# Maintaining Air Pressure



## jmmarquis (Jun 21, 2013)

OK, once again some new guy questions.

How do you guys check the air in your tires before a ride? Just a cheap gauge from the auto parts store? Surprisingly I don't see this accessory in bike supplies.

I was looking at the CO2 inflators, looks much easier than a tiny pump. However, my tires are only about 65 psi, any advice or experience on using these?

Thanks again.


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## Old_Drum (Nov 9, 2009)

You need to get yourself a "floor pump"--a larger bicycle pump that sits on the floor. It will have a pressure gauge built into it. If you get a decent one, it will last you decades. It's probably the most important bicycle accessory after a helmet.

CO2 can work well in an emergency because it doesn't take up much space and it fills the tube quickly. But it's meant to be used only in emergencies, to fix a flat on the road. Your tubes aren't meant to hold CO2. If you fill them with CO2 they will go flat overnight.


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## Old_Drum (Nov 9, 2009)

i.e. look around your bike shop for something that looks like the picture below and with a nozzle that fits the kind of valve on the tubes you use (presta vs. schrader).

View attachment 283377


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## SGMDWK (Jul 22, 2012)

"Your tubes aren't meant to hold CO2. If you fill them with CO2 they will go flat overnight. "

That might be one of the most idiotic statements I have ever read. If your tires go flat overnight it is because they have a leak, not because the gas you filled them with was short some nitrogen.

That aside, CO2 cartridges would get expensive if used routinely rather than for on-the-road emergencies. A good pump like that above, will have a pressure gauge to tell you where you are at. There are plenty of discussions on here to help you determine the best pressure to run, too.

I must admit, though, that my pre-ride routine is to place thumb and finger on either side of tire and squeeze. If I think "That feels a bit squishy" I add air. If I can barely squeeze the sidewall in, I hop on and take off. I'm neither racing, nor seriously training, so the old squeeze technique works just fine.


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## cxwrench (Nov 9, 2004)

SGMDWK said:


> "Your tubes aren't meant to hold CO2. If you fill them with CO2 they will go flat overnight. "
> 
> *That might be one of the most idiotic statements I have ever read.* If your tires go flat overnight it is because they have a leak, not because the gas you filled them with was short some nitrogen.
> 
> ...


You may think it's idiotic, but it's true. Careful, making statements like this when you don't know what you're talking about makes you look...idiotic.


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## Old_Drum (Nov 9, 2009)

SGMDWK said:


> That might be one of the most idiotic statements I have ever read.


Counter-intuitive, yes. "Idiotic", absolutely not. CO2 is more soluble in butyl or latex rubber than air, so it makes its way through the tube wall faster.


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## Old_Drum (Nov 9, 2009)

Also, it's best if you don't use the "squeeze technique" described above. You might get by with it and it's certainly better than ignoring your tire pressure. But I, for one, am not confident I can feel the difference between 100 psi (what I prefer in my rear tire) and 80 psi, which I'm pretty sure will make me prone to pinch flats if I hit a pothole with the rear. Maybe there are guys with more experience and fingers that are more supple than mine, but I doubt the OP is one of them.


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## jmmarquis (Jun 21, 2013)

I thought you were all going to say "buy a small compressor for your garage and put a regulator on it..."

I thought FOR SURE there would be some advances in technology over ye ole plunger pump.

Ok, I will plan on finding either a tiny pump or CO2 for flats, and just use a pump or compressor at home.
Thanks all!


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## Team Sarcasm (Oct 22, 2012)

Subjective as this will sound, on-board mini pumps are not as bad as you may think. I use one and have never had to complain. 

With co2 I've heard the screw on adapter is easier than the press on one, since its one less thing to worry about. I have never used co2, but a friend who tried to convince to use it me told me that.

Amazon.com: Topeak Pocket Rocket Master Blaster Bike Pump: Sports & Outdoors

This is the pump I use on my bike. Very light, easy to use. No pressure gauge but pump it up to match the other tire will at least get you back on the road.


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## SGMDWK (Jul 22, 2012)

It's a side note, but the idea that CO2 is lost faster than air seems to be part of cycling lore, but that doesn't make it true. In fact, air passes through butyl rubber faster than CO2 does. I refer you to the following: Butyl Rubber Products || Timco Rubber


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## cxwrench (Nov 9, 2004)

SGMDWK said:


> It's a side note, but the idea that CO2 is lost faster than air seems to be part of cycling lore, but that doesn't make it true. In fact, air passes through butyl rubber faster than CO2 does. I refer you to the following: Butyl Rubber Products || Timco Rubber


All you have to do is try it yourself. Everyone else knows this is the truth, are you just arguing the point to be a pain the *ss? 
Read this...
Re: Why is my carbon dioxide effusing too fast?

If it weren't an issue, why did this company go to the trouble of coming up w/ this product? 
StayFill
A lot of effort if it's a non-issue. And if it weren't true, people would find out rather quickly in this day & age, don't you think? 

Might as well read this one too, while you're discovering the truth. 
Article

This is one of the most widely known truths in cycling. You must try it yourself before you become known as one of the more ignorant posters ever.


