Searching For The Limits Of Cornering A Road Bike | GCN Doesn't Do Science

[@MrBJPitt]

A bit disappointed with this actually. Stunt guy obviously crashed on purpose. So we still don't know how much lean angle a pro can get.

[@ReiHeineken]

MrBJPitt Yep, the crash didn’t make sense. The guy just jumped off the bike.

[@ponderingfox]

Yeah, I was hoping for something like the thumbnail.

[@wcaplenor]

Yah this was bad. I usually like these "does science" bits but this was pretty silly. Gmbn did a no brakes corner video that got pretty hairy but eventually they were just honest about it and said they weren't down to keep pushing the speed.

[@cristibaluta]

Very disappointed as well, i was hoping to see at least the max angle you can get before crash, there's a big difference between the one with and without crash. And he was talking about how much can lean but i don't think it was the one that they showed, i think he was talking about the process of falling before falling. Then i was also hoping to see some physics and calculations.

[@garrickvalverde3685]

Exactly

[@NotingIsWhatItSeems]

Hype up the crash, then have the worst footage possible.

[@nugginusslover476]

@MegaAlpakka ...sooo what?

[@Jstroman221]

Hahaha 😄

[@Catcrumbs]

They had to mash a bunch of cuts together to distract from the obvious fact that he is just jumping off the bike instead of sliding out from leaning too far.

[@OUTDOORS55]

If you want to do this again get Ben spies. He’s both a ex MotoGp rider and a cyclists.

[@andersbriar5227]

I guess I am pretty randomly asking but do anyone know a good website to stream newly released movies online?

[@TwistedAnimator666]

Disappointed with that video, I was really looking forward to seeing how fast and leaned over a skilled rider could get before losing traction, not watch an obviously staged stunt - he didn’t even slide out 😕. I think Mavic did this properly a while back to advertise their UST tyres?

[@rorykoehler9018]

It was an ad for the new tires. I hope they're better than the GP4000 because they were rubbish

[@ericoschmitt]

@@rorykoehler9018 rubish? Come on, they are great all rounders to me. What do you sugest?

[@TK-zh5ck]

First time I've disliked the video you guys made.

[@monsieurboks]

They weren't even taking the racing line lol

[@reapanomin899]

For me,deep cornering(90 ISH degree cornering) at 40kph can be achieved by sitting on the top tube,and then use the cornering techniques a motorcyclist would utilise.

[@Gixer750pilot]

Racetrack tarmac is totally different to road tarmac. Track tarmac is laid for grip made up of different aggregates. Road tarmac is laid as cheaply as possible as fast as possible . Racetracks don’t have leaves , gravel , manhole covers , camber, potholes and roadkill either . Take this video with a pinch of salt

[@gcn]

We couldn't have filmed this out on the roads. Definitely way more variables as you note, which (in part) explains why there are many more crashes in racing and why you'll rarely see pros push their bike/tyres to their "true" racetrack limits. Thanks for the comment!

[@tbramfitt]

The tyres are legitimately worth more than the bike 😂

[@pssita]

But it was his "race" bike!

[@AvaPxiaO]

Isn't this the Raleigh seen on other videos (cheap bike vs hyperbike)? It is capable of reaching 50kph from the previous corner to the one in focus, so it is not that bad. How fast would you have gone with a 5k bike? Remember this channel is sponsored by a bike and component seller. You will never hear that unless you are pro-racing the difference between an #800 bike and an #8000 bike is not that great in terms of fun and exercise. Yes, a little faster, a little further, a little less tired, but emphasis on little when the money difference is ALOT! Keep shopping and paying for that bar tape used for a 5" clip.

[@kenpachinozarashi4005]

That's my problem. Every time I think of buying new tires I find a better bike that comes with better tires for less. Haha

[@GerayinTV]

I use those on my cheap fixie bike, worth every penny.

[@jjjjkkk3113]

Ur "tyres" spells much worst than the bike.

[@rossimessi1]

WHAT A WASTE OF TIME !!! Stuntman throws himself to the ground. Really GCN..... Some of us actually wanted to see what the limits of cornering are. Not a pantomime. Re do this with motorbike kit and a decreasing radius turn. Lets see the speed and angle that grip is lost.

[@gcn]

Hey Rossi - fair enough. We're going to see what we can do with a more scientific version at some point down the libe. We wanted this one to be entertaining and hope you managed to enjoy some aspects of that. All the best

[@eddyhoughton6542]

Hi Rossi, many years ago I got overtaken by a cyclist on the incredible "Arrabasada" road in Barcelona while I was on a Paris Dakar motorbike. A decent road bike can out-handle a decent motorbike on tight bends downhill, so I am really not sure how you could film a proper scientific test without static cameras. Difficult one, that.

[@rossimessi1]

Global Cycling Network The video was entertaining as usual gcn. Just left with a bitter taste from that fake ending. A lot of us are not so confident in cornering at speed so had interest in this, then the rug was pulled from under us. I think I am not alone from the number of thumbs down. I like the comedy in your videos but also expect to learn something from a video that promises insight. Appreciate you reading the comments and taking on board constructive criticism. Big fan of your work overall GCN :)

[@rossimessi1]

Eddy Houghton Yes in the right hands on a good surface it is amazing to see. A scientific test is probably unreasonable considering all the variables. But just to see a tyre loose grip whilst cornering off the brakes would probably boost confidence in what's possible.

[@yautongreporter]

Thanks gcn for this dangerous cornering demonstration. Cornering at high speed is not encouraged to general riders. The chance you get falling off your bike and get serious injury is almost a definite consequence. Better not testing the leaning limit if you want to go home safe after a ride.

