Will be trying this out on my Zwift race tonight.

It's all coming full circle and it's taken 30yrs to get here. Specialized did extensive testing on rolling resistance back in the 80s. This was when they came out with the Turbo clincher tire. The whole "narrower is faster and more aero" craze kicked off. The 1984 Olympics was also a catalyst for 'more aero' when the crazy aero pursuit bikes appeared. Was a higher pressure and narrow tire faster? Yes, their tests showed it was.... but what few realized that was on a perfectly smooth surface (like in a velodrome). Regardless road tire manufacturers took that and ran with it. Racers started running 19c-23c tires (yes... some guys ran 19c or 21c tires!) at 115-120psi! Crazy! The 19c and 21c tires died out after a few years (too many flats and damaged rims) so 23c @ 100+ psi became the norm. However on the road any bumps and other imperfections killed any forward momentum when the tire bounced up and over rather than deforming and absorbing it. Rivendell was saying this since 1996 but no one listened until recently. Being a bigger guy (61cm frame and 185lb racing weight back in the 90s (much heavier now) I would race on 25c (@95psi) and I trained on 28c tires (@80-90psi). Even though it was heavier 28c at slightly lower pressure for me was the best combo. It was comfortable and more versatile (because back then, early 90s, some of us Nebraska roadies would dive off onto a gravel road section to liven things up on training rides). Most 'racing' frames of the period could barely clear a 28c so I stuck with steel frames rather than aluminum or carbon. With the advent of gravel riding the 'all road' bike concept has really influenced bike designs and a road frame today that can only fit a 23-25c tire is stupid. Wider tires are back and there's so many tire options out there now. Today I think a 28-32c road tire is the sweet spot for fast road riding. Running at 80-95 psi (for a big guy like me, less if you're lighter) is faster over real pavement and you can ride gravel with the same tire too. Wider and lower pressure is better! 🙌🏽

Great video. Back in the old days when I was mtb racing we would have to select the exact psi for every course each race. The goal was always the lowest pressure possible because we learned that the highest traction and control allowed you to ride your fastest just like crit racing. We found the best way of determining that was high speed corners so we’d go to the fastest corner on the course and do repeats dropping the pressure until we felt the tire was no longer stable then we’d add 2 psi. That’s all it took, 2 psi to be stable again. So if your 50 psi is a bit soft try 52!

Next, I'd love to see a similar test comparing 28 to 30s

You forgot to mention rider weight. Very different number for a 50kg rider compared to a 100kg rider. You also forgot to mention that best practice is to run lower tire pressure on the front tire. Usually 5 to 10psi. Depending on rider preference. I'm 63kg. I run 62psi front 72psi rear. Latex tubes on narrow 25mm tires. NEVER pinch flat'd in hundreds of thousands of kms. On 28mm tires I'd be down 50psi front. So I suspect for the average 70-75kg rider 60psi would be ideal on 28mm tires, front wheel. Front wheels usually support about 40%-45% of the total weight. Hence the lower pressure. Lower is virtually always better. Riders think harder is faster because it feels faster, because of the increased vibration. It's an illusion. The shaking is wasted energy.

For clean tubless setup do this:

Normally run my tubeless setup at 80-85 ish. The other day I forgot to pump up the tyres before heading out. Almost went back to get the pump but decided to give it a go. Ride felt amazing - quicker and more comfortable.

I weigh about 165. I started lowering pressures when I shifted to road tubeless about five years ago. I started at around 85 F/R and I've gradually been lowering pressures. I've settled on tubeless 28s at 62/65 F/R for about two years now for fast road riding. It feels great in corners, it makes rides less tiring for my hands and I don't think it's any slower. This corroborates that feeling.

I been running 28's with tubes at 65-70 PSI for the past year on road rides and weekly crits. Love it

In the early 80s I was running 125-135psi on Continental Ultra 18mm front AND rear. Couple that with a concrete like (aptly named) Concor Profil saddle and a pair of Duegi wooden sole shoes and you're not worried about tire pressure so much. Ahhh the good old days of RAAM 83.

What some people may not consider is that the lower PSI is also beneficial to preventing fatigue on the bike over long durations. The road chatter experienced using high PSI can be taxing. This season coming I'll be on 30mm tires and likely 60/60 PSI, I am a 85-90kg rider. Right now i run 65/70 PSI on 28mm tires and it's great for all types of riding, also maybe a little tire dependent? I run conti's but have ran Schwalbe in the past which were a MUCH softer tire I found, so didn't run as low of PSI.

These videos are right up there with Shane Miller's videos. Informative, entertaining and everything explained in a way that I can understand. Keep up the great work Jeff!

maybe I'm just weird, but I'm running about 75-80psi with my normal 28mm clinchers, non tubeless. Tried 70psi and instantly felt like it was super squishy and unresponsive. haven't tried tubeless though

Internal rim width is a bigger factor that dictates the pressure, followed by tire width. A 28mm tire may measure 30mm on a wider internal rim width and can accommodate more volume thus lowering pressure compared to a narrower internal rim width. This will also affect the squishiness of the tires since the sidewalls are supported better with wider wheels. Was Blaine running the same wheels? Wheels need to be the same for this experiment.

Amazing video, can you guys do the same for tires with inner tubes. I am still in my old school 25mm conti and would like to see the results you guys achieve. Cheers

i myself went down from 85 to 70 over the last year and a half and i liked it very much. your video motivates me to try to go even lower now (i did not cross my mind until now, because of the calculators you mentioned).

i've run 100s of miles on 32mm gp5000s with tubes @ 54F 56R and have yet to pinch flat. only this past year have been experimenting with lower pressures and love it.

Absolutely love this new type of content.

Great video, thank you. Key takeaway: the efficiency curve is very flat near recommended pressure, so that you could probably adjust up or down 10-20% to get the ride character you want without really changing efficiency.

I have been surfing the low end of the pressure range for awhile and knew it felt better overall. Didn't really seem significantly slower. Thanks for demonstrating that there's actually no penalty at all, and it's just limited by handling!