Frame damage

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Postby kukamunga » Sat Feb 09, 2008 4:28 pm

sogood wrote:The sensation of speed is supposedly enhanced by a bit of bone jarring vibration. :wink:

So why do downhillers have girly long travel front and rear suspension. Sooks! :wink:

In the area I live, the sensation of speed is supposedly enhanced by a bit of alcohol (and a car) :(
God save the ABC & SBS.....
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by BNA » Sat Feb 09, 2008 4:35 pm

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Postby sogood » Sat Feb 09, 2008 4:35 pm

kukamunga wrote:So why do downhillers have girly long travel front and rear suspension. Sooks! :wink:

Because they need a technical excuse to put more weight on their bike. :lol:
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Postby stevendavid75 » Sun Feb 10, 2008 11:10 am

Roubaix bikes will often have a slightly longer wheel base and more relaxed geo.

few years ago an uncle of mine was importing SCAPIN and he actualy had a ballan team bike built for P-R and it was quite an interesting frame,
had both features as mentioned earlier as well as having rock shox ruby front susp, looked almost like a cyclo cross rig. (Oh yeah, it was steel as well)
Unfortunantly this bike was stollen (and it had never been ridden!)
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Postby sogood » Sun Feb 10, 2008 8:01 pm

toolonglegs wrote:It may be all relative... 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:

Read a bit more from this knowledgeable poster on another forum regarding this frame stiffness issue. His other works are on his site <http://www.bikephysics.com>
Yeah, I've worked out the numbers here in this forum a few times. The difference between a super stiff frame and a "noodly" frame (using measured frame stiffness) was less than 0.05% of Power. Or something like that. I can't be bothered to run the numbers again or look it up. So maybe 0.2 Watts at a big effort of 400 Watts.

In other words, the zipper on your jersey will probably have a bigger effect...

The number may not be absolutely correct but it does suggest a magnitude of the difference.
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Postby toolonglegs » Sun Feb 10, 2008 8:14 pm

....not sure those numbers mean much to me as 400 watts isnt a big effort to me...1200-2000 is,so I wonder if those 400w are seated which is when you arent really flexing the bike.Stand up and sprint may be a diference...maybee.
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Postby sogood » Sun Feb 10, 2008 8:19 pm

toolonglegs wrote:....not sure those numbers mean much to me as 400 watts isnt a big effort to me...1200-2000 is,so I wonder if those 400w are seated which is when you arent really flexing the bike.Stand up and sprint may be a diference...maybee.

If that 0.05% energy loss is true, then that's 1W of power loss when you are pumping 2000W into those cranks. But I agree, there's insufficient information in terms of the various assumptions based on what's quoted.

As I also agreed to previously, a frame with a stiffer BB is qualitatively nicer as a minimum.
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Postby toolonglegs » Sun Feb 10, 2008 8:32 pm

sogood wrote:
toolonglegs wrote:....not sure those numbers mean much to me as 400 watts isnt a big effort to me...1200-2000 is,so I wonder if those 400w are seated which is when you arent really flexing the bike.Stand up and sprint may be a diference...maybee.

If that 0.05% energy loss is true, then that's 1W of power loss when you are pumping 2000W into those cranks. But I agree, there's insufficient information in terms of the various assumptions based on what's quoted.

As I also agreed to previously, a frame with a stiffer BB is qualitatively nicer as a minimum.


not that any of that mattered to my pitiful racing effort today!. :roll:
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Postby sogood » Sun Feb 10, 2008 8:40 pm

toolonglegs wrote:not that any of that mattered to my pitiful racing effort today!. :roll:

But you were trying a totally different riding habit, which is known to be disruptive to one's race performance in the short or even in the medium term. Didn't LA lose his balls over his change? So I think you can be forgiven! ;)
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