Why Big Brakes Don't Stop You Faster, But Wider Tyres Will

[@gcntech]

Have you thought much about this? 🚴‍♂️🛞 Let us know your reactions down in the comments!

[@PrzemyslawSliwinski]

Can fenders impact braking performance? PS 2:05 - I must say this: these mudguards don't look abominable at all! Moreso, they look almost cool! If this is a subliminal message of the video then, well, it kinda works!!! :D

[@PrzemyslawSliwinski]

PPS Does it also mean the 140mm rotors, used by e.g. MvdP, have their merit?

[@凸Bebo凸]

My thought is, if your hands are too weak to stop the bike with rim brakes you should just squeeze a guitar trainer and fix your little girl grip, not buy rotors.

[@kevingregoire1042]

Yes, Contact point has a huge influence on braking, that said, This looks like a tyre commercial. More than riding technique and tyre pressure you rightly mention A word on weigh ( RIDER’S MASS ) would have been a good introduction ! It’s what should dictate tyre size, rotor size and material, pads choice and tyre compound switch point. Heavy weight rider, go for big rotors if you need to stop at the end of a descents, Go for wet and heat resisting pads, full steel rotors according to the wear rate. And of course you already know about bigger tyres, also that endurance compounds might give you better mileage and braking wear resistance than the race compounds. Less than 70kg, lighter and smaller stuff will work longer for you. Heavier riders, I know it can sound sad but don’t tune with fragile lightweight components, treat yourself to durable and safe setups. Lightweight riders, if your buddy is a heavy rider, don’t copy his setup, you probably don’t need a 32c and 180 rotor. Don’t rub lighter components in his face, you don’t want him to crash or feel discomfort, and insecurity !

[@tesdfhsdfhspodf]

i'm considering upgrading my 105 Rotors to ultegra Rotors. Mainly because they look looker but i would love to see a comparision between both.

[@lorenzobigguy]

Yeah, if you've been locking the tyre up all the time, fair enough, skids don't help you slow down, but when your lever is back to the bar and you can smell burning, it's not your tyre. The caveat here is that I'm over 100kg, the hill where I toast my brakes regularly is 14% and has a hairpin at the bottom. All the same, for me, grip isn't the issue, it's the brakes. I started with the stock TRP pads on my spyre calipers, which were borderline suicidal, I then put some more expensive pads in, which improved things, then I put an MTB disc on the front, with an adaptor on to move the caliper out, that got me stopped without any brown adrenaline stains.

[@martinh2783]

It's almost like the friction between the tyre and the road desides how fast you can stop.

[@bele13]

It is also the friction between pads and rotors, but you can engineer those way better. As the manufacturer, you can define more or less freely, which materials you use, how much contact area there is, how much force is applied etc. As a bike (or, rather, tire) manufacturer, you can only control the width and the compound of the tire. You have no control over tire pressure, system weight, road surface material, roughness, wetness... And then, it's a matter of the center of mass in relation to the contact point with respect to the sum of the weight vector and the vector of the deceleration force. So, it's quite a lot more than the friction between the tire and the road that decides it.

[@ivanteo1973]

really? remove your rotor, see if it stops.

[@eda2000-r8h]

​@@ivanteo1973Its still stop, just took longer to do so :v

[@rider65]

Ah, yes. That's physics and thermodynamics

[@martinh2783]

@ Sure, but it dosn't matter if you use disc breakes, rim brakes or a stick. The tracktion of the tire is the most limiting factor.

[@ravennexusmh]

upgrading your brakes isnt about stopping quicker. it's about controlling heat, which improves repeatibility and pad/rotor wear. smaller brakes get hotter affects wear and fluid temps etc. it also affects lever force required to achieve the same rate of decel. i love the light lever feel and awesome modulation my 180/180mm gives me with sram guide 4 piston calipers on my gravel bike. i never have to grab a handfull of lever.

[@maugerville]

Great video ! I am glad you first pointed out that if the brake isn't up to snuff than fix this first. One other thing to point out is that bigger brakes will will require less effort at the lever for those with poor hand strength.

[@gcntech]

Great point!

[@feedbackzaloop]

One more thing: bigger rotor = lesser force at the lever. Leading to less fatigue for long and/or repetitive braking and hence better modulation. That reduces risk of skidding and slipping. And you already know a slipping tyre carries less braking force than a rolling.

[@凸Bebo凸]

@@feedbackzaloop Oh yeah combating hand fatigue in cycling sure. I've spent many days climbing in the Alps only to quit cause my hand was screaming at me, haha.

[@krazy1z]

I went up to 180mm rotors on my bike due to a hand injury that prevents me from fully closing my left hand (front brakes) I also have very limited strength in the hand. It has made a HUGE difference! I like to do a lot of elevation riding so going down the windy mountain roads at 40MPH I need to be able to slow down. Something I wasn't able to safely do before the brake upgrade.

