Ti v. Carbon

[oldpotatoe]

Originally Posted by Kirk007

these tests to me are like so much statistical analysis - set it up and it will tell you whatever you want it to tell you.

It can't go unnoticed that for over a decade the mantra of carbon has been stiffer and lighter, stiffer and lighter. Nor can it go unnoticed that even in the pro ranks there is gravitation to wider tires. Cause or correlation, I dunno. I do know that I've been on bikes, one metal and more than one plastic, that felt like ass hachets compared to other bikes, with all other factors like tires being relatively equal.

I'm not unscientific - science is the foundation of my day job. I was a grad TA in statistics. But I've lived long enough to see things and experience things that are not reduceable to mathematical formulae. And I suspect there's more to a comfortable ride quality than simple measureable vertical compliance.

Ha..told this story before..while in the trenches at Morgul-Bismark..sponsored a local team..they got IDENTICAL titanium serotta bikes..the same, frame-tires-wheels-bartape, identical. 2 guys go out and ride them for the first time.

Rider one-"STIFF, responsive, crisp ride, great sprinter".
Rider two-"Vague, soft, but comfy. Poor sprinter, poor climber out of the saddle"...

[redir]

I've done hundreds of cyclocross races since I started racing in the late 90's and I can compare bikes I've had based on material and absolutely noticed a difference. The Aluminum bikes were terrible. I thought maybe I was getting to old for cyclocross because after one hour race my back was killing me. Then I raced on a carbon bike and thought hmmm, that's better. Then I raced on a steel bike and thought Ureka! I have found it! I can feel the steel frame flex over bumps the AL and Carbon frame would just jitter on.

I've always lusted over Moots CX bikes and can imagine Ti would work very well too.

On the road I don't notice a whole lot of difference between carbon and Ti but on the extreme ends I do with Al and Steel. The charts notwithstanding.

[RyanH]

Originally Posted by PaMtbRider

I can say for certain in this life and one of them is that stems do not affect ride quality at all.... I can say I’ve never experienced this.

He hasn't ridden a bike equipped with a Zipp Sprint Stem and Pro Vibe bars then. My hands sting when riding that combo.

[KarlC]

Originally Posted by Mark McM

In a Velonews Technical FAQ article a few years ago, a reader wrote in to ask if carbon handlebars would be more comfortable. Editor Leonard Zinn posed that question to several manufacturers of carbon handlebars. Half of them said, yes, carbon handlebars will be more comfortable. The other half said no, carbon handlebars are stiffer, so they will be less comfortable, and recommended aluminum handlebars instead.

Cervelo posted this article on Ride Quality, with charts to show the relative contribution of different components to vertical compliance. For front wheel bump shocks, the tire provided the largest portion of compliance (about 1/3), with the fork and handlebar providing about 1/6th each, followed by the tape at about 1/10th. The wheel and the stem contributed the least, the frame also provided very little. In the rear, the tire provided nearly 1/2 of the compliance, with saddle, seatpost and shorts providing most of the other half. Just like in the front, the wheel and the frame provided very little compliance. It should be kept in mind that Cervelo's test was for road bikes, and at the time the largest tire that would fit in most Cervelo frames was 25mm. If Cervelo were to run the test again with 42mm tires, no doubt the tire compliance would totally swamp all the other compliances. Also keep in mind that the tire is better at damping vibration and conforming to small ground irregularities.

Im thinking Cervelo only tested Carbon frames.

.

[RyanH]

Poertner and Rinard crunched a lot of numbers but did they actually *ride* the different frames they meta-analyzed through Tour's gathered data?

I had a Litespeed Classic, Focus Izalco Max and Litespeed T1sl at the same time using the exact same wheels and tires and seatpost and saddle and there was a distinct difference in perceived comfort between the three when riding them back to back. In the last two years I've owned probably over 20 different high end carbon frames and while most were pretty good and going from Ti to carbon was always a quick and easy transition, I'd always marvel at how much smoother riding my Ti bike was when I got back on it.

