I’m toying with the idea and will hopefully go to a test day to ride one.

But thought I’d gauge the STW opinion and see if anyone is going to /thinking about investing.

I’d love one but don’t have gnarr to justify it

Maybe you’ll get some gnarrr free with it.

After Cy’s latest email (“I’ve just been on a 4 day trip to Portugal riding, and I call it work” ), I’m more tempted than I was before…. Either that or I want to make mountain bikes for a living! 😉

I’ve booked a demo in April and am secretly looking forward to it. It will have to do well to compete with my Zesty though…

It does look lovely in the sunshine !!

Now, if there was a big wheeled version in the offing…

bol – Member
Now, if there was a big wheeled version in the offing…

+1

I’m waiting to try it… From the descriptions I think Cy might have designed out some of the things I love about the Hemlock. But I think I’ll get a chance to try one at fort william later in the year so you never know, I might be totally wrong.

Trying one in April, but it could well be my next frame when I can afford it.

What’s the travel on that? It doesn’t say on the info page, (least not that I can see)

Enough for a trail centre!

No simply put, it’s a cotic and it’s what all the rest of you ride fps!

But steel for the front triangle…, apart from been ‘niche’, any good reason why its better than (lighter) aluminium?

http://www.cotic.co.uk/geek/steel-full-suspension

“What we ended up with is the Rocket frame, which is weight competitive with the similar aluminium bikes out there, but has a level of durability and stiffness which is really high.”

Thank goodness there are no test days near me.

I haven’t quite got over opening the email from Cotic with the picture of the shiny stainless one. Fair put me about, that did. Shouldn’t be allowed!

Northwind

I can read marketing-speak with the best of them, but I can’t see how its as light as alloy, or stiff for the same weight – just not possible, at least with basic level of metal property understanding.

Or is it just trying to be different?

The long bit about steel “…one of the key things I wanted to improve on from the Hemlock was the stiffness of the connection between the front and rear ends, so I started with the seat tube as it’s where all the suspension pivots would be hanging from. This would be critical. I made a comparison between the 35mm aluminium seat tube we used on the Hemlock and the 35mm seat tube from the BFe. Let’s do a science bit now so you know where I’m coming from with this…..
Tubing stiffness comes from two elements; the material stiffness (the Young’s Modulus, or E) and the mechanical stiffness (Second moment of area, or I). Combine the two (EI) and you get compare the overall stiffness of the part you’re analysing when they aren’t in the same material. Usually rigid steel frames exhibit less stiffness than aluminium ones because steel is so strong that you can use it in small diameter, very thin wall tubes so despite steel being 3 times stiffer than aluminium as a material (E is around 77 for aluminium, around 210 for steel), the mechanical stiffness I is low because of the small diameter and thin wall. Because I is quartically related to diameter (d^4 is an element of the I calculation), increasing diameter from 35mm (usual steel down tube) to 50mm (usual aluminium down tube) makes the mechanical stiffness 4 times larger. And that’s before you consider that aluminium needs thicker walls than the steel tube. So the lack of material stiffness in aluminium is overcome by using mechanical stiffness. The  reason you can’t build aluminium tubes as small and thin as steel ones is because aluminium is also very much weaker than steel (typically 300-400MPa Ultimate Tensile Stength vs 1300MPa for 853), so in simple terms the mechanical stiffness in aluminium tubes is a function of needing to use lots to stop is breaking.

So, that’s the simple version of the basis of my comparisons across different materials. The key difference in this case is that the mechanical stiffness is similar. The seat tubes being compared are the same outside diameter – although the steel is much thinner wall – and aluminium can’t play it’s ‘big’ hand here as you can’t go larger on the seat tube without running into all sorts of compatibility problems with front mechs, tyres, seatposts and seatclamps. So where the mechanical stiffness is similar, you mutliply it by the material stiffness (steel is 3 times stiffer than aluminium remember) and what do you know? The steel seat tube is massively stiffer than the aluminium one. Not a little bit, but massively stiffer. Sure it’s a little heavier too, but my main concern for this part of the frame is tying the suspension pivots to the seat tube as hard as possibly to give a solid ride feel. So, all of a sudden steel is in the game!