[@pavelpavel446]

Excellent idea for a video, but pure realisation. Please redo this test properly, riding with different speeds through the same one tight corner. And with no flickering cuts, just a normal take and a slo-mo for crashes.

[@iamf6641]

@Beemrdon the stunt man can do it properly next time.. idiot

[@jorenbrook8433]

So James is more disposable than the trek madone? 😂

[@kenneth2095]

joren 02 I noticed that one too🤣🤣

[@Charliened1]

The NHS is free, fixing a bike isn’t

[@singlespeedchronicles7640]

Of course, priorities, priorities...

[@connieback7577]

I thought it was actually the stuntman who crashed. ???

[@DavidWard14]

@@connieback7577 yeah. Wasn't it? He just jumped off the bike...on a corner

[@chittytherobot]

1:17 When you are new at your work place and your manager convinces.. you are the best person to do the shittiest job in the team :) LOL !!!

[@gmbn]

Nice video guys, but we'd like to see you try it with a real bike next time 🤘

[@angrycircle]

Ikr

[@diogenes1351]

and a real cyclist

[@leonardolarocca1999]

He he. Is say that mountain bikers have more skill in the bike but they arent faster that roadies and doesnt have better physical condition. And lets be honest mountain bike are ugly and mountain bikers are uglier i mean get a suit to do tricks but pls take out that naughty bears put away that light green helmet pls

[@christiaanpretorius306]

@@leonardolarocca1999 mannnn🤣 You mad cuz you bad😁✌

[@leonardolarocca1999]

@@christiaanpretorius306 i find mtb cool but mtb riders are very cocky

[@charliewhiskey8440]

Once I entered a downhill corner way too hot, leaned the bike over much further than I usually dared and used literally every single inch of the tarmac. The thing I really remember was my FACE being uncomfortably close to the ground. The tyres were Gatorskin 23mm and they held. Good to know how far they can be pushed but never again!

[@gcn]

😱 your *face* ?!

[@KarandeepSingh-ex8cb]

Charlie Whiskey I just got my first road bike, the BTwin Triban 520 and took a turn at about 25 kmh, not even leaning much but on stock tires. Immediately crashed. I blame the wet road.

[@ericoschmitt]

@@KarandeepSingh-ex8cb or tires with hard rubber?

[@lanewells5290]

We need a gcn stig lol

[@gamby16a]

Peloton magazine had one for a spell to test bikes in their online content. Literally had a Stig helmet.

[@dansotelo228]

I too was a top-five 400cc production motorcycle road-racer before I became a Cat-1 bike racer back in the late 70s/early 80s in So Calif. My knowledge of M/C tire construction, wheel balance, and high-speed handling skills really paid off when I became a bicycle racer. It also payed off when I became a tire designer for the Japan Group. The first thing I wanted to make is a total slick road tire, and the pushback was crazy. Finally, Avocet came out with a total slick 26" tire, and it helped me convince Mitsuboshi to make slick road tires. This notion that thread vs slick on a tiny contact patch of a road tire flew out the window as we did corner grip testing in Japan. Even in wet conditions, the slick gave better or equal cornering traction. As for rotational balance, this is still a dark hole for bicycle engineers, just like aerodynamics was a dark hole with bike engineers back in the 80s. Soon rotational wheel balance will be the new MUST HAVE technology, mark my words.

[@druzzz1852]

That thumbnail tho.

[@hamdinawawi7214]

They change the thumbnail

[@druzzz1852]

@@hamdinawawi7214 Lol, why tho?

[@paulwalters5349]

😂😂😂😂

[@Noooo23523]

cringe

[@spongebobtentacles5393]

Marc Marquez should test this.

[@AhilMohan]

Thought that GCN was above click bait videos. 9 min video and only a fraction of a second footage of a fake crash not even at the tyres actual limit. Unsubscribed.

[@gcn]

Sorry you didn't like this video AhilMohan. Hope we have something you'll enjoy more soon.

[@AhilMohan]

@@gcn I didn't actually unsubscribe. I love GCN too much, but seriously, this was the lowest quality content you guys have posted in a very long time.

[@ErebosGR]

This is why I'm unsubscribing from regular GCN and only staying subbed to their GCN Tech channel.

[@NDN_FTR]

I'm guessing this was just a promo for Conti's new rubber.

[@carlblaskowitz7817]

Oh come on bro, they are allowed a few shitty ones... out of thousands of top shelf gems... mind if we have a gander at your back catalog?

[@garrickvalverde3685]

I feel like no one is pointing out that the crash was fake. I mean, there was a crash, but it wasn't James, and it wasn't a guy actually pushing the limits of a turn. The obvious differences are as follows: the guy crashing goes into the turn at a very odd angle, his outside leg is bend (not locked like James was doing prior), and his hands are on the hoods. He also crashes in such a way that he shields his face from the camera. In the quick shot that we do get to see his face, it doesn’t look like James’ stellar jaw line. Not to me anyways. I get that this is a kind of a gag video, but when I went to the comments I didn't expect everyone to be falling for it, no pun intended.

[@ErebosGR]

GCN is pinning only comments that sing their praises. That's why it's so hard to find any reasonable, truthful ones. I hate this kind of censorship through obfuscation. And yes, the video is a joke because it's not on the GCN Tech channel.

[@trekkeruss]

The reason why the stuntman has his outside leg bent is because unlike James...who was sitting on the saddle...the stuntman is off the saddle with his crotch down on the top tube!

[@SonnyDS_24]

Make a video where you custom and upgrade this bike to make a competitive with the small budget as possible !

