Steel Full Suspension Bikes

My Banshee Rune and Transition Scout weighed as much as my Cotic Flaremax for sure. My Scout had carbon wheels and everything. For me, the weight is absolutely worth it – the Cotic makes me go for just one more lap all the time, it’s a lot of fun.

Having to write marketing blurb to sell your products doesn’t mean that the engineering behind them isn’t true. I know that all too well – I’m currently trying to translate a patent onto a new consumer product into press releases and website content.

all I really wanted to know was if the weight burden of a steel FS was worth it in terms of ride and performance in the ‘real world’.

It doesn’t work like that. Cotic make nice riding bikes that happen to be made of steel. Other manufacturers make nice riding bikes out of other materials. I don’t think steel bikes are inherently superior, it’s just another choice.

after that conclusive test it’s obvious

a crosser is cheaper

a crosser is faster

Didn’t Gee Atherton race Dave Knight down the Fort William track, Gee won by quite a margin. Dave reckoned it would have been closer on a 125 as there was nowhere to use the power anyway.

Does the fact that the Cotic FS bikes have an alloy, not steel, rear end have any bearing on this sciencefest of a thread?

TBF Cy does address this in his (selectively quoted throughout this thread) article.

Paraphrasing massively again; the general goals are some degree of weight saving, stiffness to improve the rear suspension motion and pivot alignment/wear hence an aluminium back end and an increase in the diameter of the steel seat tube (which is subject to the most torque).

And then as a wee bit of what you might call “lateral compliance” betwixed the head and seat tubes is desired, a minor weight penalty is paid for a steel front end, but equivalent strength is obtained when compared to larger dia, thicker walled (hence stiffer) aluminum…

TBH it’s a fair proposition, an FS frame that uses different materials for different components based on the different requirements for each part rather than just using the same material throughout. It’s an approach common in lots of other applications (including motor vehicles and motorsports). It’s also notable that some other, bigger bike manufacturers are now mixing welded aluminum front ends with composite swing arms…

People seem to have become a little too caught up with the “material” rather than the function the whole system is trying to achieve…

TBH I’m pretty sure most people lack the sensitivity to actually perceive much difference. That doesn’t mean it’s not there or indeed benefits the rider, but maybe it’s simply better to ride the bloody thing and decide if it’s “right” on that basis, Marketing and Engineering be damned…

OP – the only way to really answer your question is to ride one. Steel has advantages and disadvantages, as do all other frame materials. Geometry, however will be a much bigger factor in how a bike rides. And the weight burden might be 500g or it might be 2kg, how important that is depends on what riding you do. Also weight in the frame is a much better thing than weight elsewhere, you’ll find with a heavier frame the suspension is able to perform better. It might seem a simple question but it’s not a simple answer, and truthfully the only person who can answer it, is you.

Make a list of bikes, and try and get demos on them. Only then will you know if you prefer steel to carbon to alloy. But don’t forget that frame material is just one factor in making a bike.

I’m pretty sure most people lack the sensitivity to actually perceive much difference.

They are probably not woke enough to breath with the trails.

Does the fact that the Cotic FS bikes have an alloy, not steel, rear end have any bearing on this sciencefest of a thread?

Half the rear end, alu chainstays and steel seatstays.

They are probably not woke enough to breath with the trails.

I suppose you deserve some credit for staying here making lame attempts at jokes instead of just disappearing after you got so comprehensively owned.

It’s posts like this that support the view that STW is full of d!cks

The OP asks a sensible question – some people give valid opinions – then someone pops up with no experience but lambasts all other opinions as invalid

cue two pages of rants (in between several reasonable posts) and the OP leaves none the wiser

mumsnet anyone?

So what’s the benefit of steel FS over carbon or ali on a trail come XC type bike?

That was the op’s original question tmb467. And it can’t really be answered. Steel can be used to make a great bike as can other materials. Everything is just personal preference.

All the chat though is just how forums are, “talking shops” where people can argue and express opinion, that’s the point of them.

