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Postby toolonglegs » Fri Feb 08, 2008 3:37 pm

Actually I think it seriously would...probably more.Talking to a trackie mate of mine and his take on the frame is a second more over 200m.They are just so damn stiff that the power transfer is amazing.
There are other factors in a frames performance than just aero dynamics...plus if i had a BT i would just ride faster because I would feel like a twat if i didn't!!! :lol:
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by BNA » Fri Feb 08, 2008 4:10 pm

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Postby sogood » Fri Feb 08, 2008 4:10 pm

toolonglegs wrote:There are other factors in a frames performance than just aero dynamics...plus if i had a BT i would just ride faster because I would feel like a twat if i didn't!!! :lol:

Here's an interesting one. According to a poster on another forum who has good technical knowledge, there's never been any tests that have shown a stiffer frame (within common production models) would go faster (for the same power of course). I haven't read enough about this issue but it's certainly food for thought.

Check BT's warranty clauses before you jump on one though! :wink:
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Postby tallywhacker » Fri Feb 08, 2008 4:47 pm

I would have thought that with a stiffer frame power that would have been absorbed by the frame bending is now transferred to the drive train.
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Postby sogood » Fri Feb 08, 2008 5:04 pm

tallywhacker wrote:I would have thought that with a stiffer frame power that would have been absorbed by the frame bending is now transferred to the drive train.

Don't know. It's a very complicated subject as there's also discussions on the return of that energy by the frame (spring analogy). Or it's a case where the theoretical difference is so small that it becomes meaningless in the real world.
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Postby mikesbytes » Fri Feb 08, 2008 5:30 pm

Never seen 531 tattooed onto somebody before

Edit: took the photo out, didn't realise it was one big photo
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Postby toolonglegs » Fri Feb 08, 2008 5:56 pm

If that is true then why are they building stiffer and stiffer bb brackets on all bikes now and there is more and more talk about torsional stiffness.
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Postby Ned Kelly » Fri Feb 08, 2008 6:10 pm

I reco it would if it is over 1kg lighter and with a better riding position than his previous bike. And that would be without mentioning the aero advantage! Dont stuff this thread up now will you!!!
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Postby europa » Fri Feb 08, 2008 6:28 pm

toolonglegs wrote:If that is true then why are they building stiffer and stiffer bb brackets on all bikes now and there is more and more talk about torsional stiffness.


It's good marketing mate.

I've read a lot of articles about stiffness, and the only ones I've read that claim any advantage in the real world give you the feeling that the colour of the lycra matters as well. Yes, you can measure stiffness advances, but in the real world, it doesn't seem to matter much.

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Postby toolonglegs » Fri Feb 08, 2008 6:57 pm

In my real world stiffness is all that matters..well on my cannondale anyway,stiff frame,wheels,stem bars,forks,chainrings,post etc.It pretty much weighs the same as my training bike...well the cytek is maybee a kilo heavier,it also has stiff wheels (probably stiffer) but when you stand up and sprint there is no comparison.
I have heard that ti frames give you a bit back in flex but personally i think flex is lost power...remember i am not after a comfortable ride,just power :D
Does anyone remember that pic of Greg Lemond powering it on his clunky old stell frame 8) ...looking at him head on you can see the pedal under the bottom bracket...thats how much he is flexing the frame!.
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Postby europa » Fri Feb 08, 2008 7:44 pm

You've also got to wonder how much of this is measurements vs feel. Maybe a flexing or stiff frame doesn't offer greater measureable performance, but if the rider FEELS better on it, he's going to do better.

It's not the technical measurements that matter in the race, it's the time on the stop watch and I'm romantic enough to believe that that figure is influenced by the mindset of the rider, not just the machine he's riding.

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Postby sogood » Fri Feb 08, 2008 10:04 pm

toolonglegs wrote:If that is true then why are they building stiffer and stiffer bb brackets on all bikes now and there is more and more talk about torsional stiffness.

Because it feels good from the rider's point of view? Because it's the same why they are making more and more curvey bike frames? Because there's some theoretical advantages? Who knows?