[@lisapet160]

Not even "that competitive", but compare performance before and after upgrade. Just wait for James to recover from the falls since we need bike-to-bike comparison, not James-to-James :)

[@jastan94]

#Building330DToMatchE36M3

[@veloriderkm]

You guys got a STIG

[@danmar007]

You can corner until you hit the ground.

[@justinbouchard]

Most underrated internet comment ever I think lol. I will be dying laughing about this at random times during the rest of my life.

[@RuiPret]

I don’t even ride a bike 😂 but love the channel, very entertaining, congrats

[@gcn]

Cheers Rui

[@valleyflaneur]

Interesting vid, but not sure you can reproduce cornering crash so easy - what about the factor of the body position? James is already pushing away from the bike when he's going down, because he's aiming to crash, and bracing for it, but that also pushes the bike lower. Chapeau for taking this on, but can't help thinking that when we're fully committed to a corner at speed, body position & line is very different. Also, think there might be something like a gag-reflex in cornering that makes it very hard to deliberately crash and match the body position. Anyway respect to James for trying!

[@gcn]

Fair point, I reckon it does difficult to crash when you're trying to crash...

[@cnewton61]

Hmmm was it James who crashed?

[@gcn]

No, it was Levan, the stuntman.

[@valleyflaneur]

Ok - please reassign chapeau accordingly!! @@gcn

[@mscbijles1256]

Well I think you just pointed out one of the reasons why this vid has 'not science' in its title ;-)

[@ronniegogs]

GCN should find a race track and test bikes on it like top gear.... Also need a GCN Stig

[@rbching3535]

Red suit, face mask, glasses and road bike helmet?

[@boomerangfreak]

@@rbching3535 Nah fullface MTB helmet.

[@MyDemon32]

@@boomerangfreak nah a triathlon helmet and his face covered by a facemask

[@boomerangfreak]

@@MyDemon32 How had I not even considered that possibility?

[@rbching3535]

@@boomerangfreak everything must be red tho

[@mitchellsteindler]

We need some science on ideal body position for cornering!

[@gcn]

Great suggestion, we'll see what we can do 👍

[@AvaPxiaO]

Put all of your weight on the outside pedal and outside palm, drop your knee as far as possible into the turn, your head and elbow. There is nothing else you "can" do and this is important at the entry of the corner. If you make the entry keep a steady handlebar, no jerky moves and corrections. Always look deep into the exit of the corner, not down when you corner, the bike just follows your eyesight.

[@zombierider2794]

Ride a motorcycle...fast. I find my years of motorcycle riding helps me pick the right apex almost every time.

[@AvaPxiaO]

I believe this can also be confusing, as your lack of ability to accelerate before or during the apex, makes the ideal apex be in a different place for a bicycle . It is almost like MX/SX where you use a bang, straighten up early to begin to accelerate, not a smooth transition like on a road motorcycle. You want to be done with the apex as early as possible to begin to pedal, this brings the apex much closer to the entry of the corner. What you need to display this graphically is an accurate GPS/DGPS and an accelerometer. Take many different lines and figure out the fastest. Then do this with a powerful ebike and see the difference.

[@wrxzboost]

agree...this video was nearly useless. it was more of a joke show than anything informative.

[@jasonbishop5408]

I've always wondered this so thanks for the video! I think Hank needs to take another run at it though! I used to race motorcycles and a big part of the lean angle you can attain comes down to body position. The knee out is a great start, but by moving the upper body and head more to the inside of the turn I think he could have hit 60km/h!

[@red00tl]

I'm not sure what to make of this video. It was too long for a joke and contained too little information to be useful. So you guys love Hank more than you'd admit to, but overall it felt like a cheap plug for the new Conti.

[@gcn]

Not intended as a plug - cheap or otherwise. Sorry to read this one didn't hit the mark for you. Thanks for commenting.

[@red00tl]

I’m sorry if I sounded too harsh; that wasn’t my intention. I was waiting for the joke part to be over and see James riding in a very aggressive stance as depicted in the thumbnail of this video, but that moment never came. So at the end of the video I was left to scratch my head wondering if this was part I of a trilogy in the making. Anyway, I love you guys and keep up the good work.

[@yannickokpara4861]

I really wish you'd checked how tightly you can go around the corner for a given speed, because lets face it... you might crash into a less skillful rider on your outside if you make a tight entry and wide exit - especially on those supremely risk averse group rides with the 50+ lads.

[@gcn]

That's one for next time - great suggestion.

[@ukestjohn]

Whoa! Easy mate. I'm 50+ (70 this Feb.) and have been riding for 55 years. Don't assume the less skilled rider will be in our group!

[@yannickokpara4861]

@@ukestjohn I'm sorry. I definitely miswrote in a way that is open to misinterpretation. The skill and age was not supposed to be perceived as being related. It was more so the case of older riders usually having children and a spouse and thus avoid risk more than young guns trying to prove 'who's got the biggest' :)

[@ukestjohn]

@@yannickokpara4861 That's o.k., as we say, "No harm, no foul."

[@vice2792ocl]

This video goes to show the lengths these guys will go for a video idea. My hats off to you gcn crew.

[@gcn]

Thanks Osiel

[@mscbijles1256]

And also important to take into account: the radius of the corner (shape), your centre of mass, the angle at which you're leaning in. I was actually hoping on a video testing the angle of lean, rather than the speed. Maybe an idea for next time?

[@gcn]

Definitely. More to come on this subject for sure.

[@awildtomappeared5925]

The gradient also matters, if you are going uphill you will have more grip, down hill, less grip because the ground is falling away from you

[@anthonylovell2271]

Also how quickly you go from upright to full lean, on motorcycles the quicker the transition the less lean for a given speed

[@frorton_9170]

Gotta love Jame's commitment. Love him !

