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Curved Vs. Straight Seat Stays(31 posts)

Curved Vs. Straight Seat Staysjrm
Oct 29, 2003 8:04 AM
Is there an advantage with either one? How do straight or curved seat stays impact the ride of the bike? What do you prefer and why?

Thanks

John
Cannondale always claimed ...Live Steam
Oct 29, 2003 8:09 AM
that their curved seat stays provided a more plush ride than straight stays or even carbon stays. That's what I heard from their rep. anyway.
Well...fracisco
Oct 29, 2003 8:50 AM
Well, my CAAD5 is a nicer ride than my CAAD3 was, with the same wheels, tires, and seatpost/seat. I can't compare versus a steel or carbon fiber frame.
re: Curved Vs. Straight Seat Staysmcteague
Oct 29, 2003 8:21 AM
Fashion, nothing more. I'm sure the marketing people will say it adds comfort but I have a difficult time believing that curved stays actually flex enough for anyone to feel. Especially with all the flex from tires, saddles and a bit from the rims and spokes. BTW, my Seven Axiom has curved seat and chain stays. The curve in the chainstays is nice as it provides a bit more heel clearence. As for the curvy seat stays....

Tim McTeague
it does flex....divve
Oct 29, 2003 8:41 AM
..when I grab the stays of a CAAD7 in my hands. I can visually see them squeezing together. It's not hard evidence for actual comfort improvement, as I can't compare between a similar bike without curved stays. There is however movement for sure:)
yes, lateral flexgtx
Oct 29, 2003 9:17 AM
not vertical flex. Don't believe the hype.
yes, lateral flexsn69
Oct 29, 2003 9:43 AM
I had an interesting discussion with Ves Mandaric of Yaqui and Mandaric cycles about this very issue yesterday. He talked at great length about frame design, vibration damping and the various myths surrounding stays versus top tube design and butting.

Quite enlightening....
Yeah, but how much of ...Live Steam
Oct 29, 2003 9:59 AM
his thoughts are opinion vs. science? Share some of what he said man :O)


A related topic - a saw a friend of mine yesterday. He was telling me how he just got back from 2003 Ironman Triathlon World Championship in Kona. He didn't compete. He was there to cheer on his neice. He is taking the year off. He hadn't done the Kona race in quite a few years. I asked him about the times and he said they were pretty fast since the last time he was there. I asked where they were making up the time and he said it was the cycling leg. We both agreed that new high tech equipment has made the greatest inpact in cycling. Some designs actually do what they claim. Justa an aside :O)
Yeah, but how much of ...sn69
Oct 29, 2003 10:05 AM
I think most of his claims are based on science. He has a degree in materials engineering and can talk tech with the best of them.

It was a long discussion, and among other things he spoke about carbon stays, specifically their design and true purpose. He (and others like Tom Kellogg) claimed that the stays are more for lateral regidity than vertical compliance. Top tube design and the tubes' butt profiles were, according to him, more critical to confort. Of course he, like everyone else of merit, said fit was more critical to comfort than any other factor.

Re: Kona. That race is slowly becomming a draft race as the rules constantly change. Don't get me wrong--Reid had a great race and a strong bike leg, but the packs of riders seen this year were far different than years past.

More later...got to go do the weekly meeting.....
The Dean guys said the same thing ...Gregory Taylor
Oct 29, 2003 10:37 AM
When I was trying to decide whether to go carbon vs. non carbon stays, John said that the carbon stays would stiffen the bike up and be fractionally lighter.
I posed the same question to Carl Strong...Chicago_Steve
Oct 29, 2003 11:10 AM
Carl's got a forum for Strong Owners and I recently asked him some materials questions...

Steve
"...One other question if you don't mind... I'd love to hear your thoughts on the carbon seatstays/chainstays that are so popular these days. I've read that they make things a little easier for the builder (less welding as the stays are prefabricated), but do they really do that much for the consumer vs. well executed metal CS/ST's? Any issues with the bonding?"

