Symox

I started another thread on running Gatorskin 28s at 80psi because I was riding below the recommended 95psi and was shocked to find out how low people are successfully running their tires. I've been out of commission for about a decade with riding. Back then it was "pump up close to max".

Only recently I'm realizing that the trend has moved heavily in the other direction. My question is, what prompted this change (for which I am infinitely grateful do to ride quality)? Is this a recently discovered phenomena? Seems strange that in hundreds of years we are only know realizing the benefits of lower pressures.

Thanks!

tyrion

Better testing - power meters, etc.

HTupolev

The biggest issue is that, despite presenting itself as a high-tech industry, budgets for novel research are tiny to nonexistent. Performance-oriented testing is mostly limited to things that can be budgeted with a predictable scope, i.e. "this much time in the wind tunnel gives us this much data that we can use for this thing." Discovering that there are performance benefits to avoiding excessively high pressure is more of an issue of discovery, nobody knew what exactly they were looking for until they found it. It's also a cumbersome thing to measure.

There were discussions about the role of tire pressure in suspension performance in the 90s, but a lot of people just kind of assumed that it wouldn't matter within the usual range of bicycle tire pressures.

The breakthroughs started to happen about 15 years ago. In 2006, Bicycle Quarterly published some roll-down results where they found inflation pressure having surprisingly little effect on performance, and the supple tubulars that they tested were performing worse at high pressures than low. Starting around 2007, while doing performance testing for Paris-Roubaix, Zipp's engineers discovered that reducing pressure more and more made the tires faster and faster on the cobbles, right up until the rim started bottoming out on the rough surface. At the time, Zipp considered this a "trade secret."
Since then, more testing has occurred, and this stuff has gradually percolated outward.

Drew Eckhardt 

1. Power meters became common among serious cyclists.
2. In 2012 Robert Chung wrote his paper on how to measure rolling resistance plus aerodynamic drag on-road using one.

shelbyfv

I think the pneumatic tire was invented about 1888.

Velo Vol 

Kids these days.

Symox

oops, I guess I should have said "decades of use"

DeadGrandpa

I only became aware of lower tire pressure a few years ago, first on 700x40 touring tires and then on 29x3 plus tires. It has been a life changing experience and I don't know if I can ever go back to the 700x23 tires on my Bridgestone. I used to love that bike.

tomato coupe

When did the low tire pressure trend start?

As I recall, it was on a Tuesday during a long cold spell in January.

Doge

About 7 years ago

Toespeas

it depends on your over all weight , id love to run 23 psi on my cross wheel but im too heavy , trying to determine what low pressure is , is impossible , the lab can only give you a base line , and then there is the actual tire material , tire width vs rim with differences will effect the performance , and just running lager tires will make it seem like 80 psi is low on 23s its still pretty firm , i run 110 and it usually airs out to 90 psi , never had an issue

its not really a trend BTW road bikes have been expanding over the years so you can fit 28s on your pure road racing machine compared to 8 or so years ago you could barely get 25mm , and with disc brakes you get even more options on the road and commute bikes that used to be limited , so now people think 28s faster , but its really more like the over technology got better , try to run 28s on an old mushy set up and it will suck and feel sluggish , but i run 38s tubeless cx wheels set , and its lighter than my old 23 road wheels !!!

znomit

Fat MAMILs don't flourish in a 115psi 23c environment.

Greatestalltime

I’m still riding high because of flats and I can’t get used to that bouncy feeling when going hard.


I know what the science says, but I’m stupid.

WhyFi

Hey - we prefer "sprinters" thankyouverymuch.

cxwrench

When people discovered physics was for real, and 'feelz' mean nothing.

MoAlpha

Tell that to the wine tasters bombinating about frames and wheels.

brianmcg123

His name is Jan Heine.

Look up the Bicycle Quaterly tests.

downtube42

I tend to think the growth of triathlons caused the first cracks in UCI's stranglehold on bike design. They did all kinds of weird stuff in search of speed without regard to rules and entrenched ideas. Around the same time that was exploding, mountain biking blew up and was like a second front on the war against conformity and single think. Once the blinders were off all hell broke loose. We had HPVs, more than five gears, aero bars, all kinds of shenanigans.

Eventually somebody did a study on tire pressure, width, and rolling resistance. It rang true for everyone who realized their MTB turned commuter on fat slicks was darned near as fast as their road machine and felt a whole lot smoother.

So I'd say about 1970 was the start, but 15 years ago was a threshold.

RChung

I think the former was way (way way) more important than the latter.