[@jgourdo]

Lots of you didn't watch through the end, it seems.

[@johndiablo68]

Not very scientific. Was hoping to see proper data, speed/angles etc.

[@AvaPxiaO]

Even if you did see data it would be meaningless for road riding. The specific data for a common street is different throughout the corner. The issue is how to position yourself to maintain control.

[@gl3906]

Title is (at least as today): 'Searching For The Limits Of Cornering A Road Bike | GCN Doesn't Do Science' - ...Doesn't Do Science...

[@snapjazz2222]

Just a bit of a correction: the contact patch between tire and road does not depend on tire width. The patch area is (bike+rider weight)/(tire pressure), regardless of tire width. However, wider tires do tend to be run at lower pressures, increasing the contact area.

[@johnbouttell5827]

The higher the speed, the more lean is required. This balances the roll torque -- generated by centrifugal force due to the turn -- with gravitational force.

[@cristibaluta]

This explanation is very good, i got confused when they showed the inward forces on the tire, the problems is the gravitational force, since is shifting from the tire to the inside there's no more grip and it starts to slide because of the centrifugal force.

[@tyc4231]

Which is why they should be applying countersteer and constant or increasing acceleration (i.e. a downhill turn for a non-motorized vehicle)

[@kirillbogomolov9117]

Huge thumbs up for James!!!

[@gcn]

👍

[@PrzemyslawSliwinski]

Especially because he would have thought he had been "a-bit-more-disposable-than-a-Trek-Madone" part of the show.

[@DrNPCabd]

@@gcn Next time make him wear a test helmet (that grey colored dummies with black and yellow quadrant-circle in the head and joints), and I suggest you a title "How many times we can use James "the test dummy" before he brokes down?" LOL.

[@nyemartin5737]

A good trick I learnt from my days as a motorcyclist is to push down on the outside pedal to hopefully make the tyres grip better.

[@sarcasmmuch8905]

He appears to counter lean, head shifted away from direction of lean, The best way is to shift body weight with your head and body in the direction of lean minimizing the amount of bike lean to make the corner, It gives a wider tire contact patch thru the corner.

[@Dennis4523]

Can we get a r.i.p for any elbows , kneecaps and skin for James?

[@evanr1940]

This is where you ask your viewers to volunteer for science. Ride with GCN ;)

[@matyourin]

Really interesting... I am always afraid to break out when cornering after it happened to me once. It would be interesting to see differences depending on the tires you use and on dry vs. wet conditions. Maybe you can get James to do those tests, too ;)

[@gcn]

If we do those tests, we might be putting James forward... 😉

[@singlespeedchronicles7640]

Entertainment value of this video was high, with loads of comedy = 8.5. Highly unscientific and inconclusive results on cornering = 3. How about considering even the speed James is traveling, tire PSI, angle and gradient of the corner, and angle of the leaning bike and rider ? I thought you might take several runs at it, and show the angle of the lean until he crashes. You could always get Emma's smarts into this game (she is the brightest GCN presenter!), and use atleast a little bit of geeky science.

[@gcn]

Thanks for the comment and glad you (for the most part) enjoyed this one - we definitely enjoyed making it. Based on the comments and feedback, we'll be updating with a nerdier, science-ier version at some point.

[@singlespeedchronicles7640]

@@gcn yes!!!! Can hardly wait... The art of falling is nearly as important (or more) than the art of rising fast....

[@gcn]

Agreed on that! Another great suggestion for a future video. Thanks!

[@HPaulModels]

Perhaps recruit Guy Martin, Valentino Rossi or another motorcycle racer to try again 🤣😂🤣😂

[@gcn]

If they want to repeat this one, we'd love to make it happen

[@nuttynut722]

@@gcn speaking of which, Guy Martin himself is a bike rider as well, should get him on the show talk about his record!

[@66smashy]

I was thinking about the comparison with motorcycles also.Competition motorcyclists lean the machine over loads but the key difference is that on an MC you are still laying on the power to the rear wheel whereas on a bicycle you cant do (pedal will hit the tarmac). I wonder if the power enhances all the forces involved to the benefit or otherwise of the amount lean you could get on. My sense of it is that it would.

[@benc8386]

@@66smashy I don't think power helps because you're just loading the tyre in another direction which takes you closer to the edge of the "traction circle". Racing motorbikes lean more because they have more grip.

[@s6p6h]

@@benc8386 they also have larger rear tyres (contact patches) to account for the power/torque and weight transfer.

[@rinonhoxha4059]

Here's my two cents: Use this fun approach to deliver a more mindful content. One video has Ollie with Yanto Barker where he leans on the bike with his whole body at different angles to test the slipping point. That segmet alone removed the burden of cornering downhill from me. Keep up the good work!

[@mhuten]

I was trying this and my pedal broke off :DD

[@mhuten]

RIP MY SPD

[@albr4]

that would be why you lift the crank up on the side in which the apex of the corner is on.

[@mhuten]

@@albr4 i was turning right it was a really hard corner and i forgot to lift up my right leg and my pedal got fucked m8. it damaged so much. Do you have a suggestion for buying spd?

[@boomerangfreak]

@@mhuten If you're talking the MTB style of SPD I'd suggest the shimano M530 as they are great bang for buck and a solid pair of pedals. For MTB riding I prefer a crankbrothers candy pedal though.