I’ve recent purchased a short travel steel FS in the form of a Swarf contour, I bought one because the design features in my opinion are well thought out for the type of riding I do, I test rode one and it felt awesome and it feels right to support a smaller UK bike designer that’s handbuilding in Scotland,.Oh yeah and its **** beautiful.

Whoever said that people buy with their heart was right, there are many aspects to what makes a great bike..what they are constructed of is just one factor. If the latest Santa Cruz carbon bling is your things knock yourself out, they just dont ignite any passion in me…I prefer steel, just because. Go ride one and make your own mind up.

For what its worth: I didn’t rate STW Wills Contour review, Trevor@ Enduro Mag review was more inline with the bike I test rode.

Well let’s have some pics then!

https://www.instagram.com/p/Bn_iaGuBhLx/?utm_source=ig_web_copy_link

Work in progress.

With the paint and bits on, you big tease

All in good time my man,.. it’s still getting the finishing touches @Swarf( and I’m still arseing about collecting parts)

Joe from Starling explains frame stiffness and why a bit of give us better. He’s an aerospace engineer with lots of experience with Carbon fibre, so probably knows what he is on about.

I have a Swoop on order, the custom geometry was a big thumbs up but as I approach middle age and have a bit of arthritis I wanted a more compliant frame than my usual super stiff alloy bikes. That’s what made me look at steel.  I have been impressed by the feel of my steel hardtail and wanted a full sus version of that.

I had never thought about lateral stiffness before I saw this video but it makes sense………..we shall shall see!

Lhttps://m.facebook.com/story.php?story_fbid=1380399148727271&id=593631864070674&refsrc=https%3A%2F%2Fm.facebook.com%2FStarlingCycles%2Fvideos%2F1380399148727271%2F&_rdr

That starling video is irritating me.

A force at 45deg is 1/√2 =0.707, not a half, that would be 30deg?

He’s right though, there isn’t a quantifiable optimum (that’s known of anyway), but some is better than either none or too much. Even the big brands are realising this, saw a press release the other day claiming the new bike was indeed less stiff than the old model.

Hols2’s car analogy is wrong on two points, one a car can control its suspension in all sorts of axis and angles, a bike just has a 2d axle path and axle rotation, a car has vertical, lateral, fore/aft, axial and camber components to it’s movement. So a lot of the sideways give is already there. Secondly cars have rubber bushes designed to take out the small high frequency movements which effect grip. Cars without bushes or with stiffer bushes trade more feedback for less compliance.

Secondly cars have rubber bushes designed to take out the small high frequency movements which effect grip.

Road cars do this to reduce noise, vibration, and harshness, not for grip. Race cars don’t do this. One of the first things that production car racers do is to replace the rubber bushings with rose joints, which have no give. This makes them unbearably noisy because all the vibrations from the road are transferred directly to the cabin. The other big thing with turning a road car into a track car is a roll cage, which will be attached to the suspension pick ups to increase the stiffness of the body shell. Of course the rules require a cage on safety grounds, but the main concern in designing the cage will be maximizing the stiffness of the body shell. Suspension performance is improved by mounting the suspension to very rigid mounts. You want the springs and dampers to control the movement of the wheels, not flex in the chassis or bushings.

That starling video is irritating me.

A force at 45deg is 1/√2 =0.707, not a half, that would be 30deg?

He’s right though, there isn’t a quantifiable optimum (that’s known of anyway), but some is better than either none or too much. Even the big brands are realising this, saw a press release the other day claiming the new bike was indeed less stiff than the old model.

Hols2’s car analogy is wrong on two points, one a car can control its suspension in all sorts of axis and angles, a bike just has a 2d axle path and axle rotation, a car has vertical, lateral, fore/aft, axial and camber components to it’s movement. So a lot of the sideways give is already there. Secondly cars have rubber bushes designed to take out the small high frequency movements which effect grip. Cars without bushes or with stiffer bushes trade more feedback for less compliance.

