Descriptive words are wasted on you.

No, nothing will be wasted. They will be saved and recycled. Fire away.

This thread has reminded me that I used to really enjoy long analytical debates about how mountain bikes work (or don’t). Since getting the FlareMax though, I find that I’ve lost all interest. I don’t know why it works. I’m not entirely convinced that Cy fully understands why it works. But work it most definitely does.

Are all great mountain bikes made of steel? Of course not. It just so happens that in over 40 years of riding all my favourite bikes (road, hardtail, fat and now full-suss) happened to be steel. But that may be coincidence or it may be that I like the look and that biases me towards them. Either way, I’m prefectly happy to accept that there are great bikes made of aluminium, carbon and titianiun and if that’s your bag, knock yourself out.

I can’t really adress the OP’s original question though as I can’t really understand why anybody would care about 2lb here or there on the frame weight. My weight varies by that much from day to day (and during a day). Heck it probably varies by that much during a long ride (and more when you factor in the water that I’m drinking), yet I don’t notice it. So it’s not a matter of whether the “advantages” of steel outweigh the weight penalty for me as the weight penalty is simply too small for me to be able to detect. Getting the right tyres, the right pressures and getting your suspension set up properly for the trails you are riding are all so much more important that a few lb on the weight of the bike.

Fire away.

Others have tried, I’m not bothering to waste any more time on you.

I can’t really understand why anybody would care about 2lb here or there on the frame weight.

This has been done to death. You don’t notice it much on your body but it is noticeable to many people on the bike due to the way some people move the bike around as they ride. To me, 2lbs on the frame is a lot. On its own it’s noticeable but if you want a light bike all the components need to be light. Altogether they make a huge difference. You may not like it, but you might – that’s why there is a choice on the market today. And it’s not a problem.

Oh dear, are you angry about something? Hope it wasn’t anything I said.

I don’t know why it works. I’m not entirely convinced that Cy fully understands why it works.

You haven’t been paying attention. It’s because “breathing with the trail.”

Funnily enough I don’t mind the “breathing with the trail”. Yes, of course, it’s a bit of marketing speak. Trying to use a nice descriptive phrase instead of equally meaningless numbers. But I can kind of see where it comes from. Not that steel bikes are the only ones to do this. My old 26″ Five was a flexy old thing and that was part of its appeal.

@molgrips it’s a fair point. To be honest we’ve probably done most of it to death really. I do think it depends a fair bit on how you ride. I really don’t notice a couple of lb on the frame weight. For example, if I had a bottle on the bike I couldn’t tell (in a blind test) whether it was full or empty. I’m definitely “old skool XC” though. Other people, who throw the bike around more than me, may be able to tell, which is fine. For them, bike weight is important, but for me, it really is irrelevant (within fairly broad limits). Some of my favourite bikes were the heaviest, but again that’s probably because I like bulldozing through suff.

The combined forces must run from the center of mass to the tyre contact patch otherwise you would fall off.

all except bump forces – they art vertically ( or slightly off it the bump is uneven)

All the other forces act thru the line from cog to contact patch but hit a bump – it kicks the wheel vertically upwards.

hit a bump – it kicks the wheel vertically upwards.

Yes, the rider needs to make adjustments to steering and body position over bumpy corners or they will crash. Thing is, we do this without even realizing what we are doing. If we had to do it consciously, we would react too slowly and would crash.

Crikey the Big Hitters have been busy on this thread!

Hols – and that is where lateral compliance in the frame helps the bike be more settled.  As I said above in the motorcycle world they found that you could end up with frames that are two laterally stiff and it led to chatter so ducatis amongst others actually reduced lateral stiffness of their frames to keep the wheels on the ground more.

is the flounce in full bounce you reckon

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

Well of course, but it’s hardly a terrible bit of marketing Woo, I’ve seen worse.

You mentioned earlier that you are a Structural Engineer hols, why not actually analyse the differnces in behaviour of these structural elements?

You could work out the respective section properties for say a 32mm OD / 0.8mm thk steel tube and the same for a 55mm OD / 2mm thk Aluminium tube and work through their respective behavious when subjected to simple bending and torque load cases, just to see how much deflection you’d be likely to see and at what point each tube would go plastic (Say on a 600mm long tube?) work out the weight differences and then at least you’ve quantified the actual differences in structural terms.

How how the properties of a downtube and top tube contribute to a given “Bicycle Chasis” as a dynamic structure has a whole heap of additional analysis for an interested individual but probably massive overkill for anyone not actually making one…

Of course without that comparison you’re simply casting doubt on the claims made by Cotic for the frame without really knowing how it actually behaves…

Personally I don’t believe a bicycle is subject to perfectly symetrical loading in a single plane so there is some merit to the idea that the frame as a structure which provides some degree of elastic response when subjected to side loads or torque along its length may have benefits, or that some elements (say a swingarm) being stiffer than others (say the front triangle) could help the ride in some way… Discuss (even more).

