Rampant Inflation
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.
Rolling out tonight with whatever is in the tyres… usually 6.5 Bar. We’ll see how that goes.
For all you OCD types, a pump gauge is never going to be as accurate as a stand-alone gauge, applied directly to the valve. Overinflate a little based on the pump gauge, then fine tune by letting out a little air in conjunction with the handheld gauge.
I just clicked the link! An interesting article on peoples perceptions.
BTW my bike has a 130mm stem and it seemed to long, especially when I compare it to modern bikes, which seem to have quite short stems (and perhaps that makes them feel more lively). However I got my bike back after a service and the mechanic adjusted the angle of the handle bars (they had twisted down quite a bit and I hadn’t noticed) upwards, and the bike felt totally different and the stem didnt seem so long.
@gianni- The Park and Silca only go 50psi too much for me…I run my track tires from 150 to 170psi depending on which wheels/tires I am running. Those guys at Track Worlds…they are pushing 200-210psi in their tires.
Is not a digital gauge the equivalent of a Smartphone on the handlebars? How much accuracy does one need here? 100 psi plus or minus a couple and you’re going to tell me your butt can tell? Back in the day we used the “Cat 2” pressure gauge, a pinch and a thumb press. In fact, most of the dumb Pro/Am riders I knew thought this was good enough, maybe that’s why team mechanics exist!
25mm Conti’s @ 95psi – thats how Im rolling @Gianni.
However, reading above, maybe its not 95 at all.
@Gianni that infernal link demystifies everything we do here, tantamount to pulling back the curtain on Oz. It is abominable and the fact that no one looked at it is a testament to the strength of our collective belief. Bah!
@Nate
Au contraire, my take on the article is that the psychological image of the bike is more important than the form, and by meditating upon, and applying, the rules a rider is freed to apply the V, firm in the knowledge that the bike is willing and only the flesh is weak.
Additionally the fact even the pro’s cant pick weight/flex/etc. means a properly prepared Tiagra equipped aluminium framed barely above BSO bike can beat a carbon fibre Super Record Pinarello if you free your mind and just apply V. Its only your mind holding you back, probably the ultimate application of the rules. Just don’t tell the VMH.
@Roobar
You mean, the famous quote by a little green bloke rings true ?
” Do, or do not, there is no try !”
@Barracuda
Or maybe the quote by a somewhat larger Belgian bloke?
“Don’t buy upgrades. Ride up grades.”
While I don’t recall seeing the link, I’m glad that you brought it back. For those that dare, it’s an excellent write-up about perception and reality.
@Haldy
Holy Shiet! I stand corrected. That’s some rock hard tires. Thanks.
“A man with one watch knows what time it is…
… a man with two watches is never sure.”
– Some Smart Guy
@Nate
You are wise. Yeah, no one is going to give that link three seconds worth of consideration, really. But it does make the point that the paint is important. That guy is correct there.
@snowgeek
That’s what I’m talking about. And the guy with three watches has too many fucking watches.
@Gianni
He isn’t wrong about the paint. But he sort of buried the lede, I never got that far into his treatise.
@Gianni
Pretty sure 3% error would mean you could be 3psi out at 100psi; percentages being exactly that…
/nitpicking
@Fausto
More likely: the 3% would mean something like “99% or 95% of all pumps of this type will be off by a max of 3%”. So it’s rather a sort of confidence intervals. Same applies to torque wrench I just bought. Not sure whether it’s 1.5% each side or 3% each side.
Given the preciseness of this thread I’m surprised no one has yet queried the impact of rider weight on net riding PSI.
Nice article, Gianni. And I like the link.
I roll 110 psi on my 25mm Conti 4 seasons, have an old school gauge on my Topeak pump.
Does anyone else have to bleed the tube a bit before pumping? Otherwise the gauge red lines and air is caught between pump and stem?
@rfreese888
Yup I always give the valve a nudge to free the seat before connecting a pump.
@Teocalli
Well, you are now, aren’t you? So what’s your take on that?
