Lower Your Tyre Pressure And Descend Faster?!

[@gcntech]

Do you ever change your tyre pressure when descending? 🛞🚵

[@oplkfdhgk]

nah i optimize the tire pressure for the most common trip i do and then i just leave it there.

[@larryt.atcycleitalia5786]

Why not just run the right pressure and call it good, going up or down? 28 mm tires around 80 psi rear/70 psi front seems to work pretty well...and has for years. Too many people obsess over this stuff, checking pressures seemingly before and after lunch!!! Just ride the bike!

[@bkmontgomery]

What is this “descending” that you speak of? Sincerely… a Flatlander.

[@MrDoccus]

No. The time it takes to change pressure offsets any gain. Also, I ride for fun and fitness; a few seconds …even minutes…do not matter.

[@RichardMaguire110]

I inflate my tyres to pressures that feel right and leave them there on a ride. I would not stop to lower pressures for descents.

[@davidmunro3188]

Great video, thanks Connor, however can't help thinking you haven't taken into account the fact that after the 1st run you know the road and can anticipate the layout/surface conditions better. It's like driving a race track, you're always going to unconsciously get quicker lap after lap. Therefore changing the tire pressures may not give the full picture here. Interesting to understand the perception of the handling though. Anyway keep up the good work, love the channel!

[@larrylem3582]

He needed to repeat the run 90 psi at the end. He actually needed to repeat all of them, many, many times...

[@jamesmcmorrow6378]

Thanks

[@gcntech]

thanks for your support!

[@10ktube]

To the viewers complaining about this being an ad, write GCN, ask for their business routing number, transfer them money for servers/staffing/editing/etc, and then they won't have ads. Even if it's an ad, it's not like they skewed physics and how the bike is reacting. Geesh.

[@0-60.tests.with.Passengers]

You're not getting the real point that's being expressed , that stand out complaint is the gaslighting behind it all , and that it's clearly sponsors first viewers second, videos are constructed around a sponsors first/viewers second philosophy.

[@Local.hero.1983]

But it's clear all gcn videos are based around sponsors,yet they try to hide it/disguise it , i think it's the trying to pull the wool over our eyes bit people get the ick about.

[@shamendra.sakthivel]

​@@0-60.tests.with.Passengers There's no gaslighting going on. What's there in running lower pressures to gaslight about? At the end of the day they've got to pay the bills and if that means a few mentions of sponsors I'm all for it. I think the benefit us cyclists get from GCN far outweighs the occasional mention of a sponsor.

[@shamendra.sakthivel]

​@@Local.hero.1983 Look mate they've got bills to pay just like everyone. U aren't paying for their expenses, why are you complaining about it? Plus the presenters always mention that they are sponsored by the particular brand when talking about it. It's also mentioned in the description of the video. They aren't trying to pull the wool over anyone.

[@schrodingerthecat]

So many people enjoy free content and think no one should make any money. Greedy.

[@Andi-r2p]

Connor was always going to be slower on the higher pressure because he said he would be, do this again blind and i might believe the results. Just for clarification, i ride 23's at 100psi and have never felt it to be skittish unlike wider tyres at lower pressures that squirm about and have given me a few 'moments'.

[@frazergoodwin4945]

I realized that the bike I'm using the most at the moment has extremely low tire pressure in the front and none in the back - yet my downhill handling is exceptional - I'm railing the curves even at very high speeds down Alpes du Zwift! Low pressure seems to work!

[@grobbosixtyone]

Or the skill of the rider 😊

[@ahnilatedahnilated7703]

I know what you mean! This last weekend, I did the ride down the Alpe in 15mn and at times I was doing 55 mph around the hairpins and with 0 PSI in my back tire it was AWESOME! The front was at probably 15. It held the road like I was on rails.

[@adadinthelifeofacyclist]

More contact area doesn't mean more grip; as you increase the contact area you lessen the contact pressure between the tyre and the road proportionally. It can make a slight difference by reducing creep as the rubber and tread flexes, however decreasing pressure will increase creep. Reducing pressure will allow the tyre to deform over rough tarmac which can aid grip, but not due to more contact area.

[@sandiegocyclingnutz]

Idea. Do "blind" tests where the rider doesn't know which setting they are riding at so there's no preconceived notions.

[@rider65]

Jan Heine did this over a secade ago...

[@toozydude2]

Being scientifically and statistically correct is not the GCN way 😂

[@johnwestwell2241]

I can't see that anyone couldn't immediately tell that the tyre pressure was either increasing or decreasing when they got on the bike. It's pretty obvious.

