140-145 and about the same psi

What is considered light weight?
I'm 160 and run 23mm tires on 24mm wheels at 90 psi.

i'm 124, 23mm and run 90. mainly cus that's what i read on flo.

would be interested to lower the psi by 10psi and test my speed assuming same power.

john

138-142 lbs lately. Run 95 psi on smooth pavement, 85 on rough, 80 on super rough/chip seal. Conti 4000S 23mm (runs almost like a 25 on Bonetrager Aeolus).

I'm 115lbs with 650cx23mm HED Jet 6 and ride with a PSI of 100 (this is down from 110psi that I used to ride). I'm sure multiple people will reply that this is too high (don't bother - I've heard it before).

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Elisha
"Triathlon doesn't build character. It reveals it."

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ECMGN Therapy Silicon Valley:
Depression, Neurocognitive problems, Dementias (Testing and Evaluation), Trauma and PTSD, Traumatic Brain Injury (TBI)

I'm 147 lbs and run max psi written on the tire. Thought that would create the lowest rolling resistance?

Kinda surprise to see so many of you riding at much lower psi like 90. What am I missing? :) What would the performance and feel effect be for me to go from 120 psi to 90?

Going too high with tire pressure actually raises rolling resistance. It causes the bike to bounce over surface imperfections in the road vs. the tire deflecting around them. This is not to say lower is better; it's that there is an optimal pressure based on your weight, the tire, and the road surface (the rougher the surface the lower the optimal pressure).

On a smooth surface (velodrome, or a smooth testing drum) higher pressure will test better.

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ECMGN Therapy Silicon Valley:
Depression, Neurocognitive problems, Dementias (Testing and Evaluation), Trauma and PTSD, Traumatic Brain Injury (TBI)

Weight: 150lbs

105 up front and 110 rear (23c)


Running Zipp 404 FC clinchers both front and rear

What is the source of this?

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http://www.jt10000.com/

and yet you continue to use a pressure that increases the power required to complete your races as well as increasing the fatigue due to rough ride. I guess successfully completing 39 triathlons and several Gran Fondoes outweighs carefully done science;) So keep on riding slower that you would and beating your body up more than necessary. Obviously one can't fix a case of deep rooted obstinance.

Hugh

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Genetics load the gun, lifestyle pulls the trigger.

Michelin.
I don't know what assumptions are made in producing that chart, so I take it with a grain of salt. I use 23mm tires, but my rims are 24mm wide at the brake track. I noticed a clear difference when going from 19mm wide wheels to 24mm wide wheels. I use 90 front and back, probably should try 85 up front, have never had a flat of any kind in 1.5 years of riding. That includes 3 potholes that I can recall.

My wife is 112 lbs. She is running Michelin Pro4 Endurance 700x23 on Flo wheels.

90 psi in the back, 85 in the front. No issues this season - no flats, etc. Tires do not appear to be over deflecting at ground contact.

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"...the street finds its own uses for things"

Unlike some people I've found that I need 5 to 10 psi more in a 650C tire than I do in a 700C tire.

I can run a 700X23 all day long at 90-95 psi but if I do that with a 650C I'm going to pinch flat on the roads I train on.

I've worked with the Conti GP4000SII and the PR4 on both sets of wheels

Perhaps other tires are different.

Edit: I'm 145lbs

jaretj

This makes sense with 700's since the total volume of the tire is less. I guess one needs a certain number of air molecules at a given temperature to keep the rider suspended. PV = nRT (after all). If the Volume goes down relative to 700C and you have the same temp it would stand to reason that one needs more pressure to avoid pinch flats.

Not too big a surprise that at 30lb heavier than the gal in question you might need a bit more pressure.

Hugh

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Genetics load the gun, lifestyle pulls the trigger.

I had to throw that (the weight) in there as an afterthought and I hoped you wouldn't miss it.

I had never thought it the 650/700 thing would amount to any difference but as soon as I got a 700C bike I noticed that I could go much lower.

I noticed the same thing with my mountain bikes between a 29'er and a 26". When I was using tubes I would run ~32-35lbs in the 26" but could run 28-30 in the 29'er. Since now I'm tubeless I run much lower.

I have a special formula for these things:

if I am running 21mm then 100PSI front and 100PSI back
if I am running 23mm then 100PSI front and 100PSI back
if I am running 25mm then 100PSI front and 100PSI back

In hot weather I tend to go for 100PSI, in cold weather 100PSI.
If I am going to be riding over cobbles, then 100PSI, if it is a smooth road, then 100PSI.

I find 100PSI works quite well for most situations!

Can put that in a spread sheet? I'm having a hard time following that formula.

You just couldn't resist could you. It always amazes me that complete strangers that know absolutely nothing about the someone, their riding, and capabilities seem to know better than that person and their coach. But hey good job on tracking down my experience from a different thread. I'm a lighter rider on 650c wheels which do typically ride with a higher pressure. I don't have any issues with "bouncing" on the road over cracks/bumps and don't feel beaten up from anything other than pushing myself. At lower psi's I've gotten pinch flats and felt sluggish on the road. I've also done my own research on the matter. It's not deep rooted obstinance but rather knowing myself and trusting the people I work with daily vice random strangers on slowtwitch that know nothing about me (and likely have no personal experience in being a 115lb female on a small frame running 650s). Gotta love the I know everything and anyone that disagrees is wrong attitude :)

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Elisha
"Triathlon doesn't build character. It reveals it."

Just curious, how does knowing someone change the physics of weight upon a tire?

I mean, if you want to prove the guy wrong, go for it. But "Knowing Someone" is not an argument

http://velonews.competitor.com/2014/12/bikes-and-tech/resistance-futile-tire-pressure-width-affect-rolling-resistance_355085


In general, unless you are riding on a glass smooth surface, lower tire pressures will absorb some of the imperfections in the road smoothing out the ride and lowering the overall Crr.

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Rodney
TrainingPeaks | Altra Running | RAD Roller
http://www.goinglong.ca

I weigh about 118 lbs and ride around 90-95 psi.

Edited to add that I race on 650c and train mostly on 700 wheels (two different bikes, obviously)... I keep the pressure around the same. If it's wet, maximum 90 psi. If it's really hot out and/or the bike's got to sit in transition for a long time, max 90 psi to allow for a slight increase in pressure from the heat while the bike sits.

You might not count this as direct experience but my dear wife has been doing triathlons for 30+ years. In that time she's probably well over 139 tris including 17 IMs with 5 trips to Kona. She is also about your size, has been riding 650 wheels for 20+ years and has had me manage her tire pressure that whole time. We have many years worth of power vs speed vs tire pressure data that confirms higher pressure is slower. You should just go head and keep running higher pressure because those darn low pressure tires "feel" sluggish and your friends "feel" higher pressure is faster. Your competition with thank you:) By the way, if you were running 110lb in recently manufactured HED Jet 6s you were exceeding the HED's maximum limit by 10% but hey you probably know better than the manufacturer.

Hugh

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Genetics load the gun, lifestyle pulls the trigger.