[KarlC]

Originally Posted by joshatsilca

Mark is right that wider can be faster to a point.. mostly as they allow you to ride lower pressures which can reduce impedance losses at similar to slightly lower casing losses as long as you aren't so wide as to be creating aero problems.

As for the relative comfort of things, here is a list from our blog of data taken 2008-2010 during the development of the 303 for Paris Roubaix that normalizes the stiffness of things to tire pressure equivalents, so consider that most pumps will be +/-5psi when new and drift from there, you can prioritize the actual effect of some of these 'features'.

1 1/8 Steerer vs Tapered 1 1/8-1 1¼ steerer (same brand carbon fork): 1.2psi
24 vs 28 spokes Zipp 303: 1.8psi
3x vs radial spoke lacing, Zipp 303: 2psi
Curved vs Straight seat stays, Carbon Frames (Model Year Change): 4psi
Carbon Vs Steel Similar Geometry Custom Frames: 4psi
Comfort/Cobble Frame design vs Full Aero frame design: 19psi
Aluminum bar to Zipp SL: 7psi
Aluminum bar to Zipp SLC: 2psi
Zipp 27.2 Seatpost to Zipp 31.6 Seatpost: 4psi
Zero Offset Zipp seatpost to 25mm offset Zipp seatpost: 3psi
Thomson post to Canyon VCLS SeatPost: 24psi

https://blog.silca.cc/part-3b-faq-an...ogether-so-far

Thomson post to Canyon VCLS SeatPost: 24psi - Now that's crazy different and hard to believe the Canyon post would make that much difference. I mean most all thinks point to lowering tire PSI 5 - 10 PSI as being the biggest difference you can feel.

.

[Mark McM]

Originally Posted by joshatsilca

Mark is right that wider can be faster to a point.. mostly as they allow you to ride lower pressures which can reduce impedance losses at similar to slightly lower casing losses as long as you aren't so wide as to be creating aero problems.

As for the relative comfort of things, here is a list from our blog of data taken 2008-2010 during the development of the 303 for Paris Roubaix that normalizes the stiffness of things to tire pressure equivalents, so consider that most pumps will be +/-5psi when new and drift from there, you can prioritize the actual effect of some of these 'features'.

1 1/8 Steerer vs Tapered 1 1/8-1 1¼ steerer (same brand carbon fork): 1.2psi
24 vs 28 spokes Zipp 303: 1.8psi
3x vs radial spoke lacing, Zipp 303: 2psi
Curved vs Straight seat stays, Carbon Frames (Model Year Change): 4psi
Carbon Vs Steel Similar Geometry Custom Frames: 4psi
Comfort/Cobble Frame design vs Full Aero frame design: 19psi
Aluminum bar to Zipp SL: 7psi
Aluminum bar to Zipp SLC: 2psi
Zipp 27.2 Seatpost to Zipp 31.6 Seatpost: 4psi
Zero Offset Zipp seatpost to 25mm offset Zipp seatpost: 3psi
Thomson post to Canyon VCLS SeatPost: 24psi

https://blog.silca.cc/part-3b-faq-an...ogether-so-far

Thanks for posting this data. I have a few questions: What size (width) tire is being used for these comparisons? Are these based on the stiffness (spring constant) of a tire on a flat surface? As noted in the Cycling Tips article (link above), the stiffness of the tire decreases when the tire is pressed against a small radius "bump". The biggest road shocks are often those experienced when hitting sharp edged obstructions, such as the edge of a pothole or a utility cover, which minimizes tire stiffness, and maximized tire compliance. If the above psi equivalences are for flat surface stiffness, then they may overstate the relative effective compliances of the bike components in many real-world situations.

[Mark McM]

Originally Posted by rchman

Poertner and Rinard crunched a lot of numbers but did they actually *ride* the different frames they meta-analyzed through Tour's gathered data?

