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Bike Pressure Gauges Are a Waste of Time and Money

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Bike Pressure Gauges Are a Waste of Time and Money

Old 05-30-20, 11:13 AM
  #76  
Sy Reene
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Originally Posted by kenshireen View Post
Help me understand this chart. I assume the lower the watts the less the rolling resistance. Wouldn't this mean that if I am running 25 that me rolling resistance will be less as I increase the psi.. although it appears that there is not a significant difference between 120 and 100.
Are these psi numbers on both front and back
Here's a better chart that emulates a real road a bit better, taken from this article.
https://blog.silca.cc/part-4b-rollin...-and-impedance

Think of the blue line being the rollingresitance.com result; Green line = excellent smooth new road; yellowline = typical not great roads.

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Old 05-30-20, 11:55 AM
  #77  
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Originally Posted by MadKaw View Post
Try changing the balance and let me know how it feels.
It feels much better. I like it hard for some reason, so front is back to 8 and rear just above that. Felt so much cleaner, smoother

But I have been reading a lot and will actually try to lower the pressure and see how that works. But I will keep the balance, with the rear slightly more than the front.
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Old 05-30-20, 12:48 PM
  #78  
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Originally Posted by Sy Reene View Post
Here's a better chart that emulates a real road a bit better, taken from this article.
https://blog.silca.cc/part-4b-rollin...-and-impedance

Think of the blue line being the rollingresitance.com result; Green line = excellent smooth new road; yellowline = typical not great roads.

On the green line... how can RR be less at 120 than 100 yet the Watts are higher at 120 than 100. What am I missing here.. I thought the Watts were a measure of RR
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Old 05-30-20, 12:59 PM
  #79  
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Originally Posted by kenshireen View Post
On the green line... how can RR be less at 120 than 100 yet the Watts are higher at 120 than 100. What am I missing here.. I thought the Watts were a measure of RR
Read the linked blog article. Basically RR.com uses a steel roller that doesn't terribly well emulate a real road. Lots of little microbumps on a real road mean that once past a threshold PSI, overinflating is detrimental to your rolling resistance/speed.
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Old 05-30-20, 03:14 PM
  #80  
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Originally Posted by kenshireen View Post
I have a Spin Doctor (Performance) tire gauge. The ONLY problem and the MAJOR problem is when I test my tire I lose significant air when I depress the gauge onto my presta valve,
Is this common for all tire gauges because it really makes it a waste of time.. I pump my tire up to 110 using my pump gauge and then when I want to double check with the tire gauge I lose 5-10 pounds.
No, its not. I've got a pressure gauge for my fat bike that reads to the quarter pound, and I don't have any issue with air loss when using it. As others have said, get one with a bleeder, pump a bit extra in, and let it out til its where you are at. I've got AccuGage, both for my fat bike and race car.

Or do what I do, and pump it up til it says something between 80-100 psi on the pump gauge, and call it good. Outside the fat bike, everything I have has a wide tolerance on tire pressure.
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Old 05-31-20, 07:09 PM
  #81  
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Originally Posted by DaveSSS View Post
25mm tires shouldn't need 100-110 psi. I have used that much in old 23mm tires, but one of the first things I picked up after an 8 year cycling hiatus was that 25-28mm tires are the new norm, with lower pressures. I only weigh 140, so I use 80 in the front and 90 in the back. Allegedly rides and rolls better.

I use a Silca pump with it's own gage that's at least 30 years old. I replaced the leather plunger once, but I have a spare that I bought 20 years ago, waiting to be used.

Hopefully the OP uses presta valve stems.
It seems to me you're using too much PSI, if you like it that way then fine, but I think you're saying you use 25mm tires, with your weight of 140 psi plus 20 pounds for bike and stuff, your psi should be around 55 front and 85 rear. That's according to PSI calculators, there is some leeway there depending on roads, weather, and how you want the bike to ride, but the pressure the calc provides is for max tire wear, best cornering and braking traction.

Scan down to the middle (2nd) calculator: Bicycle tire pressure calculator
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Old 05-31-20, 07:11 PM
  #82  
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Originally Posted by rydabent View Post
At 82 years old, I try to ride every other day.
I want to be you when I get older! Congrats for riding for so long.
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Old 06-01-20, 06:36 AM
  #83  
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Originally Posted by kenshireen View Post
On the green line... how can RR be less at 120 than 100 yet the Watts are higher at 120 than 100. What am I missing here.. I thought the Watts were a measure of RR
Agree with above: read the article. To answer one question, though, watts is a unit of power (energy per time) and the plot shows the power lost to rolling resistance AND impedance.