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## MPov (Oct 22, 2010)

SGMDWK said:


> It's a side note, but the idea that CO2 is lost faster than air seems to be part of cycling lore, but that doesn't make it true. In fact, air passes through butyl rubber faster than CO2 does. I refer you to the following: Butyl Rubber Products || Timco Rubber


I am not going to debate the science behind it, but really, have you ever tried it? Whenever I use CO2 my tire is largely deflated within two or three days.

To the OP: Get a floor pump with a gauge, check pressure before every ride. It is really quite simple.


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## NJBiker72 (Jul 9, 2011)

To the OP. 
1. Get a floor pump like everyone said.
2. What type of bike and tire do you have? I top off my race bike every time. Relaxed geo one too although I could probably go a few days or a week. My hybrid? Once in awhile. Nothing scientific.


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## Gudmann (Jun 6, 2012)

I have this one :
Amazon.com: Topeak Road Morph G Bike Pump with Gauge: Sports & Outdoors

Mini pump to have on the bike, but folds out like a mini floor pump and has a good enough gauge.


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## SGMDWK (Jul 22, 2012)

cxwrench said:


> All you have to do is try it yourself. Everyone else knows this is the truth, are you just arguing the point to be a pain the *ss?
> Read this...
> Re: Why is my carbon dioxide effusing too fast?
> 
> ...


I retire, bowed and bloodied. My apologies to all.


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## PJay (May 28, 2004)

you do need a floor pump that will go past 120 psi. some are made for kids bikes etc. and the top value on the gauge might be 80 psi.

ppl prefer close to or above 100 psi for road cycling. myself, i put clinchers up to 120, and loved an old tubular set-up i had, where i struggled with my 160 lb body to get 150 psi.

also, tire pressure gauges from the auto parts store may only go to 50 or 60 psi, cuz you rarely have auto tires go that high or higher - so you cannot just use the tire gauge you use for your car.


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## PJay (May 28, 2004)

i don't think co2 will get the tire much past 80 psi, but co2 is really used to limp your way back home.

frame pumps vary a lot in how high psi they can get - the limiting factor is usually how doggedly you want to sit there on the side of the road making tiny little pump strokes like a teenager in he at


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## cxwrench (Nov 9, 2004)

PJay said:


> i don't think co2 will get the tire much past 80 psi, but co2 is really used to limp your way back home.
> 
> frame pumps vary a lot in how high psi they can get - the limiting factor is usually how doggedly you want to sit there on the side of the road making tiny little pump strokes like a teenager in he at


You do realize that there are different sizes of CO2 cartridges available, don't you? 12, 16, 25g, etc. You can inflate pretty much any size tire to any pressure you want.


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## NJBiker72 (Jul 9, 2011)

cxwrench said:


> You do realize that there are different sizes of CO2 cartridges available, don't you? 12, 16, 25g, etc. You can inflate pretty much any size tire to any pressure you want.


Agree. It is the pump that lets you limp home. The CO2 gives you a full refill.


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## PJay (May 28, 2004)

cxwrench said:


> You do realize that there are different sizes of CO2 cartridges available, don't you? 12, 16, 25g, etc. You can inflate pretty much any size tire to any pressure you want.


i forgot abt those - i just get that one standard/common size.


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## tlg (May 11, 2011)

PJay said:


> you do need a floor pump that will go past 120 psi. some are made for kids bikes etc. and the top value on the gauge might be 80 psi.


Not if you never pump your tires to 120psi. I've never pumped a tire to 120psi, thus I do not need a pump to go that high. I think my pump only goes to 110. Suited me fine for many years.

That being said, virtually every floor bike pump goes to 160psi these days. 



> i don't think co2 will get the tire much past 80 psi, but co2 is really used to limp your way back home.





cxwrench said:


> You do realize that there are different sizes of CO2 cartridges available, don't you? 12, 16, 25g, etc. You can inflate pretty much any size tire to any pressure you want.


Yup. Or use multiple cartridges. I use co2 so that I do not have to limp home with lower than desired pressure. If I get a flat 10mi into my ride, I surely don't want to "limp home".


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## QuattroCreep (Nov 30, 2009)

NJBiker72 said:


> Agree. It is the pump that lets you limp home. The CO2 gives you a full refill.


Disagree. It depends on the pump and the skill of the pumper. 

I run a Parktool frame pump(both commuter and road bike), it will easily push a road tire to 100+psi. Even most well built mini pumps will get to 90-100psi.

The biggest thing when using a frame or mini pump is to find some thing to rest the pump head on while pumping. Find a nice size rock, tree stump, or fence post. Then rest the pump head against the object. One hand holds the pump head to the object the other hand pumps. Align every thing so you are pushing down and using your body weight. Same idea as using a floor pump at home.

I laugh every time I see a rider doing the "strong man". Holding the pump head in one hand and the handle in the other, working out their pecks wondering why the pump wont get to the advertised 100psi.


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## nhluhr (Sep 9, 2010)

tlg said:


> Not if you never pump your tires to 120psi. I've never pumped a tire to 120psi, thus I do not need a pump to go that high. I think my pump only goes to 110. Suited me fine for many years.
> 
> That being said, virtually every floor bike pump goes to 160psi these days.