[@meanredspider]

I think this is actually a pretty good and sensible prioritisation of the factors that make a difference.

[@gcntech]

Thank you!

[@pembrokeshiredan]

Tyre width does not automatically increase the contact patch area. With the same pressure and the same weight, the contact patch (combined for both tyres) is the same size. The benefit of wider tyres is that they can be run at lower pressure, and that's what increases the contact patch area.

[@aliounendayziga8669]

True bigger tires at a high pressure even decrease the contact patch

[@georgim2741]

bigger tyres are automatically bigger contact patch

[@AndrewJOliver]

Tyre pressure is literally in the video. Maybe watch before commenting

[@pembrokeshiredan]

@@AndrewJOliver Tyre pressure was covered separately. Alex said wider tyres give a bigger contact patch, which is not true. Lower pressures give a bigger contact patch, as stated in the video. Wider tyres only enable lower pressures.

[@pembrokeshiredan]

@ The contact patch area is determined by the pressure and the rider weight only. (Ignoring such things as the stiffness of the rubber.) Pressure is force divided by area, so the contact patch grows till the weight divided by the patch area matches the tyre pressure. Wider tyres make a wider contact patch, but its area is the same when the pressure is the same.

[@davidide1525]

Great Video Alex, and I like the color of your bike . Never mind what Ollie thinks :-)

[@max-eb9vi]

Removing the brakes completely and using a wall to stop is actually the fastest way to stop

[@fuzzi1002]

😂

[@noptimized]

GCN Does Science: What type of wall will stop you the fastest?

[@KNURKonesur]

use a fixie or a track bike - problem solved

[@menthel77]

I used the side of a van 30-0 in a fraction of a second. Didn't do my head much good.

[@KNURKonesur]

@@menthel77 should have worn a helmet

[@clewstah]

I really like the combinations of different brown colours on the Orbea. From the brown frame to the saddle and the rim of the wheels. Very nice.

[@jb1-f5y]

More tyre grip helps you stop faster, bigger brake rotors help you to slow down for every hairpin on an alpine descent instead of just the first 3.

[@MichaelWilliams-iv6dj]

Life is too short to ride crappy tires.

[@gcntech]

We agree!

[@williamshakespeare5646]

Life is even shorter with crappy tyres.

[@h3n488]

Driving 4 Answers did a great video on big brake mods on cars and how they do not stop your car any faster (or not significantly faster at least). The reason being that car brakes have for decades been strong enough to break the traction between tyre and road and using a bigger rotor only reduces the force needed on the brake pedal. Same applies for bike brakes. Basically a bigger rotor is only a bigger heatsink and therefore better for the reasons mentioned in the video. For cable actuated disc brakes a larger rotor could be better if it reduces hand fatigue.

[@oliverjacobs8594]

A good video with the exact same title and premise as the GCN one... I can't help but think GCN is doing a little bit of a plagiarism with this one.

[@h3n488]

@oliverjacobs8594 No no, not really plagiarism. There's a different audience and the cycling community need to hear this stuff too. I think this was a great video! Especially I liked the emphasis on good tyre selection instead of brake upgrades.

[@tallteacher]

The size of the tyre contact patch is determined by the load and tyre pressure it is not determined by the tyre width.

[@joystation1]

For the same load a wider tyre will allow you to run a lower pressure which makes the tyre contact patch larger and thus provides more grip. A larger tyre is also less liable to puncture as the force pushing the sharp object into your tyre is less, pressure = load / area eg pounds / square inch.

[@demand61]

Don't you think a wider tyre has the potential for a larger contact patch, compared to a smaller tyre? Also because a wider tyre can be used at lower pressure.

[@Randombourg]

No mention of temperature? It's a bit different commuting in the dark in sub zero temperatures than it is at 11am in Majorca. Edit: referring to effect on tyre grip

[@MisterE331]

DIdn't you guys do a video a year or 2 ago comparing different sized rotors and their stopping distance?

[@BroccoliLand]

No. That was comparing different brake tech.

[@larrylem3582]

GMBN did a month ago. Oddly, the medium diameter tested was best.

[@zygmuntthecacaokakistocrat6589]

Well, that's a contentious statement. Bigger rotors heat up more slowly under sustained braking, this leads to less brake fade, which translates to sharper and more predictable braking. I don't think you established your argument very well at the start.

[@dominicbritt]

Alex’s point is correct though - even shit disc brakes with 140mm rotors can outperform the grip of your tyres on a road bike… 160mm rotors do cope with heat better than 140s… and that’s why most road bikes ship with 160s. People bombing around on 25mm tyres at 100psi are probably wasting their time with disc brakes …. Running 30mm tyres at 60psi is a much better way to improve braking performance.

[@_Tp___]

Also, the further the distance from the centre of the wheel that the braking force is applied (aka a larger rotor), the less force you need to dissipate the same amount of energy. So it's actually wrong but I guess that's clickbait. "Why larger disc rotors don't affect braking as much as you'd think" or something like that would probably be more appropriate.