@KogaLover
On rider weight? Well if we assume that the tyre pressure relates to optimising the contact area and deflection of the tyre then a heavier rider would ride with a higher pressure than a lighter rider. So the logical extension of that is that tyre manufacturers should produce a recommended weight/pressure chart similar to what you have with suspension set up on a mountain bike.
Does it really make much difference? I tend to go for the poke test, and pump them up to 110-120psi if I’m racing.
@Teocalli
Jan Heine did that already: Tire drop/pressure graph
@KogaLover
if that’s what they mean, they should say it. 3% error at 100psi is 3psi whichever way you look at it; whether it’s plus, minus or a bit either side needs to be clear (not that it matters TBH; I wouldn’t mind betting latex tubs will lose that over a race) – just throw some random numbers at it and hope no-one asks!
@rfreese888
Sure, I usually tap the stem first and it allows the floor pump (Park Tool) to give an accurate reading.
@Oli
Interesting, thanks for that. Glad to find it just about spots it for the pressures I ride.
@unversio
Me too. Always a quick push on the valve before the pump chuck goes on. I roll at about 90 psi on Michelin Pro 4 Endurances.
@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.
@gianni saves Velominati again.
Even I’ve dropped from my beloved 120 to 115 on my 26mm tires, and I have to say I notice the difference. For me, the biggest thing about lower pressure is that shitty tires (by that I mean anything less than FMB) start to flex under power when a fat guy is the one pushing on the pedals; so long as I’m not feeling the flex, I’m happy. (I mean the lateral flex, as in the flex in the direction of bicycle, when you push hard and you feel the rim and tire not move in unison but the tire slightly behind the rim. I can’t stand that when I’m huffing and puffing up some climb and the last thing I need to know is that some of my power is going into flexing a tire, not going uphill.)
But when I ride the 26ers at 120 I do notice that I’m getting bounced around more, and I do seem to go slower, or at least I seem to struggle a bit more on the same climbs.
Anyway, I love my Lezyne and I’m now interested in that gauge. My only complaint about their pumps is that with my valve extenders I sometimes can’t get the head on tightly, and wind up eventually stripping down the thread. But Branford Bike carries them so I just go get another one for $10.
@SamV
Your bike, kit, bidon, etc. all weigh something, too.
Not true! I clicked that link!! I’ve had that guy’s plaid shirt floating around in my head since!
My riding pal raves about a certain pump head that can go onto any floor pump. Can’t recall the make/name right now though, so I’m fucking useless.
Still using a basic Park Tool pump that my VMH got in Prague when she was living there. She thought Park Tool was an Asian company trying to sound Western, but not too edgy…
@Fausto
My father is a mechanical engineer. I love running things by him that I read online or in a forum. Most of the time, he points out that they’re a load of BS.
I’m not too picky about tire pressure. The best thing I do each year for my cycling is getting rid of winter hibernation weight. Once that happens in spring, I feel much better and can get back to enjoying my rides. The obvious-yet-amazing thing is that if I’m eating right and sleeping right, everything else falls into place for me, from work to cycling.
@Nate
True. My Bike weighs ~9kg including the wheels. The bidon is another kilo. Let’s call it 10 even. Even at 67kg (including kit, helmet, sunnies, shoes, tube, CO2, levers), we’re still talking 27/40 which is just north of 60 psi on the front and 70 psi on the back.
@SamV
You are just going to have to put Heavy Water in your Bidons.
@Teocalli
Fucking awesome. I’ll have the lab manager at work order some for me. Won’t the guys at the club be impressed when I roll up with radioactive refreshment.
Is Heavy Water the type of stuff the dopey fools drink that is laden with carbon footprint morality luggage because it was shipped around the world to your selfish hands?
@Ron
Err…well….no. Then again on the carbon footprint front it’s definitely worse, http://en.wikipedia.org/wiki/Heavy_water
@rfreese888
It’s guaranteed that my tubes won’t take air if I don’t let a bit out first. I’m relieved to hear it’s not just me.
I’ll bet I’m also not the only who has a ritual of always doing one tyre before the other at a certain point in the pre-ride preparation.