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Carbon seatpost dampen ride of a stiff aluminum frame?(27 posts)

Carbon seatpost dampen ride of a stiff aluminum frame?Tahoe Gator
Apr 17, 2003 9:56 AM
With all these new-fangled bikes with their carbon seatstays to dampen the ride, I'm wondering if you can't get a bit more comforst out of an existing aluminum frame through the addition of a carbon seatpost? Granted, it's not integral to the fram and, if not in a compact frame, not as long (hence I suppose not able to dampen vibrations at as long of wavelengths), but is there real merit to a carbon post's ability to improve the ride? Or is it just weight and in reality a good Al post like a Thomson rides the same?
re: Carbon seatpost dampen ride of a stiff aluminum frame?sievers11
Apr 17, 2003 10:09 AM
Ya, it works...we have had discussions about that here before, the jury seems to be split.

Get a saddle that has Ti rails too it will help out. (assuming you don't have one already.)

I haven't liked the thomson post in the past, they have great adjustability, but I think they are way to stiff.
I'd say nofiltersweep
Apr 17, 2003 10:29 AM
Tires, wheels, fork, frame material ALL work together to impact ride much more significantly than a seat post ever could... if it were THAT easy for a seatpost to make a significant difference, there would be few $1000+ frames sold and we'd all be riding with fancy posts instead.

I'd also argue that a carbon frame does much more than "dampen vibrations"- it is almost like riding with suspension over bumps/pothole- and with out power-robbing drive train issues of suspension...
Apr 17, 2003 10:35 AM
I've tried it. Lower you tire pressure, get a good/accurate fit to ensure that your saddle height and handle bar height are not decreasing your comfort too. You'd be surprised how much less "harsh" something feels when fit is factored in.

Carbon, carbon, carbonMR_GRUMPY
Apr 17, 2003 10:36 AM
I wish that someone could explain to me, exactly HOW carbon stays and carbon seatposts dampen the ride. Two of my bikes are lightweight steel that needs no dampening. The other one is a very lightweight Aluminum alloy that gives a very good ride. Carbon stays are 1) a way to make the frame cheaper to produce (China) and 2) A way to jack up the price with new "gotta have" stuff.
I find that aluminum seatposts are flexible enough for me.
It seems that people want a bike that is "stiff" but compliant. There already is a super material like that. It's called Steel. I can see using a carbon fork, because you can save 1/2 to 3/4 pound. How many grams can you save on a 1 kilo aluminum bike, if you put on carbon stays?
no savings, actually..52-16SS
Apr 17, 2003 11:28 AM
if you look at low weight aluminum frames you will see that the ones offered with carbon stays are heavier than the exact same with aluminum stays
Apr 17, 2003 2:31 PM
As I understand it (which is hardly definitive) CF dampens because it does not transfer vibrations to the same degree that AL and steel do.

That being said, we are still only talking about vibrations, not jarring bumps.

Personally, I find it hard to believe that vibrations that are not damped by the tire, seat and chamois are going to be erased by a CF post.
No difference!alansutton
Apr 17, 2003 10:42 AM
It's all marketing...
Get a some quality tyres.
Which tires then?CaliforniaDreaming
Apr 17, 2003 11:05 AM
Having only been riding for about 1.5 years, I've not gone through enough tires to know which are more comfortable. What tires offer a quality ride and why?

Which tires then?alansutton
Apr 17, 2003 12:25 PM
Try ones with high TPI supple casings. Better Vittoria, Michelin and other quality tires offer TPI >130.
Apr 17, 2003 12:45 PM
Slick "treadless" offer the additional benefit of lower rolling resistance and better road friction.
Which tires then?c722061
Apr 17, 2003 2:01 PM
I recently put Continental Ultra 700x25C tires on my stiff aluminum bike and it is a world of difference in comfort. My old tires were Schwinn 700x22c.
re: Carbon seatpost dampen ride of a stiff aluminum frame?pnitefly
Apr 17, 2003 11:04 AM
I swear up and down it does work. My carbon post has taken a lot of the harshness out of my Spec. Allez. A carbon post won't make a crappy aluminum frame great but it will make a good aluminum frame feel smoother.
re: Carbon seatpost dampen ride of a stiff aluminum frame?CaliforniaDreaming
Apr 17, 2003 11:10 AM
Which Allez frame? I'm picking up the entry level A1 Allez with a carbon seat post. Did you change your wheelset?

re: Carbon seatpost dampen ride of a stiff aluminum frame?pnitefly
Apr 18, 2003 9:44 AM
Yeah, I changed to Race Lites. The original wheelset was not as harsh but the damn spokes kept snapping! I am 73", 180 lbs so don't even go there...
Let 5lbs of pressure out of your tires. It's free nmDave Hickey
Apr 17, 2003 11:08 AM
YES IT DOES (at least for me)Fender
Apr 17, 2003 11:29 AM
I recently swaped a Thomson seatpost for a QR carbon. First ride on the QR I could feel less tingling in my you know what. Overall road vibration was reduced, enough have a significant effect on my riding comfort. As for tires, that also helps. I use Performance Forte Kevlars for training and MIchelin Axial Pros for racing. The Performance are a lot more comforatable IMHO.
Apr 17, 2003 12:53 PM
Nothing scientific
Implement of science: it's called a rulerBergMann
Apr 18, 2003 6:32 AM
Vibration, schmibration. Take the same bike out on real roads where you hit rough pavement, potholes, speed bumps, railroad tracks, etc. and you can _measure_ the difference in the amount of flex an lightweight carbon post like an easton gets you over a Thompson.

