularity for some reason.

mirona

DannoXYZ 

Hmmm, Reynolds-953, interesting.... reminds me of the Excell tubing used at Steelman.

What do you mean by "tough"? How do you measure it? Note that stainless has more alloy varieties than just about all other structural metals. It is used extensively in industrial applications, oil-refineries, food-processing, submarines, nuclear reactors not to mention in my favorite gun the Desert Eagle. Here's some standard properties of various materials:

Chromoly-4130, annealed
density: 0.284 lb/in^3
ultimate-strength: 81.2 kpsi
yield-strength: 52.2 kpsi
elongation@break: 28.2%
modulus elasticity: 29.7 mpsi


Titanium 3Al-2.5V, annealed
density: 0.162 lb/in^3
ultimate-strength: 89.9 kpsi
yield-strength: 72.5 kpsi
elongation@break: 15%
modulus elasticity: 14.5 mpsi

Titanium 6Al-4V, annealed
density: 0.162 lb/in^3
ultimate-strength: 120 kpsi
yield-strength: 110 kpsi
elongation@break: 12%
modulus elasticity: 15 mpsi


stainless-321, annealed
density: 0.289 lb/in^3
ultimate-strength: 95 kpsi
yield-strength: 60 kpsi
elongation@break: 40%
modulus elasticity: 28.5 mpsi

Gall-Tough+ stainless, annealed
density: 0.275 lb/in^3
ultimate-strength: 232 kpsi
yield-strength: 212 kpsi
elongation@break: 24%
modulus elasticity: 26.8 mpsi

brinstar

i think 953 was found on the moon originally

sydney

Maybe IF would appreciate a 'heads up' on that?..... AFWIW with respect to the .3 mmthickness, OEM16.5 has had a .31 mm toptube since the late '90s.

ViperZ

Based on those numbers it would seem Stainless is a very suitable material, It's strong and it has a nice elasticity. The 321 is inbetween the Titaniums in strength, yet less brittle.

waltergodefroot

You will no doubt be banned from the Serotta forum for this blatant forum espionage.

Kudos to Reynolds who have not gone quietly into the night during this onslaught of new materials for bicycle frames. And kudos to them for staying clear of aluminum.

531Aussie

I wonder if they've let Thylacine back yet?

DannoXYZ 

Yeah, I think materials-selection is the easy part. It really comes down to implementation issues of structural design, manufacturing processes and cost. A SS-321 tubeset would be about 5x more expensive than chromoly and the proprietary Gall-Tough+ stuff ends up costing 10x more expensive than chromoly. In a custom-frame like a Serotta, Eisentraut or Steelman, there's so much labor and design costs built into the frame, that an extra $400-700 isn't really gonna make much of a difference. But when you're looking at mass-produced chromoly frames in the $300-400 range, then adding that extra expense for the exotic tubing may not be worth it. You'll get a better sense of "value" by going to titanium or alloy.

Since people brought up aluminium foil, here's the properties for aluminium:

Aluminum 6061-T6
density: 0.0975 lb/in^3
ultimate-strength: 42.0 kpsi
yield-strength: 37.0 kpsi
elongation@break: 12%
modulus elasticity: 10 mpsi

Aluminum 7005-T6
density: 0.100 lb/in^3
ultimate-strength: 50.8 kpsi
yield-strength: 42.1 kpsi
elongation@break: 13%
modulus elasticity: 10 mpsi

Aluminum 7075-T6
density: 0.102 lb/in^3
ultimate-strength: 83.0 kpsi
yield-strength: 73.0 kpsi
elongation@break: 11%
modulus elasticity: 10 mpsi

The comparison metric you'd want to use here is yield strength-to-weight ratios (density) as this would let you design frames that would hold up to roughly the same amount of load before they take a permanent bend. So now we're looking at (yield-strength / density):

Yield Strength-to-Weight Ratios
184 - chromoly 4130
448 - titanium 3Al-2.5V
679 - titanium 6Al-4V
208 - stainless 321
701 - stainless Gall-Tough+
379 - aluminum 6061-T6
421 - aluminum 7005-T6
716 - aluminum 7075-T6

However, you can't design something to be as light as possible for the load, there's rigidity and stiffness to be considered as well. So let's compare the stiffness-to-weight ratio (modulus / density):