There's more to high pressure pumps than just the gauge. HP pumps tend to have a smaller piston which means less force required to achieve a higher pressure. Using a pump that has a guage up to 160 but a very large piston (Pedros Domestique), my wife can barely push it down, even putting her whole weight on the handle. Sure, the small barreled Silca Super Pista pump that I have requires more total strokes, but each stroke is easy.


jmmarquis said:


> OK, once again some new guy questions.
> 
> How do you guys check the air in your tires before a ride?


Since a high pressure road bike tire *probably* needs to be pumped every day or at least once a week to be in an optimal pressure range, I think it's best to just put your pump on and give it a stroke or two, watching the gauge to make sure you're at the right pressure. No separate gauge needed.


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## NJBiker72 (Jul 9, 2011)

QuattroCreep said:


> Disagree. It depends on the pump and the skill of the pumper.
> 
> I run a Parktool frame pump(both commuter and road bike), it will easily push a road tire to 100+psi. Even most well built mini pumps will get to 90-100psi.
> 
> ...



Well I guess if you carry a very large pump you can get it up there. But most micro or even mini pumps will not. 

I carry a mini on my rain bike and a micro on my main bike, along with a CO2 cartridge. The micro is just there in case of emergency (ie, second flat or CO2 failure).


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## gabedad (Jul 12, 2012)

jmmarquis said:


> I thought you were all going to say "buy a small compressor for your garage and put a regulator on it..."
> 
> I thought FOR SURE there would be some advances in technology over ye ole plunger pump.


Pumps definitely have advanced since the old floor pump.when I started biking last year- I was amazed how much easier new pumps blow up tires.


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## Camilo (Jun 23, 2007)

NJBiker72 said:


> Well I guess if you carry a very large pump you can get it up there. But most micro or even mini pumps will not.
> 
> I carry a mini on my rain bike and a micro on my main bike, along with a CO2 cartridge. The micro is just there in case of emergency (ie, second flat or CO2 failure).


With just a modicum of effort, I can get my 23mm tires to 100psi with my very inexpensive little minipump. I've never used anything other than that, and I've never had a problem. 100 psi is all I ever pump my rear tire up to anyway.

Is it easy or quick? no. I have to brace the pump, and make sure every little (literally) pump stroke goes full length, and then just pace myself and get the air in. It's a 1-2 minute effort. But it's far more than "limping home". It's full pressure, continue the ride without concerns.


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## NJBiker72 (Jul 9, 2011)

Camilo said:


> With just a modicum of effort, I can get my 23mm tires to 100psi with my very inexpensive little minipump. I've never used anything other than that, and I've never had a problem. 100 psi is all I ever pump my rear tire up to anyway.
> 
> Is it easy or quick? no. I have to brace the pump, and make sure every little (literally) pump stroke goes full length, and then just pace myself and get the air in. It's a 1-2 minute effort. But it's far more than "limping home". It's full pressure, continue the ride without concerns.


That is exactly what I do on the relaxed bike with wide tires. But not for the more aggressive bike with 23s. I want more pressure (run 120) and less weight. I would not want to try getting to 120 with my micro. Regardless of what it advertises.


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## cxwrench (Nov 9, 2004)

NJBiker72 said:


> That is exactly what I do on the relaxed bike with wide tires. But not for the more aggressive bike with 23s. I want more pressure (run 120) and less weight. I would not want to try getting to 120 with my micro. Regardless of what it advertises.


Seems you're confused about pressure as well, but that's another discussion completely.


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## NJBiker72 (Jul 9, 2011)

cxwrench said:


> Seems you're confused about pressure as well, but that's another discussion completely.


Not a featherweight. I could probably run slightly less but most charts that everyone touts recommend around120 for the vast majority of riders.


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## cxwrench (Nov 9, 2004)

NJBiker72 said:


> Not a featherweight. I could probably run slightly less but most charts that everyone touts recommend around120 for the vast majority of riders.


What "charts" are you referring to? If you need 120psi to avoid pinch flatting on normal roads, you definitely need bigger tires.


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## PJay (May 28, 2004)

cxwrench said:


> What "charts" are you referring to? If you need 120psi to avoid pinch flatting on normal roads, you definitely need bigger tires.


This sounds like four conversations at once.

No one ever said anything about avoiding pinch flats, unless I missed a post.

I prefer to have my tires pumped up to 120-125 psi.

There is nothing wrong with that, and nothing unorthodox.

I personally cannot understand people trying to push 100psi marshmallows down the road. --But from reading RBR, it seems that most recreational road bike riders prefer 100psi, or have heard that they should go to 100psi and so they do.

There is nothing wrong with 100psi, or 120psi.

At 120, yes, the ride is a lot more harsh. Sure, I have lost some fillings and some water bottles have disappeared along the way. But I can handle it.

While I had a bike with tubulars, I loved riding that at 150psi - it was like riding the breeze. If clinchers could go to 150, I would go there.

BTW - to people pumping up to 100psi with mini-pump: what brand!!?


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## NJBiker72 (Jul 9, 2011)

PJay said:


> This sounds like four conversations at once.
> 
> No one ever said anything about avoiding pinch flats, unless I missed a post.
> 
> ...


I know of no one outside of this forum that runs that low. 

FWIW, I was referring to the Michelin chart, that always gets posted here to show that people that way 100 pounds should ride lower pressure. 