You mentioned earlier that you are a Structural Engineer hols

No, I said I studied engineering. I hated it and got a degree in political philosophy instead, intending to become a journalist. Instead I got a job as a technical writer for a company that had contracts with some well-known Asian companies. My job was to work with engineers who were posted to European subsidiaries and help them sort out their English technical documentation. Not full on technical research, but more like sales material targeted at other engineers. Some of it was cool. I worked with guys who designed nuclear power plants and the control systems for the early Prius, but most of it was mundane stuff like factory automation equipment and car parts. My bosses didn’t know the difference between structural engineering and electronics, it was all just “engineering” to them, so I got all the “engineering” stuff. It was really challenging for a couple of years, I had to sit down and learn the basic concepts of a bunch of different fields, but then it was just soul sucking boring (plus I was working for filthy profiteering capitalist pigs). I lasted six years at that before the boredom got too much to bear. Made me really, really glad I got out of engineering before it was too late. That gave me leads to my current career, which is slightly technical, but not engineering. Basically counting things and doing really simple Excel stuff.

…degree in political philosophy…

In that case (coupled with your meandering career history) I think I’ll just disregard your opinions on pretty much all topics… TTFN.

For example, if I had a bottle on the bike I couldn’t tell (in a blind test) whether it was full or empty.

I could on some bikes I think – funnily enough on my rigid bike I think it’s the most stark.  Given the fashion for going packless and loading up one’s bike I thought I’d try it.  I put two bottles and a seat pack for tools on my rigid (steel) bike with carbon forks, whilst riding around the Ridgeway area.  If you’re not familiar, it’s a by-word for tame non-technical riding which it is, however it’s not quite that simple.  The chalk dries rock hard, and ends up being very lumpy.  So in places you get a lot of very small bumps, sort of like washboard but not.  With the weight on me, I was able to hold the bars lightly and the bike would buck around under me and I could go faster; but with all the weight on the bike it was less able to buck and skip over the bumps so made it far more laborious.  I felt like I was crashing into every bump rather than skimming.

Tangent anyway – it would have been more relevant if I’d compared an alu rigid bike alongside it 🙂

I could tell you what material the bottle cage bolts were 😀

coupled with your meandering career history

I don’t really think of it as a career so much as random leaps towards whatever option seems to involve the least work. On the bright side, I have contributed massively to Wikipedia, so it’s not like I’ve just been wasting time slacking off.

No, I said I studied engineering. I hated it and got a degree in political philosophy instead

Were the philosophy and politics classes done separately? It’s just that you seem to be much better at the latter than you are at former 😆

Is Wikipedia where you found that formulae you keep regurgitating to imply you are an engineering expert?

I am not a genius like you, I am an airline pilot (semi killed manual labourer) but I do know that steel bikes feel really great because they have bit of give in them. So when a frame designer that is infinitely more clever than me tells me the science behind it I tend to believe them.

I have a Starling Murmur , its nice really really nice .

HTH .

https://janheine.wordpress.com/2018/01/28/myth-4-stiffer-frames-are-faster/

https://janheine.wordpress.com/2017/06/06/expert-discussion-on-frame-stiffness/

That point I missed earlier about road cars using rubber bushes to make them lesss noisy may be relevant in this case. Bikes generate very little rumble because they don’t have big resonant panels (apart from Orange 5 swingarms 😉 ) but they will vibrate. And you will feel that vibration through your hands and feet. Will a more flexible frame reduce that?

Fatigue really matters on long descents. That’s why we care about grips and handlebars.

hols2, I’m glad to hear you don’t work as an engineer because you’d be decidedly mediocre at it!

Incidentally, all my bikes bar my Brompton have alloy frames, the old 100mm XC hardtail with toddler seat and the modern 150mm hardtail and 160/140mm full-sus bikes.

I know that a lot of bike journalists write a lot of rubbish but not all of them do. And you will see a theme of them becoming aware of the effect of frame compliance (regardless of material) on bikes, to the point that the ones with more give (but enough stiffness to go where you point them) are highlighted as being better on rough gnarly trails whilst stiffer frames are great park or trail centre bikes but beat you up more on natural enduro style descents. All these journalists can’t be deluded, it isn’t a conspiracy!

And work the numbers out if you can be bothered – it’s pretty much all about downtube stiffness.

I’m starting to think poor hols is just after a bit of attention.

hols2, it is clearly a bit of copy for marketing, that bit about breathing with the trail, copy is copy, it’s not claiming to be a bit of engineering is it? My issue with your output is mostly that you’re contending that there is obective truth, only, and that poetry (as you put it), or even just description, doesn’t express truth. Seems a bit bleak.

Perhaps have a look at some phenomenology – that messes all your claims of objectivity up in one fell swoop. Or read Prufrock, or even better, Four Quartets. That was pretty good at expressing truth when everything was upside after the last world war and no one knew what the point was – kind of like this thread.