[@AndrewJOliver]

It’s measurable, not an argument. You have a hypothesis, prove it and make a video showing your findings.

[@bsbbernal]

Do you have research that proves heat affects brake performance on road bikes? The friction and heat generated from slowing down a sub-100 kg rider are not going to be anywhere near hot to create substantial amounts of brake fade.

[@warrenyoung173]

​@@bsbbernalThe Bike Sauce channel did a physical experiment on how fast bike rotors cool to ambient. Soon enough for a MAMIL between corners. If you're heavy and drag your brakes YMMV.

[@DrFlashburn]

Bigger is better. Just go back to rim brakes and your rotor is the size of your wheel.

[@davegonzalez7906]

As usual, well said Alex! Great video and summary about stopping better and riding safer! Wider tires, yes! Then check/optimize the tire pressure.

[@gcntech]

thank you Dave!

[@kidShibuya]

Ok but given that I can barely reach the levers from the hoods a large disc rotor did help me get more out of the slight pressure I am able to apply the top very top of the lever.

[@ariffau]

GCN has been pumping great informative videos ever since going independent. It feels like Jon Cannings is presenting again. Thank you!

[@JonCannings]

Hello! Glad you are loving what we are doing!

[@andrewzach1921]

Thanks for the video

[@BroccoliLand]

When it comes to v brakes or mech disc brakes, it's important to apply pressure at the end of your brake levers for smoother brake pad pull. Most make mistake by applying pressure at the middle of the levers, which requires harder force.

[@joystation1]

When you are braking on a loose surface it's best to start with a mid-lever pull as you are less likely to skid / lose grip should you apply more braking force than the loose surface can cope with.

[@BroccoliLand]

@@joystation1 My point is that applying pull at the end of the lever gives you more precision, control and less strength. It's literally mechanics 101. The brake lever is like a scissor. The shorter the length, the harder the pull. If you want less braking, just apply lighter pressure at the lever end. At the end of the day, all you're doing is just pulling the brake wires & triggering the brake calipers.

[@ghostwriter9266]

So your title should say, Bigger brake don't give more braking power, but help/assist bike control

[@terrymorse]

One minor clarification. The contact patch area of a bike tire is merely a function of tire pressure and rider+bike weight, so similarly constructed wide and narrow tires *at the same pressure* will have the same contact patch area. However, the wider tire will have a shorter and wider contact patch, while the narrow tire will have a longer and narrower contact patch. The wider contact patch can reduce the risk of skipping in a turn, but for braking hard in a straight line, I don't think there's much of a performance difference.

[@ChrisCapoccia]

It depends a lot on where you ride. I don't have any long windy alpine descents near me and don't feel like I need more powerful brakes. Last year the biggest braking incident was when a car turned right in front of me. I was actually surprised how quick I stopped and avoided hitting the car even though a foot somehow popped out of a pedal. Another nearby driver was also surprised I didn't need a witness about who was at fault for a crash because I hadn't actually crashed.

[@nathanielpowys8689]

grip isn't always the limiting factor when braking. If you are braking in a straight line and it is dry you will just do a stoppie. If you are braking in the wet (low grip) or leaning the bike over while braking, you are grip limited and then grippier tyres will make you stop faster. If you watch motogp riders, they never crash while braking in a straight (unless its wet and they are grip limited) because they just stoppie but you always see them crash mid corner where they are grip limited. if you want to reduce stopping distance in a straight line the best thing you can do shift your weight back to prevent a stoppie.

[@martinhusfeldt9583]

Bringing your mass center back behind the saddle will help you stop faster. The rest is up to a decent grip to the lever. Good tyres and possible some new brakepads can also help..

[@kai_v_k]

I think there is an important part not put enough emphasis upon: rider weight. The grip of the tyre increases with weight, the braking force of disc brakes does not. So a 100kg rider needs a 50% larger rotor than a sub 70kg rider. That's why I will settle for a 180mm setup with 4 pistons. I used to love in a hilly area where I even had 203mm in front though with a two piston setup.

[@neilshannon9930]

Being a bigger fella I tried 203mm rotors on the road bike and found they’d vibrate the fork under braking. They go out of true a bit more often as well.

[@凸Bebo凸]

At 100kg it's almost impossible to hold 40 km/h on a bike. You should just ride steel bikes, all modern bike tech is useless if you are fat, and dangerous as well because it will snap on you.

[@niallmanchester]

@@凸Bebo凸sweeping statement. I’m 107kgs and ride carbon bikes (road, gravel, XC, trail): especially my gravel bike, on sometimes rocky trails, carbon rims included. Ride 3-4 times a week. Never damaged a frame nor rims, no more problems with punctures (tubeless) than the next person. True enough about holding 40kph on the road: no, can’t do it. We can debate whether carbon is needed over alu or steel, but steel is not necessary.