I'm 170 or maybe 175 after this weekend.  I could go as low as 100 psi but I would not want to on my Tarmac. Now a nice cruising ride or rough gravel ride, sure.


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## cxwrench (Nov 9, 2004)

PJay said:


> This sounds like four conversations at once.
> 
> No one ever said anything about avoiding pinch flats, unless I missed a post.
> 
> ...


Sure you can inflate your tires to whatever you want. But...

It's well known that you get better ride, better traction, and yes...slightly lower rolling resistance at lower pressures. So, yes...you can inflated them to whatever you want, but you're definitely confused about the effects of pressure and what it does or doesn't do for you.


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## tihsepa (Nov 27, 2008)

Jeebus 120? 150?

What are you guys 300 pounds on 21's?

CX, dont waste your time with this. 
I love the comment about nobody outside of the fourm running less than 120. Or whatever was said. I have no idea what other people run for pressure. Nor do I care. This is the only place I have ever seen it discussed. 

Remember, everything is faster, better, smoother or whatever on the internet.


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## Old_Drum (Nov 9, 2009)

Just 150 psi? If you want to go even faster, I suggest dispensing with pneumatic tires entirely.

View attachment 283685


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## NJBiker72 (Jul 9, 2011)

Old_Drum said:


> Just 150 psi? If you want to go even faster, I suggest dispensing with pneumatic tires entirely.
> 
> View attachment 283685


Even better just run them completely flat. You will be lightning fast and oh sooo comfy.


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## tlg (May 11, 2011)

PJay said:


> There is nothing wrong with that, and nothing unorthodox.


Nope... nothing wrong if you enjoy a harsher and slower ride. 



> I personally cannot understand people trying to push 100psi marshmallows down the road. --But from reading RBR, it seems that most recreational road bike riders prefer 100psi, or have heard that they should go to 100psi and so they do.


If you don't understand, perhaps you should educate yourself. Once you understand... you'll get it.



> At 120, yes, the ride is a lot more harsh. Sure, I have lost some fillings and some water bottles have disappeared along the way. But I can handle it.


 Wow... now that sounds unorthodox. 




NJBiker72 said:


> I know of no one outside of this forum that runs that low.


Does that mean you've asked every single person on earth outside the forum... or you don't know a lot of people?


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## Social Climber (Jan 16, 2013)

PJay said:


> I personally cannot understand people trying to push 100psi marshmallows down the road. --But from reading RBR, it seems that most recreational road bike riders prefer 100psi, or have heard that they should go to 100psi and so they do.
> 
> There is nothing wrong with 100psi, or 120psi.
> 
> At 120, yes, the ride is a lot more harsh. Sure, I have lost some fillings and some water bottles have disappeared along the way. But I can handle it.


Maybe we don't have the same masochistic tendencies that you do  When I ride I prefer any suffering to come from burn in my legs and lungs, not lost fillings.


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## Cyclin Dan (Sep 24, 2011)

SGMDWK said:


> It's a side note, but the idea that CO2 is lost faster than air seems to be part of cycling lore, but that doesn't make it true. In fact, air passes through butyl rubber faster than CO2 does. I refer you to the following: Butyl Rubber Products || Timco Rubber


Cycling lore or not, do me a favor. Go let all the air out of both tires on one of your bikes. Fill one with CO2, full the other with your floor pump. Check them in 24-36 hours and see which had more pressure. I'll bet you anything the one filled with CO2 has about HALF the pressure of the other.


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## Old_Drum (Nov 9, 2009)

NJBiker72 said:


> Even better just run them completely flat. You will be lightning fast and oh sooo comfy.


In seriousness though, you would concede that pneumatic tires are a significant upgrade to just putting an iron band around a wheel like they used to do on penny-farthings, right? And you would also concede that this affects both speed and comfort because pneumatic tires absorb some of the vertical displacement you would experience riding on a solid wheel (thereby giving you better traction and less severe bumps)?

The point that everyone is trying to make is that it's possible to increase the psi in a pneumatic tire to such an extent that it can't absorb vertical displacement and is similar to riding on a solid tire (making the bike slower and less comfortable). I suppose reasonable minds can disagree about where this occurs, but I'm willing to bet it's somewhere south of 150.


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## NJBiker72 (Jul 9, 2011)

Old_Drum said:


> In seriousness though, you would concede that pneumatic tires are a significant upgrade to just putting an iron band around a wheel like they used to do on penny-farthings, right? And you would also concede that this affects both speed and comfort because pneumatic tires absorb some of the vertical displacement you would experience riding on a solid wheel (thereby giving you better traction and less severe bumps)?
> 
> The point that everyone is trying to make is that it's possible to increase the psi in a pneumatic tire to such an extent that it can't absorb vertical displacement and is similar to riding on a solid tire (making the bike slower and less comfortable). I suppose reasonable minds can disagree about where this occurs, but I'm willing to bet it's somewhere south of 150.


I do not disagree at all. However, most of the research I have seen still points to around 120 for your typical recreational cyclist. Maybe I will go back to 25's at some point, after this set of tires wears out but I am pretty happy with the 23's and from what I have seen I should be at or near 120. Most people I ride with are in a similar state of mind even if they weigh less than me.