[@mhuten]

@@boomerangfreak im road biker im not using mtb spds but thx for you comment

[@echtogammut]

I've leaned over hard enough scrape my pedal (one time) and my shoe (twice). With the pedal it was an emergency evasion around an ambulance parked at the blind point of a downhill, hairpin turn. Scraping my shoes has happened on various descents. A big factor of how far you can lay the bike over is just how much force you can exert on your outside leg. The stuntman's crash occurred because he attempted to sit up. Any crash due to loss of grip is going to be a low-side crash, with a clean separation of the rider. The real trick isn't cornering so deep you scrap your knees on the ground, but bringing the bike back up.

[@lisapet160]

Good example on how elders encourage youngsters to spread the wings and fly...

[@gcn]

I guess that's one way of looking at it Lisa 😉

[@joelkton1]

Come on, guys. At 21 seconds in you can see him throw the bike. No shots from the front of him losing it. Staging the fall makes having watched the whole video pointless.

[@theparalexview785]

That was a bit different in production style from your usual videos. Liked it. Wanted to see that slide repeated in slow motion, though. And if looked like the pants were already torn up before then. Pre-worn or did we miss some outtakes?

[@gcn]

Glad you liked the video. Pre-worn + outtakes. 👍

[@theoriginaldarbster]

I don't care how disappointed some people were with that video... you guys are hilarious and I thoroughly enjoyed it!

[@Sprinklesofjoy]

Surely you'd choose a left-hand bend to protect the rear derailleur etc?

[@parkerheathiii4881]

As one who has probed and provoked the limits of adhesion on 2 wheeled vehicles with and without human power for a number of decades, I enjoyed this immensely. Thanks again guys, for making yet another fun and informative video.

[@D.Eldon_]

Pathetic! The video of the crash was lousy and failed to show the lean compared to the previous tests. It would have been far better to have a stationary camera with a clear view of the corner to provide a consistent frame of reference for each test. The addition of the heavy clothing and pads for the last test surely skewed the results, changing the aerodynamic drag (an important external force in the tests), weight and center of gravity. And Si's confusion between centripetal and centrifugal forces was the worst.

[@PinkAsAPistol]

A composite of different shots, while on the previous attempts, the whole thing was shot as stated. But suddenly in the final attempt, there's a second camera. In one shot he's holding the bars properly and at the other, where he falls, his hands are on the hoods. The line is completely different between shots and even if they were of the same attempt - which they are not, as they do not match at all - there would have been a huge time gap between them and we would be unable to know if he supposedly washed out till he fell. Pretty sure that even the stated speed is incorrect. The whole thing is staged. Seems like he falls intentionally, at the safest way possible, taking account at the circumstances, then you pretend to have explored some meaningless limit when you didn't even do that. Then there's the thumbnail that leads viewers into thinking you were going to do some meaningful thing, like explore the limits of leaning. So the point is not that you don't do science. The point is that you do nothing other than mislead viewers into useless content and underestimate their intelligence.

[@tomrachellesfirstdance7843]

Was he trying to crash on purpose the crash looks silly he is not even on his seat crotch on the stem and turning really sharp instead of progressively turning and he doesn't even start to the left of the road tightening the corner loads. I know the are tounge in cheek but this one isn't the best.

[@teuluPaul]

I did a skid training session in a car, and one thing which was interesting in terms of impact on grip was this: The amount of force which can be generated by a tyre patch in contact with the road is limited. If you have other forces at play such as braking or accelerating, then this will reduce the amount of force which can contribute to keeping you going in the right direction. In other words, accelerating out of a corner when your still banked over is a risky proposition (as demonstrated by James's racing crash at the start). It also means braking before the corner is better than going in too fast and trying to brake heavily once you are leaning over.

[@dapster]

You know who would be perfect for this test? MATT STEPHENS!! #BringBackMatt

[@FlatSpinMan]

Loved that scene with Dan explaining the role to Hank. Really, genuinely funny.

[@gcn]

Thanks JMS 👍

[@nerdexproject]

The jokes were strong in this one!😂

[@DuncanInUK]

This is exactly how I got in my first major bike crash back in Year 9! The scars are still here!

[@kingonthehill7]

Another Physics cringe is that the cornering forces are technically described as centripetal (inward), rather than centrifugal (outward). There are in fact no outward, centrifugal forces generated during cornering. Centrifugal force is a fictitious force that are used to describe motion in non-inertial reference frames. In the normal earth (non accelerating) reference frame, the cornering force is the friction force which points inward, not outward. The force was correctly shown as inward in the video, but was incorrectly described as centrifugal force. Another way to look at corning forces, is that the natural tendency of the bike is to go in a straight line (Newton's first law). To deviate away from the straight line in the inward direction around the corner requires a inward (centripetal) force (Newton's second law). Overall. enjoyed the video. These comments are intended to be educational rather than criticism. Keep up the good work mates :)

[@gcn]

Thanks for the technical comment! Appreciate the feedback and knowledge sharing. Pleased you enjoyed the lighter side of the video too 👍

[@luigimarioviespoli7825]

The centripetal force was mentioned as the force driving the cornering, while the centrifugal force was correctly called "apparent". There was no problem with that explanation, also considering that it doesn't pretend to be dynamics course.

[@carlosflanders518]

Nothing wrong with mentioning centrifugal forces as appropriate. Calling it fictitious is a stretch. There is quite a lot of material out there in the interweb concerning physics of cornering and very little of it is accurate.

[@cliftt]

Global, Good to see u accept constructive feedback.

[@roichir7699]

Missed is the decrease in force normal to the ground during leaning which is essential for friction. Whereas the area of friction is not so much important. As counterintuitive as this is, its physics. en.wikipedia.org/wiki/Friction is a good start in this topic. Sorry guys at GCN, I just hoped for a better explanation about the physics an of course a real test of the limits, which you can of course precalculate with some simple experiments. Just use the planned rubber and asphalt combination in a experiment where you pull a 1kg weight. Use a scale like you did for weighing your bikes to pull the experiment until it slips, do some calculations and you are good to go.

