Go Back  Bike Forums > Bike Forums > Road Cycling
Reload this Page >

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 05-03-12, 08:26 AM
  #276  
zigmeister
Senior Member
 
Join Date: Mar 2011
Posts: 892
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 6 Post(s)
Likes: 0
Liked 1 Time in 1 Post
Originally Posted by Psimet2001 View Post
It was all covered. The formula isn't something that I personally derived off of hours of empirical testing.....

It is a derivation of pressures and ratings that the late great Sheldon Brown posted. They are starting places and have worked for the vast majority of riders trying them. In general and after 20 years of doing this I have found that the vast majority (near all) of riders ride at pressures that are simply way too high.

Argue all you want but it won't change that truth. Funny how in the last year or so everyone has started raving about lower pressures and big tires and wide rims.... guess this thread was before its time.
I asked because I read a recent article about tire pressure and a formula, it used the bike weight also, which as I mentioned, could change the pressure by nearly 7-8% at my weight personally.

I run Zipp FC tubies, which means around 120psi I run my tires at 170lbs, 16lbs full ride time bike weight/water bottles/shoes/clothes etc..

Plus, I've read several articles and quotes from Pro mechanics and tire pressures they run for guys about my weight on similar equipment, and come to my tire pressure number.

Of course, bumpy brick crit course, the pressure drops 20psi sometimes, but average nice road racing back to normal 120psi range. But, everybody has their ideas/theories.
zigmeister is offline  
Old 05-03-12, 08:56 AM
  #277  
Vlaam4ever
Senior Member
 
Vlaam4ever's Avatar
 
Join Date: Nov 2008
Location: Lake Claire, GA
Posts: 802

Bikes: 2008 Giant TCR Advanced

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Originally Posted by Psimet2001 View Post
Sorry. I started getting paid for my tips
You'd think you'd have a happier photo i your avitar.
Vlaam4ever is offline  
Old 05-03-12, 11:12 AM
  #278  
Psimet2001 
I eat carbide.
Thread Starter
 
Psimet2001's Avatar
 
Join Date: Jan 2006
Location: Elgin, IL
Posts: 20,593

Bikes: Lots. Van Dessel and Squid Dealer

Mentioned: 20 Post(s)
Tagged: 0 Thread(s)
Quoted: 600 Post(s)
Liked 23 Times in 18 Posts
Originally Posted by Vlaam4ever View Post
You'd think you'd have a happier photo i your avitar.
That was a happy avatar. I was about 8 beers in at that point.
__________________
PSIMET Wheels, PSIMET Racing, PSIMET Neutral Race Support, and 11 Jackson Coffee
Podcast - YouTube Channel
Video about PSIMET Wheels

Psimet2001 is offline  
Old 05-25-12, 10:46 AM
  #279  
JohnnyCyclist
Poseur Extraordinaire
 
JohnnyCyclist's Avatar
 
Join Date: Jun 2010
Posts: 341
Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 40 Post(s)
Likes: 0
Liked 1 Time in 1 Post
I haven't read all 275+ posts in this thread, so if my question was addressed in post #xxx, forgive me.

On my two road bikes, I run different tires (poseur decision to color-coordinate, nothing more). One says "inflate 90psi to ...", the other says "inflate 100psi to ...". Both are 700x23.

The formula gives me (rounded) values of 115/105.

Could the stated inflation values on the tires be taken into account? On the "inflate 90psi to ..." tire, I could drop 10psi from the formula-calculated values, run 105/95, and still be within the range specified by the tire manufacturer. There are some rough roads in my area, so a slightly lower tire pressure would be welcome. Would this 10psi drop increase rolling resistance that much and/or make the tires more prone to flats?

Thanks.
JohnnyCyclist is offline  
Old 05-26-12, 10:54 AM
  #280  
Psimet2001 
I eat carbide.
Thread Starter
 
Psimet2001's Avatar
 
Join Date: Jan 2006
Location: Elgin, IL
Posts: 20,593

Bikes: Lots. Van Dessel and Squid Dealer

Mentioned: 20 Post(s)
Tagged: 0 Thread(s)
Quoted: 600 Post(s)
Liked 23 Times in 18 Posts
Ignore the sidewall. Inflate as you like. Adjust to suit.