If roads were smooth as glass then impedance wouldn't come into play and you could ride on tires inflated to any pressure they could hold. But the tire deformation and vibration induced by rough surfaces takes up rolling energy, too. Think of it this way: you're riding along and hit a bumpy patch. You feel your bike vibrating as it goes over the bumps. Where is the vibrational energy coming from? That's right, your kinetic energy is being transformed into vibrational energy. High pressures are more efficient, apparently, at making this conversion. So as tire pressure rises, at some point the additonal vibrational energy loss (called impedance) becomes signficant.

What's so striking about this figure (Thanks very much for posting, Sy Reene) is that it confirms Jan Heine's point. For riding on real roads with bumps and such, the inflation has only minor impact over a very wide (60-110psi or so!) range. So, find a pressure that's comfortable for you and ride without too much concern for rolling resistance.

(Unless you ride a track bike on a very good velodrome- then, pump 'em up).
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Old 06-01-20, 07:04 AM
  #84  
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I know this isn't the most accurate of explanations, but I always thought of part of the reason that overinflated tires results in increased rolling resistance as, if the tire is so hard that you're bouncing, you aren't able to maintain consistent contact with the ground, which results in 2 sources of lost power: (1) when a portion of your forward horizontal momentum gets converted to vertical displacement as you bounce upward, energy that would otherwise be used to push you forward is wasted, and (2) when you lose contact with the ground (or decrease your contact with it) as you bounce, the energy you are transferring to the pedals isn't further converted to speed because your tires aren't pushing against anything. Neither of these are actually causing resistance in the most traditional of senses in that they're not increasing friction and making it harder for the tire to roll but they're causing energy input to turn the wheels to be wasted and not directly converted to force pushing you in the forward horizontal vector, so they count as resistance.
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Old 06-01-20, 09:07 AM
  #85  
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The phenomenon of losing pressure when hooking up a guage happens will ALL gauges. When air moves into the gauge, pressure in the tire drops.

HOWEVER, how much it drops depends on a few things:

1- the volume of air in the pressure gauge (the bigger it is, the more pressure is lost in the tire.

2- The volume of the tire (the bigger the tire, the smaller percentage of air is lost)

3- The pressure in the tire - the greater the difference in the tire and atmospheric pressure, the more air needs to move into the gauge to equalize the pressure.

#2 and #3 go a long way to explaining why people may have a big issue with pressure dropping on a set of 23s pumped to 120psi, but with the same gauge could check the pressure a dozen times on a 4.8 fat tire pumped to 6 psi and not detect any change in pressure..
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Old 06-01-20, 10:43 AM
  #86  
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A device that can be called gauge, gage or guage can't be reliable.
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Old 06-01-20, 11:14 AM
  #87  
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allegedly, with presta, the escaping air is not from the tire, it is just the air in the pump hose (when using a pump with a gauge)
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Old 06-01-20, 11:58 AM
  #88  
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Originally Posted by GlennR View Post
Maybe it's a poor design. I would suggest getting a different gauge.

Personally i use a floor pump with a built in gauge. Is use the same one everything and whatever the number is, it's consistent. If it drops a few psi when I take it off, it's always the same. And the number doesn't matter as long as it rides the way I like.
Back to the tire gauge and difficulty in removing some from the Presta valve - With the Meiser Accugage for Presta valves, I find it is very easy to apply the gauge and to remove it. It's much easier than the old Silca track pump head, and the dual head on my Cannondale track pump.

I don't really care about the accuracy, just ease of use. The Silca track pump matches the Meiser pretty well.
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Old 06-01-20, 12:00 PM
  #89  
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Originally Posted by Kapusta View Post
The phenomenon of losing pressure when hooking up a guage happens will ALL gauges. When air moves into the gauge, pressure in the tire drops.

HOWEVER, how much it drops depends on a few things:

1- the volume of air in the pressure gauge (the bigger it is, the more pressure is lost in the tire.

2- The volume of the tire (the bigger the tire, the smaller percentage of air is lost)

3- The pressure in the tire - the greater the difference in the tire and atmospheric pressure, the more air needs to move into the gauge to equalize the pressure.

#2 and #3 go a long way to explaining why people may have a big issue with pressure dropping on a set of 23s pumped to 120psi, but with the same gauge could check the pressure a dozen times on a 4.8 fat tire pumped to 6 psi and not detect any change in pressure..
And for some designs the volume of air in the hose.
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Old 06-01-20, 12:06 PM
  #90  
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Originally Posted by wle View Post
allegedly, with presta, the escaping air is not from the tire, it is just the air in the pump hose (when using a pump with a gauge)
If a presta valve is filled with a pump that has a gauge, there will be no loss of pressure, when the hose is removed. The presta valve seals when the pressure on both sides of the seal is the same.

If a gauge is later used, the stem nut has to be loosened, something has to press down on the stem to allow air out and some small amount of air travels into the gauge, so a small amount of pressure may be lost, but it should be very little, if the gauges has a properly designed rubber seal around the stem.