[@sepiarain]

I used to love putting my shoulder into corners and every day managed to take a sharp corner at a decent speed with a good lean until one day my bike just gave out from under me unexpectedly and I absolutely ate road... There must’ve been oil in the road or something. But yes, it has annihilated my confidence for taking sharp corners at speed, something I used to enjoy about my riding.

[@peglor]

Annoying to see the wider tyres grip better fallacy paraded out again - at the same tyre pressure the contact patch area will be exactly the same no matter what the tyre width (It's longer on a narrow tyre, but the contact patch must increase until the tyre pressure times the contact area equals the load on the tyre). Grip due to friction (At the scales used here anyway) is independent of the contact area. The reason wider car tyres grip better is because the tyre carcass needs to flex less to get a given contact area, so the tyre heats up less at speed, allowing a softer rubber to be used without the tyre overheating and delaminating on long motorway runs. This is the same reason that at the same tyre pressure a wide tyre will have lower rolling drag than a narrow one. Wide tyres will put more stress on the rim than narrow ones for a given tyre pressure, and the massive comfort benefits to being able to run wider tyres at lower pressures without pinch flats and with the same rolling drag as a rock hard narrow tyre is more useful to more riders than a slight decrease in rolling drag with narrow tyre harshness.

[@404nobrakes]

Wider tires have more volume and thus require less pressure to achieve the same rolling resistance. It's why 27.5+ mtbs run at 12-15psi whereas vintage road bikes run at 120. A 28mm tire on a 21mm internal-wdith rim can be run at 60psi instead of 120 on vintage bikes. If the load is the same (about 75 lbs on each tire), then the contact patch is double the size on the wider tire than the narrower one. If you scale this up to a 650b x 50mm tire that runs at 25psi, you get almost 5 times the contact patch. At that point, you DO get more grip due to the interaction of the tire with the road.

[@tjfreer294]

Finally the real GCN guys are back

[@JT-pg2bu]

Should have got Guy Martin doing this

[@klaasdeboer8106]

I remember going downhill in france where a corner turned out to be a decreasing radius and longer than I thought, I was on a hardtail mountain bike with semi slicks. I am lucky that apart from my mistakes the road surface was good and it was very warm. Interesting how many thoughts fit in a split second, I kind of remember how I found the space to counter steer and lean way further than I have ever imagined and made it! I was about three centimeters from the white painted stripe at the side of the road. It felt ike magic as if my tires were glued to the tarmac and I could really feel the g-force pressing and how incredibly close I was to the ground. Must have looked like motorcycle cornering on a circuit. I think the high temperature has actually saved my life.

[@famzino]

That sounds epic

[@fprintf]

I missed "GCN doesn't do science" in the title, was expecting to see faster and faster cornering until a real crash. Kindof disappointed actually especially given the thumbnail of the video. And I can't even unsubscribe 'cause it was a "suggested video" for me.

[@gcn]

Sorry you were disappointed by this one @fprintf. Thanks for commenting, though. We appreciate the feedback.

[@AliJardz]

I love the split screen shots so much. Awesome.

[@jens6398]

Amontons' Second Law: The force of friction is independent of the apparent area of contact.

[@gcn]

Had to Google that just now... And thanks! 👍

[@BikeItUK]

GP5000's got my attention, not sure the demonstration proved the limits of cornering, but this is explained later in the video and made me smile, poor lad. The weight of the rider apex of the corner weather conditions and skill of the rider all contribute. But all in all great production, fun and entertaining and some great looking new tyres. Thanks for another great video. All the best Andy

[@gcn]

Thanks for the comment Andy, really pleased you enjoyed the video 👍

[@rodolfojuan1892]

who would like to see a trek madone getting scratch yikes

[@charlieharper4975]

In all my years of riding, I only lost traction once in a corner going about 45mph. I didn't crash, I just slid across the road...... into the oncoming traffic lane. Fortunately, there was no oncoming traffic.

[@jonglass]

Levan Doran: Stuntman: White Walker/Starship Trooper/GCN Cornering Video

[@OverMotoren]

Don't forget you're running insanely narrow tyres. Not only for contact patch, but also for lean. The wider the rim, the more you need to lean for the same corner. Just because the wider rim makes the wheel lean more outside the center line than a narrow one would. And in this case, the other way around. It would be interesting to see how you'd fare with a fatbike, for instance. Take it to the dirt and use Cyclocross tyres on the narrow bike, to level the playing field. Or see if you can find fatbike slicks ofcourse.

[@gcn]

We'd love to try it with fat bike slicks. Great idea.

[@boomerangfreak]

@@gcn Is there such a thing as fat bike slicks? And if there is why would you wanna ride them? I do not see a fat bike as a fair road/urban bike tbh.

[@oscararavena5816]

nice to see you dan.

[@vagabondingwithjasondaniel4495]

I’ve nominated this video for the “Thumbnail of the Year” award.

[@godwindracing6056]

GCN should get Jason Engineering Explained to explain the science of riding pushbikes around corners at speed

[@fadenseiden]

hell no

[@grumpynerd]

Back in the era of narrow tires, when we all ran them at the top of the rated range, the turn onto my home street was at the bottom of a steep hill. After years of making that turn, I habitually took it as hard as I could; I knew exactly how fast I could do it. Then one day as I was leaning into the turn, I saw that somebody had dropped a foil gum wrapper on the street. It was over two bike lengths ahead of me, but I was using every bit of grip I had. I was stuck to my line as if I were on a rail. I watched helplessly as my skinny front tire rolled over the gum wrapper and slid out. Moral of the story: don't litter. Also, when you're using everything you have, you've got nothing left over for a safety margin.