[@凸Bebo凸]

@@niallmanchester If you can't go fast you aren't getting the benefit of carbon, sorry bro. Also the bike shop and other riders laugh at fat guys on carbon. Good luck making better choices in the future.

[@niallmanchester]

@@凸Bebo凸 I can lose weight. You're stuck with that pitiful personality.

[@niallmanchester]

@@凸Bebo凸 I can tell the difference between an 8 kilo road bike and an 11 kilo one and I’m happy with my choices. Thanks for the good wishes, all the same. Hope you get better, too. Personality-wise.

[@tonysadler5290]

Too large a rota can cause your front wheel to lock up due to the increased leaverage on the wheel. Now, I can only speak as a mountain bike rider. Once I set my psi, and favoured tyre combination I found that by decreasing my rota from 220mm sram to a 203mm shimano ice tech set up with 4 pot slx caliper up front gave me the most beneficial results and controlability/feel. On the heavier e bike it's 203mm ice tech rotas with 4 pot calipers front and rear. Whereas on the non e bike trail bike its 203mm ice tech rota and 4 pot caliper up front, but a 180mm rota ice tech and 2 pot caliper on the back. On the lighter hardtail, it's 180mm ice tech 2 pot rota front and 160mm ice tech rota 2 pot caliper on the back. The ice tech rotas dissipate heat better and aren't prone to warp or fade, thereby alowing me to use the smaller rotas and therefore, apply a breaking force without overwhelming the traction of the tyre. Brilliant video, thank you Alex.

[@SniperSnake50BMG]

First: I have done exactly that with my main; 203mm front 140mm rear. Abs second: is the same argument with tires with cars on tracks

[@b.griffin317]

Thank you for justifying my purchase of GravelKing SS 45's filled to -5psi from Silca's recs.

[@soumafan]

wait. so as long as i can generate enough braking force with my rim brakes to break tire traction to the road, i DON'T need to upgrade to discs? thanks, you've just saved me a ton!

[@rider65]

Such a silly illogical comment

[@nekekaminger]

As long as you can generate enough braking force with your rim brakes to break tire traction to the road, you can't improve your stopping power just by upgrading your brakes. However that says absolutely nothing about whether the stopping power you have is good enough for your needs. If you need more stopping power you may have to upgrade to discs because using wider tires may not be possible with rim brakes.

[@glenni249]

Yeah the main benefit of changing to discs is consistent performance in wet conditions where rim brakes tend to come on much slower because of water on the brake tracks, along with the ability to install wider tyres because you're not limited by the calipers.

[@soumafan]

@@glenni249 i'll give you that. in fact, i'll give you both of those and add one more: if i'm riding in the mountains i think i'd prefer discs so i don't have to worry about overheating my rims. i'm not saying there isn't a place for discs, just that for me & most of my riding on roads with only moderate hills, my 28s and rim brakes are fine. (and cheaper!)

[@glenni249]

@soumafan yeah my road and tri bike are both rim brake and they work fine and were nice and inexpensive picking them up second hand. In saying that, I'm limited to 26mm before I start risking the paintwork so with the roads around where I am, I'd definitely be getting discs if I had free choice.

[@trroland1248]

What I learned from this video: I would like that Orbea Orca lightweight to be my next bike. 🤔

[@darkounet3478]

The caveat though is that friction does not really depends on the surface of contact patch... Greater contact patch = less contact pressure = less grip by area = quite similar grip overall... Of course material and texture of the tire do make a much bigger différence.

[@Heon_X]

This video made me realize that having rim brakes has a much higher leverage, almost like using a 700c rotor 🤯 (of course there's also traction and modulation but still interesting)

[@rg807]

Please get someone from Brembo on so they can explain how brakes work. If you're braking in a straight line, on a dry road, because 80% of the braking is going to be on the front, and your body weight is being multiplied by the force of deceleration, it's going to be almost impossible to lock the front tire, thus the tire won't have much impact on braking performance. Brakes work by transferring energy (heat), so generally larger rotors and calipers do in fact brake better because they are able to transfer more energy.

[@saltyman37]

yes, but then you just go over the bars and that becomes you limiting factor. I can even do a stoppie/endo with my rim brakes

[@rg807]

@@saltyman37 That's my point.

[@fotmheki]

I agree with you, Alex, as always depends on the situation. In longer descent or with more weight larger rotors heat up less then smaller ones delaying the possibility of vitrification of brake pads, in this case you will have more braking power with larger disc rotors. On flat tyres is the most important factor

[@rider65]

No, there is not "More Braking Power" with larger rotors. Only an increase of heat absorption-disappation. Staving off fade a bit longer. You cannot increase brake forces by installing larger rotors.

[@raginganarchist]

Reaction speed also plays a large part in stopping distance. This tends to get slower as we age. I personally find video games very good training for reactions.