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## PJay (May 28, 2004)

Nimble Tire Pressure Advice

that link is informative.

i jogged and skateboarded for a couple decades before buying a roadbike.

as a kid, i skateboarded all ove the place. i would ride 3 miles to get to the local skatepark. i would ride a half mile to my buddy's home all the time.
we rode in parking lots regularly.

skateboard wheels are very hard - well past bicycle wheels- firmness is measured in 'durometers.' and skateboard wheels range from maybe 85 to 95 durometer.

so, maybe my comfort with a jolting skateboard ride make it no big deal to have a bumpy ride.

i definitely can tell the difference between clinchers with 100 psi, 110, and 120. i prefer 120 because it is generally faster.

this is short-term pre/post: I ride a bit, decide the bike seems slow, check pressure, see it is 100 psi, pump them to 120, then perceiev that riding is easier/quicker.

i really don't care whose theory i am defying, and i am convinced enough to not have to go find some orthodoxy on this.

some of cycling is perception and opinion. if other riders believe they are faster at 100psi than 120psi, more power to ya.

in the beginner's forum, i would definiteyl encourage a beginner to try pressures from 90 or 95 to as high as 125, and see what they prefer.

i really don't care what other ppl ride, but i think the decent thing to do is to share realistic views with new riders.

next, let's all pontificate on the best lubricants.


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## thekarens (Jul 17, 2012)

There's no perceived about it. You are going faster or not. A Garmin or whatever can determine that. 

I don't care what psi anyone rides. I ride lower because there's lots of chip seal and I prefer a more comfortable ride and personally I'm not any faster or slower within 20 psi.


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## Old_Drum (Nov 9, 2009)

I've also read that speed-wise the optimal psi is slightly above the pressure at which you'd pinch flat (due to the decrease in vertical displacement and better contact with the road). There is an interesting little debate on that, and I'm not sure it's really resolved. I'm sure the answer depends on the bumpiness of the surface you're riding on.

In any event, I'm convinced the speed difference is negligible unless you're talking about very low or very high pressures. The key then should be comfort. I've tried 120 psi but with my weight (150lbs) and the bumpy roads I ride on (Los Angeles) it sucks. If 120 psi feels good to you I say go for it.


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## tlg (May 11, 2011)

PJay said:


> Nimble Tire Pressure Advice
> 
> that link is informative.


That link is anything but informative. It doesn't take tire width into account. So it's worthless. It also says never to run lower than 90psi. Which is crap. My GF weighs 90lbs. She doesn't run anywhere near 90psi. Hell, I'm 168lbs and run 80psi front and 90-100psi rear. 




> i definitely can tell the difference between clinchers with 100 psi, 110, and 120. i prefer 120 because it is generally faster.
> 
> this is short-term pre/post: I ride a bit, decide the bike seems slow, check pressure, see it is 100 psi, pump them to 120, then perceiev that riding is easier/quicker.


You got bit by the placebo bug. You obviously didn't do any scientific testing. Because if you did, you'd have different results.



> i really don't care whose theory i am defying, and i am convinced enough to not have to go find some orthodoxy on this
> 
> i really don't care what other ppl ride, but i think the decent thing to do is to share realistic views with new riders.


Realistic views? There is nothing realistic about what you "feel".


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## NJBiker72 (Jul 9, 2011)

PJay said:


> Nimble Tire Pressure Advice
> 
> that link is informative.
> 
> ...


Here is the chart that always seems to get posted:
Michelin Bicycle USA - A better way forward®

Basically the same info as your article, which classifies a large rider as someone over 170 lbs. Ok, I fit in that (would like to drop a few), but yesterday tried on new LG shorts, size small, they fit perfectly. And at just under 6'0"? Not like I am exceptionally tall.

So, combining these two pieces of expert advice, it makes sense to run at the higher pressures for most Americans.


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## cxwrench (Nov 9, 2004)

PJay said:


> Nimble Tire Pressure Advice
> 
> that link is informative.
> 
> ...


"generally" "perceive" "decide the bike _seems_ slow"

Very scientific. The following paragraph is copied directly from your link, and i agree w/ most of it, especially the parts talking about suspension and traction. The differences in speed between 100psi and 120psi would be very hard to feel for just about anyone, but there is no way to argue that you wouldn't have better ride quality and increased traction at the lower pressure. Who wouldn't want a smoother ride and more cornering/braking traction?
It all boils down to the fact that you're under informed, and stubborn to boot. You're unwilling to listen to logic and science, because what you "feel" and "perceive" have to be right. Hmmmm, my tires "feel" fast so they must be fast.

The paragraph from Nimble...

We find many reasons not to inflate your tire beyond the 130 PSI limit. Heavier riders or riders on suspended bicycles can ride at the 130 PSI limit while lighter riders should ride at 90 to 110 PSI. *The Negative consequences of high inflation pressures include: (1) elimination of the principal shock absorber on a bicycle significantly impacting rider fatigue and equipment wear, (2) degradation of handling from the smaller contact patch (increasing slip rates and side wash out), (3) loss of traction (loss of rear wheel acceleration, and braking skids) , (4) marked increase in flat tires (less tire to road conformance, greater puncture load behind road hazards), and (5) more rapid catastrophic flat tires. * If you demand high inflation pressures consider our tubular composite wheels which work with tires rated to 220 PSI, however exactly the same advice pertains to tubular tires. Do not over-inflate tubular style tires, for the same reasons, it offers no performance benefits and carries the same detriments of increased shock, and worse handling, traction and flatting.


