# TI vs Carbon stiffness question



## magic32 (Nov 16, 2001)

I currently race a 2005 Ultimate in Northern California. The 64K question at least for me is am I giving up much wattage in competeing against similar riders on carbon bikes.

I have never seen any articles or reviews of the Ultimate that talk about it in comparison to carbon bikes. I'm not worried about the weight of the bike because when I have my race wheels on the bike weighs in at about 16.5 lbs which is very respectable. I'll just take that extra 1.5 lbs off my fat butt......

I recenty rode a friend's Specialized SWorks and, at least by the seat of the pants, seemed to accelerate\respond better then my Ultimate. 

But the last issue of Ride magazine had a test of a Linskey custom and Ride's jig data showed the bottom bracket area to be extremely stiff. I think it was second in the test to the Specialized and much stiffer than the Storck for example.

The other question of course is can anybody really feel the difference, or does it matter, when were are talking about deflections of less than .5 mm.....

Any info or thoughts from someone who has ridden extensively or raced both types of materials would be greatly appreciated.


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## Mark McM (Jun 18, 2005)

*Stiffness comparisons*



magic32 said:


> I currently race a 2005 Ultimate in Northern California. The 64K question at least for me is am I giving up much wattage in competeing against similar riders on carbon bikes.
> 
> I have never seen any articles or reviews of the Ultimate that talk about it in comparison to carbon bikes. I'm not worried about the weight of the bike because when I have my race wheels on the bike weighs in at about 16.5 lbs which is very respectable. I'll just take that extra 1.5 lbs off my fat butt......


Asking which is stiffer, carbon or titanium, is like asking which is heavier - a pound of lead or a pound of feathers. Stiffness depends not only material, but how much is used, where it is put, and how it is joined. You can use either material to make ultra-stiff frames, or ultra-flexible frames. It comes down more to design and construction than simply material.

As far as power loss due to frame flex - this is a hotly debated subject, and there really is no concensus as far as how much power is absorbed by the frame. At least for the typical range of bike stiffnesses. I think that all would agree that if a frame was so flexible that if under maximum pedal loads it flexed so much that the bike became hard to control, then whether the frame absorbed any of the power or not the rider would simply not be able to use maximum power.



magic32 said:


> But the last issue of Ride magazine had a test of a Linskey custom and Ride's jig data showed the bottom bracket area to be extremely stiff. I think it was second in the test to the Specialized and much stiffer than the Storck for example.


I'm sure the test accurately measured the flex under the load that was applied - but the important question is: Did the loads applied really reflect real-world pedaling loads? Everyone has a different pedaling style, so different riders may have different impressions of the stiffness of a particular frame.



magic32 said:


> The other question of course is can anybody really feel the difference, or does it matter, when were are talking about deflections of less than .5 mm.....


That depends on the load that created the .5mm of flex. If the difference in flex was .5mm under maximum pedal load, then no, probably nobody would really be able to tell the difference. But if the .5mm deflection was under only a small load, and the maximum load pedal load created a 20mm difference, then yes, some people would be able to tell. But is even a 20mm difference enough to change the the amount of power that got to the rear wheel is another question ...

As far as the bike "giving up much wattage in competeing against similar riders on carbon bikes," consider this: In the Tour de France, there is a reason that the award the Yellow Jersey to the rider and not the bike.


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## magic32 (Nov 16, 2001)

Mark,

Thanks for the reply. According to RIDE they apply a 40 Kg weight on the crank to determine the flex. I would have to dig up the issue where the laid out exactly how the testing is conducted. It might not be apples to apples based on the crank but I would think they would mount a neutral crank arm on each bike.

And I knew somebody would go with rider vs bike.......

I feel I am putting in as much time and effort as my work load and schedule allows. Approx 12 or so hours a week. Also working with a coach and power monitoring\training which has helped tremendously. I'm an older guy (47) and have the ability to pickup a bike if I feel it is warranted. I can't put in anymore time on the bike so if some additional wattage to the rear wheel can be added through a purchase I might consider it based on the cost and ROI of those watts.

Thanks


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## Eric_H (Feb 5, 2004)

*The Pepsi challenge*



magic32 said:


> Mark,
> 
> Thanks for the reply. According to RIDE they apply a 40 Kg weight on the crank to determine the flex. I would have to dig up the issue where the laid out exactly how the testing is conducted. It might not be apples to apples based on the crank but I would think they would mount a neutral crank arm on each bike.
> 
> ...


Your Ultimate is definitely one of the stiffer rides out there, regardless of frame material. Those short chainstays plus the downtube equals a brutally quick ride. Your friend's S-Works might have felt stiffer for many reasons - different tires/wheels/tire pressure/cranks/bars/stem - all will contribute. The only way to know for sure is to have two bikes with identical setups except for the frame, but this is for the most part completely impractical for the average joe. Call it the Pepsi taste-test challenge, you need to ride each bike blind with the same componentry to eliminate both bias and differences due to anything by the frame. Pretty darn hard, IMO. 

FWIW, the best racing I have ever done was on a reasonably flexy Merlin Extralight, 2002 model. I have been on stiffer bikes the past couple of seasons (aluminum, al+cf mix) but I can't really say that I noticed a difference in how I rode. I am going back to racing a Ti bike this year, like you I am on the older side (39) so I am perfectly happy to spend the $$ on what I want. I prefer Ti for its durability and simplicity. I'm sure for out and out efficiency Ti bikes are not the absolute, but I also know that I can usually think of ways to squeeze more out of myself before my bike is ever the limiting factor. BTW, if you know of anyone selling a 57 cm LS Ultimate from 2006 (non-carbon stays, conventional headtube) I'm interested.


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## magic32 (Nov 16, 2001)

Eric,

Thanks for the response. As for durability the week after I rode my friend's Specialized he was involved in a crit crash and that frame and fork are now in 4 separate pieces. The bike was run over by 3 or 4 riders. Completely destroyed the bike.

Not sure a TI bike would have survived either but would probably have stood a better chance. 

Thanks


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## davidka (Dec 12, 2001)

I have seen photos of crashed Specializeds and they seem to break at the tube joints (this has been getting press in Euro racing). I wonder if the Ti would've survived...

Another way to think of the Wattage/frame flex issue is this: a revolution of the pedals is a revolution of the pedals. As Mark McM pointed out, it would take an inordinate amount of flex to actually absorb power (I bet more is lost in the wheels). At this point it's more about inspiration. Does your Ultimate feel fast?


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## barbedwire (Dec 3, 2005)

Most all of the high-end carbon frames on the market are stiffer than most of the high-end titanium frames on the market. For example, the top 2 frames from each of the carbon lines of Look, Ridley, Cervelo, etc. are stiffer than the top of the lines from Merlin, Litespeed, Seven, etc..


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## Nessism (Feb 6, 2004)

barbedwire said:


> Most all of the high-end carbon frames on the market are stiffer than most of the high-end titanium frames on the market. For example, the top 2 frames from each of the carbon lines of Look, Ridley, Cervelo, etc. are stiffer than the top of the lines from Merlin, Litespeed, Seven, etc..


I agree, particularly with a Vortex where the major axis of the down tube is oriented vertically and does not do a whole lot to shore up side to side bottom bracket stiffness. That said, I'm strongly in the camp that does not believe that a little side to side flex in the frame causes energy loss - flex on the down stroke is returned on the up stroke. In fact, super stiff frames tend to skip the rear tire around if your pedal stroke is not super smooth which I believe has the potential to loose more energy than frame flex.


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