Stiffness

matt.rochfort

Been reading alot about superstiff frames. How much does it make a difference to have a really super stiff frame around the bb and headset to the speed and handling of the bike in "normal" riding situations or is it just when sprinting or hard climbing. i ride a CAAD 9 which is supposed to be pretty stiff and efficient - how much more efficient would a stiff carbon frame be? Would it be noticable in most real world situations? Frames like Canyons ans Storcks are supposed to be really stiff. Would I notice a drammatic difference from the CAAD9?

EKIMIKE

For me it's rather subjective. Lab figures will never mean much to me or alot of people for that matter.

I've got a Canyon and all i can say is that it feels different to ride compared to my alu Bianchi. It feels more efficient and effective. I can't lend any science to it and i can only compare between two bikes, but it's definitely noticeable. Obviously you could point to the 'Maximus seat-tube' or 'VCLS seat-stays' but to be honest i don't care. Brands have to market their products.... USP's.... e.t.c.

Whether is makes me faster.... pffft. Meh, really couldn't care less. It's simply a pleasure to ride a nice bike.

Personally, you get what you pay for to a certain extent. If it cost more it's probably better. How much better is debatable. I personally wouldn't pay for a 3.5K frame considering some of the stuff that can be had for a third (or less) of that price.

morxy

Be wary of excessive stiffness. I can see how it bosts efficiency, power transfer etc.. But isn't it the case that a super stiff frame might be relatively uncomfortable on a long sportive? Harsher ride?

danowat

Marketing spin?

MaxwellBygraves

EKIMIKE wrote:

Whether is makes me faster.... pffft. Meh, really couldn't care less. It's simply a pleasure to ride a nice bike.

+1 It's just good to ride a good bike.

tri-sexual

any cycle manufacturer can make a super stiff bike but the secret lies in making a bike which is stiff yet compliant (comfy) and light weight.
the caad 9 bikes are pretty stiff/ efficient (due to oversizing) yet they have hourglass seat stays to make them more compliant.
the stiffer you make a bike frame the more you have to do to make it more comfy, check out cannondales supersix carbon frames, massive tubing all round espcially round the BB area but cannondale use very slim seat stays to add comfort.
in short its great to have a super stiff bike but in the real world its a compromise because riding a super stiff (uncomfortable) bike can be slower than a softer (more comfortable) bike.
i doubt you will notice much difference between your CAAD 9 against a superstiff carbon in terms of power, if you want to increase power output, work on fittness and strength (explosive power) rather than a change of bike.

balthazar

"Stiffness" of a frame only has meaning laterally, because a frame twists in response to pedalling action. Vertically, all frames are practically rigid (deflection is off the bottom of the scale).

Even then, differences between frames are minimal. Large frames made from slim aluminium tubes are the most flexible (ie. ALAN/ Vitus frames from the 1980's, not seen anymore- or Speedwell titanium), and small frames made from oversized tubes (of any material) or CFRP monocoques are the least flexible. There is some test data here:

http://www.sheldonbrown.com/rinard/rina ... etest.html

to give you an idea of the deflection ranges.

Much is said about frame stiffness. I think most of it is BS (frankly), but in general, I don't think a frame can be too stiff. On the other hand, a very flexible frame might not actually be so problematic, despite feeling a little peculiar (it certainly never seemed to bother Sean Kelly). In practice, modern frames are all broadly similar in this respect, regardless of material or construction. The rest is marketing.

When I ordered my bike, I chose the largest diameter tubing (EL OS) available from the Columbus range my builder preferred, on the basis that, all else even, I'd prefer a more rigid frame- especially as I'm fairly tall.

mozami

tri-sexual wrote:

any cycle manufacturer can make a super stiff bike but the secret lies in making a bike which is stiff yet compliant (comfy) and light weight.
the caad 9 bikes are pretty stiff/ efficient (due to oversizing) yet they have hourglass seat stays to make them more compliant.
the stiffer you make a bike frame the more you have to do to make it more comfy, check out cannondales supersix carbon frames, massive tubing all round espcially round the BB area but cannondale use very slim seat stays to add comfort.
in short its great to have a super stiff bike but in the real world its a compromise because riding a super stiff (uncomfortable) bike can be slower than a softer (more comfortable) bike.
i doubt you will notice much difference between your CAAD 9 against a superstiff carbon in terms of power, if you want to increase power output, work on fittness and strength (explosive power) rather than a change of bike.

Do things like hourglass seat stays and thinly drawn tubes really make a difference? A read over a sheldon brown that no matter what you do to frame shapes they re not gonna flex that much to provide vertical compliance. The dominant factors for compliance are tyre pressure, saddle, seatpost diameter, length of chainstays, flex at seatpost insertion and then seat stays - roughly in that order.

Brian B

I have a Storck and find the stiffness of the frame exceptional and really feel it helps power transfer. I always feel a massive difference when I switch from my winter bike which is a Orbea and thats pretty stiff as well. My Storck descends like its on rails and can really push it on on the flat.

Downside is though it can be preety unforgining on the body when doing 100mile plus ride but I have done over 140 miles on mine.

thiscocks

My previous Bianchi full carbon 928 was a really nice comfortable ride and also pretty stiff and weighed in at 7.5kg. It was probably as comfortable, if not more as my current steel frame. Proves that not all carbon frames are uncomfortable.

vorsprung

I ride long distances so a comfortable bike is important to me

My best bike 2007-2010 (RIP) had a titanium frame. Obviously titanium is not cheese and it transmitted power just fine. I thought that if I got a "stiffer" transmission that would be a small amount more efficient then the bike would be less comfortable to ride.

After my old Ti bike went out of service, I got a new bike. This is made of carbon fibre and is very comfortable. At the same time I have been surprised at how "stiff" or efficient it feels for converting pedal pushes into forward motion. This is compared with my old Ti bike, an Aluminium racing bike I use regularly and my steel commuting bike.

So, bikes are not made equal for stiffness and stiffness does not necessarily equal discomfort

tri-sexual

mozami, regarding your comments about material shapes and how it can change the way a material behaves.
material shapes can have a massive effect on how it performs
the most basic example i can think of is a piece of square paper, take two supports (eg two thick books or similar) and rest the paper flat between these two supports, the weight of the paper will deflect the sheet so that it will have a problem to support its own weight.
take the same piece of paper, fold three or more straight folds along its length and try again, you will find that the you have made the paper stronger and can easily support itself, you have added nothing but strength has increased.
turn the paper the other way and you will find that the folds have made the deflection worse /weaker.
when it comes to bike design, a "rake" on the end of road forks can add alot of comfort to a set of forks.
on a cannondale flash, the seat post is designed to deflect in one direction only, this adds comfort for the rider.
the best example i can think of is the cannondale scaple chain stay, it is designs to flex upto 4 inches allowing full suss set up without the need of bearings etc, the chain stay itself flexes in one direction only. so it just illustrates how material choice, design, shape and application can change how it performs overall.