The new and the old.
Lezyne offers a digital pump gauge retrofit that I couldn’t resist. For $35 US one can pry out the old and thread in the new. The primary benefit for me was reading a digital scale rather than a needle on a gauge, way down there. Yes, I’m old. The new gauge reads out in single digits. The old needle gauge reads out depending on one’s eyesight and ability to see where the needle stops relative to the 2 psi marks. Houston, we have improvement.
The new Lezyne gauge also goes to 300 psi (20.6 bar)! FFS, who cares? This is a bike pump, who needs the 150 psi to 300 psi pressure? The Park and Silca both go up to 220 psi (15.2 bar) which is still 100 psi more than even track racers use. I dare a pump manufacturer to make a road pump that goes from 50 psi to 150 psi. Frank could use it as it still goes up to 150 psi and everyone else might have much more accuracy from the dial. I kid Frank.
The Lezyne digital gauge also claims a maximum 3% error which I assume means plus or minus 1.5 psi at 100 psi. Everything and I mean everything has an error associated with it and I appreciate knowing this error. Nothing is absolute, not even death. I’m not dead yet. The real question is what happens when one hooks all three of these pumps to one manifold. The Silca and the Lezyne were only off by 2 psi but I would not have been surprised to to see them off by 10. The Park and Leyzne were spot on which is reassuring because the Park gauge looks to be a very professional piece of work. Anything is accurate until one has two or more of them for comparison.
Yes, I know this last paragraph will be ignored and I should move it to the top. Should you care more about tire inflation? Yes, you should. Since not one person clicked on this link in my post about chains (yes I’m watching all of you, Google analytics knows everything), the take home message was this: Aero wheels do make a real difference in speed and tire pressure is the biggest (only?) influence on perceived “vertical compliance”/ride stiffness/road feel/comfort. With 25mm tires, one can experiment with lower pressure and not flirt too much with pinch flats. It’s just air; a very cheap way to dial in your ride.
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@Oli
Neat article. Maybe I'm an idiot who can't read charts, but at 54 kg's total, it looks like I should be rolling my 25mm's just shy of 50 psi each?! That seems mighty low to me...
@SamV
I think the key is that they are only measuring tyre drop. You are going to have a min pressure to prevent the tyre rolling off the rim (for instance) and at the top end the pressure of a tyre can't be linear for the heavyweights. So I would expect an S curve in reality. It is interesting the min recommended pressures that say Vittoria Corsa's or Pave's as stamped on the tyres is pretty high compared to what I would guess most folk ride - and certainly well above that chart.
Tires and pressures... I swap wheel sets and tires amongst my bikes almost as much as I swap out socks on my feet. I never, ever have more than 90 psi in my tires. And mostly in the 70's. +/- 3% I guess but whatev... The HED + wheel sets and 25c's ? 70's... More narrow rim bed on DuraAce wheel sets with a 23c ? 80's/and yea, maybe a little over 90 in back. Just all depends on that day's vibe. Tires are Conti's, Specialized or Vittoria Pave's. I really like Speshy tires. I love the Pave's for right time/place. Conti's ? They work but nothing special. Days of riding high pressures are long gone. And I'm not exactly a flyweight at 77+kg.
@Gianni I've been thinking a long time about exactly that: a digital Lezyne pump. For what sounds like exactly the same reason. Cheers
@Teocalli @samv
I think that they are dividing up your total weight between the front and rear wheel, according to the percentages listed on the page above the chart. Then once you calculate the front and rear wheel loading, you can match it to your tire size and get the recommended pressure from the chart.
@wiscot
Front 102 PSI and rear 107 PSI, 25mm Gatorskins, Mavic tubes, Conti hi-pressure rim tape on 2012 Open Pros. No flats in over 2 years with riding 100 to 200 miles every week -- off and on. Also ride a tubular wheelset 32h GP4s with Conti Sprinters that are holding their reputation as well at 120 PSI.
@clarksonxc
Indeed but I believe @SamV's point is that if you split 54Kilo front and back he'd only need to blow into the tube to get it up to pressure on the chart. Guess it would save on a track pump though.
@Teocalli
That is my point. Believe it or not, I'm 54kg in my entirety. So per wheel, it's roughly 25/29 front/back. Based on that chart I may as well wrap my rims in plastic wrap. I'm not saying the science is bad, but I am saying that there appear to be limitations to the scaleability of it. I've only just recently started experimenting with air pressure, but I don't plan to go anywhere near that low. I've got but one set of wheels for the foreseeable future and I need to keep the rims off the pavement.
@Gianni
I didn't click because I read it the day it was published (and I've linked to it whenever a "this bike's more comfy than that bike" argument here). I have to say I'm very pleased to hear so many Velominati pumping their tyres to sensible pressures that match their weight. Too much pressure and even a cotton FMB will feel like an Armadillo. Good tyres, latex tubes and 90psi of pressure, and my 8 year old all-aluminium frame will take me past 200km in comfort.
Lezyne pumps are the tits. Love the screw-on head. Had a gauge fail after three years of hard work, went for the cheap $12 analog replacement and - good as new.
@KogaLover
Yeah, I think you are right. So one could be off by 6 psi really. In the long run reproducibility is more important.
Oh jesus, 3% at 2 sigma. We have veered off the bike path into a boggy ditch. As I said, nothing is certain.
@Gianni
I should probably point out I'm an engineer, so I kind of make a living out of picky. Fortunately I'm also a cyclist so can appreciate the subtleties of getting one's pressures just so, and always +5 psi in the rear tyre. Borrowing a TT bike at the weekend with a 24mm tub on the front and a 19mm on the rear just about fried my tiny mind though. I also (despite the sheer ridiculousness of it) have a deep lust for the Silca Ultimate. I can't justify one but I need one.