Tire pressure
 

Listen to the podcast on this page if you want a better understanding, it's worth the 40 minutes - https://cyclingtips.com/2016/08/cycl...and-pressures/

I watched a video on Youtube and he was on it. That's what got me thinking and asking the question in the first place. I guess that I can drop the pressure in my tires and see what difference it makes. Thank you!

It's physics, not feels. Depending on what your starting point is lower will nearly always be faster. You ever ride skateboards? If the answer is yes you can think about this for a second or 3 and figure it out.

I have 622 x 25 mm Conti GP 5000 tubed tires. I generally use 100 psi front and 115-120 rear. I tried running lower, but I was both slower and felt more tired in my legs. Not to mention a few bridges I go over would have me pinch flatting where the asphalt of the road is lower than the concrete approach to the bridge.

I actually kept track of my rides and took the six best times out of 12 rides for each different pressure and the higher pressures had the best times and the perceived effort of them was easier.

My suggestion is to keep track of your data and pressures and do your own trials to figure out what works best for your normal ride conditions. When I ride bumpier than normal roads, I do lower the PSI in my tires.

And of course there is a chance my pressure gauge is off. But do you know for sure yours isn't also off?

The only reason you use the pressure you do is because you think you're faster? How long is the ride and what were the time differences? Rolling resistance is by far the least difference and the last reason you should ride lower pressure. Traction? Better at lower than you're using. Ride quality? Better at lower than you're using. Those points can not be argued.

I guess if the roads you ride on are super smooth those higher pressures could work. Up to 120psi sounds like a LOT though! I used to bang 100psi into my skinny road tyres years ago, but these days I am slowly coming around to the lower pressure thing.

https://silca.cc/en-au/pages/sppc-form

On 25mm (tubed) tyres, I tend to run 85/90psi F/R which "feels" around the sweetspot for me. I am a lightweight and the roads are fairly rough around here.

(zero scientific testing has been performed by me to prove/disprove this)

According to silca data, fastest pressure on corse asphalt is 90-100 psi.

https://silcavelo.eu/blogs/silca/par...-and-impedance

You might do a search here on Bike Forums on tire pressure. You'll get enough hits to give you several days of reading. There's nothing new since the last tire pressure thread a couple weeks ago. Everything you want to know and more can be found in a simple search.

Some of this is IMO debatable. Without rider weight being known that is. Traction - I'd say this depends on how much deflection/deformation of the tire there is into the road surface (due to the rider's weight) and there's probably a an ideal -- I suppose running at 30psi would offer oodles of 'traction' - but that's not viable for other reasons. So a heavy rider's 110 psi might offer same traction as another's (lower weight) 90 psi, etc.

Not sure what 'ride quality' is. If just 'comfort' then maybe. If it includes high speed handling/cornering, or avoiding pinch flats, then again, rider weight input is a necessary variable.

No, not think, I know.

I use the pressure that both my data and legs tell me let me be faster and feel like I actually put out less effort to do so. I have very smooth asphalt that I ride on with very tiny aggregate for my main ride.

The rides were 22 to 33 miles in length. I did the first 12 rides at the lower pressure. And the last 12 at the pressures that have always been normal for me. Thinking that maybe it was just that I got better fitness for the second set of data, I went back and found the same rides before the time I spent at the lower 90F and 95R PSI. Both before and after were faster times. And my perceived effort for the rides at higher pressures was less and much more enjoyable. At the lower pressures my legs were always complaining.

Of course it's all relative to my pressure gauge, so maybe mine reads high. But I'm thinking it's not off by that much.

I don't really care what pressures people ride. I just want them to find what works for them on their riding surface and not just simply pump their tires up to a pressure that was given to them by something or someone else.

What did your power data look like?

If you are interested in speed speed speed it is always good to look to what the pros are doing. They want to win and have tons of consultants looking at all the science. I have read some articles on recent pressure trends in the pros which I can't find now. But here is a page where one team recommends pressures: Best Tire Pressure for Racing - Skyline Pro Cycling .. 90/95 for tubed and 78/83 tubeless on 25c tires. -5psi for 28c.

I run 30c tubeless at about 60/65 which is maybe 5psi below what they are doing if you take off a bit more for my larger tires. Thats about where I want to be, I'm not a racer and would prefer a somewhat smoother ride without toooo much sacrifice on the speed.

I didn't have a PM at the time. Perhaps I might get interested in doing this again. Though I'll probably wait till I put some 28 mm tires on the bike. And that might be next year since I have one more spare 25 mm left on the shelf.