[@gcntech]

👀

[@Music-pq8cm]

Now do the test climbing the hill with the same 3 pressures. Are the downhill gains at the lower pressures negated by uphill losses at the lower pressures?

[@jeffreywilliams3646]

Winnipegger* here.I've only ever done one descent; on a hill I didn't know, on a bike that was not mine. Terrifying. I would be interested to hear an interview with Tom Pidcock on the topic, if you could get him. *Winnipeg, Manitoba, Canada, is used as the template for billiards tables. Here, you can watch your dog run away from home for three days.😁

[@urouroniwa]

I grew up in Winnipeg and live in a fairly hilly area of Japan now. Give me climbs any day of the week and spare me from the descents. It's taken a lot of practice to get used to them. BTW, I miss watching thunderstorms in the summer miles and miles away. I'm surrounded by mountains now and can only see about 2km 🙂 Don't miss the cold winters, though...

[@alanmckellar908]

Awesome tires! Appreciate you running the experiments.

[@oiwjefiojwweg]

to save your time. 7:09

[@paulgrimshaw8334]

I was wondering why they call it “optimal pressure”. And here I thought it was a ruse by “big tire”. Maybe vaccinations aren’t bad after all…

[@shamendra.sakthivel]

3:20 c'mon guys u should've cleaned the lens. Spent a few seconds rubbing my screen only to realise it was a speck of dust 😂 (just above the tree)

[@terryg652]

Also note, he only coasted down the hill (to rule out variables). Had he pushed as fast as he could, the time differences would've been greater as the lower pressures would've allowed him to corner even faster.

[@joshuaborne4721]

To remove any psychological bias i would have had a separate person perform the tyre pressure and keep the information from the rider.

[@terryg652]

He coasted down the hill without pedaling. Psychological bias doesn't affect gravity and time.

[@bobfoster687]

@@terryg652. Position affects wind resistance. Getting more aero can affect the results.

[@zedtony8110]

Low tyre pressure can save you a couple of minutes, pumping up the tyres.

[@gcntech]

😂

[@nigewright8246]

Great review, very interesting

[@mkenyon7429]

Now try in the rain or at least wet pavement. Using higher pressure and falling will add lots of time for the decent. Of one makes it to the bottom.

[@lax2sfo778]

Which part of Spain this is? Absolutely scenic!As expected, lower pressure is comfy and gives you confident,

[@josephharvin5095]

It looks like the CV7361 between Dénia and Xàbia (aka Jávea), Alicante province, Spain.

[@gavinsmith28]

Tubeless pressures are so low, for those of us oldies still running clinchers and tubes! What difference would that make, in your opinion?

[@TESTA-CC]

Stay on tubes and clinchers, much faster and less prone to punctures.

[@pandatactical4530]

@@TESTA-CC🤦‍♂️🤦‍♂️🤦‍♂️

[@tonysadler5290]

​@@TESTA-CCI've been tubless on all my bikes save one, since 2015 when I bought my first set of tubless tyres. Punchers = 3. Yep just 3 across 4 bikes. Seems to work for me!

[@terryg652]

@@tonysadler5290 It's hilarious when people like TESTA spew nonsense about things they know nothing about. I've been tubeless since 2015 as well. 75,000 miles. I've had two punctures where I had to stop and top off the air. I've had a few others that that sealed up and I was totally unaware of until later. I would never ever go back to tubes.

[@tonysadler5290]

@terryg652 yeah, thinking about it I must have had a few that sealed themselves that I wasn't aware of - but only 3 that needed attention. Thank you for your reply. Sometimes when I tell others of my experience with tubless, they think I'm exaggerating. All the best, regards Tony Sadler South Wales UK 🏴󠁧󠁢󠁷󠁬󠁳󠁿

[@NeoPayneHK]

thank you

[@gcntech]

You're welcome!

[@gregjs9665]

I did TRY changing my tire pressure when descending but I just wasn’t fast enough to grab hold of the valve stem. And those spokes are brutal on the fingertips. So I went back to pulling over and coming to a complete stop first.

[@markx5]

Nice one Connor 👍 how about doing the same test on the flat & also on climbs ?

[@gcntech]

funnily enough, Conor didn't seem very keen doing the test uphill! 😂

[@RAG0407]

Has gcn seen the shift to tpu tubes? I have found i can go down to 50 psi on 700x28c. For me this seems the fastest. Some say tpus r faster than tubeless. But is that true?

[@reinholdachleitner2069]

True,my 28mm are 48 front 65 rear and are really comfortable.

[@Jari1973]

Next, a straight line without curves 👍

[@peterjanovcik9973]

My tyre pressure is synced with my blood pressure depending on how much money I've spent on the latest cycling gadget. In case of overspending, my tyre pressure drops to 0 bar in order to stop me from riding the bicycle and this avoiding wearing out the components.