Maybe you should offer Joe the benefit of your far superior engineering knowledge? He seems pretty open to input and maybe he could learn a thing or 2 about frame building from you?

Hmm that said, his bikes do get rave reviews for both build and ride quality and he used to be an aerospace engineer so maybe he knows his stuff after all?

his bikes do get rave reviews for both build and ride quality

The disagreement here is not about ride quality. It’s about the claim that a steel frame will flex so much that it will enhance the ability of a 6″ travel suspension frame to keep its rear wheel tracking the ground. That’s marketing bollocks.

The frames are steel because they’d have to be built in Asia if they were aluminium, so the marketing benefit of a boutique brand would be lost. To make a steel frame as stiff as an aluminium one would be very heavy, so the marketing guys came up with “breathing with the trails” as a “it’s not a bug, it’s a feature” comeback.

You can change the feel of a bike by changing tyres, tweaking tyre pressures, adjusting spoke tension, changing wheels, adjusting the suspension air pressures/spring rate/preload/damping etc, changing handlebars and grips, changing seatpost and saddle, etc. Unless you do really exhaustive comparison testing of all those things to isolate the effect of the frame material, you really don’t know what it is that’s causing one bike to feel harsher than another. FFS, if you change the tyre pressures by 5 psi, the bike can go from horrible to great and vice-versa.

I did ask kelvin to post his notes from all his exhaustive testing of prototypes, but he must have been busy, I haven’t seen anything yet.

On a two wheeler when it leant over the bump forces will be vertical but the suspension travel will be  at an angle.  Especially with telescopic forks this leads to binding in the suspension components and thus reduced small bump compliance

Racing motorcycles found this to be a limiting factor quite a while ago and had to actually reduce stiffness in frames as the superstiff frames they had developed led to adverse effects when hitting bumps when leaned right over – mainly chatter IIRC

Of course this is also exacerbated by the very low profile tyres used which have greater lateral stiffness

This effect must be present in MTBs to some extent – whetherit actually affects most of us I doubt.

So some lateral flex in frames will certainly have an effect on  feel and performance when hitting bumps when leaned over and may well make it feel less harsh

My ti bike is incredibly harsh showing its not all about materials by any means – it has short thick and straight chainstays and seatstays which is where the harshness comes from.

I just love the slim and simple shapes of steel frames and I particularly like the way the top tube and seatstays line up on the Contour, beautiful. And I also like the idea of owning a bike from a British company. But I’m a tight Yorkshireman so I’ll be sticking with my MK1 Rocket till there are more on the 2nd hand market…

And I’ve got a City and Guilds in hairdressing so I’m qualified to judge style, shape and colour 😉

I just love the slim and simple shapes of steel frames

When I’m riding a bike, I don’t care how it looks. I’m the guy with zip ties holding all the brake hoses and gear cables on because it guarantees they stay put even if it looks like shit. I do enjoy nice looking bikes, but only for looking at, not for riding. The point here is that people are spouting marketing bollocks about steel frames improving the ability of the rear suspension to keep the wheels tracking the ground because of “breathing with the trail”. I call bullshit on that and I’m still waiting for kelvin to post his extensive notes from all the prototypes he rode while perfecting the breathing thing.

The frames are steel because they’d have to be built in Asia if they were aluminium

no they wouldnt orange build a shedload of non steel frames maybe someone should tell them

Orange build their frames by welding together pieces of sheet metal. They don’t do the complex hydroforming stuff that the Asian manufacturers do because it would be mega-expensive to tool up for that. Correct me if I’m wrong, but I think Cotic have their aluminium rear ends manufactured in Taiwan. Building aluminium bikes is a bit trickier than steel, AFAIK, so doing the aluminium bits in the UK would need investment in factory equipment beyond what is needed for steel. Hence the outsourcing to Asia. It’s not that it can’t be done in the UK, it’s just that it wouldn’t be economical for a boutique manufacturer.

Maybe you should offer Joe the benefit of your far superior engineering knowledge? He seems pretty open to input and maybe he could learn a thing or 2 about frame building from you?