This is like a recipie - follow it to the T and you'll get a result. Add some flavor on your own and get something that tastes a lot better.
__________________
PSIMET Wheels, PSIMET Racing, PSIMET Neutral Race Support, and 11 Jackson Coffee
Podcast - YouTube Channel
Video about PSIMET Wheels

Psimet2001 is offline  
Old 05-26-12, 02:07 PM
  #281  
Youngin
ub3r n00b
 
Youngin's Avatar
 
Join Date: Sep 2007
Location: Minnesota
Posts: 1,368

Bikes: Bianchi Via Nirone, Trek 6000SS, Zebrakanko FG

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Hey Psimet, sorry to hijack the thread. Just wondering how long a quote takes, about to pull the trigger on a set of wheels but wanted to give you a chance first.
Youngin is offline  
Old 05-26-12, 03:46 PM
  #282  
rubic
Slogging along
 
rubic's Avatar
 
Join Date: Feb 2007
Location: San Fernando Valley, SoCal
Posts: 1,148

Bikes: Cannondale Synapse '06, Mongoose titanium road bike '00--my commuter. Yes, Mongoose once made a decent ti road bike.

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Wow, this is an old thread. So Psimet, here is a question for you concerning the air pressure formulas that you posted. In the last couple of years, some rims have gotten wider such as the Velocity A23 at 23mm. I am told that these wider rims can run a lower air pressures. How can this formula be adjusted for 23mm rims?
rubic is offline  
Old 05-29-12, 02:51 PM
  #283  
CyLowe97
Up on the Down Side
 
CyLowe97's Avatar
 
Join Date: Mar 2005
Location: Chicago(ish)
Posts: 6,330
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 3 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Originally Posted by Psimet2001 View Post
That was a happy avatar. I was about 8 beers in at that point.
This post made my day.

Your avatar moment was a marked improvement over your "gimme the ****ing keys!" moment at the day's first rest stop.

Good times, man, good times.

Back on topic: What's more optimal: washing the bike every three months or every five? I always forget.
CyLowe97 is offline  
Old 06-20-14, 10:20 AM
  #284  
Psimet2001 
I eat carbide.
Thread Starter
 
Psimet2001's Avatar
 
Join Date: Jan 2006
Location: Elgin, IL
Posts: 20,593

Bikes: Lots. Van Dessel and Squid Dealer

Mentioned: 20 Post(s)
Tagged: 0 Thread(s)
Quoted: 600 Post(s)
Liked 23 Times in 18 Posts
2-3 year bump. As some of you know (the ones who are still around) a lot has happened. Social media drew away the vast majority of heavy content posters on forums like this. My business took off like a rocket, etc.

It's a slow Friday and I am literally waiting for some glue to dry so...

In the hiatus I have done a lot: worked with tire manufacturers, glued thousands of tubulars, built thousands of wheels by hand, developed and run neutral race support services, sponsored and pitted for UCI ranked pro road and cyclocross racers, Fielded pro women's teams at NRC level events, etc.

Pretty sure I have a few new tips to offer and most likely would be able to contradict some previous tips. I learn more everyday and have no problem looking at something I may have done before and admit it was wrong if it truly was.

Since I obviously don't come out here much anymore there isn't much of a point in saving tips I can think of now so I will just share what comes to mind.
__________________
PSIMET Wheels, PSIMET Racing, PSIMET Neutral Race Support, and 11 Jackson Coffee
Podcast - YouTube Channel
Video about PSIMET Wheels

Psimet2001 is offline  
Old 06-20-14, 10:50 AM
  #285  
Athens80
Senior Member
 
Join Date: Aug 2007
Posts: 1,155
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 115 Post(s)
Liked 3 Times in 3 Posts
Originally Posted by Psimet2001 View Post
Since I obviously don't come out here much anymore there isn't much of a point in saving tips I can think of now so I will just share what comes to mind.
Nice.

I am interested in the question of whether wider rims like the A23 change the air pressure recommendation for a 25 tire, all else being equal.
Athens80 is offline  
Old 06-20-14, 10:56 AM
  #286  
vwchad
Senior Member
 
vwchad's Avatar
 
Join Date: Jan 2011
Location: Everett, Washington
Posts: 595

Bikes: 2013 Focus Izalco Pro, Soma Grand Randonneur

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 6 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Originally Posted by Athens80 View Post
Nice.