[@stuartmisfeldt3068]

Can you do this for bikes with tubes?

[@MortenSJ1982]

Name om that pump you are using

[@Pixel10Bro]

The Song from 4:50 - Don't Give up (Def Lev)

[@MrCyclist]

Low pressure will give you pinched punctures and dented rims when you hit 90 degree pothole or an ugly railway crossing. Any gains, if any, are inconsequential for a fun ride that 99% of us ride each time.

[@LegSpinna]

0:42 Going to take it on with no pedalling. 2:38 Errrrrr!

[@mvm9407]

So is this an objective test, or does it all come down to confidence?

[@JIMMYHIBBS1]

Lower the pressure too much and the handling is affected ….. hate that feeling when you can feel the front tyre squiring

[@rider65]

It's because your 'feel' skills need work. 👍 Work on proprioception and vestibular system skills.

[@JIMMYHIBBS1]

@ thanks for that mate … I’ve been in the BCF road race squad, competed in National Time Trials, Crits, and on the velodrome and ride gravel 50% time these days …. Personally I don’t like the handling on my bike when the tyre pressures are on the lower side …. but it’s always nice to have advice from someone who doesn’t know me, my bike, my tyre and wheel combo, the geometry of my bike, my preferred tyre pressure, or type of riding I do … so thank you 😁

[@rg807]

Tires are the primary, by far, suspension that bicycles have. Of course tire pressure matters.

[@oplkfdhgk]

how do those p zero tires compare to gp5000? i see alot of people using them but i don't really get why because as far as i know they are slower.

[@hoanglong4138]

Gp5000 puncture resistance is just worse than p zero race

[@oplkfdhgk]

@@hoanglong4138 good to know. thank you for answering my question.

[@kaiwren2604]

@@hoanglong4138 In my experience, GP5000STR tubeless gets a puncture once in 2-3 years or once in 30-45K km. By puncture I mean a major one that cannot be sealed by itself and you need to stop to fix it. Actually tyres wear out before they can get a puncture. In my case front tyre lives up to 10-15K, rear 5-6K km.

[@yogatriathlete]

1 second difference between "optimal" and low pressure should be considered equal because of margin of error, especially because of multiple factors that affect your descending time such as changes in wind, line choice, how many vehicles were driving up the hill causing turbulence, etc... You're probably better off riding with something in between, such as 67psi. No increase in rolling resistance, more comfort, and more grip for when you're actually pushing the limits on the descent rather than just coasting down the hill

[@92376]

Tubulars are the best for high speed descending

[@askmeaboutmattweiner]

Because...they can be run at lower pressures compared to tubes and clinchers?

[@bobmckenzie394]

Not Conor’s personal email address was it?

[@gcntech]

Not too personal at least

[@bobmckenzie394]

@@gcntechchampion. Thought I’d best flag it

[@VishnuRajendranAmboo]

Exactly especially when you shit roads 😂😂 75psi is my sweet spot

[@VictorElGreco]

You can’t put a price on confidence. That’s what makes optimal pressure, well… optimal.

[@theFatTubist]

I live on a dual carriage with a very high speed delta. I have to cross the road often and it’s very twisty, so I use my mirror very often to make sure the coast is clear for either the cross, or for when space for cycling goes away in a right turn and I need to enter the road. It took me 2 months to really get the hang of it. The one you threw away is the best. But once I got used to it, it’s not distracting at all and I’m not constantly checking it. The radars are useless for the kind of visibility I need. I would not ride without one now. I’ve also found it very useful during group rides to see if my rear is clear for maneuvering

[@ssaunders2k]

Isn’t lower being better dangerous advice for someone running hookless ?

[@mikekent9488]

I love this. Thanks for sharing

[@gcntech]

Hey, thanks for the comment and it is great that you enjoyed the video!

[@Drew-e8s]

I feel that it's time to bust this myth about contact patch and grip. Friction is dependent on just two factors, i.e. the co-efficient of friction (the material) and the force applied (weight). Surface area is not part of the equation - think about it logically, with a smaller contact patch and the same weight the downward pressure is increased, conversely a larger contact patch will give a lower pressure. Consider the two ends of a drawing pin, the same force but more pressure at the point and less where you are pushing with your thumb (try it the other way round - ouch!). Of course if you introduce a tread and a soft road surface, e.g. mud, it becomes more complicated, but for slick tyres on a road the contact area is irrelevant.

