[Closed] So -Steel FS bikes...

True but even a pound in frame difference can make a frame feel different can't it (to any rider).

[i]The irony of saying we shouldn't question an essay which talks about questioning others logic?[/i]

Not saying people shouldn't question, just saying that there some ideas regarding stiffness and appropriateness of steel and alu on that page that add to the discussion (they don't end it).

Is there any info on the 18bikes website about the frame Matt?

True but even a pound in frame difference can make a frame feel different can't it (to any rider).

and i think some people can over analyse about the "feel" of a bike.

From Cy's explanation

The key thing here is that steel was right for this application, right for the Rocket, where high loads are going into the frame from the long forks and the type of riding a 150mm travel trail bike encourages. This meant that the high strength of steel made the weight of the frame competitive with other materials with a level of strength and durabilty we were really happy with.

[b]In other applications - shorter travel frames for instance, say 100mm both ends - where loads are lower and the riding conditions aren't expected to be as arduous, these don't suit steel so well because you can't go much lighter than the Rocket in steel whilst maintaining the durability. You end up with a short travel frame which would be very heavy for its class and massively over strength.[/b]

The bold bit is exactly what I started off referring to.

I think too much emphasis is placed on the weight of frames etc,

Except when we're comparing different materials in frame manufacture. Only a maniac would buy a frame which id the same price and rides identically to another but is heavier.

Only a maniac would buy a frame which id the same price and rides identically to another but is heavier.

Unless that maniac had other concerns that were not served by the lighter frame (and were served by the heaver one), such as longevity, repairability, or something else not covered by your overly general sweeping statement 😉

Taking Cy's essay from a geeky perspective (I'm sure he's right and I'm wrong as he's more qualified than me).

He quotes the 2nd moment of area in his reasoning why a 35mm seatube is better in steel than aluminium.

But the 2nd moment of area deals with bending a tube/beam/object.

Why not apply the polar moment which deals with the application of torque to the beam? The seatube is essentialy fixed at the top tube and downtube, then twisted at the pivot in CY's design?

[edited]
I think I've thought it through, correct me if I'm wrong.

To build a 'perfect' frame (irrespective of weight), you would want to minimise the the 2nd moment of area (which would allow the wheel to twist, which is bad), but still allow some polar moment to let the wheel track the ground on flat (but rough) turns (which is good).

Wors - Not as yet, there are some more news stories if you look back through the archive but not a huge amount. As I said, the tube bending has caused a real delay. The most up to date stuff is in the news story I linked to already and in the [url= http://www.flickr.com/photos/18bikes/sets/72157627836859954/ ]Flickr Set[/url]

EDIT - [url= http://www.18bikes.co.uk/news.php?articleshow=573 ]Here's[/url] one of the other news stories

So are we going to get a lugged FS one day? Would lugs increase stiffness or strength? For someone with no idea how to build a frame, I'm finding it all very interesting.

Proper old skool construction lugged steel FS with modern geo & supension would be WIKKID.

So are we going to get a lugged FS one day? Would lugs increase stiffness or strength? For someone with no idea how to build a frame, I'm finding it all very interesting.

The problem is luggs have to be cast or forged, both carry tooling costs, and unlike road bikes where the geometry & tube diameter hasn't changed in 50 years amd only changes a little between sizes, you'd probbaly need a different set of luggs for every design and size of frame, which would be prohibitibly expensive.

Would the following statements be too contentious?:

-Steel should at least be considered for certain elements within an FS bike frames where there is a balance to be struck between Strength, stiffness and weight, as it is not always the case that aluminium or steel offers the optimal choice in all cases (See Cy's linked article about his own experiences when designing the Rocket)... Basically an open mind is better than an entrenched position...

-In general steel lends itself to fabricating prototypes, short runs and custom frames for both HT's and FS bikes better than aluminium...

-Not all steels are the same, and hence 853 and 953 frames cost plenty more than generic gas pipes welded together with a DMR sticker slapped on...

-Weight is not the only performance criteria for any bike...

There are three things that determine how a bike handles. In DECREASING order of importance:

1) Geometry
2) Tube thickness (stiffness)
3) Material (weight)

Since steel has a higher tensile strength than aluminium, you can use thinner tubes of a smaller diameter - hence the frames may be not as stiff for the same (or heavier) weight. Titanium has a higher tensile strength as well, hence thinner tubes and lighter weight, but again tube diameters tend to be fixed (by the aviation industry originally), so stiffness will suffer.

Any decent steel builder working with 853 would laugh at the idea that one couldn't make a good FS frame - after all geometry is already established. It would however be uneconomic compared with the high throughput mass production of aluminium frames, and it's easier just to make hardtails instead.

How stiff a bike with 3" of travel needs to be is a moot point. But I'd love an 853 single pivot frame.

The way I see it Cotic make steel frames, thats their position in the market. So they want to sell a f/s frame, it makes sense for them to develop a steel one. Its different and will apeal to their existing customer base. All the guff about it being the right material for the job is just marketing.

How come all the armchair engineers start with "i'm no engineer" but all the armchair marketeers don't start with "i'm no marketeer" before spouting rubbish.

Cy's post explains everything perfectly about why he chose to use steel.