Very little idea about frame building, its the trigonometry that I think is wrong. A force applied at 45deg is balanced by two forces at 45deg to it but perpendicular  to each other equal to 1/√2 of the original force.

Also if you were to measure forces in a corner you would have gravity (vertically down), the cornering force (centripetally) on top of that, and impacts from the ground at any angle (they might be vertical, they could be horizontal in any direction)

“It’s about the claim that a steel frame will flex so much that it will enhance the ability of a 6″ travel suspension frame to keep its rear wheel tracking the ground. That’s marketing bollocks.”

If you remove your massive head from your arse, take your blinkers off and actually try to learn something, you’ll quickly find that the chassis stiffness is critical to the handling behaviour of ALL vehicles and for two-wheeled vehicles it is an established fact that too much longitudinal torsional stiffness has a negative impact on cornering grip and predictability.

Just actually THINK about it. What the hell do you think happens when you take a 3kg frame made of carbon, aluminium or steel, attach it to some wheels and then have 80+kg of human levering most of their mass through a lever attached to the BB, lean it right on its side so the suspension isn’t working in the right direction and then hammer it through a bumpy corner pulling well over 1G? I mean, how obvious is it to anyone with an ounce of engineering intuition that the frame will flex and twist and that that will help it grip the ground?

I’m no great rider and I can tell the difference between 20 and 22psi in my front tyre, it’s really obvious. And that’s on a bike with 160mm forks. Watch a super slow-mo of a DH bike in a corner and it’s twisting and bending.

This NOT about steel vs other materials – it’s about how you use them. Steel is vastly stiffer than aluminium as a material. A bike that is too stiff is not good in rough trails. The fork needs to be stiff not to bind. The rear suspension components need to be stiff and only move as designed. But BB to head tube needs to have some perceptible give under riding loads.

I will never cease to be amazed at how some people struggle to understand the complexity of real world scenarios. I mean, if you’ve got 160mm of travel why does the tyre pressure matter, or the wheel stiffness, or the bar stiffness or the grips? Come on, wake the **** up!

All the cotic frames up until this one weren’t UK made, so on that front they could have had them made from aluminium if they wanted. Their first FS bike was aluminium, so they could have had them made from aluminium if they wanted. There’s clearly something about the steel beyond ‘make it in the UK’. From the original rocket tech stuff it’s initially about getting the main pivots/seat tube stiff enough, but you’re perhaps a bit off saying it’s just about UK manufacture.

The combined forces must run from the center of mass to the tyre contact patch otherwise you would fall off. Unless your body is massively misaligned with the bike (i.e. you have the bike vertical and your body hanging off to the inside of the corner), the forces in a corner will still be running close to through the centerline of the bike, so the suspension and frame shouldn’t be twisted massively.

If you have the bike leaned right over and hit a bump hard enough to twist the frame to the same order of magnitude as the suspension travel (i.e you are cornering on the flat with the bike laid right over and run across a large root or rock), then you have awesome ninja MTB skills and I don’t think it will make any difference whether you ride a steel or aluminium frame. I’m just a mere mortal, so trying something like that would see me skidding down the trail on my arse.

“Unless your body is massively misaligned with the bike (i.e. you have the bike vertical and your body hanging off to the inside of the corner), the forces in a corner will still be running close to through the centerline of the bike, so the suspension and frame shouldn’t be twisted massively.”

There’s your first mistake. When you ride a turn on a MTB the bike is leant over further than the rider and the rider places most of their weight through the outside pedal and the inside grip. A good rider will constantly weight and unweight the bike to find grip, unloading before turning and then placing maximum load at the moment of highest lateral acceleration. That’s how you corner fast, you generate momentary downforce when the most grip is needed. You cannot do this as effectively if your centre of mass stays in the same plane as the centreline of the wheels.