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## NJBiker72 (Jul 9, 2011)

cxwrench said:


> "generally" "perceive" "decide the bike _seems_ slow"
> 
> Very scientific. The following paragraph is copied directly from your link, and i agree w/ most of it, especially the parts talking about suspension and traction. The differences in speed between 100psi and 120psi would be very hard to feel for just about anyone, but there is no way to argue that you wouldn't have better ride quality and increased traction at the lower pressure. Who wouldn't want a smoother ride and more cornering/braking traction?
> It all boils down to the fact that you're under informed, and stubborn to boot. You're unwilling to listen to logic and science, because what you "feel" and "perceive" have to be right. Hmmmm, my tires "feel" fast so they must be fast.
> ...


How many riders are not "heavy" based on that standard? Which was exactly my point. Sure lighter may be good for racers and very lightweight people but not really for your everyday cyclists.


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## cxwrench (Nov 9, 2004)

NJBiker72 said:


> How many riders are not "heavy" based on that standard? Which was exactly my point. Sure *lighter* may be good for racers and very lightweight people but not really for your everyday cyclists.


What do you mean by "lighter"? And do you mean to say that "everyday cyclists" need higher pressure for some reason? I'm confused by your post.


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## NJBiker72 (Jul 9, 2011)

cxwrench said:


> What do you mean by "lighter"? And do you mean to say that "everyday cyclists" need higher pressure for some reason? I'm confused by your post.


Yes. Generally charts and info seem to say between 110 to 130 for riders over 170 pounds. 170 is not exactly a Clydesdale.


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## cxwrench (Nov 9, 2004)

NJBiker72 said:


> Yes. Generally charts and info seem to say between 110 to 130 for riders over 170 pounds. 170 is not exactly a Clydesdale.


You must be looking at some old charts. It's _generally_ accepted that pressures over 110-115psi are an indication that larger tires are needed. "Everyday" riders are most likely interested in the best ride, traction, and durability they can get. Quality tires at around 100psi max for the rear and 10-15% less front are what provide that. Tire size is determined by body weight. You wouldn't put a 90lb woman on the same tire as a 200lb guy, would you? 
The Nimble link you provided specifically states that higher pressures reduce both ride quality and traction. I'm 170lbs, and i ride a few different wheel sets. Here are the pressure/tires i use:

Tubular road wheels: Challenge 22mm Forte 100psi rr/85 frt
Clincher road wheels: Michelin Pro4 SC 25mm rr(actual width 27) 85psi/Bontrager R2 25mm frt (actual 25) 80 psi
Tubeless road wheels: Bontrager R2 23mm tubeless 90rr/80frt
Tubular track wheels: Concrete track, 21mm Zipp tubulars 100rr/90frt, on wood track 130rr/120frt for sprint events
I bet that i'll roll just as fast as you will at 120 if not a tiny bit faster. I'll absolutely, positively guarantee i'll be more comfortable doing it, have better traction at all times, and my tires will last longer.


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## NJBiker72 (Jul 9, 2011)

cxwrench said:


> You must be looking at some old charts. It's _generally_ accepted that pressures over 110-115psi are an indication that larger tires are needed. "Everyday" riders are most likely interested in the best ride, traction, and durability they can get. Quality tires at around 100psi max for the rear and 10-15% less front are what provide that. Tire size is determined by body weight. You wouldn't put a 90lb woman on the same tire as a 200lb guy, would you?
> The Nimble link you provided specifically states that higher pressures reduce both ride quality and traction. I'm 170lbs, and i ride a few different wheel sets. Here are the pressure/tires i use:
> 
> Tubular road wheels: Challenge 22mm Forte 100psi rr/85 frt
> ...


I did not post the Nimble link. I posted the Michelin. Both give the benefits of higher pressure. Nimble says not over 130 but certainly over 100 for the majority of riders. 

And even you seem to run some tires higher. 

Some people want the softer ride. Sometimes I do as well but not on the more aggressive set up. Then again I prefer not riding that on as rough roads as my other bike.


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## PJay (May 28, 2004)

What's in a tube? - Slowtwitch.com

some more data.

also, an interesting test was mentioned on another site:
find a long downhill and time how long it takes to roll from start to end with no pedaling.

run this trial at diff tire pressures.

the optimal pressure will have the fastest time - for that road surface.

another discussion noted a reason why too much pressure will slow you down - along with the weight of the bike moving forward, it also moves up and down over bumps.

if pressure is higher, the entire bike and rider gets moved up and down, as well as forward.

when your energy gets sidetracked from moving you forward to moving up and down, you need to contribute more energy to get back to the same speed.

if the tire deflects to absorb the bump, rather than the entire bike and rider getting deflected up, the bike and rider keep the energy going forward, and don't have to add the additional energy to move from the up-down to forward.


