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Psimet's tip of the Day

Road Cycling “It is by riding a bicycle that you learn the contours of a country best, since you have to sweat up the hills and coast down them. Thus you remember them as they actually are, while in a motor car only a high hill impresses you, and you have no such accurate remembrance of country you have driven through as you gain by riding a bicycle.” -- Ernest Hemingway

Psimet's tip of the Day

Old 04-23-08, 01:31 PM
  #1  
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Psimet's tip of the Day

I thought I would create a place to share some of the nuggets I have gotten or given while on BF. I will come back and update this thread when I think about it. Probably no more than once a day though.



Tip 1 - Inflate your tires before every single ride. Know what the proper inflation pressure should be for your tires. Inflation requirements will vary by rider, bike, tires, conditions, etc.

Below you will find equations that you can use to help determine an appropriate starting point using your weight and the tire's size. Adjust from these baselines to suit needs and conditions.

Proper inflation is the easiet way to avoid flats.

Tire Width=20: Pressure(psi) = (0.33 * Rider Weight in lbs) + 63.33
Tire Width=23: Pressure(psi) = (0.33 * Rider Weight in lbs) + 53.33
Tire Width=25: Pressure(psi) = (0.33 * Rider Weight in lbs) + 43.33
Tire Width=28: Pressure(psi) = (0.33 * Rider Weight in lbs) + 33.33

Tire Width=32: Pressure(psi) = (0.17 * Rider Weight in lbs) + 41.67
Tire Width=37: Pressure(psi) = (0.17 * Rider Weight in lbs) + 26.67


Example: You are 150lbs running 28's

Pressure (psi) = (0.33*150) +33.33 = 82.83psi (rear)
Front Pressure = .9*Rear Pressure = .9*82.83psi = 74.55psi front


EDIT: I added () in order to make the equations make more sense. I think some people are doing the math incorrectly.
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Last edited by Psimet2001; 06-03-08 at 08:42 AM.
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Old 04-23-08, 01:37 PM
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My tire doesnt hold enough air, now what??

BTW, do you accomplish ANYTHING at work, thats WORK related?? ALSO... I saw that little comment in the other post about someone descending. Might cost you a few beers this weekend for me to "forget" it.
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Old 04-23-08, 01:42 PM
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You have a typo, the front pressure should be multiplied by rear pressure not by front pressure

This should be a fun thread.
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Old 04-23-08, 01:43 PM
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first i need the freaking tip on how to tell what tire size i have?!@? geesh.

later.
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Old 04-23-08, 01:43 PM
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Originally Posted by Psimet2001 View Post
Front Pressure = .9*Front Pressure = .9*82.83psi = 74.55psi front
Can't... get it... to work.

Head hurts. Is it like the sound of one hand clapping?
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Old 04-23-08, 01:44 PM
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Originally Posted by Kimbercop View Post
My tire doesnt hold enough air, now what??

BTW, do you accomplish ANYTHING at work, thats WORK related?? ALSO... I saw that little comment in the other post about someone descending. Might cost you a few beers this weekend for me to "forget" it.
Are you sure he works? I just thought everybody posting here during the day didn't work, like me...
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Old 04-23-08, 01:48 PM
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Old 04-23-08, 01:58 PM
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I come in at 109 rear, 98 front. That is about what I use on wet, relatively smooth roads in a race. Seems a little low to me for dry conditions. On bad pavement I'd be risking a pinch flat.
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Old 04-23-08, 02:01 PM
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I come out at 99.8psi for my 23s

i think that is a bit low really - according to my gauge on my pump (probably wrong) I put 120psi in often
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Old 04-23-08, 02:02 PM
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Now I have to carry a scale as well as a pump in my bike kit?

No need to reduce tire pressure while riding to compensate for fluid loss; your tires will do it for you.

With a little practice, of course, one should be able to do these calculations in one's head.
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Old 04-23-08, 02:11 PM
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Holy crap, I did the math, but the answer I got was
"Pump your tire up as much as you can you fat b@stard. If the tire blows, stop the lesson."
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Old 04-23-08, 02:14 PM
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Thanks, I havent seen this before.

Ive been trying to dial in my pressures during my last few rides few rides.

Ill try the front pressure=0.9Xrear pressure tonight.
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Old 04-23-08, 02:15 PM
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Originally Posted by Psimet2001 View Post
Front Pressure = .9*Front Pressure = .9*82.83psi = 74.55psi front [/COLOR][/I]
Infinite Loop!!....ERROR...Core Dump
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Old 04-23-08, 02:21 PM
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Psimet, it doesn't matter how many excuses you want to come up with (tire pressure being one of them), you'll still get dropped and we'll still yell at you.

That is all.
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Old 04-23-08, 02:22 PM
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I fixed the infinite loop

Yes...I do work...although we did block access to Bikeforums on our firewall here....wonder why.

Not to worry. BF nerds helped me supply my addiction.

I do not currently - nor do I have plans to - work for pcad or any of his subsidiaries. I should though because then maybe I could afford some Zipps...even if they were used and from ebay.

I will forever remain ....off the back...

Kimbercop - You know I was joking *as I reach for my wallet and hail the waitress*
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Old 04-23-08, 02:31 PM
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This is funny PSI.

My WalMart tires on my schwinn commuter only go to 100psi. I'm in trouble.
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Old 04-23-08, 02:32 PM
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I never did calculus in HS, but thanks.
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Old 04-23-08, 02:33 PM
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Lets make more jokes about how stupid we are.
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Old 04-23-08, 02:36 PM
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The tires on my Radio Flyer three wheeler don't seem to have a place to put air in them.

What now, genius?
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Old 04-23-08, 02:49 PM
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so, 89.6 rear, 80.64 front? that seems seriously... low.
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Old 04-23-08, 02:52 PM
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Maybe these values are for charity rides...
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Old 04-23-08, 02:56 PM
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Ya those numbers seem low. Here's a useful tip: The easiest way to prevent flats is to buy a pair of Specialized Armadillo tires. Unless you run over a razor blade or an industrial sized nail, you will not get a flat, and they last for ever.
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Old 04-23-08, 03:09 PM
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yeah, everyone knows armadillos will prevent pinch flats.
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Old 04-23-08, 03:14 PM
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Originally Posted by jsharr View Post
Psimet works at UselessBikeTriviata Inc., a subsidiary of PCadhatesyou Worldwide Holdings Ltd.
Are those publicly traded companies?
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Old 04-23-08, 03:15 PM
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- *shakes head* - most riders ride with their tires pumped way too high. Seems they all decided to post today.
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