Steel back in the peleton...

[rouxtjie]

Shameless plug for Niner.

 

They order their own "custom" 853 tubes from Reynolds (drawn differently, varying wall thickneses etc.). This to me suggests that Niner have put some thought into the design. Whether that thought translates into a "better" frame is impossible to tell in the real world though.

 

I like the brand.

 

And the colours.

 

:-)

and they put a sick sprayjob on it....winna wena.

[rouxtjie]

Those curved tubes have got to have something to do with it. Form and function blended.

 

The Jones truss frame apparently has amazing ride qualities for a non-suspended frame.

 

Same principles apply.

their spaceframes are beautiful....the truss, my palette is still battling with it I won't lie.

[Eldron]

It some sort of indicator of how much repeated punishment a tube can take below its known breaking point before it starts konking in....like a level of fatigue... I think

 

Ping Ping Ping.....Eldron!!!!!

 

Ok now you've made me access parts of my brain thatb haven't been used in years.

 

Ultimate tensile strength is measured in pressure (mpa, psi, ksi - whatever) and the number is the maximum pressure a standard sample can take before it breaks. Like Christie says - it is almost a meaningless number because by the time the sample breaks it has been deformed irreversibly.

 

A better number is Youngs Modulus - this is the pressure required to deform the steel in the elastic zone (meaning it will return to its original form when the pressure/froce is removed. This is a measure of stiffness - much more relevant to making bicycles.

 

So if the Youngs Modulus of 853 is higher than True Temper (and I think it is) then you can either make a lighter 853 frame that will "flex" the same as the True Temper or a frame that will flex less for the same weight. Make sense?

 

It's all pretty silly really - if we wanted lighter frames we'd buy alu or carbon. With modern hydroforming of alu you can get pretty much any property you want. Same with carbon - because you can make prettty much any shape you want you can get almost any property you want.

 

Steel is silly but fun.

[rouxtjie]

Ok now you've made me access parts of my brain thatb haven't been used in years.

 

Ultimate tensile strength is measured in pressure (mpa, psi, ksi - whatever) and the number is the maximum pressure a standard sample can take before it breaks. Like Christie says - it is almost a meaningless number because by the time the sample breaks it has been deformed irreversibly.

 

A better number is Youngs Modulus - this is the pressure required to deform the steel in the elastic zone (meaning it will return to its original form when the pressure/froce is removed. This is a measure of stiffness - much more relevant to making bicycles.

 

So if the Youngs Modulus of 853 is higher than True Temper (and I think it is) then you can either make a lighter 853 frame that will "flex" the same as the True Temper or a frame that will flex less for the same weight. Make sense?

 

It's all pretty silly really - if we wanted lighter frames we'd buy alu or carbon. With modern hydroforming of alu you can get pretty much any property you want. Same with carbon - because you can make prettty much any shape you want you can get almost any property you want.

 

Steel is silly but fun.

again...great post. I gets it now.

[Eldron]

again...great post. I gets it now.

 

Good because my brain hurts. It gave up that info relucntantly!

[Chro Mo]

again...great post. I gets it now.

+1!

 

love these discussions!

[Christie]

Yield stress & Youngs Modulus are good parameters to compare imo.

[GoLefty!!]

It's all a bit romantic in my opinion. There is not doubt that alu and carbon are both better materials for making a bike. I'm just getting old and harking back to days gone by :-)

 

 

How are aluminium and carbon fibre "better"? is this the lighter stiffer arguement again?

[GoLefty!!]

Yea from what I am reading it seems to be much of a muchness, where lots of custom US builders are switching over to OX Platinum...lots of people thought it was because OX was better, more rust resistant blah blah blah, turns out it was because of the exchange rate and with reynolds(british company) you dealing in pounds / euros and with OX(american) you dealing in dollars. Seems like there is nothing between them, both can be drawn thin and have air hardened properties.

 

PS, but it seems some of the manufacturers are sneaky russians though, they would proudly put the reynolds or TT sticker on the frame, but only build the main triangle out of it and use 4130 or high tensile for the rest....blixems

 

 

This is not a new practice and harks but to the days when "steel was real". Many 853 bikes had 501 or 531 rear triangles and many True Temper and Columbus frmaes used straight gauge rear stays (Chain and seat)

[Eldron]

How are aluminium and carbon fibre "better"? is this the lighter stiffer arguement again?

 

Yup. That and almost infinite design capability.

No corrosion.

Thicker sidewalls allows for more forgiving manufacture.

More suppliers.

