what does “STIFF” mean?

Ah, but who’s trolling, and given your serious reply, are you feeding him?

Me and yes.

Full or empty, sfb?

So, the stick is absorbing energy of you pushing it?

We have finally debunked Newton’s 3rd law.

Don’t be a dick. It’s absorbing it by converting it into stored potential energy. Then when you let go, it pushes your hand back.

Try another experiment. Hold one end of a metal bar, and have someone hit it with a hammer, it’ll feel harsh. Now try the same thing with a wooden pole, see if it feels different.

Hey brant – any comments on my serious question about why you’re considering the main triangle front end as a cantilevered beam, and why the seat tube stiffness is important?

Look at the loading on the main triangle. The way the fork tries to rip the front end off under loads. 140character postings only now sorry.

Here is pictures of 2 different seat stays, for arguments sake lets say they are both the same material frames, the same setup tyres etc, the tubing of the frames is exact in every way, diameter, wall thickness everything, the only difference is the bend in the seat stays who believes the curved stays would make the bike ride differently?

Full or empty, sfb?

I’m impressed if you can FILL one :o)

Now try the same thing with a wooden pole, see if it feels different

we’re getting slightly sidetracked here as there are not many wooden bikes made (bar the bamboo ones featured a while back). Wood has far higher hysteresis than most metals.

It’s absorbing it by converting it into stored potential energ

correct, to a point, but then you get it back just as troublesome as before 🙁

who believes the curved stays would make the bike ride differently?

yes, when you get the tyres muddy they’ll clog up like mad on #2

but then you get it back just as troublesome as before

Quite possibly worse. Boing said Zebede.

Did I kill this thread or did it die of natural causes?

Pretty sure the curve in the seat stays is to absorb, deflect,dampen, (whatever term you choose), in any other words, to soften the blow of any irregularities ridden over, Ok its not suspension but that curve is a spring (for want of a better description) to take the shock of stuff your riding over…

If its not curved for that reason then I will eat my springy curvy stayed hat…

Ketchup with that hat?

I’d suggest that based upon your comments, it’s very effective at the reason it actually is like that, at least for some people…

Would you like to re phrase that a bit, not quite sure what you mean?

Anyhow, its the weekend, I am outa here.. enjoy your weekend ride people.

marketing

Damn, got to this thread too late. For what it’s worth I’d say that it’s almost impossible to isolate a single variable in something like bike material and design.

I’m much more inclined to think that changes in tyre pressure of variations in geometry make much more noticeable effects than subtle material changes. Add in the massively variable human that gets on the bike and you’ve got a can of worms. Terrain, temperature, personal muscle fatigue! Do people really think that minor changes in stiffness are going to make immediately noticeable differences compared to these multitude of other factors? Take a step back and think of all the things on the bike and the effect they might have. I’ll willingly concede that some parts of a bike make very immediate and noticeable changes.

I mean for chuff’s sake, my own bike feels massively different every time I ride on the bloomin’ thing, I’m sick of it!

Do people really think that minor changes in stiffness are going to make immediately noticeable differences

‘common sense’ says if you make a change, you should be able to feel it, otherwise, why bother ? This has positive aspects in that, if you can convince yourself that something you have done improves your performance, you may well actually do better, but it’s all too susceptible to superstition and gullibility, and hence religion, politics and marketing 🙁

People are always going on about crank lengths and how much difference that makes, or saddle position, yet I have 2 different length cranks, and have tried sliding my saddle right from one end of the rails to the other without any perceptible difference. Of course, this may just be a matter of non-belief 🙂

There’s more than just the stays to consider tho. There’s the tyres and wheel too. So my guess is that with a flexy rear triangle, the initial hit on a typical rock would send a shockwave up the frame whose initial sharpness would be damped to a greater or lesser extend due to the frame’s modes of vibration absorbing the high frequency component (hence rounding off the square edge). However the rebound could well come when the wheel’s slightly unweighted – since the main part of the impulse has lifted the bike up in the air a bit.. so the rebound could end up being absorbed by the tyre.

My thoughts (and experience) are still that a more flexible rear end (in certain directions) make a more comfortable ride. How would you explain the fact that my mate’s handjob I rode seemed to take the edge of the bumps?

Surely in that case common sense means ‘not thinking things through’, but who am I to judge.

To further cement my viewpoint, despite the fact you’ve nodded your head in agreement. I doubt given the deformation from your own skin and the tyres, that someone will be able to detect mm to sub mm changes in deflection resulting from minor stiffness changes.

To respond to the stuff about ‘the whole roadie community’ and carbon fibre frames. A large number of people believing something does not make it true. That’s ridiculous, pathetic logic. Apologies for the strength of my words.
I’m going to steer well away from the obvious parallel with theological concerns and use tennis as an example. The little string damper thingies, EVERYONE who plays tennis KNOWS that these dampen frame vibration. You can do a very simple very quick test to discover that this is absolute bulls balls. I suppose that example might also be more relevant because of sport and vibration, and perception through physical interaction. There, I’ve justified it to myself.

molgrips, if you’re using scientific explanations, use a scientific approach.

1. How do you KNOW that the cove was more flexible.

2. What objective measure do you have that the ‘edge’ (more definition needed) was taken off the bumps.

3. How isolated was the variable? Did you weigh the same? Tyres? Pressure? Geometry the same? Terrain the same? Temperature the same? Muscle fatigue the same? Fitness the same?

Rather than make up some blurb from an advert seen on the back page of MBR think it through rationally, remove your own personal attachment to the evidence and assess it as subjectively as possible. Come to your own conclusion.

Interesting thread, just caught up with it all, i’m of the opinion that you can feel a difference, it might be fractions of a millimetre in actual flex, but there is definitely a different feel. I’m surprised there’s not more people with this view giving all the inbred/cotic/dialled lovers on here that go on about their steel hardtails.

so the rebound could end up being absorbed by the tyre.

Why doesn’t the tyre just aborb the bump in the first place if it does such a good job of absorbing the rebound?

How much flex do you actually think there is in the rear triangle of a “flexible” double diamond frame? Ballpark figure in mm of vertical deflection due to a typical bump force?

it might be fractions of a millimetre in actual flex, but there is definitely a different feel.

So how is that going to make a noticeable difference given a bump of several cm in height and 50mm of tyre flex?

So how is that going to make a noticeable difference given a bump of several cm in height and 50mm of tyre flex?

50mm of tire flex, how big are your tyres?

I never mentioned that it would make any difference over any particular size of bump, its a different feel which is difficult to quantify but its there.

how big are your tyres?

A bit more than 2″ 🙄

Sure it’s a different feel – it’s just that what you’re feeling is lateral flex, not vertical.

re carbon and roadies thing, there seems (to me) to be a difference. I transferred all my kit from an aluminium frame to a carbon one and the first couple of rides had me checking and rechecking that I hadn’t got a puncture because of the way the carbon frame felt. We’re not talking huge bump absorbtion or magically flexing seat/chain stays, but the carbon did seem to iron out that (again another indefinable personal thing) road buzz. Whether this is attributable to the materials used or to a difference in build is another unknown, but I could tell a difference.

A bit more than 2″
Sure it’s a different feel – it’s just that what you’re feeling is lateral flex, not vertical.

Fair enough if you hit something like a kerb square on you might get that much travel out of your tire, not generally riding, your rims would be constantly fecked. You seem convinced your right, have you ridden lots of different frames?