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## cxwrench (Nov 9, 2004)

NJBiker72 said:


> I did not post the Nimble link. I posted the Michelin. Both give the benefits of higher pressure. Nimble says not over 130 but certainly over 100 for the majority of riders.
> 
> *And even you seem to run some tires higher*.
> 
> Some people want the softer ride. Sometimes I do as well but not on the more aggressive set up. Then again I prefer not riding that on as rough roads as my other bike.


ONLY on a wood track that is obviously perfectly smooth. Never over 100 on the road. 



PJay said:


> What's in a tube? - Slowtwitch.com
> 
> some more data.
> 
> ...


This defines what rolling resistance is.


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## PJay (May 28, 2004)

cxwrench said:


> ONLY on a wood track that is obviously perfectly smooth. Never over 100 on the road.
> 
> 
> 
> This defines what rolling resistance is.


No; that is not rolling resistance. Rolling resistance is the resistance to forward motion of the wheel. The up-and-down might be called deflection, and is more a matter of the second law of motion. Relevant, but not rolling resistance.


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## cxwrench (Nov 9, 2004)

PJay said:


> No; that is not rolling resistance. Rolling resistance is the resistance to forward motion of the wheel. The up-and-down might be called deflection, and is more a matter of the second law of motion. Relevant, but not rolling resistance.


What about this? Copied and pasted from Widipedia about "rolling resistance". 


Over inflating tires (such a bicycle tires) may not lower the overall rolling resistance as the tire may skip and hop over the road surface. Traction is sacrificed, and overall rolling friction may not be reduced as the wheel rotational speed changes and slippage increases.

Whatever you want to call it, it will happen less at 90psi than at 120. Fact.


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## tom93r1 (Jul 19, 2009)

Cyclin Dan said:


> Cycling lore or not, do me a favor. Go let all the air out of both tires on one of your bikes. Fill one with CO2, full the other with your floor pump. Check them in 24-36 hours and see which had more pressure. I'll bet you anything the one filled with CO2 has about HALF the pressure of the other.


I had been wondering why my tires seemed to deflate more quickly when I used a CO2 inflator and I just figured it out a couple weeks ago. When you use the CO2 you freeze the valve stem. Pop the inflator off and screw the valve back in. Now wait a minute at this point for it to thaw, you can screw the valve down quite a bit more. Leaky frozen valve stem loses more air than what is passing through tube walls.


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## NJBiker72 (Jul 9, 2011)

cxwrench said:


> ONLY on a wood track that is obviously perfectly smooth. Never over 100 on the road.
> 
> 
> 
> This defines what rolling resistance is.


I know I descend faster with higher pressure but we can agree to disagree.


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## tlg (May 11, 2011)

NJBiker72 said:


> I did not post the Nimble link. I posted the Michelin. Both give the benefits of higher pressure. Nimble says not over 130 but certainly over 100 for the majority of riders.


They both give incomplete and inaccurate info. Neither indicate that you should run different pressure front and rear. You do that right?

Your Michelin link says "the chart below should give you a reasonable guide of where to start when experimenting". Well if you did experimentation, you'd find you'd be faster and more comfortable at lower pressures.



> Some people want the softer ride. Sometimes I do as well but not on the more aggressive set up.


What in the world does an aggressive setup have to do with it? Why would you want a slower and bumpier tire on an aggressive setup? 



NJBiker72 said:


> I know I descend faster with higher pressure but we can agree to disagree.


Rally? So you did detailed testing of this? Please share the data from your testing results which prove your "theory".


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## NJBiker72 (Jul 9, 2011)

tlg said:


> They both give incomplete and inaccurate info. Neither indicate that you should run different pressure front and rear. You do that right?
> 
> Your Michelin link says "the chart below should give you a reasonable guide of where to start when experimenting". Well if you did experimentation, you'd find you'd be faster and more comfortable at lower pressures.
> 
> ...


Why are you soft tire peoole so unrelenting? To answer your first question, yes I run a little lower in the front. More like 110 in 23s. 

And yes Really . I ride the same roads quite frequently. A couple of good steep descents to get away from home and to get back. So I have experimented with different pressures. And 120 is definitely faster for me over those roads than 110 or 100. Is it significant? Not much. Maybe 0.5 mph at speed. Now the one road is very well paved. The other fairly but with a few holes. I know where they are and try not to ride over them. 

If I want to ride bumps and gravel I take out my other bike with wider tires amd inflate them less.


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## tihsepa (Nov 27, 2008)

NJBiker72 said:


> Why are you soft tire peoole so unrelenting? To answer your first question, yes I run a little lower in the front. More like 110 in 23s.
> 
> And yes Really . I ride the same roads quite frequently. A couple of good steep descents to get away from home and to get back. So I have experimented with different pressures. And 120 is definitely faster for me over those roads than 110 or 100. Is it significant? Not much. Maybe 0.5 mph at speed. Now the one road is very well paved. The other fairly but with a few holes. I know where they are and try not to ride over them.
> 
> If I want to ride bumps and gravel I take out my other bike with wider tires amd inflate them less.



.5 mph on account of the difference between 110 and 120 psi?
Only a reality on the internet.


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## PJ352 (Dec 5, 2007)

tlg said:


> They both give incomplete and inaccurate info. Neither indicate that you should run different pressure front and rear.


As it relates to the Michelin link, I disagree. In the text, it states "_the most important variable that affects what the proper pressure should be is the load your tires are asked to carry_".