 

It all depends on what you consider "better"...steel definitely has its place but that place is not top level racing.

[rouxtjie]

 

 

 

This is not a new practice and harks but to the days when "steel was real". Many 853 bikes had 501 or 531 rear triangles and many True Temper and Columbus frmaes used straight gauge rear stays (Chain and seat)

I believe so, I would still like a bike that is completely made from one type, maybe just from a completeness point of view...damn OCD

[GoLefty!!]

these days if you want a full 953 or OX, or even 753 or whatever you will have to go the custom route.

Even with carbon bikes, the manufacturer will seldom use the T1000 Toray Carbon fibre in the whole frame. Its used mainly in high load areas where wall thickness needs to be kept low. then even will carbon there is even less guarantee that what they said is in the frame is actually there...

Despite Carbon's great properties the failure rate on frames is still too high with cracks being common and this is partly due to the unforgiving nature of carbon to structural damage.

 

Aluminium. yeah easier to form than steel but requires mor eenergy to manufacture and process. Sureits light but the grades used for bicycle manufacture have poor fatigue resistance and the designer compensates by making it lighter and stiffer. they then resort to fancy tube shapes to change the vibration pathways tp get some level of comfort back but by and large they fail miserably.

 

So I'll go outon a limb and say that I disagree tht steel has no place in the toplevel racing. I beleive that it does have a place especially for races like Paris Roubaix and other classics. Perhaps the extra half kilo in weight is not ideal for long days in the mountains, but the ride quality and forgiving nature of a steel frame is ideally suited to longer flatter stages. I also don't believe the weight give away is a significant part of the total mass to be propelled. Steel frames have competed favouraly against carbon frame in past TDF e.g. 1990 where Miguel Indurain rode a Steel Pinarello Prince againsts LeMond on a TechnoVitesseTubi TVT (Now Time).

 

The frame material is not the most important aspect of a race frame design.

[Eldron]

these days if you want a full 953 or OX, or even 753 or whatever you will have to go the custom route.

Even with carbon bikes, the manufacturer will seldom use the T1000 Toray Carbon fibre in the whole frame. Its used mainly in high load areas where wall thickness needs to be kept low. then even will carbon there is even less guarantee that what they said is in the frame is actually there...

Despite Carbon's great properties the failure rate on frames is still too high with cracks being common and this is partly due to the unforgiving nature of carbon to structural damage.

 

Aluminium. yeah easier to form than steel but requires mor eenergy to manufacture and process. Sureits light but the grades used for bicycle manufacture have poor fatigue resistance and the designer compensates by making it lighter and stiffer. they then resort to fancy tube shapes to change the vibration pathways tp get some level of comfort back but by and large they fail miserably.

 

So I'll go outon a limb and say that I disagree tht steel has no place in the toplevel racing. I beleive that it does have a place especially for races like Paris Roubaix and other classics. Perhaps the extra half kilo in weight is not ideal for long days in the mountains, but the ride quality and forgiving nature of a steel frame is ideally suited to longer flatter stages. I also don't believe the weight give away is a significant part of the total mass to be propelled. Steel frames have competed favouraly against carbon frame in past TDF e.g. 1990 where Miguel Indurain rode a Steel Pinarello Prince againsts LeMond on a TechnoVitesseTubi TVT (Now Time).

 

The frame material is not the most important aspect of a race frame design.

 

Great post - agreed on most points (not sure about referencing steel versus carbon 25 years ago though ;-)

 

Agreed - alu is the harshest of the 3 materials. One man's harsh is another man's stiff though - more energy into going forward and less into bending the frame. Swapping comfort for speed - a racers perogative. Alus biggest drawcard is its price - way cheaper than the other two. This is why Mr. Joe Average will own alu. Makes sense.

 

I actually agree with you on the Paris Roubaix example. It's difficult to quantify how much time you lose due to being "beaten up" by your frame and I do think it's a number that people under estimate. In a typical ~60km mtb race like the Nissan series etc I think many people would be happier on a steel bike than alu even if they were a bit slower. Unless you're a proper hardcore racer steel deserves a good look (cost permitting of course).

 

It would be interesting to see what the material of choice would be if the UCI raised the minimum bike weight to 8kg. More money would be spent on efficiency versus comfort/lightweight versus comfort etc.

 

I completely agree on your last statement though and unfortunately this is where steel falls way short of the other two materials. The best you can do to steel is butting and some tube ovalization (any more than that and the engineering hours and cutting/welding are insane). Tubes are not the best bike shape because they have similar properties in all directions - in a bike you want vertical compliance with horizontal stiffness (and a variety of other things like compliant seat stays but stiff chain stays, rigid head tube but compliant fork etc). Carbon has almost limitless shapes and kicks alu and steel to the curb in design capability.