[@makantahi3731]

3:20 wrong, wrong,the maximum force when braking on the front wheel is when it lifts you onto the front wheel, so the front tire is loaded with the full weight of the bike and the rider and therefore the pressure must not be less than the maximum allowed

[@M3GRSD]

This is funny to me because I literally when in the opposite direction. I don't ride tyres wider than 25mm, and I purposely swapped the 160mm rotors for 140mm, front and back. It makes the bike look smart.

[@MichaelWilliams-iv6dj]

The need to practice braking skills is that about 70-100% of your stopping power in any situation comes from the front brake. Most people who are new to cycling aren’t going to be comfortable using the front brake that forcefully

[@makantahi3731]

summary, the video missed the point, if you want to be able to stop as quickly as possible, practice braking so that you don't fly over the steering wheel, but that you are lifted onto the front wheel, everything else is a marginal gain

[@ANDREJSIJKA]

Sure It is Logic, we use bigger discs to avoid overheating during long downhills..

[@steven-bc7ts]

I wanted larger disc rotors because they look better. Had to settle for 180mm though.

[@Cloud-zq8mf]

Bigger rotor diameter means a lot for steep n long descent

[@saltyman37]

yes, we all know but that wasn't the point, nor was it about hand force/fatigue. It was about breaking distance in one single emergency stop.

[@humpy125]

Bigger rotors and 4 piston calipers are about feel and modulation

[@gcntech]

There is some amazing debate in the comments!

[@matt_acton-varian]

A lot of people I see missing tthe point. The video does not dispute that bigger rotors are better at modulation, heat dissipation and overall power, but that there is a reason that road bike disc rotors are 140/160mm and not 220mm like on DH MTBs. Hydro disc brakes are in many cases more powerful than the the maximum threshold of grip and traction force exerted on the tyres. By increasing that threshold, you can look to eek more power from your brakes without locking up. Skidding on your tyres will increase stopping distance and shorten their lifespan.

[@danalbert5785]

Really good information! One condition I have not seen addressed is . . . I can't seem to find the "direction of rotation " arrow until after I have installed the tire! Statistically I should get it right 50% of the time but I seem to get it wrong 80% of the time. I am way too lazy to then uninstall and re-install the tire.! So, what are the risks? Riding with my direction of rotation arrow in the wrong direction does what exactly? Is my life in danger?

[@saltyman37]

tread on road bike tires has no effect, deeper tread on touring/MTB tires is directional and getting it wrong can decrease grip in certain conditions

[@jakethesnake1976]

Ultimately, tyre grip is the limiting factor, but I don't think the benefit of increased lever modulation that bigger discs give you should be overlooked. Much easier to control 50% lever pull of a well setup disc bike rather than having to grab all you can on a rim brake 😬

[@meibing4912]

Have been saying for years that too many people are using too large rotors - for no good reason at all. If you are not racing down an Alpine Mountain weighing 100 kg you can get along with small rotors. And save some weight.

[@Cycle.every.day.]

Gcn going berserk with tyre videos in the last month...oh,wait pirelli is a sponsor.

[@gcntech]

Hi, thanks for the comment. Pirelli are a partner of ours, regardless of this - there is so much talk right now of tyre width and pressures. And still the debate of disc brakes goes on too. We hope that you enjoy the content. Thanks 👍

[@matt_acton-varian]

So are Shimano. Dura-Ace rotors and pads can cost as much if not more than a set of performance tyres. You are going to see product placement when a channel is given said product in order to make videos. I don't actually recall this video making any specific claim as to a model of tyre from Pirelli being better than its competitors in any context. It is not a perfect system but it is the way the world works, and GCN have always tried to keep as neutral as possible when discussing products either from sponsors or their rivals. Not all sponsored channels (of any genre) will talk about a subject that covers generic information and still be fair to the wider industry. By saying "we are sponsored by X to make this video but the science and information applies to any brand" you are still given the ability to make your own choices as to what you buy and where from. It merely states that even if you are loyal to a different brrand you can be confident the information given will still be relevant. No gimmicks, no crass claims, no misinformation. As a Brit I am often uneasy particularly with the way American based social media creators force advertisements on its consumers in tacky and cringeworthy ways, but product sponsorships are a necessary evil of the industry. I would much prefer the diplomatic approach as made by GCN than other influencer groups flogging snake oil for likes.

[@jthomas4859]

There was no mention of how the front tire does essentially all the braking at the limit. The rear is almost lifting off the surface, and will skid instantly if it's braked too hard. "fishtailing".

[@loeurnchim213]

Yasssssss super Nice ❤

[@SY-ve5qm]

Kinda related to the tire topic, is there reason why you guys donot use the black cap for the valve?

[@gcntech]

this is a really great point. Some of us feel there is no need for it, and they create extra aerodynamic drag, whereas others use them as they can help prevent the valve core getting clogged up with debris!

