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What do you guys make of this "test" between bikes with different flex?
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http://janheine.wordpress.com/.../23/what-is-planing/

I like some of Jan's stuff, but I can't wrap my head around this one - it just doesn't make sense.

The term "Planing" has become a bit of joke within my riding group.

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Last edited by: Bonesbrigade: Nov 24, 14 7:41
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Re: What do you guys make of this "test" between bikes with different flex? [Bonesbrigade] [ In reply to ]
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I don't think I'm big or strong enough to flex any bike frame.

jaretj
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Re: What do you guys make of this "test" between bikes with different flex? [Bonesbrigade] [ In reply to ]
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He sure comes up with some doozies sometimes to rationalize his love for all things 650B randonneuring related ;-)

http://bikeblather.blogspot.com/
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Re: What do you guys make of this "test" between bikes with different flex? [Bonesbrigade] [ In reply to ]
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Heine sells SKF Isis-standard bottom brackets.

This is a very good thing.

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´Get the most aero and light bike you can get. With the aero advantage you can be saving minutes and with the weight advantage you can be saving seconds. In a race against the clock both matter.´

BMANX
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Re: What do you guys make of this "test" between bikes with different flex? [Bonesbrigade] [ In reply to ]
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Needs way more data. There were four bikes, how come only data from two of them? It is hard to draw conclusions since Bike 2 had both the highest and lowest power of the data presented, so this is very noisy data and they are trying to draw conclusions from a difference even smaller than that spread.
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Re: What do you guys make of this "test" between bikes with different flex? [chaparral] [ In reply to ]
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You have to buy the magazine issues I believe to see more data.
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Re: What do you guys make of this "test" between bikes with different flex? [jaretj] [ In reply to ]
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jaretj wrote:
I don't think I'm big or strong enough to flex any bike frame.

jaretj


Nonsense. Get on your trainer and look down at your bottom bracket when you ride

who's smarter than you're? i'm!
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Re: What do you guys make of this "test" between bikes with different flex? [veganerd] [ In reply to ]
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if you raced on your trainer, that'd be a real problem

-mike

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http://howtobeswiss.blogspot.ch/
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Re: What do you guys make of this "test" between bikes with different flex? [veganerd] [ In reply to ]
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On the typical trainer, the front tire is the contact point at the front. I would think the tire sidewalls are a more likely part to flex.
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Re: What do you guys make of this "test" between bikes with different flex? [veganerd] [ In reply to ]
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What's this trainer thing your speak of? :)

jaretj
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Re: What do you guys make of this "test" between bikes with different flex? [Rambler] [ In reply to ]
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Rambler wrote:
On the typical trainer, the front tire is the contact point at the front. I would think the tire sidewalls are a more likely part to flex.

They do. So does the frame.

who's smarter than you're? i'm!
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Re: What do you guys make of this "test" between bikes with different flex? [jaretj] [ In reply to ]
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jaretj wrote:
What's this trainer thing your speak of? :)

jaretj

Something that makes a minnesota winter a tad more bearable :)

Well, that and netflix

who's smarter than you're? i'm!
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Re: What do you guys make of this "test" between bikes with different flex? [Bonesbrigade] [ In reply to ]
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I like some of Jan's stuff, but I can't wrap my head around this one - it just doesn't make sense.

I think the concept is similar to putting a spring inside a rear hub to cause windup (some guys actually marketed that a few years ago). It makes the beginning and peak of the power stroke "softer" and the energy is returned in the later part of the stroke as the force applied by your leg eases up. Any gains would be due to your muscles responding better to this sort of resistance profile. Oval rings depend on a similar effect.

I'm definitely not impressed with the data he has presented in his blog, and I have a feeling if I got into the details I'd be disappointed... like I was with his rolling resistance tests.



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Re: What do you guys make of this "test" between bikes with different flex? [rruff] [ In reply to ]
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I used to flex the heck out of my Trek 1220 bottom bracket when doing seated sprints. Could visibly see it swing back and forth. Totally nonscientific experience, but if I simply hit the BB area perpendicularly, it was easily clear just how much that bottom bracket could move with just a small amount of force (different load path/type, I know). My current CAAD10 is miles better in this respect, and honestly, I can't really tell when the BB is flexing.
Last edited by: justkeepedaling: Nov 24, 14 21:36
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Re: What do you guys make of this "test" between bikes with different flex? [Bonesbrigade] [ In reply to ]
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So the idea is that the flexy frame (or really any part of the bike) could help "absorb" some of the energy during the more powerful section of one's pedal stroke and "release" it during the weaker section which balance out the "dead spot"... this could have some theoretical merit but no way accounts for 15% difference in power. The issue is far less relevant in the context of non-metal bikes (90%+ on this board?). Even less w/ higher rpm riding.

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Re: What do you guys make of this "test" between bikes with different flex? [threefire] [ In reply to ]
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Sean Kelly rode a vitus noodle for most of his career. He was one of the best sprinters of the day. He has said just that. The frame was like a spring. He would sprint at a rythum cadence that the frame lso the frame would snap back and help him go faster.
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Re: What do you guys make of this "test" between bikes with different flex? [lacticacid] [ In reply to ]
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It's also worth noting that Sean Kelly's preference was not (and is not) common among sprinters.
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Re: What do you guys make of this "test" between bikes with different flex? [rruff] [ In reply to ]
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rruff wrote:
I like some of Jan's stuff, but I can't wrap my head around this one - it just doesn't make sense.

I think the concept is similar to putting a spring inside a rear hub to cause windup (some guys actually marketed that a few years ago). It makes the beginning and peak of the power stroke "softer" and the energy is returned in the later part of the stroke as the force applied by your leg eases up. Any gains would be due to your muscles responding better to this sort of resistance profile. Oval rings depend on a similar effect.

I'm definitely not impressed with the data he has presented in his blog, and I have a feeling if I got into the details I'd be disappointed... like I was with his rolling resistance tests.



I have a feeling that since the testing protocol involved switching two bikes between two different riders for alternating runs, small differences in how the bikes fit the rider probably made for a huge source of "error" in this "scientific" test.


Also, its 2014... who the heck is racing with titanium bikes these days?
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