[@nickhagemeijer4162]

Should be mentioned that, although confusing, the size of the contact patch doesn't affect the co-efficient of friction at all. A wider tyre will feel more stable and offers more support. Grip comes down to rubber compound, the mass of rider and bike and the road surface.

[@Sean-if7rp]

Nick Hagemeijer Contact patch does affect the grip, but only to a small degree on a road bike, tyre pressure and sidewall thickness have more of an effect on the cornering of the bike

[@philipk4475]

Does this hold true even when dealing with a real world scenario? i.e. imperfectly smooth roads? I know that in doing the simple physics calculation, the size of the contact patch cancels out, but in a real world scenario you don't have a perfectly smooth piece of tarmac - there are bumps and holes and loose pieces of gravel, and so a very narrow tire may simply have 'bad luck' for a split second and have all or most of its contact area on poor substrate, and it only takes a split second for a tire to lose traction. This happens to reflect what we know from real world riding - that wider tires inspire much more confidence in cornering.

[@Sean-if7rp]

philip kerpen Only to some degree I think, it’s about striking the correct balance between the load placed on the tyre, sidewall thickness, rider weight, surface etc

[@mob1235]

A wider tyre is for accelerating out of a corner or braking into a corner. For the corner itself it has no grip advantage. You just have to use more bank angle for the same speed.

[@Sean-if7rp]

mob1235 Banking helps for bringing the centre of gravity close to the corner which of course helps Corning, dependant on the pressure and the speed, banking can also help increase the contact patch of the tyre

[@barrietylerUK]

I am a (very very) experienced motorcyclist...1975+ despatch rider (UK) etc When the front wheel losses grip you fall. If only the back wheel does you can save it - by straightening out ie going wider on corner exit, or stamping yr foot down (ouch)...suddenly standing the bike up more into yr thigh as you hang off more sometimes re-establishes more back wheel grip... (Careful with fast left handers-UK) - yr run off is oncoming traffic not the hedge!) So.. Run a grippier front tire - either by compound or lower psi (bigger contact patch and hotter(deg C) tire) That way the rear tire will always loose grip first, a safer index to how close to the the limit you are. ...as the rear wheel starts to step out or slide you can feel when to bail out of the lean a little....if this *starts* with the front tire , its all too fast and Bang youre off.! Yr stunt rider, lol , came off cos his front went - look at the slow mo. ...hopefully - lol - sometimes the front goes first especially when starting to lean under braking....keep the front wheel happy on corners!...miss bumps , drain covers, painted lines, kerb debris etc! PS look up the "Canard" airplane set up - its in reverse [to bikes] re front and back - but a Canard can never catastrophically-stall [crash] because the smaller front wing is angled to stall *first* before the main rear wing does, (this lowers the nose and stops a big stall). It's the "lesser end" protecting the "important end"... ((Canard is french for duck - I suppose cos how they look)) So a grippier front tire is no guarantee like the no-stall Canard - but it should help. How optimum that tire set up is for TT etc averages is someting idk.

[@snoworder]

lower pressure and higher tyre temperature should increase grip

[@wreams2964]

4:41. Can we just applaud that shadow clipping.

[@KingofStreet3]

Not that far. I have a nice foot long scar on my left shin to prove it. Took the turn at 20mph

[@mscbijles1256]

Flying Lap Productions These speeds, you reach them on a normal road bike? Are these corners on a descent, or is it all muscular power?

[@KingofStreet3]

Nah I'm a rookie on a road bike. Didn't pick a proper line when taking the turn plus 25mm tires/tyres didn't grip much

[@AvaPxiaO]

No way your exit speed will be higher than your entry speed unless you are coming down at 30' and braking heavily into the corner. This is not a motorcycle, no throttle can be applied. Cornering linearly from the axis coming in is deceleration. After cornering 90' your speed on one axis is 0. Your speed on the vertical axis (exit of 90') can only be due to hard acceleration from 0 (at entry), which you can not do on a bicycle, even on steep descends. 50mph exit? With a 53/11 you are at full speed/cadence on exit?

[@simonbeal2148]

Remember watching the late Ronnie Smith doing similar on a motorbike seeing how far you can lean till you crash, not easy to do on purpose goes against your better judgement

[@austinshoupe1506]

It's an odd little video with a couple funny moments and no science ("GCN doesn't do science"). Dont watch if you take these kinds of things seriously.

[@roxic1212]

This was hilarious, well done James thanks for the effort👍

[@nickgates6829]

Great vid boys, but check your physics. Physics 101 says surface area does not play a role in force of friction, only U: the two materials involved, and N: the mass and acceleration of gravity. To check this, take a gym disc weight where one side surface area is substantially larger than the other. Lay the minimal surface side down on a surface and increase the angle until it slides. Flip it over to the large surface area and repeat. They slide at the same angle. Same mass, completely different surface areas, an equal force of friction generated. In my racing days, we changed the tyre type to suit conditions, not the pressure. To increase the force of friction (or angle in this case) you need to change the material the disc sits on, or in the white walker's case, the type of rubber on the tyre. Let's send him out there again! Corner 2.0.

[@gcn]

Cheers for the comment Nick. Food for thought and glad you enjoyed this vid.