From here, the next stage is a full weight analysis of a steel version of the frame. The seat tube was a little heavier than the alumium one, so I needed to be sure that lot’s of ‘little bit’ heavier’s didn’t add to a whole lot heavier on the whole frame. The comparison was with the final 2011 spec Hemlock. Again, steel has the power to surprise. When you’re looking at making a hard riding bike that needs a lot of durability and strength steel comes into it’s own as it’s so strong and durable. Aluminium, conversely, needs to be used copiously in a frame of this type to make up for inherent low strength. That great big 50mm down tube on the Hemlock weighs about the same as the 38mm steel down tube on the Rocket, but the Rocket down tube is stronger. Same with the top tube. In fact the only place on the frame where it didn’t make sense to use steel was the swingarm, as the large machined pieces required for the bearing housings and dropout sections would not only have been unnessarily heavy, the machining of steel is very expensive compared to aluminium so it would have been much more to make. So the swingarm is aluminium in nice big sections to tie the pivots and axle together properly. Play to the strengths of the material in the location they need to be used.”

B R – The key thing (which is covered from my email thing above) is that for the part of the frame holding the two ends together, steel is stiffer. For the rest of the front triangle, steel isn’t any heavier, is stronger and is stiff enough. Come and have a test ride and see what you think.

Getting the first couple of production frames just in time for Bespoked Bristol early next week. Getting excited now. I’ll be firing some photos out the mailing list people as soon as I have them.

tthew – The Rocket is 150mm travel and designed to use 140-160mm forks. I’ll go and check the product page as that should be fairly obvious really!

We’ll be mucking about with big wheel versions of the droplink suspension in the summer. It’s going to be an interesting time seeing how they go.

It’s going to be a toss up between a Rocket / the RC405 replacement / Yeti AR5C for me I think.

I can read marketing-speak with the best of them, but I can’t see how its as light as alloy, or stiff for the same weight – just not possible, at least with basic level of metal property understanding.

Or is it just trying to be different?

As soon as you compare steel with “alloy”, you lose all credibility, as steel is of course an alloy (of Iron and Carbon amongst other things)

Sorry to be pedantic, but I work in the metals trade and these things are important. 😀

Oh, and back on topic; if the Rocket is as good as the Soul I’ve just bought, then it’ll be hard to resist.

I can read marketing-speak with the best of them, but I can’t see how its as light as alloy, or stiff for the same weight – just not possible, at least with basic level of metal property understanding.

It had me scratching my head too, but it does make sense if the size/shape of the object is already defined (the seatpost) then the steel one will end up stiffer. Aluminium makes stiffer tubes where there are no such constraints, eg downtubes as you can make a big aluminium downtube without adding weight or sacrificing stength. Which leaves you with 2 options, build the whole front triangle from steel (cotic), make it from non round tubes (monocoques like the MK2 spesh enduro, intense M1 etc), have a big CNC machined pivot/BB assembly (lots of people) or go for something inbetweeny like a hydroformed seatube like my pitch has (round at the top, but a bigger/chunkier square section down by the pivots.

This also disproved the ‘steel hardtails are more comfortable’ statement as the chain and seatstays are pretty well defined sizes, having to fit between tyres and chainrings etc. It’s all in the shaping of the stays (eg hourglass seatstays) and 27.2 seatposts.

So cotic’s solution might not be the lightest (although it’ll probably be lighter than a lot of aluminium 150mm frames), but is probably by far the simplest (other than ignoring the problem and accepting a flexy frame), which makes it good engineering in my book.

This also disproved the ‘steel hardtails are more comfortable’ statement as the chain and seatstays are pretty well defined sizes, having to fit between tyres and chainrings etc. It’s all in the shaping of the stays (eg hourglass seatstays) and 27.2 seatposts.

But does it? The seatstays on the Soul are under 20mm diameter, the chain stays little larger (though ovalised). There’s plenty of room for significantly bigger stays – and as the relationship is quartic you only need to increase the diameter by 20% to double the second moment of area. Not as much wiggle room on the seat tube but certainly enough to make a big difference. Also, with these smaller diameter tubes the wall thickness has a greater effect upon I.