I am interested in the question of whether wider rims like the A23 change the air pressure recommendation for a 25 tire, all else being equal.
I believe the answer is yes, but I'm curious to hear his thoughts as well as I'm not sure how much.
vwchad is offline  
Old 06-20-14, 10:56 AM
  #287  
Psimet2001 
I eat carbide.
Thread Starter
 
Psimet2001's Avatar
 
Join Date: Jan 2006
Location: Elgin, IL
Posts: 20,593

Bikes: Lots. Van Dessel and Squid Dealer

Mentioned: 20 Post(s)
Tagged: 0 Thread(s)
Quoted: 600 Post(s)
Liked 23 Times in 18 Posts
I worked neutral race support for a multi day stage race a few weeks back. Race consisted of a circuit race for the pro men/women on a friday, TT early saturday morning, Road race saturday afternoon, crit on Sunday.

I gotta be honest - I felt like I wouldn't be needed much at all until the crit. Boy was I wrong. 6am on the morning of the TT I had a line by my tent that didn't slow down until noon.

1. Racers (I include myself in there) are idiots...errr....I mean have a lot of opportunities to learn new things.
2. If you are coming to a TT and bringing special TT specific equipment - ride it BEFORE driving 5 hours to the event. That way you'll realize what is out of order since the last time you rode it. Remember that tire you needed to re-glue? well you do now and that's a better time to realize it rather than 30 minutes before the start of your TT.
3. If you are "switching" to carbon wheels....bring carbon pads. Keep extra sets in the car at all times.
4. If you want to make money at a race: bring carbon pads and sell them.
5. Gearing....really guys - this isn't hard. Make sure it works....oh and taking it to a shop is nearly meaningless. It's only as good as the person who worked on it and an unfortunate side-effect of an ever changing industry that has tiny profit margins is that even the good shops really can't pay enough to keep the good ones...so you got the bad one.

....and with that I got a business call and need to go work on something. I'll see if I can pop back to this.
__________________
PSIMET Wheels, PSIMET Racing, PSIMET Neutral Race Support, and 11 Jackson Coffee
Podcast - YouTube Channel
Video about PSIMET Wheels

Psimet2001 is offline  
Old 06-20-14, 10:58 AM
  #288  
Psimet2001 
I eat carbide.
Thread Starter
 
Psimet2001's Avatar
 
Join Date: Jan 2006
Location: Elgin, IL
Posts: 20,593

Bikes: Lots. Van Dessel and Squid Dealer

Mentioned: 20 Post(s)
Tagged: 0 Thread(s)
Quoted: 600 Post(s)
Liked 23 Times in 18 Posts
Originally Posted by Athens80 View Post
Nice.

I am interested in the question of whether wider rims like the A23 change the air pressure recommendation for a 25 tire, all else being equal.
It does. Roughly start with 5 psi less and adjust to suit. I plan on doing some studies with different tires and draw some new curves using basic deflection measurements and the current models that are common in the market. Knowing some of the tire guys now will help as well.
__________________
PSIMET Wheels, PSIMET Racing, PSIMET Neutral Race Support, and 11 Jackson Coffee
Podcast - YouTube Channel
Video about PSIMET Wheels

Psimet2001 is offline  
Old 04-15-15, 06:46 AM
  #289  
Wanderer
aka Phil Jungels
 
Wanderer's Avatar
 
Join Date: Apr 2005
Location: North Aurora, IL
Posts: 7,989

Bikes: 08 Specialized Crosstrail Sport, 05 Sirrus Comp

Mentioned: 5 Post(s)
Tagged: 0 Thread(s)
Quoted: 139 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Another age bump....... Thanks a lot - now I gotta get bigger tires!
Wanderer is offline  
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
spectastic
Bicycle Mechanics
4
07-05-19 06:39 PM
MiloFrance
Classic & Vintage
2
09-25-14 11:50 AM
youarehydrogen
Singlespeed & Fixed Gear
7
07-30-09 09:08 AM
superduper54
Singlespeed & Fixed Gear
8
07-03-09 01:48 PM
Blacksail
Singlespeed & Fixed Gear
6
03-09-09 08:33 PM

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off


Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

Copyright © 2018 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.