[@mattbrady1426]

Tires do not follow a physics 101 understanding of friction for a number of reasons; this is not a good way to model the problem. The lateral force component in cornering scales with the slip angle of the tire. This relationship is nearly linear early in its curve, but it becomes highly nonlinear later in the curve. The nonlinear section corresponds to the tire's "limit of grip," so to speak. This is where the classical model fails with respect to tire width. Tire load sensitivity is nonlinear. So changing the load while holding width constant, or vice versa, results in a nonlinear change in the threshold for the nonlinear part of the slip angle vs. lateral force curve, i.e. the grip limit of the tire. This is why, all else constant, a wider tire in many cases can provide more grip - they can often allow higher slip angles before the curve becomes nonlinear due to tire load sensitivity not scaling linearly. GCN's claim about contact patch is related but definitely not the sole reason for the change in slip angle, but it definitely does not follow the classical model.

[@Epitome63]

That the coefficient of friction is independent of surface area applies only to smooth surfaces. It is possible to have a coefficient of friction greater than one.

[@videoID2]

So, you're saying that road racing motorcycles don't need tires any wider than road racing bicycles. Interesting. Just why do you think motorcycle tires got wider and wider over the last fifty years? More rubber on the ground actually does mean more grip, everything else being equal.

[@sth6027]

I love the title haha! I mean it's hard to determine when a bike rider will tip over in a corner because there are just so many things to take in account: rider + bike weight, entrance speed, angle, tyre material and therefore friction coefficient, tarmac friction coefficient, stability and balance...

[@gcn]

Cheers sth!

[@ipikture]

So again I ask why has there not been more development towards a radial ply bicycle tire? When motorcycles went from bias-ply to radial ply the cornering speeds and adhesion increased dramatically. And add to it the reduced rolling resistance of a radial ply tire versus a bias ply tire. Look forward to hearing your responses has any of these tire manufacturers that you worked with discussed this? Again thank you and I'm really glad he didn't high side.

[@bretmohler9719]

there is some info on why radial may not be ideal for road bikes. sheldonbrown.com/tires.html - in the part about 'How a Tire Supports its Load' and 'Rolling Resistance'

[@LEGOrinzler]

@@bretmohler9719 wow seems like a great site thx for the link

[@timeslowingdown]

@@bretmohler9719 Interesting.. but he said they were only ever made for a few years. Could radial ply tires that don't feel bad to ride be developed if more time and money were invested into it? Doesn't seem impossible.

[@bretmohler9719]

@@timeslowingdown I'm sure and I wasn't speculating anything just that was the reason it has maybe been economically not viable. Sometimes manufactures don't do something because the cost is just not sustainable. I'm sure if enough RnD went into it they could improve but maybe the trade off is so slight they rather just focus on getting similar results with non radial plys.

[@timeslowingdown]

Ahh okay, yeah makes sense.

[@AndrewSmith-cd5zf]

Credit for jumping off the bike at speed - but we all know that this is not how it goes down in real life - actual bike riders rail the corners til something gives.

[@NemanjaPantelic]

Great Conti commercial :)

[@deimosphob]

I really like tires with thin contacts for going straight and long flat contacts for cornering, it gives your bike a really cool feeling, almost like its more nimble, and also keeps the bike nimble for straight-line speed despite the tire looking wider, and being slightly heavier, and looking weird on a road bike, are honestly the best for competition, especially when you have tracks with many corners.

[@fissionchips8840]

Fabulous video 📹 absolutely loved the ending!!!! 😁👍

[@gcn]

Thanks!

[@NexuJin]

I had a feeling this wouldn't be what it seem it would be. The "GCN doesn't do science" gave it away :)

[@ilkerercen5994]

Nice video! Do you mind sharing the tyre width and air pressure with us please?

[@gcn]

I'll have to get back to you on this one, but yes, definitely.

[@CauliflowerEars1]

Also an idea of the diameter of the curve at the apex of the line he took round the corner please. It's a bit hard to tell from the zoomed in footage. I appreciate this isn't GCN does science, but might as well have a go ;)

[@ivyking4149]

One minute into the vid and I can allready tell everybody right off the bat; the amount of grip a car or a bycicle tire has is tremendous. One can hardly believe the actual grip of a rubber tire. I presume as long as the speed is good and there are no loose particles in the corner lying down while cornering is easy as pie.

[@sharktamer]

thought they were going to pan to james still lying on the road

[@martinfisker7438]

Fun vid, you did get your science a little wrong though. Theres no centrifugal force, the centripetal force is simply accelerating you laterally

[@Nonameyoutue]

Just another day at the office......

[@dublinvids5146]

Hired a Bleeper Bike in Dublin in December and hadn't been on a bike in years. Ground was slightly damp as had been raining earlier and flying down a road (with no helmet) decided to take a right turn at speed (with all the confidence that I was on one of my old bikes) and as soon as I leaned in the front wheel slip and I smacked my right cheek bone and brow off the concrete. The sound it made I can still hear. Stood up and a crowd of Christmas shoppers surrounded me telling me to sit down. I'm grand says I picking my bike up but slowly noticing that blood was dripping all over my hands from some place. Turned out I'd given myself a nasty cut. My own fault of course. I'll get back on a back one but will make sure to have a little more cop on and decent helmet.

[@aponcapone]

I was a serious scooter and motorbike driver and all tough I ride roadbikes for over 12 years now I still think I could get more lean angle on it. I can do curves quite well I think but I am just scared that I scratch my nice bike..

[@AGMTB.]

Serious, yet you say driver and not rider lol

[@edwardo123]

I think another important thing to consider is the temp. Warmer tarmac and warmer tires will produce more grip than cold tires on cold tarmac. Same reason why i use tire warmers on my motorcycle, and get the best grip when the temp is hot outside