It’s not like steel hardtails are more comfortable in a suspension manner anyway, more that they damp the high frequency buzz, and that’s something you notice in your feet and hands when descending, when you aren’t (I hope!) sitting down.

The seatstays are a contributing factor, and as menitoned, it doesn’t have to be much size increase to get big stiffness increases. Remember that aluminium is much thicker walled as well as bigger diameter too. It is only part of the story though, as the front triangle has quite a big impact on how comfortable a bike feels by the way it flexes and allows the bike to ‘breathe’ with the trail. It’s not just vertical impacts that make a bike feel comfortable, it’s also that slight give along the length, the slight moulding to the terrain which makes it easier to ride.

As soon as you compare steel with “alloy”, you lose all credibility, as steel is of course an alloy (of Iron and Carbon amongst other things)

Didn’t realise the Pedants were in…, and I used ‘alloy’ in its general sense, to mean ‘aluminium’ (I did use to work for Alcan).

Good of Cy to pop up, and as we are moving to a rocky area in the summer, maybe an FS will be better for me than my current Ti HT. And happy to be proved otherwise that its more than marketing speak.

The seatstays are a contributing factor, and as menitoned, it doesn’t have to be much size increase to get big stiffness increases.

Which ironically is why I couldn’t get on the the Mk1 BFe I owned. I don’t think I’d have broken it in a million years, but the seatstays were enormous! Ghengis Khan was known to be more forgiving…

Loving the look of the Rocket though, and if it rides as good as it looks it will sell out in no time… Oh, and please for god’s sake, stop sending me emails with Stainless Steel Frames in! I was dribbling for hours… I don’t think I’d actually care how it rode, when it looks that good!

Didn’t realise the Pedants were in…

Hi there, you must be new. Welcome to stw!

Did we ever resolve the whole “position of brake mount affects braking” argument?*

*by which I mean “did anyone convince me?”, and I don’t think so.

boriselbrus – Member

As soon as you compare steel with “alloy”, you lose all credibility

Not really, it’s just a linguistic shortcut. My 456 isn’t made of “carbon” either 😉

Not really, it’s just a linguistic shortcut. My 456 isn’t made of “carbon” either

Arrgghhh, no it isn’t. “Ally” is a linguistic shortcut. “Alloy” is a specific term which could equally apply to steel, aluminium, magnesium or titanium when used in a bike frame material context.

Sorry, I know I’m being pedantic, but in the industry I work in, “ally” is frequently used as a shortcut for aluminium. “Alloy” is never used as it could mean pretty much anything. And yes, referring to aluminium alloy wheels on cars makes me get equally irrationally irritated!

boriselbrus – Member

Sorry, I know I’m being pedantic, but in the industry I work in, “ally” is frequently used as a shortcut for aluminium. “Alloy” is never used as it could mean pretty much anything.

That’d probably be dead relevant if we were having this thread on metaltrackworld.com.

I agree it wouldn’t be relevant on most threads but when you are arguing the differences of steel versus alloy when steel is an alloy I’d say it is pretty relevant.

moby – hence the 19mm round stays on the current BFe!

cynic-al – I think I explained somewhere else, but if you’re not convinced, come and ride the bike. The braking’s really neutral on the back of the bike. It’s noticably better than quite a few bikes I’ve ridden, and due to the work I’ve done with moving the brake caliper around I’m sure it’s a real effect.

Were you influenced by Guy Garvey, Cy?

Edit – and Hijack – I’ve just had my Mk1 Soul powdercoated in Matt Black and it’s officially the best looking bike ever. But as I’m now dodging all the mud and puddles it’s totally ruined the riding experience.

brake calipers should go at the bottom of the whhel to lower the c of g

nuff said

LOL @ compositepro! Good point.

BigJohn – Member
Were you influenced by Guy Garvey, Cy?

Edit – and Hijack – I’ve just had my Mk1 Soul powdercoated in Matt Black and it’s officially the best looking bike ever. But as I’m now dodging all the mud and puddles it’s totally ruined the riding experience.

Picture? you’ve got to come up with the proof, we can’t just take your word for it now, can we?