Finally ,someone that explains clearly and scientifically why a lower tire pressure or more accurately the correct tire présumâmes you faster and better than just pumping up to120 psi. Thank you.
Hi Josh. I have just twigged onto the videos after following the podcasts since they started. With regards to the Parthenon, I hope you are taking the piss. The picture is of a building in Nashville!
Thanks for noticing and yes, the real parthenon is no longer symmetric ;-) I also went to school at Vanderbilt and looked out at that building from my window for 4 years, so thought it would be fun to use here!
Hi Josh. Glad to hear it was an informed choice of image. Perhaps the original Parthenon’s shift to asymmetry could make an interesting case study. While the original was designed and built seeking ‘perfection’, the changes over time have led to a better insight on both the culture an history of it’s region. Often these changes make for, in my opinion, a more interesting and possibly better outcome. It just depends on your parameters for ‘better’. Love your work and keep the great content coming.
@11:18 It's interesting that looks a lot like the drag curve for an airplane. I guess they're both a combination of two curves that have opposite slopes. @17:44 that cobbles curve probably makes a good argument for tubeless and tire inserts?
Great explanations and a nifty calculator with more in it than I thought at first glance (the pinch flat/rim damage piece is awesome). Does the slope and intersect point of the "impedance" part of the curve change if one is riding say a BMC URS with front and rear damping, vs say a straight up conventional frame and fork?
Lower vertical stiffness in the frame will generally move the impedance pressure higher if it is undamped, but will push it lower if it is damped as frame member deflection from say carbon, ti, or steel has less hysteresis than the tire casing, but any damped suspension element will have much higher hysteresis than the tire casing. The real beauty of systems like the URS is that they give you much more flexibility, you can run lower pressures with less pinch flat or rim damage risk, while generally being able to run higher pressures with a shallower impedance curve angle.
@@SILCAVelo Hmm -then should one be able to run at a lower overall RR at higher pressure than your calculator says if you are on say a GT grade with undamped fiberglass seat stays?
I was recently building a new set of deep section disc break wheels. For my mtbs I now always use asymmetric/offset (spoke holes) rims. There are a few brands that offer also deep section offset rims for road bikes. I was hesitant though because I was unsure if I would compromise aerodynamics. Have you got any experiences with such offset rims?
Theoretically this will affect aero making the system more aero in wind from one direction than from the other, but in practice the effects are going to be insanely small and we've never managed to actually measure then in field testing.
Yes, you can use the Chung Method to find your own sweetspot.. OR you can use the calculator to leverage the thousands of data points of others ot help get you 99.99% of the way there. And tubes, tubeless, tubular.. doesn't matter, the air pressure drives spring rate which is what we're after here.. so doesn't matter what type of system you are running, the optimal pressure will be same (within gauge error ;-) as the tire type is not driving spring rate, but only the damping..
really enjoyed the information and presentation of this video but there was a persistent high pitch whine throughout that was a little distracting. any one else notice that or just me?
Gave up at 4 mins 30, you haven't even mentioned "Bicycle Rolling Resistance". Please do a video on Bicycle Rolling Resistance, and provide a link for anyone who doesn't understand symmetry.
The Parthenon in Centennial Park, in Nashville, Tennessee, is a full-scale replica of the original Parthenon in Athens. It was designed by Confederate veteran William Crawford Smith and built in 1897 as part of the Tennessee Centennial Exposition. - Wikipedia
This knowledge has had an asymmetric impact on me. I cannot unlearn it.
Finally ,someone that explains clearly and scientifically why a lower tire pressure or more accurately the correct tire présumâmes you faster and better than just pumping up to120 psi. Thank you.
Thanks Maurice!
Hi Josh. I have just twigged onto the videos after following the podcasts since they started. With regards to the Parthenon, I hope you are taking the piss. The picture is of a building in Nashville!
Thanks for noticing and yes, the real parthenon is no longer symmetric ;-) I also went to school at Vanderbilt and looked out at that building from my window for 4 years, so thought it would be fun to use here!