Carl
"There is a lot of disagreement on this issue mainly because its personal preference that determine if the carbon stays attributes constitute a benefit. My opinion is that on an aluminum frame they help dampen high frequency road buzz. On steel and Ti. They are a cool looking option that costs more money but do not offer any weight advantage or ride improvement (improvement in this case is measured by my preferences). It can however be argued that in the case of the Columbus Muscle rear seat and chainstay system you can stiffen up the frame a bit with little consequence in ride quality or weight. So the bottom line is what the rider wants and what their budget is.

To address your last comment I find it easier to build without the carbon than with. You basically end up building the rear end twice when you use the carbon stays."
yes, lateral flexgtx
Oct 29, 2003 10:06 AM
I've come to the conclusion that it's all total bs. The main issue is where your butt is with regards to the rear wheel--the bus metaphor used by Sheldon Brown is a good one--if you're closer to the rear wheels in the bus you're gonna bounce around more. You can make a frame stiffer or flexier in lateral plane, but any differences in vertical compression are totally insignificant. The front of the bike is a bit different because the fork, stem and bars can flex in the vertical plane. Also, on a compact style frame you could add a long seatpost out of something like ti that could flex and add some comfort. Or a seat with flexy rails or bumpers. But don't expect compression out of the frame no matter what the design is or what it's made out of--a conventional frame is two triangles and triangles don't flex. If you want comfort from your frame buy a frame with longer c-stays. I know people make all sorts of claims about carbon frames, but even here I think it's quite insignificant compared to tire design, tire width, sidewall construction and inflation.

http://www.sheldonbrown.com/frame-materials.html
heres the situation....jrm
Oct 29, 2003 10:41 AM
Im having a frame built and the builder wants to use sloped seat stays. Ive allways had straight stays and like there power transfer, stiffness and strenght. The frame will be built up with a 1-1/8 headtube diameter.

Im also 185lbs and ride hard. By hard i mean i am kinda abusive when it comes to my road bike. The bike will built up with durable parts vs. light stuff.

Any suggestions?
heres the situation....collinsc
Oct 29, 2003 10:54 AM
I imagine most people will tell you to let the builder do it his way.

Since the whole discussion here is negating any differences in stay design, the argument works backwards too. How do you know that your previous straight stays were in any way involved in the power transfer, stiffness and strength you have experienced in the past?
OK..jrm
Oct 29, 2003 11:06 AM
asthetically i prefer straight vs. curved. Iveasked the builder if i can go with straight stays. is it wrong to ask? I know this is going to sound lame but without the use of of a better term..its is my money.
OK..collinsc
Oct 29, 2003 12:28 PM
Right, it is your money and if you prefer one look over another then by all means you should request it.

I was just saying that you shouldnt attempt to undermine the knowledge and experience of your builder. If he feels that the same effect will be achieved with straight stays then he should have no problem suiting your needs. If I was a builder, I would be a bit insulted if someone came to me and said "I think what youre doing there is bullshit, do it another way please", however if it is purely aesthetic then there is no argument.
You already answered your own question.sn69
Oct 29, 2003 1:15 PM
It's your money--have it made the way you want. Perhaps, however, it's worth your time to specifically ask the builder why he/she favors the curved stays.
heres the situation....gtx
Oct 29, 2003 11:05 AM
With regards to the rear triangle design I do like the Breezer style dropouts. Lighter, strong, and should be less flexy laterally--less rear wheel squirm. But I think the curved stays won't make a difference in comfort (though the 41.5 c-stays should help a bit--vs. the 40 cm c-stays found on some bikes). But then again Tom Ritchey seems to feel otherwise about curved stays, and I don't consider him overly fond of bs and hype. When I had a custom frame built for me in 89 I had the builder make it as stiff and solid as possible--beefy downtube, stays and fork. I'm 140, it's still my main ride, and I never regretted that decision. Bike fits me perfectly and is very comfy.
Cannondale's stays curve in the other plainLive Steam
Oct 29, 2003 11:17 AM
Meaning laterally from center to side. I am sure it makes some difference compared to what your builder has planned.
Serotta Hors Categorie Flexes...Spiderman
Oct 29, 2003 11:07 AM
Along with their newer carbon version, the ST.

