853 Is it really better? « Singletrack Forum

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853 Is it really better?

91 posts & 34 voices | Started 2 years ago by I_Ache | Latest reply from clubber

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armchair experts

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toys19 - Member

tracknicko - Member

small differences indeed. but combined with geometric changes they certainly may well be noticable.

Nope. Anyway this is twisting what everyone else said, they said same geometry same shape etc 853 and 520 will fell exactly the same. I concur.

See the below image. Deflection of the free end (thats the right handside)= (w(l^3))/12EI if we make w, l E and I all equal to 1 then the deflection is 1/12E where is youngs mod then:

e = 200 gpa (thats 200 with 9 zeros) deflection = 4.1667 e-13
e = 204 gpa defelction = 4.08496 e-13
e = 207 gpa deflection = 4.025 e-13
So if we fiddled witht he numbers to make them 4.1667 mm, 4.08496mm and 4.025mm I'll bet you cannot tell the difference. Or even 4.167cm 4.084cm and 4.025 cm thats a difference of 1.4mm over 4cm, its small.

Posted 2 years ago #
djcombes - Member

I'm with the naysayers - two frames with identical design in 4130 and 853 will not feel different. I don't think it's clear whether the DN6 and 853 versions of the frame are an identical design.

I don't think you can underestimate the effect of psychology in a sighted test either. Just look at all the rubbish that people talk about hi-fi cables (just to open another can of worms).

Posted 2 years ago #
tracknicko - Member

what? L and W are both 1?
thats a wierd shaped beam but nevermind i take your point...

right eff this. all im saying is.. there IS a change in stiffness. particularly if OD and ID are changed between models and gussets added removed as well...

indeed i was saying there IS a difference in youngs modulus.

so don't 'EPIC FAIL' me like some kind of engineering keyboard hero. Technically you are wrong. whether by much, and whether you can feel it or not is another issue.

Posted 2 years ago #
djcombes - Member

@toys19 - To put it another way: there's 3.5% difference between 207 and 200. That means there's a 3.5% difference in stiffness (if you make two identical shapes with the two different materials). Really no need to make it more complicated than it is.

I don't actually think there would be a 3.5% difference in YM between 4130 and 853, but I haven't seen any more than estimates yet. Engineering calculations are not generally accurate to 3.5%, so I'd still consider the two figures to be identical for most working purposes.

Posted 2 years ago #
freegan bikefascist - Member

djcombes

I don't think it's clear whether the DN6 and 853 versions of the frame are an identical design.

yeah, it is clear, Cy clarified higher up that the butting is different between 853 and DN6 versions of the Inbred frame (853 has thinner tubes).

cy <- Mr Cotic, incase you didn't know (as if!) and were wondering about his quals.

853 Inbred used 0.8/0.5/0.8. DN6 use 0.9/0.6/0.9. DN6 is therefore between 16% and 19% stiffer depending on the tube OD.

that plus the gussetting at the head tube of the DN6 version will be enough to change the feel significantly. but the argument seems to have moved on into a physics lesson

Posted 2 years ago #
Andy - Member

No way is purple or red a better ride than blue. I cannot accept that.

Posted 2 years ago #
clubber - Member

As one of the relatively few people to have actually owned and ridden a purple bike, I can categorically state that it's better

Posted 2 years ago #
toys19 - Member

djcombes - Member

@toys19 - To put it another way: there's 3.5% difference between 207 and 200. That means there's a 3.5% difference in stiffness (if you make two identical shapes with the two different materials). Really no need to make it more complicated than it is.

Not to mention that if I hadn't simplified the above calc you actually find that the difference in E has very little effect on the deflection, what makes a massive difference is section.

so don't 'EPIC FAIL' me like some kind of engineering keyboard hero. Technically you are wrong. whether by much, and whether you can feel it or not is another issue

You did make an EPIC fail lets face it, technically I am right, you were just spouting stuff without any technical or practical knowledge. There are no differences in youngs modulus between aluminium alloys. If you want to split hairs by your method of accuracy I can guarantee you that no two frames are the same, small diffs in diameter, differences in the welds, maybe more paint on one than another, be careful what you buy imagine if you ended up with one that was too stiff...

Posted 2 years ago #
Andy - Member

clubber - Member
As one of the relatively few people to have actually owned and ridden a purple bike, I can categorically state that it's better

But did you ride it back to back with a blue bike? No....I thought not.

I on the other hand had a Purple kona (eggplant actually if you want to split hairs) at the same time as a Blue kona. Can you guess which was better?

(The blue Kona was also 853 as opposed to the Purple which was 4130; but thats pure subjective cooncidence here ).

Posted 2 years ago #
cynic-al - Member

I'll EPIC FAIL whoever I like, particularly those who claim to disprove Young's modulus!*

*I am aware this doesn't really make sense.

Posted 2 years ago #
toys19 - Member

cynic-al - Member

I'll EPIC FAIL whoever I like, particularly those who claim to disprove Young's modulus!*

*I am aware this doesn't really make sense.

Don't worry we got the gist..

Posted 2 years ago #
djcombes - Member

Missed the comment by cy.

I think that some of the engineers are making the point that a difference in feel between frames is down to a change in the design, enabled by different material properties, rather than some feel of the material itself.

We all agree: there's shouldn't be any need for anyone to argue over this.

Posted 2 years ago #
freegan bikefascist - Member

djcombes

We all agree: there's shouldn't be any need for anyone to argue over this

you appear to have forgotten what site you're on. check the URL *slowly* and then rejoin the group...

Posted 2 years ago #
toys19 - Member

I think that some of the engineers are making the point that a difference in feel between frames is down to a change in the design, enabled by different material properties, rather than some feel of the material itself.

Bingo

Posted 2 years ago #
IdleJon - Member

Andy - Member

clubber - Member
As one of the relatively few people to have actually owned and ridden a purple bike, I can categorically state that it's better

But did you ride it back to back with a blue bike? No....I thought not.

I on the other hand had a Purple kona (eggplant actually if you want to split hairs) at the same time as a Blue kona. Can you guess which was better?

I had a purple Tange Prestige frame, which was immensely springy, and eventually broke.

Ridden back to back - at a distance of 13 years - my current white 853 frame is much stiffer, far less springy and definitely not broken.

All components are exactly the same, except where they aren't.

I like white ( At the moment, because it's clean.)
Egplant on the other hand is a pointless food.

Posted 2 years ago #
MrSmith - Member

Bingo

it doesn't take an engineer or frame designer to work out that tubing dimensions of a frame can change if the material properties allow it.
tubing O/D specs are freely available on the internet along with the butting specs. it's not rocket science just tubes thicker at the ends and thinner in the middle joined together.

Posted 2 years ago #
soobalias - Member

pffft, eggplant is not a good purple for riding, far to dark and infected with the dullness of blue.

Posted 2 years ago #
clubber - Member

Imperial purple is the only shade of purple to have.

Posted 2 years ago #
IdleJon - Member

^^^^^^^ That's definitely blue.

Not remotely purple.

Therefore not as good, by definition.

(It also seems to be a midget's bike?)

Posted 2 years ago #
Macavity - Member

Second Moment of Inertia

Posted 2 years ago #
clubber - Member

Definitely purple and I'm the tallest midget you'll ever meet

Posted 2 years ago #