As historical context, the first version of my paper was written and distributed in April 2007, the week *after* Paris-Roubaix. I didn't know Josh Poertner at the time but he was testing tire pressure in prep for Paris-Roubaix the previous month, so neither he or anyone could've used what I wrote in April 2007 back then. I'd been discussing how to do it on the old Wattage List since early 2003 so I *suppose* it was possible he and others were paying attention but I didn't write anything up in one presentation until 2007. (The kids were on spring break, and my wife had made us rent a vacation home for a week that didn't have wifi or an internet connection in a spot where the spring pollen was so bad my allergies kicked in and I couldn't ride my bike outside at all, so I wrote that damn thing in a foul mood with a bad attitude. Had she rented that place in 2006, I would've written it a year earlier). Heine had been talking about lower pressures, but he had also been talking about wide 650B tires, so his recommendations were kinda indistinguishable between wide 650B tires and lower pressure in them. That is, track and TT tires at the time were the narrowest and run at the highest pressures; road racing tires were a little wider and run at lower pressures than TT tires; so when Heine suggested running 38mm wide 650B's, it sorta made sense you'd run them at lower pressure. MTB people had been running wide tires at very low pressures for years -- it kinda made sense that if you were going to run 38's, you'd run them at lower pressure. What Heine *didn't* suggest, as far as I could see, was lowering pressure on standard 21 or 23mm road tires. Plus, his experiments were crude and, frankly, not detailed enough to be replicable. I wrote him a couple of times to ask for details on his test protocols and he blew me off. Finally, I think Heine's audience was *mostly* the kinds of people who would subscribe to and buy from Vintage Bicycle Quarterly, so they weren't exactly mainstream. So if you're asking "when did the low tire pressure trend start among mainstream riders," I'd say it was much later: probably around seven or eight years ago. When I bought my last road bike six years ago, I got the aero bike that, at the time, had the largest fork clearance possible so I could run 25mm tires at lower pressure when most other aero bikes were limited to 23's.

asgelle

I would say the breakthrough came when Tom Anhalt showed his field test results against roller data (on Slowtwitch.com as I remember). Before that, the common wisdom was that rolling resistance monotonically decreased with increasing pressure. Tom showed that out on a road, there was a break point where the steady decrease abruptly changed to an increase with pressure. That really opened the floodgates as others began doing similar tests and it wasn't long after that the mechanism was identified. I can't remember what year that was but he used virtual elevation so it must have been after 2007 (but probably not much after).

RChung

Yeah, that was 2009. I think of that as opening the door, but I don't think people started walking through it until they could replicate and verify the results themselves. Here's a link to Tom's 2009 article on ST: https://www.slowtwitch.com/Tech/What...ube__1034.html

I think part of that was we had to wait a little while longer until mainstream tire and wheel and bike (and pump) manufacturers made changes that recognized this and started offering a wider set of choices.

HTupolev

If we're talking about the 2006 publication, it was actually just two road tubulars - one 21mm and one 28mm - where he specifically measured a performance improvement from a pressure reduction. But he was doing very coarse testing, not sweeping a wide variety of pressures to determine an optimal point.

And he was trying to test a lot of things, not just pressure, so permutations were a general problem. For example, the article says that latex tubes are a little slower than butyl, but notes that the latex tube used in the testing was very thick, and leaves the performance of lightly-constructed latex tubes as an open question. (In recent testing with different rubber, he has apparently swapped his position to "latex tubes are significantly faster.")

At any rate, the article certainly wasn't a thorough survey of everything we know now. More just one of the early data points suggesting that the pressure question was something worth taking a closer look at.

asgelle

But wasn't it common knowledge (at least for readers of the Wattage group) well before Tom wrote his article for Slowtwitch? At least that's how I remember it. If the question is when did the trend start, I'd put it at early 2009 when the door was opened. After that it was exponential growth.

And while it did take a while for equipment makers to catch up, the paradigm shift from as high as possible to better too low than too high was in place pretty quickly for those who understood the result. I still used 23's but dropped the pressure from 120+ psi to 105.

RChung

Well, maybe. We had discussed Tom's "breakpoint" findings on Wattage and ST (and via email) before that in part because we weren't sure that he hadn't made a mistake and perhaps there was something screwy with his data or procedures or something. Eventually I was convinced it was real. That was an early example of sharing methods and data to convince people what you were doing was right. But I was never sure how widespread something got on Wattage. There was an awful lot of arguing going on at the same time, so I was never sure who was listening and how much effect it was having. People could agree with you on three things and disagree with you on seven so it was hard to keep track. It was the Wild, Wild, West and it was great.