“If you have the bike leaned right over and hit a bump hard enough to twist the frame to the same order of magnitude as the suspension travel ”

The twist in the frame doesn’t need to be of the same order of magnitude as the suspension travel for it to matter. Not even close. How much does a DH tyre carcass conform mid-corner? And yet riders care about their tyre pressure to less than 1psi?

If you have the bike leaned right over and hit a bump hard enough to twist the frame to the same order of magnitude as the suspension travel

…your bike is broken. Try another straw man… or except that, no matter what the material, stiffness in different parts of a frame are often tuned, rather than the same ultimate stiffness all around being the goal.

It’s about the claim that a steel frame will flex so much that it will enhance the ability of a 6″ travel suspension frame to keep its rear wheel tracking the ground.

That’s not what’s being claimed, really.

Suspension only moves up and down, not side to side.  When riding down a rocky trail, the rocks aren’t all neat perpendicular steps – they are strewn haphazardly all over the place.  The surfaces your wheels hit are sloping at all angles.  These will present sideways forces to your wheels.  Much of that is absorbed by tyres and probably most of it by the rims.  That’s why many complain that carbon wheels are ‘too stiff’.  If too much of this sideways force is transmitted to the bike it’s going to be pulled sideways all over the place as you ride.  From your moving frame of reference, this would feel like the bike being pulled all over the place.  On a suspension bike the swingarm probably twists about the fore-aft axis too, which would also absorb some sideways impacts. When the bike is leant over, this flex would also be helpful in stopping the bike jumping around too much.  I’m guessing this would be the biggest but not the only advantage of having a little twisting flex available in the frame.  I’m sure there are videos somewhere of frame flex in a FS.

I am not an engineer but I do have a Physics degree.  And whenever someone makes absolute pronouncements like you have hols2 I am immediately sceptical!

EDIT That’s not to say that stiffness wouldn’t give benefits elsewhere – like power transfer when pedalling etc.  So it comes down to where you ride and what you like.  Just test the bike and pick the one that feels best.

You cannot do this as effectively if your centre of mass stays in the same plane as the centreline of the wheels.

The center of mass of the combined bike and rider has to stay reasonably closely aligned with the tyre contact patches or else the bike will rotate around the contact patch and you will crash. You adjust for small changes in this over bumps through the steering and adjusting your body weight, but you can’t have the sum of the forces massively misaligned or you will crash. That’s just brute physics.

My scepticism is that the flex in a steel frame will be so much bigger than in an aluminium or carbon fiber frame that it will assist the rear wheel in tracking the ground in a bike with 6″ of rear suspension travel. I’m not saying frames don’t flex, just that they don’t flex several inches. I’m also not saying that the resonance properties aren’t different, just that I don’t believe that the supposed extra flex in a steel frame is going to have a positive effect on the rear suspension.

How much does a DH tyre carcass conform mid-corner?

A lot more than a steel top tube does. Watch some videos, it’s amazing how much tyres roll around. Or just pump your tyres up to 100 psi and see how it feels when they don’t flex.

Although, to be fair, my first suspension bike was a 1999 Spesh FSR. Goddam that thing flexed a lot. Pedalled well, but was always worried it would snap in half. It eventually snapped in half on the cast section at the front of the chainstay, just behind the lower pivot. Great little bike, but that flex was really disconcerting.

I’m not saying frames don’t flex, just that they don’t flex several inches

Well, we can all agree with that strawman. What a waste of time.

Well, we can all agree with that strawman.

That strawman was what the disagreement was about. So when can we expect you to post all your detailed technical records of the prototype testing you like to boast about?

I’ll repeat myself…

I’m a very average rider. My notes would be something like “whoop” or “woah”…of little use to anyone.

Feel free to …

… whatever.

If you want to believe that no one is doing real world testing, including tuning the stiffness of different parts of a frame, no matter what materials they are using, so be it. Why should I care?

So “breathing with the trail” is just some bullshit someone made up?

Edit. Another sneaky stealth edit there kelvin.

Time waster.

So it is just marketing bollocks then?

Descriptive words are wasted on you.