Depends. If you're running latex tubes, then they're much more pinch-resistant than butyl. If you're running tubeless, then it's a non-issue.

Anyway, the idea is that "sweet spot" of tire pressures is not so high that you might get near the "breakpoint pressure" for whatever particular surface you go on...and not so low that you increase your likelihood of pinch flats.

If you can't accomplish that, then you might want to consider running wider tires...or, lose some weight ;-)

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http://bikeblather.blogspot.com/

Well...now you're just making me feel left out ;-)



Not just the "smooshing", but the the asphalt will also tend to "cure", or harden over time (probably an out-gassing effect). Some of the slowness of a brand new surface may be coming from the surface itself being somewhat soft...which is then getting into the types of things needing consideration for off-road uses.



Tend to be...but there can also be sections that aren't. I recall doing the CBR "State" TT near your house one year (the full 40K out and back course on the south edge of Edwards AFB, not the SCNCA course). There was an ~1/2mile section in that which was VERY rough...and it was easy to pick out in the power file later due to the dramatic speed reduction vs. the power output. If I knew then what I know now, I probably would've run wide tires (wider than I did at the time) at considerably lower pressures, just for that one section (gone over twice - out and back).



Well...we have to be careful to separate vibration effects on muscle power producing ability vs. vibration effects dissipating energy in the body tissues. Softride's thesis was more of the former than the latter. Also, if you're relying on a suspension system between the tire and the rider to reduce vibration energy making it to the rider, then those are going to be energy dissipating effects as well, and not as fast as using the tire for as much "suspension" as possible...especially considering that fast tires are by definition low energy dissipating ones as well...know what I mean? :-)

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http://bikeblather.blogspot.com/

"I recall doing the CBR "State" TT near your house one year (the full 40K out and back course on the south edge of Edwards AFB, not the SCNCA course)."

well, that was your problem. you should've stuck to the much closer (to my house) SCNCA course at lake los angeles. then you could've run 100psi ;-)

"we have to be careful to separate vibration effects on muscle power producing ability vs. vibration effects dissipating energy in the body tissues. Softride's thesis was more of the former than the latter."

i defer entirely to your memory and understanding of this. i was at that time making sure they didn't sell any bikes, making sure i sold all the bikes (or at least giving that my best effort). i was less eager to understand their thesis in depth, lest i fall over the edge and start agreeing with them.

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Dan Empfield
aka Slowman

Hi Dan,

More good fodder for the psi poll here:

http://flocycling.blogspot.com/...pressure-change.html

Scott

I did both that year...and the SCNCA course sometimes has some pretty rough cracks and such that need to be avoided...I remember the 2nd leg in particular requiring some careful "path selection"...



Yeah, as I recall there were some studies showing how vibration exposure reduced muscular power production.

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http://bikeblather.blogspot.com/

For 23mm tires with narrower internal rim width I would only ever ride between 85-90psi. It's a sweet spot for smoothness and least energy to rotate, at least on NZ and Australian chipseal. If I'm ever on smoother surfaces, it's 90-95.

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'It never gets easier, you just get crazier.'

You left off one of the other variables...how much you weigh :-)

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http://bikeblather.blogspot.com/

Usually yes. But it depends. For example, SC State TT championships is a very flat road but with relatively average pavement. The tire choice at that race front vs. rear and their associated pressures came into play when setting up my bike. Same thing with NC State TT champs. Charlotte motor speedway 10mi TT's (monthly series) also required adjustments related to tire choice (~20mm Conti SS tire on Zipp 808 FC) and pressure (that vs. the SW TC in back, for example, at 700x24).

Low 60s. If I had an extra 20kg to cart around I expect that I'd be running slightly higher pressures.

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'It never gets easier, you just get crazier.'