Poertner did something better - he did blind testing with groups of experienced (you might even say "expert") cyclists. Here's a quote Poetner from an article on the SlowTwitch web site called "Thoughts on Science and Perception":

I've participated in numerous blind product studies over the years where we controlled bikes or the wheels (I've done this twice with a bike manufacturer during development work around a pro team, and many times with wheels) with fabric shield tensioned between seat post and stem, flat black rattle can paint on everything, etc. In each of these studies, the entire subject group including pro riders, engineers, and other industry people with LOTS of experience, struggled to find any real differences between any of the bikes, until after the study was de-blinded and everybody (including me) instantly began to try and rationalize it all… This is just human nature, we all do it, and from experience, it is nearly impossible NOT to do it.

One of the major discoveries was that after controlling for seat post (round post shimmed into aero frame so as to not give it away) not a single rider found the aero road bike to be less comfortable, less compliant, etc, than the identically setup 'endurance' or 'roubaix' bike (clearly this leaves room for the aero seat post to be why people feel aero bikes are less compliant..seatposts generally have more effect on bike compliance in the lab than frames do, but that's another story). We ran blind wheel tests a couple of times a year at Zipp to benchmark competitive wheels and our own prototypes, and we also found that blinded riders were generally unable to tell the difference between stiffness and inertia, had no reliable feedback on weight, lateral stiffness, or comfort in general, and in the end were generally only able to pick out the aero wheels because they were riding laps around a closed park environment using power, so the more observant ones would notice speed differences. In the end, we sort of determined that when riders didn't know what they 'should' feel, they really struggled to find differences in stiffness, compliance and weight between frames or wheels. The strongest correlation we ever saw was to tire pressure, but not in the way you would expect. Almost everybody assumed the setups with lower tire pressure to be the endurance bike and would then score it exactly as you would expect a magazine review of a comfort bike to look…so we determined that we all naturally would latch onto something we were confident in, in this case comfort, and then would proceed to perceive everything you expected from that bike: less aero, less stiff, better damping, etc. Imagine the shock for the group when it turned out that the it might have been a super stiff race bike, or an aero road bike! Let the rationalizing begin!

Reports from other blind tests have shown riders have similar difficulties distinguishing between different frames in blind test, even when "everybody knows they should feel different."

[Kirk007]

I wonder if test subjects would discern a difference after a 5-6 hour ride over hill and dale? I've read respected builders talking about this when questioned about frame material differences. And for the studies - how different are the bikes - material, construction, rider position, rider size and on and on - lots of variables.

I will freely admit that most of my current road bikes - ti, steel, carbon - with similar geometry and wheels - feel pretty much the same most of the time. I'm not surprised given they are all custom, have similar dimensions and given the sources - Sachs, Kellogg, Kirk, Hampsten. But there are some differences, like how they feel when you jump out of the saddle or are pushing hard up hill.

I had an early Serotta legend at the same time I had a MXL Landshark. The Serotta just felt sluggish going up hill in comparison to the MXL bike. Every time. Geometry? material? all of the above? And I ride a big bike and am a big rider - DK states a firm preference for steel over ti for riders my size. I wouldn't dismiss his opinion based on these blind studies.

At the end of the day and perhaps more to the OP's original question - I don't think there's a substitute for personally spending time on different materials/geometries/builders' takes. I find that I continually gravitate back to metal bikes. They are the ones I most frequently grab even though my carbon bikes is arguably, by some objective measures, the best "performance" race bike. And we don't ride blindfolded. How we feel about the bike - aesthetics, memories all contribute I think to how we experience something - like how the bike "feels" when we are on it.

[Mark McM]

Originally Posted by Kirk007

I wonder if test subjects would discern a difference after a 5-6 hour ride over hill and dale? I've read respected builders talking about this when questioned about frame material differences. And for the studies - how different are the bikes - material, construction, rider position, rider size and on and on - lots of variables.

I would think that in fact they'd have even more trouble telling the difference. From experience, I know that a bike that felt light and fast at the start of a ride will feel heavy and slow at the end of the ride. Same exact bike, different human perceptions.

Then add in that humans constantly adapt themselves to their surroundings. I've had a case where I've ridden one of my bikes for a few months, and then switch to another bike, at first, the 2nd bike just felt "wrong". But after a few rides, I adapt to the bike and it feels right. After riding the 2nd bike for a while, when I jump on the 1st bike, it feels "wrong" - even though a few months previous it had felt right.