[@stuartdryer1352]

You are definitely right, but modeling a tire-road interface on a moving bicycle may be a bit more complex because, in effect there is a vibration that depends depending on the texture of the road surface as the wheel turns over it. So possibly the tire pressure is affecting the average time of contact between the rubber and the road as opposed to the average surface area? I'm just guessing here and I'm not an engineer.

[@Drew-e8s]

@@stuartdryer1352 Absolutely. The dynamics involved both in a straight line and when cornering seriously complicate the overall picture, but I've just had enough of hearing this simple falsehood about larger contact areas improving grip!

[@fukav1am]

A constant coefficient of friction is an oversimplification.

[@zedtony8110]

@@Drew-e8s the coefficient of friction is in fact reliant on both surfaces not just the one, think about it

[@Steve.M]

That model of friction that we learn in school, which doesn’t include a term for area, is pretty good for hard materials. It doesn’t really hold for soft materials like rubber tyres, which deform under load. Much of the grip of a tyre comes from hysteresis losses in the rubber causing a reaction force that opposes slip. The greater the volume of rubber going around the hysteresis cycle, the greater the force. Therefore, the more rubber on the road, the more grip you get. An interesting thing about the simple model of friction in hard materials is that that friction kind of does depend on area too, at a microscopic level. Two hard surfaces are rough at a small scale and make contact at a relatively small number of points. The pressure at those points is so high that the materials yield, increasing the area of contact until the pressure falls below the yield strength of the material. The friction force then depends on *that* area, an area which is created proportional to the normal force.

[@whowanderz]

You might want to cut out Connor's Gmail out of the video

[@_Tp___]

Yeah 😂. You don't even have to put your email in for the tyre pressure calculator anyway, it's just a data collection thing

[@gcntech]

What’s the worst that could happen?

[@johnstrac]

So the optimal pressure was fastest ? I'm going to write that down so I don't forget.

[@TESTA-CC]

Pressure needs to be higher, your putting more force through the side walls. If pressure is lower you run the risk of deformation of the tyre and it collapsing on a corner, especially with tubeless.

[@rider65]

Depends on the tire and its sidewall construction. #CompassTires

[@robinseibel7540]

Nope. If the tire isn't deforming, then you've got a crap tire. I'm not sure where you're getting your ideas about tubeless tires from, but they're not correct. The fact is that all else being equal, tubeless tires can be run at lower pressures than clinchers because a tubeless tire is much less likely to pinch flat.

[@Cycle.every.day.]

Vision/Pirelli/Silca ad? Which is fair enough,channel needs to keep the lights on we know.

[@ibnchukkara]

When in Zwift I am a god on the downhills, even with the standard pressure they offer......

[@rider65]

🤢🤮

[@gcntech]

@ibnchukkara what pressure do you run on Zwift?

[@ibnchukkara]

@@gcntech the pressure I impose on myself with nobody watching🤣. Sorry for my dumb comments .... informative video.

[@kidShibuya]

Just terrible music for this....

[@arturduarte113]

Poor editing. Music is way too loud, cheese. Thanks for the pressures. With the current temperatures, it should hv been about gravel tyres. Bad timing. Poor timing. The roadies are all on Zwift.

[@ertugyigitgezici7634]

Yeah this sponsor and ad situation is out of control, blocking the channel from my account

[@bubblesezblonde]

[@bobwilkie5721]

What about the cyclist's weight.

[@andrewzach1921]

His weight didn't change

[@rider65]

#JanHeine Come on gcn...😂 you're regurgitating old ideas and proven concepts. Jan was WAY ahead if everybody 20 years ago...

[@MTBScotland]

just one big advert for your sponsors lol

[@tuccimane6607]

I think u guys are full of bologna. Low presser feels so slow. I think u guys just want everyone to be slower than you are. #tireconspiracy

[@rider65]

'Feel' is a perception. 🙄🤦‍♂️

[@andrewmcalister3462]

And this is where feeling is misleading you. Going faster = more vibration. But more vibration (from rock hard pressures) does not mean you are going faster.

[@terryg652]

You can't measure feelings. But you can measure time. And his time measurements, and Jan Hein's, and every pro cycling team says your feelings are bologna

[@tuccimane6607]

Oh I timed it big boy. It definitely way slower. U just wonna be faster than everyone it’s ok I get it.

[@terryg652]

@@tuccimane6607 Wonna? 🤣 You didn't time crap. You 'wonna' use a real timing device like actual knowledgeable people like Jan Hein and every pro cycling team. Because pro cyclists want to be slower 😂😂😂😂😂

[@matthewclements8661]

8 seconds not much? 8 seconds is a ridiculous amount of time saved, especially when descending! An 8 second gap would be massive.