In addition, with the cannondale rear ends, i don't know if they would "flex" to absorb the road shock, but rather the road shock would resonate through the rear triangle but end at the bend the stays, not continuing along to the seat cluster, in theory, creating a smoother ride.

I think the theory behind it is something i actually learned from this board that would apply. the idea is that if you hold a pencil on the edge of table with your hand/finger, with half of it sticking off, and you "pluck" it you can see the vibrations continue up to the point where your hand/table are. i would think the same principle applies to this.

Can anyone say for sure? I am just a mere advertising guy, not a physicist.
in an hourglass shape lateral flex....divve
Oct 29, 2003 11:14 AM
...results in vertical compliance, or better said, when you bump up the stays in theory yield inward and as a result allow for vertical compliance.

(Again not claiming it actually matters to your butt. I don't have to facts to back it up either way.)
re: Curved Vs. Straight Seat Staysbcm119
Oct 29, 2003 10:46 AM
I don't believe the shape of the seat stay affects the damping qualities of the frame. Materials in the seat stay, ie carbon vs. aluminum vs. steel, affect the road feel of a frame, but not the damping. Aluminum will transmit more buzz, and carbon will feel more muted, but both will cause your seat to rise the same amount over a bump in the road.
Steel or Ti?cyclopathic
Oct 29, 2003 12:06 PM
Shimano or Campy?
True Temper XO Prem / Shimano 105jrm
Oct 29, 2003 1:56 PM
Re: True Temper XO Prem / Shimano 105kilimanjaro
Oct 29, 2003 4:36 PM
Jrm,

Just curious, is your builder Curtlo?
Re: True Temper XO Prem / Shimano 105jrm
Oct 30, 2003 7:24 AM
yup...
re: Curved Vs. Straight Seat Staysinnergel
Oct 29, 2003 12:48 PM
I took a tour of Seven Cycles a couple of weeks ago and asked this exact question. The guy who was giving the tour and one of the frame builders both said that the curved seat and chain stays allowed for the possibility of running wider/larger tires than straight, and that all their bikes had them. No mention of ride quality or anything like that.
my experience has beenmoschika
Oct 29, 2003 1:08 PM
that the curved stays does take some of the 'edge' off rough roads or trails.

you've seen my mtb. there is hardly any chatter on my rear when riding someplace like annadel. i equate that to the stays. i can feel that difference regardless of the seat or tires i've used and changed over the past few years.

i went with the same design on the road too. and again i feel that same damping effect.

but again this is my experience and works for me. placebo or not, i don't care, i like it.

and if someone is building it, they should build it how you want it, straight or curved, unless they are doing it for free.
my experience has beenjrm
Oct 29, 2003 2:05 PM
Actually I'm using the same builder you used mainly so i could get a great road frame built up with True Temper OX Platinum. I asked about the straight stays and doug said it was no problem so now the wait starts. oh its gonna be dark green met with black decals for a stealthy look to deter interest.
my experience has beenmoschika
Oct 30, 2003 3:04 PM
sounds good. post a pic when it's done. we'll have to do a road ride up here when it's ready.
Ask To See The DataHeron Todd
Oct 29, 2003 3:21 PM
The bike industry is full of interesting claims but little actual data. Some companies like to spout off about their engineering prowess but fail to show what and how they test. I know plenty of folks within the industry and toured design centers. The level of testing being done is extremely basic. I think that it is safe to say that most companies selling the advantages of carbon rear triangles and curved stays made their claims after having done absolutely no quantitative testing. So, take it all with a grain of salt.

Todd Kuzma
Heron Bicycles
LaSalle, IL 815-223-1776
http://www.heronbicycles.com