Schrader valves are much more prone to losing pressure when a gauge is used.
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Old 06-01-20, 12:27 PM
  #91  
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Originally Posted by Road Fan View Post
And for some designs the volume of air in the hose.
Yes. The hose would be part of the gauge. Though I donít know of many tire pressure gauges that use a hose, other than ones attached to a pump.
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Old 06-01-20, 12:52 PM
  #92  
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Originally Posted by Reynolds View Post
A device that can be called gauge, gage or guage can't be reliable.
Who gauges the gaugers?
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Old 06-01-20, 01:00 PM
  #93  
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Itís called the observer effect. Itís quite profound with low volume/high pressure tires.
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Old 06-01-20, 01:36 PM
  #94  
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Originally Posted by Hikebikerun View Post
Thereís a joke about quantum mechanics somewhere in here but I canít put my finger on it...
I am not sure about joke, but part of the Heisenberg Uncertainty Principle is you can't measure a property of something without disturbing (or changing) it.
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Old 06-01-20, 02:03 PM
  #95  
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Originally Posted by Bill in VA View Post
I stopped using a pressure gauge for a bicycle after about 6 uses, for the same reasons. I now only use the educated thumb to feel how hard or soft it feels. I used to use Silca the floor pump gauge, but only to get to the point where I check with my thumb and give it a pump or 2 more of let some air out. Never has a snakebite flat, so it must be working.
Originally Posted by noimagination View Post
Agree. The thumb test is good enough for bicycle tires.

(May be different if you're a racer - I wouldn't know, never raced.)
A Gatorskin at 80psi feels significantly stiffer to the thumb test than a GP5000 at 100psi.
I'm not saying you should be using a separate pressure gauge, but it's worth looking at your floor pump's gauge to at least get some consistency when you use it, especially if you have more than one bike or set of wheels with different tires.

Originally Posted by kenshireen View Post
I weigh 180 and average 15 mph when riding. I will drop my pressure to 110/100. I have never had a road flat... only had a flat when my bike was sitting in my garage on the rack.. could not figure... heat was not bad
Consider giving this a listen: https://cyclingtips.com/2016/08/cycl...and-pressures/
There is a strong tendency for you to *feel* like you are faster when your tires are pumped harder but aside from the increased vibration, there isn't really much to prove it and there are other factors at play such as the 'suspension losses' that they talk about in this podcast, but also the fact that tires wear faster when pumped harder (because you put more pressure on a narrower part of the tread), are more likely to get punctures (because the tread/casing can't deflect around the sharp object), etc.

Also, a recent GCN video tries to combine the effect of 'rolling resistance' and 'suspension losses' on a graph to understand how there might be a sweet spot:
https://www.youtube.com/watch?v=7dx_y0KVkj8

Last edited by nhluhr; 06-01-20 at 02:10 PM.
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Old 06-01-20, 05:03 PM
  #96  
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Originally Posted by kenshireen View Post
I have a Spin Doctor (Performance) tire gauge. The ONLY problem and the MAJOR problem is when I test my tire I lose significant air when I depress the gauge onto my presta valve,
Is this common for all tire gauges because it really makes it a waste of time.. I pump my tire up to 110 using my pump gauge and then when I want to double check with the tire gauge I lose 5-10 pounds.
I test pressure with my fingers. When it softens I use a floor pump.
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Old 06-01-20, 06:57 PM
  #97  
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Just a heads up about pressure gauges

My motorcycle club held a wrenching session dealing with pressure gauges. The host provided a "CALIBRATED" pressure source and you could check your own gauges against it. I had four. None of them were within 5 lbs of the correct pressure. You could test at varying pressures to see. I just selected 35 lbs and then put the difference on a piece of tape on the gauge. Most of mine were indicating a higher pressure than what they were actually connected to, i.e. using them as they reported the pressure would result in underinflated tires. I don't know whether incorrect pressures are more of a concern on bicycles or motorcycles but in both cases it can be serious. Just an FYI.
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Old 06-01-20, 09:32 PM
  #98  
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Originally Posted by freeranger View Post

Tires don't need to be inflated to max. psi, in fact, most roll better if run less than max.
Interesting! Where do you got this info from? Has somebody done proper field experiments? I'm very curious!
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Old 06-02-20, 06:37 AM
  #99  
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Originally Posted by halloleo View Post
Interesting! Where do you got this info from? Has somebody done proper field experiments? I'm very curious!
Here ya go-probably others, this is the one that I had prev.read: https://www.roadbikerider.com/the-ti...-jan-heine-d1/
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Old 06-02-20, 09:42 PM
  #100  
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Originally Posted by livedarklions View Post
It's the Michelin Uncertainty Principle.
;-)
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