In any case, as commented by that poster, there are no studies that proves a stiffer frame is faster. From my point of view, I also like stiff frames. But where's the level of stiffness beyond which there's no more significant gains on the diminishing return curve? Lots of questions. I remember a article in CyclingNews last year where that commented that the marketing people are thinking that this stiffness angle is reaching the end of the line.
Last edited by sogood on Fri Feb 08, 2008 10:10 pm, edited 1 time in total.
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Postby sogood » Fri Feb 08, 2008 10:08 pm

Ned Kelly wrote:I reco it would if it is over 1kg lighter and with a better riding position than his previous bike. And that would be without mentioning the aero advantage! Dont stuff this thread up now will you!!!

Track bikes are heavy. No weight weenism with track bike!
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Postby Falcodore » Sat Feb 09, 2008 1:13 am

I wonder if the owner of the tartan frame is/was a member of the Black Watch or is a member of the Campbell clan.
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Postby sogood » Sat Feb 09, 2008 6:05 am

Found some interesting write-ups on this stiffness issue. Definitely more food for thought.

http://kirkframeworks.com/Flex.htm

And this little story.

A few seasons ago, a pal who was the product development guy at Specialized told me this story...

The guys at Specialized wanted their xc world cup pros to ride their full suspension bikes in races, but the riders wouldn't go for it. They said they were too slow. Every lap they rode, at the test course at Napa the riders came back, said the full suspension bike felt slower, it was slower, they knew it. Ben (my pal) took out a clip board, stop watch, and started timing every lap of every one of the team guys over the week. You know what? The slowest lap on the full suspension bike was faster than every lap on a hard tail, yet the Pro's said exactly the reverse. After showing the riders their times, they all switched to the full suspension bikes, it just took the data. Perception is not always reality. Feeling fast is not always fast. Feeling fast is about feedback from the ground, not how much speed you actually have...

The other part of the discussion is more complex... getting pedal power to
the rear wheel, how much does stiffness play a role in that?? Front triangle lateral stiffness so you can pull on the bars and push down on the pedals...
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Postby toolonglegs » Sat Feb 09, 2008 8:25 am

It may be all relative...as I am 103kgs and have some power in my legs the amount I flex a 63cm frame compared to what a 70kg rider on a 54cm frame wont be equal.A smaller frame should be stiffer but the rider would put out less power.A 63cm frame has a lot longer tubes everywhere and I would get a lot more leverage due to body length...so what i think is a stiff frame (and the parts I use to make the bike stiffer) may only make it on par with a smaller frame with lightweight parts.
I think there is a reason Magnus and Tom ask for extra wrapping on their bikes...2000w output in a sprint compared to Bettinis 1300w and a difference in frame size is quite difference.
I have race on my training bike and dont get the same feel in a sprint even thou physically I feel great.All you have to do is put it on a mag trainer and see the deflection in the BB,so add to that flex top tube and head tube in a sprint and that is alot of flex....
Just thinking aloud :roll:
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Postby Kalgrm » Sat Feb 09, 2008 9:19 am

More thinking aloud from me too:

As riders we see stiffness as the ultimate objective in a frame (in many cases - not all think this way...). Are we being fed a line by the marketing gurus?

I watch divers on their spring boards. They want their boards to flex. By doing so, they get controlled return on the energy they put into the board, which then launches them into their dive.

How come the flex we generate in a frame is considered lost to us? Doesn't it get returned to the drive line as we lay off the power?

I haven't put all this into a simulator or done any force diagrams, so it is all just speculation on my part. Still, I can't see why a frame can't be used to momentarily store peak power and return it as we drop power through our pedal stroke.

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Postby Hawkeye » Sat Feb 09, 2008 10:40 am

I'll throw my two cents in here.

On flex return perhaps cancelling out losses, I suspect much depends on the speed and timing of the flex return. I can see a situation (in theory) where the flex springs back and the timing is right and speed increases (positive feedback loop) and another situation (most of the time) when the timing/speed is wrong and it works against you.

This is certainly the case with surfboard fins where epoxy fibreglass and plastic composite fins suck, but polyester fibreglass fins built the right way really bring the board alive. They all flex, the only difference is how fast.

That said, I have no idea how you'd be able to direct flex return to help propel a bike and better brains than my feeble sample have been working on it for decades without achieving much.