Anyhow, my bike’s better than your bike. And the OP should defo get one.

As someone that has the job of doing much of the engineering and writing the marketing copy for another business, if you want to sell a product to a wide range of customers then you can’t describe it as you would to an engineer. And also, if you describe it in precise engineering terminology including giving all the numbers related to the performance, then you make it a damned sight easier for the competition to steal your ideas. It’s a fine line to tread, being honest and convincing and appealing without giving all the proprietary but hard to protect info away: https://barefacedbass.com/ (thousands of words of me doing my best at that).

I like the “fatter warmer mellower and rounder with a nice edge and bite to the treble” bit. Mysteriously  need a speaker that’s taller than me…

https://www.pinkbike.com/news/1992-slingshot-team-issue-now-that-was-a-bike.html

Final Review: Slingshot Ripper 29er Mountain Bike

what is a proper degree these days what are the talking bobbins useless ones where people go to university to study

The only things i have learned in four pages are…..

1: I still think steel full suspension bikes are the best based solely on my riding experience and the fact steel bikes are just  plain prettier.

2: Some of you can’t half waffle on.

3: I really want a go on that Slingshot Ripper

it’s pretty much all about downtube stiffness.

According to the bike designer, it’s about the toptube, not the downtube.

You seem to have overlooked my point, which is that a frame cannot flex to the same order of magnitude as a 6″ rear suspension. I’m not saying steel bikes don’t feel nice to ride, just that a frame cannot flex enough to help a wheel track the ground the way multiple inches of suspension travel do.

So when a frame designer that is infinitely more clever than me tells me the science behind it I tend to believe them.

He’s not telling you anything scientific, he’s spouting marketing bollocks. The next frame designer will tell you the exact opposite and quote some other made up “science”.

Love a bit of steel and really looking forward to a visit to the Stanton HQ to try out and order my new Switcher FS frame.  Just got to decide on the colour

And you are missing the point hols.  Its that few mm of lateral flex that makes a bike feel less harsh and track the ground better when leaned over because at high lean angles the suspension cannot work effectivly

“You seem to have overlooked my point, which is that a frame cannot flex to the same order of magnitude as a 6″ rear suspension. I’m not saying steel bikes don’t feel nice to ride, just that a frame cannot flex enough to help a wheel track the ground the way multiple inches of suspension travel do.”

I didn’t overlook it – I clearly stated that frame flex does not have to be of the same order of magnitude as suspension travel for it to have an impact on handling.

Let me put it another way – what if we make the frame far too flexible? According to your logic, as long as the frame flex is not at the same order of magnitude then it will have no impact on the feel of the bike. So on a DH bike with 200mm of travel the rider will not notice if the bike flexes sufficiently to cause 20mm of vertical movement at the wheels.

Does that sound logical?

I remember ages ago there was an excellent article regarding how frame feel was influenced by resonance and harmonics, but I can’t for the life of me find it.

That said, this article might provide a few clues:

https://www.tms.org/pubs/journals/JOM/0511/Burleigh-0511.html

TJ, this is just the first video that popped up so feel free to link to one that does illustrate your point, but I’m afraid I don’t see where the bike is leaned over so much that the suspension is locking up and the rider is relying on frame flex instead.

Think there’s something along those lines on Jan Heine’s blog jivehoney, he talks about the bike ‘planing’.

More roadie related.

I’m no scientist like some of the Profs on here, but I do know that karters will use different torsion bars on different tracks.  Almost as if the flex had some bearing on handling…

So on a DH bike with 200mm of travel the rider will not notice if the bike flexes sufficiently to cause 20mm of vertical movement at the wheels.

We’re talking about the frame twisting so the wheel can move laterally, not vertically. My point is that that much lateral flex would feel absolutely horrible. Or so I imagine, the only experience I have had that is remotely similar was when the chainstay on my old FSR cracked. It wasn’t too hard to notice that the back wheel was off doing it’s own thing.

karters will use different torsion bars on different tracks. Almost as if the flex had some bearing on handling

Karts don’t have proper suspension, so they use chassis flex instead. In a regular race car, the aim is to have a very rigid spaceframe or monocoque to mount the suspension to, then use springs, dampers, and swaybars to adjust the suspension characteristics. Karters can’t do this so they adjust how the chassis flexes instead. Completely irrelevant.

In any wheel size discussion on FS bikes it’s everyone shouting about racing results, but not so in this thread. Is the enduro/DH racing scene awash with steel framed bikes at the upper levels?

It all gets a bit complex when steel is 3 times stiffer than alu though; I had a steel full suspension bike with a burly steel rear end…

Even though it had a puny by modern standards 135QR axle, it tracked like a downhill bike, with a noticeable improvement in holding a line on off camber sections compared to the alu enduro bike I had before it.

Nonetheless, despite this stiffness, it also had a pleasing level of compliance.

Wasn’t the lightest mind…