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PostPosted: Wed May 02, 2012 10:43 am 
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in the industry
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Posts: 713
Location: Luxembourg / Sweden
Franklin, perhaps you misunderstood my point?

Of course a frame needs to have flex - the questions are where and how much.

Too stiff a frame is wasting energy just as too soft is.
Handling and comfort are critical to performance and the experience of riding a bike.
Everything goes hand in hand.
The bike is a system that has to work in conjunction with the rider, a designer obviously needs
to make choices and compromises. To KGT's point, we feel that comfort seems to be commonly
neglected in the pursuit of light/aero/stiff.

I simply wanted to show that too much flex would waste energy and that the returning pendulum or
spring analogy is overly simplistic and not very accurate or even directly applicable.

The rocket analogy was simply a lighthearted attempt at conjuring up a dramatic image of efficiency on a trajectory,
in contrast to a crabbing rear wheel of a bicycle. It was also a wink at Ruegamer who famously used to sport the slogan :
'INFUSED WITH ROCKET SCIENCE'
(As I'm sure you would agree, the most efficient means of launching a rocket on a ballistic or orbital trajectory is
a vertical launch. An airplane like takeoff would obviously also be achievable but would require significantly more energy.)

Will be bowing out of this conversation at this point.
Let the arguments rage on! :mrgreen:

/a

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Posted: Wed May 02, 2012 10:43 am 


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PostPosted: Wed May 02, 2012 10:55 am 
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Franklin wrote:
4. Frame flex is countered and made worse by body flex. The joints of the cyclist are not static. When a rider flexes his frame, he also will flex his body. It remains to be seen if taking away the flex in the frame simply means all that flex will all of a sudden become forward speed instead of being transmitted towards the riders body.


That's exactly to the point. People selling bikes try to persuade us that the rider "does not exist". We can only make valuable studies by studying the rider-bike system and not just the bike itself.

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PostPosted: Thu May 10, 2012 10:52 pm 
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Where have my posts gone??


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PostPosted: Thu May 10, 2012 10:55 pm 
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There is more than adequate flex in the tyres and especially the wheels to demand a stiff, or really stiff frame. No question about it.

You are asking the wrong question probing the value of super-rigidity of the frame. It is a misnomer.


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PostPosted: Thu May 10, 2012 11:06 pm 
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horse wrote:
Where have my posts gone??


They're still here.
You know, for posterity. Like this entire thread. :D

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PostPosted: Sun May 13, 2012 8:51 pm 
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So for all my long winded anti-aero talk earlier in this thread....I just won my first race yesterday with a Ridley Phaeton (aero alu training bike) that I only used cause it was wet and nasty and my Campag UT chainset on my Merckx has caught that awful knocking disease....an 8km solo break with the last 5km flat run into the finish...I won by 3 seconds....was it the aero frame?


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PostPosted: Mon May 14, 2012 2:03 am 
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you won the race. the aero frame helped.


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PostPosted: Tue Feb 26, 2013 5:19 am 
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Long time lurker and first time poster. Just starting to get serious about cycling and have enjoyed reading many threads on this forum from insane weight weenie builds that I would be too terrified to ride to basic reviews of pedals. I am currently a competitive collegiate oarsman and I am looking to get into competitive cycling as a form of cross training and something to satisfy my competitive nature during the off season. I plan on mostly doing crits and a couple road races. I love the idea of a WW bike and its more affordable now than ever but with my body type I feel like it might not be the most realistic for racing. I am 6'2 (188cm ) and probably 190lbs (86kg) in riding gear. So I'm wondering if anyone has any experience/ideas/feedback for the situation. When I'm 190lbs would I be better served by going with an aero frameset, 60mm wheels and accepting the weight penalty but having a stiff+fast frame or going for something more minimalist ( cervelo r3 comes to mind ) with a lightweight wheelset and having something more flexy but nimble+responsive?

Thanks in advance!


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PostPosted: Tue Feb 26, 2013 5:24 am 
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If I were your size :P, I would go R3 with some deep wheels. Great combo, stiff, light, somewhat aero from the wheels, and very very capable on a variety of terrain.


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PostPosted: Tue Feb 26, 2013 5:51 am 
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That is what I was leaning towards as well, even on the drops I'm still probably not that "aero" so I'd negate everything the engineers worked so hard for :twisted:
Love the look of the R3, ideally I would want 38mm tubulars for the low weight+ rotational inertia, but would they be stiff enough?


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PostPosted: Tue Feb 26, 2013 11:37 am 
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fitnessfiend wrote:
I am 6'2 (188cm ) and probably 190lbs (86kg) in riding gear.


As it happens I do the bike fitting for the national rowing program here in New Zealand (so I've set up a few current olympic champions). Based on that I'd suggest you go for heavy and aero - making power will not be your problem - overcoming drag and the risk of breaking things are bigger problems for you. If you want to optimise your competitive chances make some sensible component choices to keep the weight down and maybe 50mm tubs for racing so that you don't feel too compromised on the weight front.

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PostPosted: Tue Feb 26, 2013 12:29 pm 
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Surely you'd still prefer to go with one of the aero frames that is more appropriate to power output as well though. A bike like the S5 with it's narrow-is-aero design wouldn't be my first choice.

Yes I know Thor rode it successfully in 2011, but good for him, I'm a similar size to the OP and always prefer something more connected on the front end - perhaps in this case the aero bikes to look at then would be a Madone, Foil, Venge or Propel.


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PostPosted: Tue Feb 26, 2013 1:48 pm 
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I would think aero and stiff. If you are tall and heavy your watts/drag is going to be better than your watts/weight. The surface area (and drag) increases more slowly than weight as you get taller. You have a better chance of a solo breakaway on flat (aero) than in the hills(weight) against an average group of riders at your level. I agree with js, those would all be good choices for you.

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PostPosted: Tue Feb 26, 2013 10:19 pm 
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This thread is hilarious. The test numbers aren't accurate, so take an error margin of 50% to the claims made and use that number. Aero frames/wheels will certainly not be slower than the normal versions. Anyway, Is anyone seriously calculating Aero Watts Saved/$ or Aero Watts Saved/gram to determine what their next frame will be? In the end you'll end up riding 10 different bike frames and picking the one that feels/fits the best.


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PostPosted: Tue Feb 26, 2013 10:51 pm 
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haven't read through 14 pages so maybe i'm repeating someone. but what i miss in the aero frame and wheel testing process is how the handling is affected. sure, a bike like a cervelo s5 might be aero, but how much more is it affected by cross winds?how much harder is cornering with such a frame compared to a "standard" round tube frame?cornering with 90 mm rims is harder than with 40 mm rims and it is the same for the frame. think of sailboats: the longer the fin keel, the more stable it will go straight on, but it's harder to change direction. i'm pretty interested about e.g. scott foil and trek madone. a kamm tail might add "forward direction stability" but at least it should not be affected by cross wind.
when you look at pro teams, some have their material selection affected more by marketing, some by actual testing and listening to riders. when you look at the second group of teams it's pretty obvious that they rather go with the stiff and light frameset combined with the perfect wheel setup for the race they enter, that is weight one day and aerodynamic the other day. think about zakeens bike. aero everywhere but he uses the classic round tube frame. positioning on the bike is of huge importance!


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