's Forum Archives - General

Archive Home >> General(1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 )

Stupid theoretical question/flamebait--compact ti vs. AL(19 posts)

Stupid theoretical question/flamebait--compact ti vs. ALgtx
Jan 14, 2002 1:12 PM
So, regarding the new trend toward compact frames, I'm wondering... what's the point of buying anything except AL? Assuming you are a big fan of ti, wouldn't a compact AL frame with a long ti post be just as comfy (and cheaper and lighter and stiffer) than a ti compact frame with a long AL post? Assuming geometry, fit, fork and wheels are the same (though of course there are too many other variables for "all things to be equal"). Just how beat up do you think you get by stuff coming up through the cranks/pedals vs. the seat and bars?

Playing devil's advocate here...
Jan 14, 2002 1:19 PM
"Assuming you are a big fan of ti, wouldn't a compact AL frame with a long ti post be just as comfy (and cheaper and lighter and stiffer) than a ti compact frame with a long AL post?"

should just read:

"Wouldn't a compact AL frame with a long ti post be just as comfy (and cheaper and lighter and stiffer) as a ti compact frame with a long AL post?"

And when I said "wheels"--that means same wheels/tires/inflation.
hellifiknow, but . . .morrison
Jan 14, 2002 1:24 PM
i know my compact ti frame with a ti post is more comfortable than my compact al frame with al post
Jan 14, 2002 1:25 PM
I had a feeling someone would say that! :)
hey wait!gtx
Jan 14, 2002 1:41 PM
if both bikes take the same size seat post, maybe you could swap posts and report back to us. Just be sure to use the same wheels.
You're on. Give me 'til Fri. (nm)morrison
Jan 14, 2002 1:46 PM
great!!! nmgtx
Jan 14, 2002 1:47 PM
One thought is that the seat stays are the main culprit...PdxMark
Jan 14, 2002 1:24 PM
for transmitting high frequency vibration through an AL frame and into your saddle. Hence part of the rationale for the new carbon stay designs for AL (and some Ti & steel) bikes.

So, maybe, a compact Al frame will still give you close to "regular" Al-style high frequency vibration. A compact Ti frame might still give more of a Ti ride despite the long Al seat tube. So then what's the difference between "long" & "short" Ti seat stays???

How's that?
Jan 14, 2002 1:30 PM
I think compact geometry tends to be stiffer, not more compliant. So, assuming Ti is more compliant than Al, compact would be better suited for Ti than Al to compensate, right?

Jan 14, 2002 1:47 PM
right, but with compact frames you usually show a lot more post. A short ti post on a normal-style road frame won't do much for the "ride quality" but a long ti post on can make things more comfy (I'm thinking something like putting a Moots post on a TCR). Lots of mtbrs use ti posts to make their AL hardtails more comfy.
yes, but...Dog
Jan 14, 2002 1:57 PM
The seatpost is not the only conduit for vibration, nor the only source of compliance. The whole frame matters, too.

Also, I don't think you actually get much compliance from a rigid seatpost. What you look for there is vibration damping, which likely only really is reduced with carbon fiber. Metals tend to resonate or vibrate much more than carbon, according to what I've read.

On the other hand, Ti tends to be more compliant when the tubes are being stressed, with is what you feel, I think. This likely matters more in the main frame tubes, rather than the seatpost.

Why not just get carbon and be done with it?

re: Stupid theoretical question/flamebait--compact ti vs. ALjrm
Jan 14, 2002 2:34 PM
Compacts are pretty uncomfortabe. Its not that the vibration is comeing from one area. its that its coming from the short wheelbase, 120 Psi tires, and short as$ stays.

ON steel now, and its real comfy, but not very responsive.
re: Stupid theoretical question/flamebait--compact ti vs. ALjp2
Jan 15, 2002 6:10 AM
when did the wheelbase on compacts become shorter than standard frames?? are you sure you know the meaning compact geometry? last time i checked, wheelbase was the same.
re: Stupid theoretical question/flamebait--compact ti vs. ALmackgoo
Jan 14, 2002 4:30 PM
It's cheaper to replace the post when it fails than to keep the post and replace the frame.
Design is everythingKerry Irons
Jan 14, 2002 5:59 PM
You can't really make this kind of statement without taking into account the variables of tube shape, butting, diameter, and wall thickness. If the two frames (and posts) were designed to the same "compliance point" then the frames would only differ (slightly) in weight. You can't make assumptions about what the seat post does with shocks and vibrations sent to it if you don't know the wall thickness. And, you get vibration through the bars and pedals, not just the seat. So, what's your point?
Design is everythinggtx
Jan 14, 2002 7:08 PM
no statement or point--it's a question. And this is why I wrote "of course there are too many other variables for "all things to be equal." But if the wheels, tires, stem, bars and forks are the same, vibrations through the bars should be about the same. So that leaves the pedals and the seat. I have yet to hear of a compliant, comfy AL post (most long mtb style posts are built pretty beefy so they won't break). So if you have a comfy ti post (say a Moots) on a compact AL frame, and the AL frame (for the sake of making the question easier) is as stiff as a board, and you have a typical AL post (say a Thomson) and the ti frame is built "comfy"--and the geometry of the two bikes is the same--well, what will the difference be in "ride quality?" How much of what people consider to be "comfort" comes through the pedals vs. through the saddle? Maybe it's a silly question, but I don't know how to write it any clearer than that.
Jan 15, 2002 5:49 AM
After riding a bunch of different Ti, Carbon, steel, and Al framesets I'm pretty convinced that tubing type makes little or NO difference in ride "feel". You will be able to find nice riding frames in all materials and conversely you can also find harsh (or "whatever") riding frames in all materials. Don't try to over analyze this issue.... !

BTW: A compact frame design doesn't change the inherent stiffness or "whatever" of a frame! Another total bullshit "difference". I've got one so don't tell me otherwise.

The more I ride the more I realize these endless frame debates are like public masturbation....... pretty pathetic and rather embarrassing. ;-)

Thoroughly embarrassed for adding my BS to the thread
Jan 15, 2002 9:36 AM
seems like you and Kerry went out of your way to misread the question. Or maybe I didn't phrase it correctly. It's more of a seatpost question--you know, compact frame, longer seatpost, thus perhaps more role of the seatpost in perceived "ride quality" of the bike. Whatever, it's in my original post. Back to important Litepseed fit questions...
Santa Cruzgtx
Jan 15, 2002 9:45 AM
Santa Cruz had the same basic idea