 

All my opinion of course - I'm a newly reformed carbon or steel man. I have one alu bike left - a hectically rigid Fuji track bike which turns an already bumpy Hector Norris park into a kidney battering day out.

[Kiwi]

Interesting article about steel in bikes by Cy Turner - Cotic Bikes.

 

Why steel?

 

Cy is a qualified Chartered Mechanical Engineer with 18 years experience across the railway industry as well as in bicycle design.

 

One of the most notable features of the Rocket is its choice of material. Up to a point I've been expecting rolling of eyes and 'what of have those silly steel sniffers at Cotic gone and done now?' and 'why on earth would you use steel on an FS bike? It'll be flexy and heavy, surely?' type questions. I'll be honest with you, before I started this project I'd have been right there with you if someone else had built a steel FS bike. Although we love steel for our rigid frames, the Hemlock was aluminium because, well, that's what you make full suspension frames out of, right? I'd not challenged assumptions at all with that bike, I'd just done what everyone else did. And that was the plan when the Rocket project kicked off. I was focusing on geometry and suspension feel and all the other improvements that I've talked about in the other essays I've written recently. But a couple of things made me challenge those assumptions.

 

Firstly, I'd come back from the trade shows in late 2009 quite disillusioned with the road bike market of all things. At Eurobike there was all the usual carbon loveliness and aluminium swoopiness, even a bit of ti, but anything steel and skinny tyred seemed to be trying incredibly hard to look like it'd been built in a shed in Italy in 1953. It made me sad, because I do love steel as a material for rigid frames. Despite the fact that any frame made from steel would be heavier than the above materials I felt that no one building something modern and forward looking in steel on the road was doing the material, and its fans, a disservice. You could build a road bike with lovely feel and durability at a great price and I thought there was a gap in the market, so I designed a road frame to fulfil this brief. Although we've not moved that project much further forward, I'm really pleased to see that Condor have taken the batten and run with it with their Super Acciao. What this highlighted, when we were talking about the road project, was that what we appreciated about steel: its durability, its strength, its feel and the look. I guess you could say there was an element of dogma involved, but it wasn't that there were no advantages to using steel, it's just that weight wasn't one of them and we liked the other upsides.

 

Secondly, as I was kicking around the specification of the new bike with some of the guys I ride with, and one of them asked why I didn't just start with a BFe front end and graft the suspension onto that. His point being that, with its 35mm seat tube and other large diameter tubes, it's incredibly tough and strong and not exactly a shrinking violet when it comes to stiffness. With my firmly held assumptions I dismissed this out of hand, but when I mentioned it to Paul (Cotic's organiser extraordinaire) he reminded me of our conversations about road bikes and asked why I hadn't looked at it harder, so now my bluff had been called!

 

It was time to do some numbers and justify myself properly. Remember, 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 its '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' heaviers 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 its 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.

 

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. I also have to come clean at this point and also admit that I love how it looks too. There, I said it.

 

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. 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. So whilst the Rocket is a great use of the material, we won't be dogmatically using steel for all the other suspension projects we're working on. Just as with the Rocket, I'll sit down and do the numbers and make an informed choice, only this time I won't need pushing into it by other people ;-)

Edited February 11, 2014 by Kiwi

[GoLefty!!]

Nice article. He could over coem the weight in the swin arm components through using sheet materials and form it either via Hydro forming or HERF. Cost goes up of course, massively but its a design vs cost challenge, nothing more.

[Eldron]

Interesting article about steel in bikes by Cy Turner - Cotic Bikes.

 

Why steel?

 

 

Awesome article. My initial instinct was always that alu was best for duallies because the harshness of alu didn't matter - stiff base with good suspension makes for a good bike!

 

I would have liked him to add some numbers to the "not a bad weight penalty" though - normally when people give actual numbers and science for the pros and vague words for the negatives the negatives are bigger than they are letting on ;-)

 

 

Edit: Whoa - it weighs 3.5kg...

 

 

Also not sure about the diameter limiters - you can make some big ass diameter tubes on dualles - Cannondale have been doing it for years.

 

The theory is sound though - large diameter steel tubes can be hectially stiff (with a weight penalty of course).

 

Nice looking frame! I really enjoy straight gauge simple tubing...

Edited October 3, 2013 by Eldron