Stiffness-to-Weight Ratios
105 - chromoly 4130
89.5 - titanium 3Al-2.5V
92.6 - titanium 6Al-4V
98.6 - stainless 321
97.5 - stainless Gall-Tough+
103 - aluminum 6061-T6
100 - aluminum 7005-T6
98.0 - aluminum 7075-T6

Interesting to see that the materials are similar in stiffness-to-weight, eh? That means a frame designed from these materials to be similar in weight, assuming similar designs, will have similar stiffnesses as well. However, titanium or aluminium will end up being 2-3.5x stronger for the same stiffness as chromoly. And ordinary 304 stainless is actually weaker than chromoly for the same stiffness, 321 is similar and the exotic stuff ends up about the same as high-end titanium & alloy materials at 3.5x stronger for the same stiffness as chromoly.

As a designer, you've got to strike a balance of these two factors in addition to the design, manufacturing and costs as well.

DocRay

All those materials numbers are worth thinking about, but the real truth about application to bikes is vastly different after welding, and the ability to form ceratin shapes in those materials. You cannot extrude stainless for example.
"100% stainless" is a meaningless term, there are >50 alloys of nickel, chromium and steel with different properties.

One big weight adavantage of SS is that it does not have to be painted or coated.

white lobster

That must be why, starting on day 2, the IF bike on display had a big pad strapped to the top tube right about where the handlebar would hit.

Extremely cool bike, though. The stainless is very industrial-looking.

viter

Not quite. Check out https://www.reynoldsusa.com/english.html. In addition to steel tubing, they also make titanium, aluminum and magnesium (has anyone ever made a bike with this stuff?), not to mention their carbon fiber division at https://www.reynoldscomposites.com/Main.asp

waltergodefroot

Didn't know that. Now, can you show me a frame made from this special order only tubing?

2manybikes

Bridgestone Kabuki Submariner Bikes with stainless tubing.

DannoXYZ 

Yeah, stainless fabrication is much closer to aluminium and titanium than traditional chromoly. It has to be TIG-welded with argon shielding gas on the inside and outside of the tubing. I'm sure the alloy they're using has some Ti in it to fight hydrogen embrittlement and carbide-migration at elevated temperatures. As with welding aluminium and titanium, the composition of the filler-rod has to be compatible with the base metals.

Depending upon the pre-heating, radius and thickness of the weld, and post-weld annealing, you can actually end up with a joint that's stronger than the tubing because it's thicker and has gradual and smooth blended contours which minimizes stress-risers. So welding stainless isn't any different than alloy or ti, you just have to know what you're doing. Some of the nicest stainless fabrications I've seen are custom exhaust headers for Harleys and race cars; simply works of art!

bostontrevor

I and some local folks visited IF in July and they mentioned they were testing some skunk works steel for Reynolds that would totally blow everyone away and completely reshape how we think about steel. They said they were actually thinking about moving away from Ti and back into steel for this stuff. Looks like this is it.

Baldanzi

I'd love to see this come to fruition...I work in the pharma industry and we use/spec stainless steel for practically everything in "clean" spaces (ever see a stainless steel computer and mouse? Its pretty funny actually). We use mostly 306, or 316L stainless.... Oh it would be so cool to see a bike made of this 953. Cramerotti had a dedaccai stainless on their clearance page a couple of years back. Stainless is VERY hard to fabricate/weld etc. I'm sure IF will do it right...but really weird stuff can go wrong if the stuff is handled wrong during fabrication. For example, every tool that touches the s.stl must also be s.stl otherwise you may imbed non stainless steel in the material whis with then rust. We've had a lot of bone-head fabricators build something only to see it rust later on becasue you find out somone polished if with a non-stainless steel wite brush and the stairs (in this case) began rusitng becasue little particles of the wirebruss were imbedded in the stainless. Even hammers and wrenched should be stainless during the fabrication. Welding the stuff is a PITA. I'd love to find out some more about the composition of this stuff. I'd love to have a frame like this.....

Wind 'N Snow

Yeah but you know, my stainless stuff always gets this gunky residue when I put it in the dishwasher. I hope at least it comes in some nice patterns, errr I mean geometries.

bostontrevor

They mention that it's difficult to work and I wouldn't be surprised to see a program similar to the 753 certification before a builder is allowed to use it.