[@stevenjoyce421]

Is 2025 another year of GCNs obsession with wide tyres!

[@gcntech]

maybe, maybe not. Make sure you subscribe to find out!

[@stevenjoyce421]

@ well said. I’ll keep watching

[@Thezuule1]

The same argument applies to rim brakes. If you can pull your brakes and completely lock the wheel, the weak point in the system isn't the brakes it's the tires.

[@RedWingsninetyone]

Aren't larger rotors simply about heat dissipation for better braking performance under harder loads? Thus the reason MTBs can have 200mm and larger.

[@tecbarrett8331]

I have installed a 160-180mm flat adapter for my front brake and it seems to be working okay

[@gcntech]

hi, if it works for you, that's all good!

[@MTBScotland]

yeah they will

[@7mpowerd]

Like cars and motorcycles. If your brakes can lock up the wheel, then you don’t need any more breaking power. You need more traction. bigger brakes are more efficient and can handle heat and abuse.

[@makantahi3731]

you almost guessed it, the adhesion of the tire to the surface is not a problem, but when you fly over the steering wheel, have you ever had a tire on the front wheel of a motorcycle that would slip when braking in a straight line on dry and clean asphalt, you didn't, unless you put a wooden wheel

[@7mpowerd]

@ yeah you’re entirely wrong there. As someone who used to teach an MSF class, we literally have a training aid showing what happens when you lock up the front wheel. Literally a video of a closed course with an experience rider, locking up the wheel to show a front skid and how to recover from it. A non-ABS motorcycles, even single disc set ups can lock up the front wheel with improper breaking.

[@makantahi3731]

@ your whole story is abstract. all racing motobikes are short and not designed for maximum braking which could cause the front wheel to slide under proper braking, same with bikes, both should have a very long front fork to prevent lifting over the front wheel. point to a yt video where a production motorcycle has a shorter stopping distance than the best car and is at least 5 times lighter. if a wheel on your motorcycle slips due to braking, it means that you are braking in a corner or the surface is contaminated, and that is not the topic of this video and cannot be solved, I can brake with maximum force on any bike, to get on the front wheel which is still spinning and if I press the brake harder, I will fly over the steering wheel, so I didn't need abs

[@7mpowerd]

@ your whole response seems like one who has never ridden a motorcycle or taught classes on one. Sticky tires and powerful brakes can induce an over bar crash. However on a road going bike or motorbike. Many times the brake overcome available traction and skid. This you let go and reapply proper pressure.

[@7mpowerd]

@ in a perfect world yes modern performance tires will be able to best the braking force. Where you lift the rear. In the real world many times you’ll skid before you over bar it. If you’re braking with any sort of sense. You never grab a handful of brake. You apply appropriate controlled force

[@mathewjames4137]

Is it this simple? I think the tyre pressure charts optimise rolling resistance rather than braking force. From a physics standpoint it's coefficient of friction and the downward force that affect stopping force, a smaller contact point has a greater downward force per square mm so as long as we don't reach the limits of the tyre material to grip the road, pressure shouldn't affect braking. For example F1 uses wider tyres because of the limits of the materials used and tyre temperature management. In theory an F1 super tyre material that wasn't affected by higher temperatures would be better as a narrower tyre may have aerodynamic gains. In addition a smaller contact patch for a car is less likely to aquaplane in the wet not something a mere mortal like me is going to worry about on a bike. All that taken into account I am still happy with my move to wider tyres and lower pressure. It's more comfortable and has a noticeably lower rolling resistance with little to no noticeable impact on braking. Please note everything changes at the limit of performance where the pros ride. I have no idea how pressure and tyre size impact where the limits are.

[@adamsandler4076]

I would recommend using 140mm rotors front and rear on a road bike. It is better to have control and know the limits of your tyres rather then having too powerfull brakes and locking the brakes. I feel terrified just thinking about 180mm rotors with hydrolic brakes on an Alpine descend...

[@bike-doctor.france]

It could be perfect to show this during a test; Just try to compare a 2 piston caliper with 140mm disk versus 4 piston Hope RX4+ caliper with 160 floating disk, and long term review with the two type of components. My clients have already choose ...

[@rangersmith4652]

Effective braking is best achieved by riding at speeds that reflect conditions and rider skill. Assuming whatever braking system one has is working properly, the actual equipment is probably the least important factor.

[@JamesSmith-qs4hx]

In 40+ years of cycling I've never had an issue with stopping on a bike - Save your money peeps.

[@凸Bebo凸]

lol, people acting like you can't modulate to near wheel lockup with 9 dollar Dura Ace pads and rim brakes will never cease to be hilarious. They don't understand once the wheel locks up that's it, you've braked too hard, and that any brake can do this.

[@MrJhockley]

Bigger Brakes less fade, easier to feather.