Put that same post on a compact geometry frame, you have even more flex.
Ride it offroad, even more flex.

Deflection of shock = comfort.
And you've done this? What was the measured difference? nmczardonic
Apr 18, 2003 10:40 AM
Aluminum + light rider, may = hard rideMR_GRUMPY
Apr 17, 2003 1:25 PM
If you weigh over 160 and have a super light Aluminum frame, you shouldn't any problem with too rough a ride.
If you are very light yourself, you may need a carbon bike, or one of those super light steel ones for comfort.
You get problems with 3 to 3 1/2 pound Aluminum frames. Those suckers are way too stiff, unless you are over 190 pounds.
What are you talking about?alansutton
Apr 17, 2003 1:37 PM
The material composition of a frame has nothing to do with the way it rides! NOTHING! You say aluminum rides stiff? Ever ridden a Vitus or TVT or ALAN frame?
The design to the frame has more to do with ride character than material.
What are you talking about?russw19
Apr 17, 2003 1:54 PM
Alan, you are splitting hairs here... you are talking 20 year old poorly designed French frames to what I am sure Mr. Grumpy is talking about is modern ultra light thin walled computer designed Aluminium frames. To compare those is like trying to say a Model T was simply a lesser designed car than say a Ferrari 360 Modena. Sure, it's true at face value, but there's a little more going on there than that.

That said, did you ever ride a 1st generation Cannondale frame? I did (I was also 130 lbs at the time) but I had such a stiff frame that I had a tough time keeping the rear wheel on the ground over big bumps. That bike was a replacement to my Vitus and it was way stiffer and tracked better too. I had a bunch of friends who rode Vitus frames in the 80's and I never saw the allure in them after I got off one. They were crap. Flexy noodle crap. And again, I was 130 lbs at that time.

Apr 17, 2003 6:29 PM
Yes, I had an R400
My point was, that if you stick a 140 pound rider on a 3 1/2 pound Aluminum frame, you are going to have trouble. A rider of that weight needs either a super light Aluminum frame( 1 kilo), a lightweight carbon frame, or a very lightweight steel frame (True Temper S-3). Anything else, and the rider will get hammered when riding.
When a rider gets over 170 pounds, he has many more options. Light and middleweight Aluminum, any carbonfiber, any titanium, any steel.
When he gets over 200 pounds, he has to start getting carefull again. Midweight Aluminum, Titanium, or standard steel.
Apr 17, 2003 4:12 PM
And anyone who says "yes" has to be more sensitive than the princess-and-the-pea, or more likely susceptible to the placebo effect mentioned above. CF is by definition very rigid, and although it dampens vibrations it doesn't "absorb shock." More meaningful for bars than for seatposts IMHO.

You'll get a much better improvement for less money by buying some 700X25 tires or a slightly softer saddle.

That being said, I have a CF seatpost. It was a frivolous expenditure 'cause I like the looks. But I don't pretend that it makes my bike ride differently.
No impact IMOpmf1
Apr 18, 2003 4:46 AM
I own several bikes and have a number of different seatposts. I have never felt any difference in carbon vs. aluminium posts in any bike I've owned. I suspect that people who tell you they do are imagining it.

Seatstays are relatively long, while a post is pretty short. Therefore, a carbon seatpost will have much less, if any impact. Maybe on a compact frame geometry it might have some impact.

IMO, the best deal on a seatpost is American Classic.
Flexibility (not material) of post makes _major_ difference!!!BergMann
Apr 18, 2003 6:25 AM
As someone who's been riding mountain bikes competitively for over 15 years, I can tell you that the type of seatpost you are riding makes a _major_ difference in the shock and vibration that is transmitted to your bod. Riding off road you can feel and literally _see_ a lightweight post flex under load on rough terrain.

All other things being equal (frame, post diameter, length, etc.), there are several key factors:

1) amount of post exposed
2) flexibility (not material, per se!) of the post in question
3) roughness of terrain

Speaking from my own experience riding hardtails in 4+ hour marathon events:
6+ inches of exposed post with a resiliant Ti (Syncros, Alien) or carbon (Easton) shaft will make a night and day difference vis-a-vis an unforgiving albeit reasonably light post like a Thompson. Sure the engineers will tell you that some materials do a better job of dissipating vibration than others, but the major factor in comfort is how wall thickness and material come together to influence flexibility of the shaft. As for whether lightweight aluminum will do, I'm not aware of any _truly_ lightweight aluminum posts that could compare with the carbon and ti posts I'm talking about (i.e. sub 200g in 350mm+ length), but even if they did exist, I wouldn't trust beercan-thin aluminum in a place that could potentially do serious damage to my anatomy.

Returning to a road-specific context: putting the same post on a conventional road frame with a mere 3-4" of exposed post and riding that bike on relatively smooth roads will definitely reduce the difference you feel, but there is a difference. Put the same post on a compact geometry frame and go out and ride the same roads again and you'll see what I mean.

As for a list of pragmatic things you can do to improve your comfort, the tip on getting a resiliant set of tires is a good one.
If you don't have a ti-rail saddle, I suggest you try one. In conjunction with a good carbon or ti post, this will add another measure of comfort.

The bottom line is you'll have to experiment to see if a component swap makes an appreciable difference for your setup.
Since you can get a quality carbon post like an Easton EC70 on ebay for around $70 bucks, I'd say start there before you throw money at a new frame.