Hi Josh. Glad to hear it was an informed choice of image. Perhaps the original Parthenon’s shift to asymmetry could make an interesting case study. While the original was designed and built seeking ‘perfection’, the changes over time have led to a better insight on both the culture an history of it’s region. Often these changes make for, in my opinion, a more interesting and possibly better outcome. It just depends on your parameters for ‘better’. Love your work and keep the great content coming.
Any way you could create a phone app of your pro tire pressure calculator? I would happily pay for that app. I use the web calculator all the time.
Same me toooo
Very interesting data! Thanks for sharing this. Please just check your mic having some noise
@11:18 It's interesting that looks a lot like the drag curve for an airplane. I guess they're both a combination of two curves that have opposite slopes.
@17:44 that cobbles curve probably makes a good argument for tubeless and tire inserts?
Brilliant ideas
Thank you! 😊
Great explanations and a nifty calculator with more in it than I thought at first glance (the pinch flat/rim damage piece is awesome). Does the slope and intersect point of the "impedance" part of the curve change if one is riding say a BMC URS with front and rear damping, vs say a straight up conventional frame and fork?
Lower vertical stiffness in the frame will generally move the impedance pressure higher if it is undamped, but will push it lower if it is damped as frame member deflection from say carbon, ti, or steel has less hysteresis than the tire casing, but any damped suspension element will have much higher hysteresis than the tire casing. The real beauty of systems like the URS is that they give you much more flexibility, you can run lower pressures with less pinch flat or rim damage risk, while generally being able to run higher pressures with a shallower impedance curve angle.
@@SILCAVelo Hmm -then should one be able to run at a lower overall RR at higher pressure than your calculator says if you are on say a GT grade with undamped fiberglass seat stays?
I was recently building a new set of deep section disc break wheels. For my mtbs I now always use asymmetric/offset (spoke holes) rims. There are a few brands that offer also deep section offset rims for road bikes. I was hesitant though because I was unsure if I would compromise aerodynamics.
Have you got any experiences with such offset rims?
Theoretically this will affect aero making the system more aero in wind from one direction than from the other, but in practice the effects are going to be insanely small and we've never managed to actually measure then in field testing.
@@SILCAVelo Good to hear! Then my next rims will be asymmetric for they improve lateral stiffness and better left/right spoke tension distribution.
So, Josh, how does one find the 'sweet spot'? Does the Silca Pro Pressure calculator get me there? Also, does the calculator account for tubeless?
Yes, you can use the Chung Method to find your own sweetspot.. OR you can use the calculator to leverage the thousands of data points of others ot help get you 99.99% of the way there. And tubes, tubeless, tubular.. doesn't matter, the air pressure drives spring rate which is what we're after here.. so doesn't matter what type of system you are running, the optimal pressure will be same (within gauge error ;-) as the tire type is not driving spring rate, but only the damping..
really enjoyed the information and presentation of this video but there was a persistent high pitch whine throughout that was a little distracting. any one else notice that or just me?
Gave up at 4 mins 30, you haven't even mentioned "Bicycle Rolling Resistance". Please do a video on Bicycle Rolling Resistance, and provide a link for anyone who doesn't understand symmetry.
RUclips does include the ability to scroll forward and back through videos. It's handy if you want to skip something.
will a seatpost suspension help in rolling resistance over cobbles?
If it works like a mtb fork I imagine it will use a lot of energy
I don't want to nit pick, but that's not THE Parthenon.
The Parthenon in Centennial Park, in Nashville, Tennessee, is a full-scale replica of the original Parthenon in Athens. It was designed by Confederate veteran William Crawford Smith and built in 1897 as part of the Tennessee Centennial Exposition. - Wikipedia
Matt Searels Interesting. Which means it illustrates Josh’s point perfectly. It’s still not THE Parthenon. 😊
Unfortunately the REAL parthenon is non longer symmetric.. ;-)