So I think the pragmatic solution has been, if you can't direct it to help you then eliminate it as much as possible especially around the frame twisting around the BB under the application of power.
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Postby europa » Sat Feb 09, 2008 11:52 am

The other thing to consider is that perfect stiffness isn't always desirable.

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Postby kukamunga » Sat Feb 09, 2008 12:43 pm

europa wrote:"The other thing to consider is that perfect stiffness isn't always desirable"

I'll have to run that one by my wife and see what she says! :lol:

IMO, at the end of a hard day on the bike:

stiff bike = stiff body :x

flexible bike = flexible body
:)

If you've got a personal masseuse to give you a rub down at the end of a hard race session, go the ultra-stiff bike. Otherwise:

a bit of flex = a bit of comfort

Ever heard of "Built for comfort, not for speed" ? 8)

Speaking of flex ....!
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Postby Kalgrm » Sat Feb 09, 2008 12:53 pm

It seems that we are told to spin because we need to apply less torque to develop our power, meaning less damage to our joints. Less torque means we are not going to introduce much flex in the frame either.

That also indicates that the only times we make the frame flex are under the same conditions we usually try to avoid when riding over long distances: standing and powering.

Therefore, a stiff frame would really only help when you are sprinting or powering up a hill (in other words, racing). At all other times, the same frame is punishing your body. That implies that a casual or recreational rider doesn't get a lot out of a stiff frame beside a stiff body. Is that correct?

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Postby europa » Sat Feb 09, 2008 1:18 pm

Spot on Graeme. There's too much of the assumption that cycling equals racing or pretending to race. For big, strong blokes like toolonglegs who do actually race and do so seriously, that's all relevant of course, but you don't need a racing bike to ride your own stage of the TdF on the weekend, especially when all you're racing against is yourself.

Maybe I'm just getting old. I must confess that the MG spends more time touring than she does sprinting these days and that recumbent seems to be encouraging a similar attitude 8)

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Postby sogood » Sat Feb 09, 2008 2:02 pm

toolonglegs wrote:It may be all relative...as I am 103kgs and have some power in my legs the amount I flex a 63cm frame compared to what a 70kg rider on a 54cm frame wont be equal.A smaller frame should be stiffer but the rider would put out less power.A 63cm frame has a lot longer tubes everywhere and I would get a lot more leverage due to body length...so what i think is a stiff frame (and the parts I use to make the bike stiffer) may only make it on par with a smaller frame with lightweight parts.
I think there is a reason Magnus and Tom ask for extra wrapping on their bikes...2000w output in a sprint compared to Bettinis 1300w and a difference in frame size is quite difference.
I have race on my training bike and dont get the same feel in a sprint even thou physically I feel great.All you have to do is put it on a mag trainer and see the deflection in the BB,so add to that flex top tube and head tube in a sprint and that is alot of flex....
Just thinking aloud :roll:

I agree and have been thinking along the same line. The stiffness sweet spot of the regular line may not have carried to a larger frame or for a heavier rider. Hard to find those data. In any case, stiffness has been extensively used as a selling point up to this point.
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Postby toolonglegs » Sat Feb 09, 2008 3:53 pm

I agree that there is no need or want for a super stiff bike if you are just riding and not racing.My cannondale is a race only bike,but when i dod happen to ride it for non races it is still fairly comfortable but not as comfy as my cytek.On the one day my cannondale was taken down a very rough bit of road i thought i was going to lose my teeth...so i dont know how they do Roubaix!...i suppose speed smooths things out and also not caring about the longevity of a frame.
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Postby sogood » Sat Feb 09, 2008 4:17 pm

The sensation of speed is supposedly enhanced by a bit of bone jarring vibration. :wink:
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Postby kukamunga » Sat Feb 09, 2008 4:22 pm

toolonglegs wrote:On the one day my cannondale was taken down a very rough bit of road i thought i was going to lose my teeth...so i dont know how they do Roubaix!...i suppose speed smooths things out and also not caring about the longevity of a frame.

A Roubaix/ Pro rider has got a masseuse/ physio/ chiro/ shiatsu/ doctor/ chemist/ vet/ dentist/ mechanic waiting for them at the end of each day to fix them (and their bike) up! That's the main difference between them and Joe Average hack bike rider (oh.... and maybe the fitness bit) :cry:
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