just as a reference for the OP
all reference on clinchers, with light weight butyl tubes
Back in the 90's I started running 'lower' psi, in high end 23c Michelins - that was 105 rr and 100 frt, at the time I was 164 lbs +-
Then mid to later 90s and early y2k went down to 95 rr and 90 frt - 160 lbs, also 23c same type tire.
Early 2010s I went down to 90 rr, 86 frt - still 160 lbs. some 23c some 25c, but same psi within a couple lbs. mostly Conti GP 4000
In 2021, back on bike after long stint with still ongoing illness, 150 lbs, ran 85 rr, 80 frt, 23c & 25c
Just a month ago had some recovery from serious food poisoning, which took me down to 142 lbs... AND recently started using TPU tubes in Rubino Pros 23 & 25c - running those at 75 rr, 72 frt.
In all these situations cases, I've never felt the pressures were too low. Not rock hard ride, but also not very 'comfy'.
I can tell the difference in tire quality, re performance. I would occasionally give lower than listed pressures a try, but mostly noticed the 'handling' experience proved to be the biggest difference.
Depending on the tires you use - better quality tires giving better 'compliance', feel and speed - I would start with the pressure numbers from respected online sources, and see how they feel.
A Super hard tire might feel 'fast', but depending on your riding surfaces, that may not prove true.
Weight being a consideration, but at a certain point, additional pressure isn't going to support you better or roll faster - it'll just be super harsh.
Tubulars and tubeless, of course, will resolve differently...
For me, my riding can vary so much depending on how I'm feeling, that using actual ride numbers to compare just isn;t valid.
But If I have a good day, and the bike and tires felt good, then whatever pressure I used, is prolly not a deciding factor...
Ever since Y2k, as clincher road tires improved dramatically, the lower pressures have sure 'felt' fast and allowed way better traction on those roads which had 'heavy' surfaces.
When and If I go to wider profile, going even further down is certainly in the cards - except 23 & 25 still feel great to me...
Ride On
Yuri

So it's worthless. It is fairly widely reported that higher pressures feel faster, which will in turn mean you felt it went easier.

Worthless?

I still don't understand why some of you think it's worthless or that I'm misunderstanding something.

How am I to interpret that when doing the same route of the same distance and compared the times. I was faster when the tires were filled to the higher PSI than I was with the PSI recommended by Silca and others. My roads are very smooth. I can't help it if yours are not.


Perhaps you are just saying my perception of my perceived efforts is worthless. However they seem to agree with the data I collected that shows better times for the same distance on higher PSI tires. My legs didn't like the lower PSI.

Simple. You are not "allowed" to not follow current orthodoxy, that is, "soft tyres are faster". Above I posted a link to some actual data, clearly showing the faster pressure on normal roads are much higher than current consensus suggest. As mentioned above 90 psi and into the 100+ psi territory depending on road surface conditions. Only in case the road is very rough, lower pressure is faster. Me, I'm routinely riding in the 50-60psi range, for comfort, and I'm slow at any pressure anyway :-)

IMO the easiest and best answer is "it depends"...
It depends on so many more variables than just test data depending on how that data was gathered.
1: Are you a bulldozer rider? Do you smash and bash your way over everything when you ride? If so you may be better off with wider tires at higher pressures to avoid constant pinch flats. If you're a "light rider"...and I don't mean how much you weigh...you can use a more narrow tire.
2: Pavement...if the pave you generally ride on is smooth and obstruction free like lovely new asphalt you can use a more narrow tire at higher pressures...the tire is not chattering over every bit of surface pebble and there aren't potholes, tire eating cracks, etc. If you're riding on s hit roads then wider and a bit less air may give a better and faster ride.
etc etc etc
There is no "one answer".
I'm 140lbs and ride 23mm Vittoria Corsa clinchers with basic butyl tubes at 90 psi. I've not had a flat in years...sigh now the cycling gods will be out to get me...I'm a very light rider due to the lessons of others and practice. I've tried 25mm Conti GP5000's and they felt slow even at 90psi. It may just be perception but they felt slow to me and that is all the science I needed...I'm doing the riding not someone in a white lab coat in a room telling me I'm wrong.
Considering back in the '80's I did TT's on 19mm sewups at 140psi while I was 135lbs I'd say I'm doing ok and don't worry about cornering anymore lol.
Ride what feels good for you and don't worry about the "science"...

First get a new pressure gauge, so you know what pressure is really in your tires. Too low with tubed tires will result in pinch flats. Use the pressure calculator at zipp.com. There's no reason for the rear tire to have 10-20 psi more pressure.

Best change I've made is to have frames that can use at least 28mm tires. Many now fit up to 32. Wider rims are also wise. I'm running the new Zipp 303s hookless rims that have an internal width of 23mm. With 30mm tires, I use 54/57 psi. The tires measure 31.5mm inflated.

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No, it is worthless because you have no idea whether or not you just put out more power, exactly because you say you felt better with harder tyres. As I already said and as you conveniently ignored, it is common knowledge that harder tyres feel faster. That definitely can make you feel more comfortable and pedal harder.

Do the test with a power meter and get back to us, I would actually be interested in that.

You are linking to a site that uses power to baseline but cry about conspiracies about someone who didn't use power to baseline.

I think it's a bit harsh and incorrect to say 'worthless'. You did catch that this was a measured result on repeating the same ride 24 times? Yes, it would be worthless perhaps if only done 2-4 times.

It isn't worthless in telling the person that they prefer higher pressures, agreed.

It is worthless when trying to make a data backed assertion about tyre pressures.

As I wrote, I would very much like to see them repeat this but with a power meter.

His assertion, backed by his own data, is that he is faster with higher pressure in his tires. Is that in dispute? No matter if he had a power meter or not, Iride finds himself faster with the pressures he prefers. I don't think he's said 'do as I do'.