[@danc1829]

As my rim brakes can lock the wheels wet or dry this is why changing to disc has always been pointless imo. I can also fit 30mm tyres on my road bike no need to go any wider

[@julianwing7813]

I used to have a rim brake aeroad then swapped for disc brake version I am on the light side but carbon wheels on rim brakes are dreadful just about get away with it in the dry but in wet not good.stuck with rim brake for 7 years thinking as they are lighter they are faster but disc beats rim on every test much faster as well

[@meanredspider]

A stick in the spokes will lock your tyres - why don’t you use that….?

[@gcntech]

@@meanredspidersounds a bit dodgy

[@meanredspider]

@@gcntech - 100%. I bought the Volagi Liscio when it was first available directly from Volagi in the US (I’m in the UK). For those that don’t know, the Liscio was probably the very first commercial disc road bike. I spent a very long time trying (at least) to explain to rim brake evangelists the benefits of discs over rims. The “I can lock my wheels” with rim brake argument I’ve heard hundreds of times. My response is that you can lock your brakes with a stick. It’s a fatuous argument. You make a great point that braking is all about how you apply the brakes and that, for me, is what discs do so well and so consistently in such a wide range of conditions.

[@einundsiebenziger5488]

30 mm is too wide already.

[@hallisoft1926]

Saying more contact patch gives more grip is too simplistic. Whether braking or riding there is a certain amount of force applied to the contact patch of the tyre. Increasing the contact patch does not affect friction. Friction is a result of force (mass, gravity), and the coefficient of friction between road and tyre. As the contact patch area increases the total force remains constant, but the force per area (lb/in2, N/m2) decreases. Reducing pressure and increasing the contact patch is beneficial in so much as the tyre is better able to follow the road surface imperfections and is more likely to find 'grip'. However, doubling the contact patch would not ,for example, come close to halving your stopping distance.

[@abdelmajidhassane9979]

Regardless of benefits shown by the better dissipation of heat granted in big brake rotors, the braking torque is bigger and proportional to disc radius.

[@michaelnewman4302]

Alex explains what increases grip but never mentions why grip matters. Skidding. Until your tire breaks loose from the road surface and starts to skid, grip is irrelevant. Up to that point, it's 100% about reducing the rotational speed of the wheel. As others have mentioned, brake setup, rotor size, piston count, and pad material can all affect the efficacy of the braking system. Concentrating on tires is meaningless in terms decreasing stopping distance unless the increased stopping distance is due to locking up the wheels.

[@camonin]

Interesting execution on filling up the monthly P Zero marketing quote. Increasing tire contact patch is relatively meaningless - somehow cars tend to stop with a relatively small contact patch compared to car's mass. You could call GMBN to provide solutions based on actual physics - increasing brake rotor size provides ample benefits, as the leverage increases quite considerably 140 -> 160 and 160 -> 180mm.

[@theantichrome9842]

But Alfonso, you guys have done videos in the past comparing panic stops with different rotor sizes and the larger rotors always stopped shorter.

[@凸Bebo凸]

lol, people acting like you can't modulate to near wheel lockup with 9 dollar Dura Ace pads and rim brakes with a tiny amount of hand power will never cease to be hilarious. They don't understand once the wheel locks up that's it, you've braked too hard, and that any brake can do this. Bring on the 300mm pizza cutters though, I need bigger laughs. Make sure they only come in center-lock and cost 119 dollars each.

[@saltyman37]

if your in the drop, sure. but from the hoods that takes a lot of hand force

[@凸Bebo凸]

@@saltyman37 Bullhorn bars with brifter bar ends exist, regular tri brake levers, etc. You can get a small brake lever with a ton of leverage in an aero position.

[@凸Bebo凸]

@@saltyman37 You can get a little tiny Paul V-Brake and stop instantly, there are a lot of options.

[@TowZatya]

I use 3,5 bar and calculator says i should use 2,5 bar. But i work with my bike and my city is so hilly, so i need this less amount of friction between bike and road. I dont have problem with braking except that i sometime heat up my brakes to much and like last time i ride a bike it was rainy day and my rotor got so hot that there was awful amount of water vapor coming from it. Ofc when there is snow etc. i lower my pressure drastically, but i quite a few times ride on literall ice on 3,5 bar and it was quite fun

[@RussellVossen]

Anyone else think they took inspiration from Driving 4 Answers?

[@wojciechopyrcha9116]

On MTB we dont have this problem. All roadies riding on MTB are shocked or atleast surprised how much grip we have, especially offroad.

[@PhilR-b8]

More nerdy bike tech Alex. Short sweet and digestible

[@gcntech]

Your wish is our command! We'll do more dives into the nerdy world!

[@ingomaa3454]

But on a long descent, the size of the disc makes a huge difference

[@reoencarcelado5904]

@“Why big-brakes won’t stop you faster, but wider-tyres will”: Wider-tyres will because of bigger friction (ie. bigger rolling-resistance). It’s simple[/simply] Physics.