I attended a talk by Damon Rinard, and he talked about work he had done involving "just noticeable differences" and how it applied to bike feel (he was testing differences like vertical and lateral stiffness, steering trail, etc.). He said that different riders had different thresholds of percent difference that they could distinguish. But for the smallest differences, riders could only reliably detect the differences if they switched from one bike to the other almost instantly (like, no more than 30 seconds between bikes). If more time than that elapsed, the riders could no longer feel the smallest differences between bikes.

After a ride of 5 or 6 hours, a rider's general perception of a bike will change through fatigue, they will have had some time to adapt to the new bike, and they'll have lost much of the frame of reference of their experiences with other bikes. So I expect that after a long ride, they would be even less able to reliably distinguish small differences from other bikes.

[tsarpepe]

I haven't done any blind tests, but no one can convince me that I won't tell the difference between a Ti and carbon bike. It's that pronounced... When Ti hits a whole or uneven place on the road, there is a very characteristic dull thud. With carbon, it's more of a rattle; it's not the same as when aluminum rattles, but it is a rattle.

[Mark McM]

Originally Posted by tsarpepe

I haven't done any blind tests, but no one can convince me that I won't tell the difference between a Ti and carbon bike. It's that pronounced... When Ti hits a whole or uneven place on the road, there is a very characteristic dull thud. With carbon, it's more of a rattle; it's not the same as when aluminum rattles, but it is a rattle.

So, the main difference between titanium frames is the sound they make when they hit a hole? If you were wearing earplugs, could you tell the difference?

Human perception can often get mislead by extraneous sensory input. Jan Heine wrote about in regard to why people long believed that higher tire pressure was faster:

Higher tire pressure cheats you into thinking that you are going faster, because it also increases the frequency of the vibrations: higher pressure = higher frequency.

It’s natural to assume that this means: higher pressure = higher frequency = higher speed, but that is incorrect. Instead, you are looking at two different mechanisms that both increase the frequency of the road buzz.

Even after years of riding supple, wide tires, this ‘placebo’ effect sometimes plays tricks on me. A supple tire absorbs vibrations better, so it can feel slower – until you look at your speedometer.

Perhaps perceptions about ride compliance can be linked to which bike "sounds" more comfortable. I actually experienced this first hand after buying my first set of deep rim aero wheels (Campagnolo Eurus, with 38mm deep aluminum rims and 20 bladed spokes). At the time, common wisdom was that deep rimmed wheels gave a harsher ride than shallow rim wheels. Logically, I knew there really shouldn't be difference, because no wheel any meaningful vertical compliance. But when I first rode the Eurus, I actually had the perception that they rode smoother than the my shallow rim 32 spoke wheels. How could this be? After riding a bit more, I had another realization: These wheels, with fewer and more aerodynamic spokes, were quieter than my 32 spoke shallow rim wheels. My mind had converted quieter into smoother.

[RyanH]

I had a pair of Lightweights that even with 22mm tires pumped to 110 psi felt smoother than my Reynolds V shaped wheels with 25mm tires at 80ish psi. I think vibrations affect our perception.

I can feel the difference in frame material in the pedals, you feel less in the pedals with Ti. This again can be due to vibrations. I know different materials carry vibrations of different frequencies and mixing two materials can cancel out vibrations.

[tsarpepe]

Originally Posted by Mark McM

So, the main difference between titanium frames is the sound they make when they hit a hole? If you were wearing earplugs, could you tell the difference?

When I wrote about rattle vs. thud, I meant not just sound but the quality of vibration too. So yes, I would be able to tell with earplugs on, I think.

[Kirk007]

Maybe its just a matter of the fact that at a personal level perception is reality when it comes to riding a bike for many (most?) of us unless we're racing when factors that influence absolute speed matter.

For instance, taking Jan's observation re the perception of going slower on wider tires - I get that; I have a bike with 650b x 47 tires that on the road feels slow even when my computer tells me I'm within the normal range of speed variability for me on my road bikes. Despite that objective reality, I don't enjoy riding that bike on pavement nearly as much; in large part because it feels slow.