I won't deny that it takes a modicum of intelligence to apply the fact that f/r weight distribution being ~ 45/55 (respectively) on road bikes needs to be considered. But being a guide/ starting point, by its very nature Michelin is telling users to tailor PSI's based on all pertinent data.

Judging from feedback I've seen re: the link, seems a tall order for some...


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## tlg (May 11, 2011)

NJBiker72 said:


> Why are you soft tire peoole so unrelenting?


Because you keep posting. And what you post is... well... wrong and unsupported with facts.



> And yes Really . I ride the same roads quite frequently. A couple of good steep descents to get away from home and to get back. So I have experimented with different pressures. And 120 is definitely faster for me over those roads than 110 or 100. Is it significant? Not much. Maybe 0.5 mph at speed. Now the one road is very well paved. The other fairly but with a few holes. I know where they are and try not to ride over them.


And when I say what you post is wrong... this is EXACTLY why. 
This is not testing data. This is your interpretation of what you "feel" over conditions with many variables. I ride the same roads all the time too. And my speeds vary 0.5-1mph. Always with the same tire pressure. Thus there's other causes for the speed difference.

You need to find a long hill. Coast down the hill (no pedaling), in the same rider postion, with no braking. Accurately time your decent at the same start and stop lines. Perform several runs at each tire pressure from 120psi down to 80psi. Do it all on a day with no wind to affect your results. After you've done this and provide the data can you be taken credibly.

Of course this has all be done already. And the results disprove what you "feel" simply riding around at different pressures.
Science and Bicycles 1: Tires and Pressure | Off The Beaten Path
Bicycle Quarterly: Performance of Tires | Off The Beaten Path
_"Perhaps the most influential topic in Bicycle Quarterly has been our research on the resistance of tires, first published in Vol 5, No. 1 (above). It is not a coincidence that 5 years after that issue was published, professional racers are adopting wider tires and lower pressures. "_

200903_PSIRX_Heine
http://www.vintagebicyclepress.com/images/TireDrop.pdf


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## cxwrench (Nov 9, 2004)

NJBiker72 said:


> Why are you *soft* tire peoole so unrelenting?


It's not "soft", it's correct, or not stupid hard. Which is supported by actual testing, not perceived results.


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## Old_Drum (Nov 9, 2009)

After surfing around from the Bicycle Quarterly link tlg posted, I ran across this chart from Bicycle Quarterly that seems pretty helpful and accounts for a front/rear difference. It does require some modicum of intelligence though, because it requires you to calculate wheel load based on the percentages they provide.

Oops. Forgot the link: http://www.bikequarterly.com/images/BQTireDrop.pdf


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## NJBiker72 (Jul 9, 2011)

Deleted. Not worth it.


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## tlg (May 11, 2011)

Old_Drum said:


> After surfing around from the Bicycle Quarterly link tlg posted, I ran across this chart from Bicycle Quarterly that seems pretty helpful and accounts for a front/rear difference. It does require some modicum of intelligence though, because it requires you to calculate wheel load based on the percentages they provide.
> 
> Oops. Forgot the link: http://www.bikequarterly.com/images/BQTireDrop.pdf


That link was in my post. True, it takes some work to calculate front/rear weight difference. But I wouldn't say it takes great intelligence. Just a bathroom scale.

It also gives in the link general ratios for Randonneur, Racing, and City bikes. These are plenty accurate for just about anyone, just pick your riding style.

To make it even easier, use the second calculator. It has the 40/60% and 45/55% values right there for you.
Bicycle tire pressure calculator


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## tlg (May 11, 2011)

NJBiker72 said:


> Yours is not testing data either. It varies by road and weight. Get over yourself.


 You obviously didn't read.


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## NJBiker72 (Jul 9, 2011)

tlg said:


> You obviously didn't read.


Actually I did. Interesting article. But maybe you should read it too:



> Very high tire pressures don’t roll *much* faster. Above an “adequate” tire pressure, the tire’s speed increases only very slightly with higher pressures. This contradicted the tests performed on steel drums, including those by TOUR.


and relating to road condition:



> Tires should not be tested without a rider on the bike. Most of the energy is lost in the rider, as vibrations cause friction in the body’s tissues (suspension losses). That is why testing in the lab can be misleading. In the lab, higher pressures roll significantly faster, but on the road, the suspension losses increase with higher pressures and cancel the advantage of the reduced tire deformation.


and 



> There still are some questions about tires that remain to be answered: whether clinchers truly are faster than tubulars; at what point the advantages of wider tires turn into disadvantages (it is unlikely that a 100 mm-wide tire rolls faster than a 50 mm-wide one), and whether tire deflection due to pedaling causes additional resistance when running very low pressures (in our tests, the rider coasted).


All pointing to variations based on rider, weight and road condition, which is exactly what I have been saying.


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## PJ352 (Dec 5, 2007)

tlg said:


> To make it even easier, use the second calculator. It has the 40/60% and 45/55% values right there for you.
> Bicycle tire pressure calculator


I've used that calculator before and found it to be pretty much on target with my pressures. Even the 5% variance doesn't change PSI's enough to matter to me. 6 at the front and 8 at the rear.

I'm a lighter rider @ 136-140 lbs., so as always, YMMV.


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