Its a bit like top trumps... Your John Deere might be better in some categories than my Fendt but I out do you in other areas. Both have strengths and weaknesses, you just choose which ever is going to give you the best outcome. in this case, steel trumps alu.

Why not apply the polar moment which deals with the application of torque to the beam?

Relationship's the same, ie double area moment and you double the polar.

ie for a tube, once you adjust the wall thicknesses of the steel (lets say 0.9mm) and Al (would then be 1.9mm) tubes to give the same load-deflection figures, the resistance to torsion will be the same too. If the tube was shaped you could adjust this relationship but no point in that area of the frame that I can think of offhand, plus you need to get a seatpost in there..

I'm sure it can be explained better than that though.

Anyway, interesting thread. I was going to say that most brands make Al frames because Al is easier to shape and machine and people want techy looks in a product like that, there's no real reason not to use steel. There's a market for the simple aesthetic, the durability of steel for a tough bike appeals and something unique always stands out. Bike purchases aren't usually rational decisions are they? )

All the guff about it being the right material for the job is just marketing.

It's the right material if used in the right way, as is Al for a different FS frame design. I think FS bikes have matured in design now, geometry and ride feel makes more difference than linkage type. So a proven design on a durable frame appeals to me. But then I'm a rider who got bored of looking for the 'next thing' a long time ago, so my opinions don't represent a very profitable market ) I'm more likely to buy a Rocket than most FS bikes if I wanted another FS bike though, so if there's enough riders seeing it from that pov then it deserves to do well. Plus it's a cool name, I'd want flames on mine.

anyway, all this Steel vs Al vs CFRP vs Ti guff is just guff.

as all engineering graduates know, the best material for bike frames is bamboo...

(amazing combination of strength/stiffness/weight - it's the future)

if two frames weigh the same, cost the same, same travel, stiffness, geometry, features etc but one was steel one was aluminium, [i]would it make any difference[/i]?

*me being one of those people initially but after this thread probably not 🙂

This is not about the ALU Steel debate. It is about selling bikes.

I am genuinely envious of everyone here with an engineering background; my passion for bikes leads me to want to understand more and this thread has helped to open my eyes to some of the what must be a myriad of variables in the design process that us "armchair ________________ s" cannot hope to understand without going back to school!

However, I am no armchair marketer either; I have run my own business in Japan for over 10 years and am acutely aware of the nature of marketing one's product to the local market, as will be Cy and the team at Cotic. It is my experience and opinion that whether it be bikes, hair gel, education or you name it, the marketing challenge is the same.

Sell your goods and services........to people who in many cases don't understand them.

Cotic have the unenviable task of trying to convince the average rider (who loves to think they know about bikes!) to buy their bikes. Those same riders who, as I suggested earlier, the majority of which actually know nothing, zero, zilch, didly squat about the nature of working with materials in product design. And that includes me. They only know what the groundswell of opinion in the marketplace believes.

All businesses face the same challenge. Yet what I like personally about Cotic and Cy is that they try their damn hardest to pitch the info they give about their bikes at a number of levels (Read the newsletters and you will see). To the engineers and pseudo ones, they open up the thinking behind their product, to the rest of us they go with (as we do here in my business) the "honest" option. You can trust us, we won't shroud it in soundbites.

Count the number of times Cotic output will tell you the following ideas: "we are doing nothing new"; "it's not a new concept", "There's nothing spacial here", "Don't get sucked in to the marketing hype of us or others"; "Droplink?? It's only a name guys!" "Riders tell me they like it" and so on.

So, if you are an engineer, Cy will tell you what has influenced his decisions.
If you are not, he won't force it down your neck, neither will he try to pull the "new name for an old idea" wool over your eyes, instead just challenge you to try it out and tell him you don't like it.

And it works.
And that is how you would have to sell a steel FS bike in my experience, because you are swimming against a tide of ignorance and that is just how it is and if you ignore that your frame is dead in the water.

And that is Cy's brilliance. He has got it just right. Keep an open mind, challenge the old with facts and figures for the engineers and be "honest" with the rest of us.

To me, as a business owner I look at Cotic and see this "You can trust Cotic; we are honest with you"

That is what Cotic is and their marketing from that perspective is brilliant.
There's a market here in Japan waiting to be educated Cy. Your dealer here has only a handful of the first generation Souls and their presence is... have to be honest.... non-existant. No-one ahs heard of you over here but everyone wants a go on my BFe....

Ah, the honesty dollar 😉

But seriously, this is one of the most interesting threads I've read in a while. I do love steel bikes, probably for no more reason than my first bike was a P7 and I like skinny tubes.

Much of the armchair engineering I read about is then used to justify my opinion so to see framebuilders giving their reasoning is great.

I'll be honest (that word again), I hadn't dared look at this thread at all until now. I just posted that link because someone told me it'd be useful in this context and I'd just written it.

It's all been covered really, but basically the Rocket is steel because it's got no significant weight disadvantage to an aluminium frame of a strength I'd be happy with, it's super durable and once the numbers (both mechanical and financial) started looking promising, I just wanted to. As quoted above, not all the droplinks bikes we'll do will be steel. Some will where appropriate, others will be something else as appropriate to the design brief.

that means bamboo, right?