DIY way to stiffen rear triangle?
10-29-18, 09:29 PM
#51
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I've heard the foam thing third hand (maybe in the track forum?) that Keirin racers in Japan did/do spray it into their frames to increase stiffness. I couldn't imagine it actually does anything.
10-29-18, 09:39 PM
#52
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The flaw in that argument as I see it is that even if the frame does act as a perfect spring, and returns all the energy stored in it when flexed, it does not necessarily mean it returns the energy in the most useful way. For example, since the frame is releasing the energy at the same time as you are easing up on the force on the pedals, it may go into slowing your pedal stroke down more than making the bike go faster. In other words, the energy may get transferred from a very efficient spring (the frame) to a terribly inefficient spring (your legs and body).
10-29-18, 09:48 PM
#53
C*pt*i* Obvious
Another thread whereby the OP has not responded to anyone.
Yet the pointless conversation continues, and nobody asks the obvious questions like:
What kind of frame, or bike do you have?
Any pictures?
How does this compare to other frames or bikes?
Why is frame flex so important?
Surely its easy enough to get a stiffer (or more flexible) bike?
Yet the pointless conversation continues, and nobody asks the obvious questions like:
What kind of frame, or bike do you have?
Any pictures?
How does this compare to other frames or bikes?
Why is frame flex so important?
Surely its easy enough to get a stiffer (or more flexible) bike?
10-29-18, 11:25 PM
#54
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Yes, now the losses are crystal clear (in the imagination), just not detectable or measurable. Very convincing at ~100 Hz!
10-30-18, 06:25 AM
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10-31-18, 08:41 AM
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Easiest way to reduce rear triangle flex without drilling, hacks, welds, etc...
...is to increase the surface area contact between the frames rear dropouts and the hubs locknuts or end caps.
There's a reason why old school track hubs would have oversize locknuts versus the regular road model of the same model line hub.
But then again...if you're someone spending your whole time watching your BB swing both ways...
...you're riding the wrong addiction.
(No dirty minds please...)
=8-)
...is to increase the surface area contact between the frames rear dropouts and the hubs locknuts or end caps.
There's a reason why old school track hubs would have oversize locknuts versus the regular road model of the same model line hub.
But then again...if you're someone spending your whole time watching your BB swing both ways...
...you're riding the wrong addiction.
(No dirty minds please...)
=8-)
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5000+ wheels built since 1984...
Disclaimer:
1. I do not claim to be an expert in bicycle mechanics despite my experience.
2. I like anyone will comment in other areas.
3. I do not own the preexisting concepts of DISH and ERD.
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5000+ wheels built since 1984...
Disclaimer:
1. I do not claim to be an expert in bicycle mechanics despite my experience.
2. I like anyone will comment in other areas.
3. I do not own the preexisting concepts of DISH and ERD.
4. I will provide information as I always have to others that I believe will help them protect themselves from unscrupulous mechanics.
5. My all time favorite book is:
Kahane, Howard. Logic and Contemporary Rhetoric: The Use of Reason in Everyday Life
10-31-18, 03:24 PM
#59
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Yeah, I never felt like planing was very plausible; the energy stored in the frame will be released at the moment when the very least of it will be transferred into forward motion. For that not to be the case, propelling bike and rider forward would have to be easier than other things it could do.
11-02-18, 03:41 PM
#60
Senior Member
I did the foam in the frame tube thing way back when my job was spraying foam. What it does is completely eliminate the possibility of condensation forming inside the tubes. A steel frame will not rust from inside out after being foamed. Foam doesn't have any kind of structural strength that would be noticed inside a steel tube. Also weighs nothing. And at least seemed to make the bike a bit quieter.
11-03-18, 11:19 PM
#61
Senior Member
..
The concept of planing is difficult to test. Heine's contention is that a rider can actually put out *more power* on a frame that planes for them. They went so far as to have visually identical frames with weight equalized in a true double-blind testing environment. Two of the three testers were notably faster on the more-flexible (thinner-walled steel) frame, consistently over number of trials. B...
.
The concept of planing is difficult to test. Heine's contention is that a rider can actually put out *more power* on a frame that planes for them. They went so far as to have visually identical frames with weight equalized in a true double-blind testing environment. Two of the three testers were notably faster on the more-flexible (thinner-walled steel) frame, consistently over number of trials. B...
.
11-04-18, 12:59 PM
#62
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The difficulty is, different riders (weight, power, pedaling style) interact with frames differently.
One thing that makes this easier to think through is to go back to the days when steel bikes were normal, and tubing sizes were all the same dimensions. Cheaper steel had thicker walls, and hence stiffer tubing. And stiffer frames were slower (and not just because of the weight).
Of course, that doesn't prove anything for certain (because conventional wisdom has often been wrong).
11-06-18, 08:19 PM
#63
Peugeot PSV10 or somethin
Thread Starter
OK, this thread really took off! I had to take a break for halloween.
To answer the question, I am riding a 59cm Peugeot PSN-10. The tubing is Super Vitus 980, my cranks are Ultegra 6800 and my rear wheel is a HED Belgium C2 with a Dura Ace 9000 hub.
I do some spinning and some mashing... if I could find a way to wrap the stays in carbon and ensure there was some way to get it back off again if I didn't like it, I'd totally do it!!
I used to weigh around 130 and now I weigh 150lbs. I have noticed that some of the springiness went away. Going over bumps can be more of a "squish" feeling than a bounce. This would imply to me that its not all that uncommon for a frame to be too flexy.
To answer the question, I am riding a 59cm Peugeot PSN-10. The tubing is Super Vitus 980, my cranks are Ultegra 6800 and my rear wheel is a HED Belgium C2 with a Dura Ace 9000 hub.
I do some spinning and some mashing... if I could find a way to wrap the stays in carbon and ensure there was some way to get it back off again if I didn't like it, I'd totally do it!!
I used to weigh around 130 and now I weigh 150lbs. I have noticed that some of the springiness went away. Going over bumps can be more of a "squish" feeling than a bounce. This would imply to me that its not all that uncommon for a frame to be too flexy.
Last edited by Stormy Archer; 11-06-18 at 08:23 PM.
11-07-18, 10:29 AM
#64
Banned
Time to either get a new bike, frame of oversize tubing since you are tall so tubes are longer..
or just live with it as a feature, not a flaw.
or just live with it as a feature, not a flaw.
11-07-18, 07:20 PM
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I'm not sure how much stiffness a missing bridged frame would gain if a bridge was added, at the usual location. Years ago Bicycling magazine had a series of articles involving what was then considered leading edge engineering, a finite stress analysis computer modeling, of bike frames. They used a few different arrangements of frames including with and without chainstay bridges. Their findings were that the CS bridge didn't change the results. My seat of my pants experience bears this out.
I attribute the focus on stiffness as a selling quality began about the same time. Cannondale had just begun to go to the bank on Klein's patented use of oversized tubes to increase frame stiffness. Those of us who rode small sizes already knew the truth, overly stiff frames increased rider fatigue and this led to a slower end of ride. Andy.
I attribute the focus on stiffness as a selling quality began about the same time. Cannondale had just begun to go to the bank on Klein's patented use of oversized tubes to increase frame stiffness. Those of us who rode small sizes already knew the truth, overly stiff frames increased rider fatigue and this led to a slower end of ride. Andy.
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