[@martinmorsch7507]

Bigger rotors do slow you down better. There are two things going on: A „limit“ of force that the tyre contact patch can relay to the ground, and your ability to precicely apply this force. If your rotors are smaller, you need more break pressure, ultimatley you need to press more and I am sure, that your resulting breaking force will be: Inconsistent, too weak or too strong. This will cause: Wheels locking up, losing grip or simply not breaking enough. Because youre probably really scared of your back wheel breaking out or you going over the bars, youll break less-just to be safe. For this reason only, I am certain a bigger rotor is an advantage. I have been riding Hydraulic discbreaks for more than a decade now, as I used to be a mountainbiker first. This is the reason caliper breaks are worse at breaking. Theyre too inconsistent, causing you to be unable to ever break „at capacity break force“. Out of safety (im talking dry, ideal conditions ofcourse)

[@nlfiets]

Grip and the size of the contact patch area are not related (offroad tires with profile then it is different). Anyone who ever seen the formula of grip will understand that.

[@GK-zr9cq]

@nlfiets correct! It seems that equating wider tyres with more grip is a common misconception. Coefficient of static friction is the ratio of the force parallel to the tyre and road needed to break them apart and the normal force pressing those surfaces together. The friction equation tells us that given a certain coefficient of friction, the maximum lateral force the tyre will withstand before it loses grip is proportional to the force pressing the tyre to the ground. There is nothing in that formula about patch area or shape. Cornering grip is also independent of rider weight, as while a heavier rider pushes the tyre down with more force than a light rider, his weight will also exert a stronger pull to the side (ie weight cancels itself out). So it all boils down the the rubber compound and the surface you're cornering on (wet or dry tarmac, gravel, oil, mud, sand, manhole covers etc.) A couple of caveats ... high pressures may induce the tyre to leave the road due to bounce, whereupon the coefficient of friction becomes zero, so wider tyres at lower pressures would help. Also wider tyres with knobs provide mechanical grip, which is different to the static friction described above.

[@SergioCristancho]

Change the diameter of your rotor discs... Will do one more nightmare for your maintenance or your mechanic when you service... Because the position of the calipers will change that will require some extra parts adapters and that is more weight and Screwfix in the most vulnerable area... Your forks are designed for one specific rotor diameter and add more than that add extra torsion not to get worried but uncomfortable with time and time on your handling. Why do I know this and more... 😅 Silly me had to prove and see for myself what if... And take notes.

[@ANTPS32CREWCHIEF]

The only time you need to stop in a race is at the finish. 😮

[@gcntech]

Or if there is a big crash in front of you 😢

[@contempt137]

You are correct that larger brake rotors will not increase brake performance. You completely failed to explain why they don’t. It’s the calipers that can increase braking performance. Calipers squeeze, rotors get squeezed. It’s mechanical leverage driven by hydraulic pressure. My explanation is grossly simplified, but true none the less. Decent tire advertising though. 😊

[@JonPaul]

Personally I like the dark orange bicycle. Brown is a tricky color, more a matter of perception than anything> kzbin.info/www/bejne/rZmXkoqQh9mHrbc EDIT: It occurs to me that the smarty pants scientist you have, who keeps complaining about the brown would know that it's not really a color but rather our brains glitching on a lack of information.

[@neilmdon]

yellow is important

[@jameslee-pevenhull5087]

Please check the physics. You might be incorrect. A larger brake rotor offers the opportunity for a wider brake track. Braking effectiveness follows Square cm of contact area. If the brake pads are the same size, the advantage is then heat dissipation. Go to the automobile race world and tell them a wider brake rotor has no advantage. Ha Ha Ha. When a large amount of braking is in the circuit, a narrow tyre will concentrate the weight of the car onto a smaller area, giving better downforce to avoid skidding. This vid is an advert for Pirelli tyres. The info about brakes, and in some way, tyre width, is dubious.

[@christianwirth6965]

Oh so Ollie visited Pirelli? He never mentioned that before!

[@gcntech]

He also did Tour des Stations... He doesn't mention it much

[@coonepaul]

I respectfully disagree. As a mountain biker who also rides gravel, I don’t think I’m speaking out of turn by saying this issue has been explored to the nth degree in the mtb tech world and I think you’ll find that the overwhelming result is bigger rotors result in more braking force and thus quicker stopping thus more powerful breaking ability. And the tyre traction idea is null and void considering mtb surfaces are anything but solid and consistent. Yes, tyres make a difference, but do a stop test on an XC hardtail with racy tyres with 140mm rotors and 203mm rotors and tell me which one stops you quicker????

[@_Tp___]

work done = force x perpendicular distance, can't argue with physics.

[@coonepaul]

@ so are you agreeing or disagreeing? Automotive world shows larger pads and discs = more stopping power. Mtb world shows larger discs = more stopping power. Not sure why road bikes would buck the trend, it’s consistent across other areas. This video should have been titled “wider tyres and better pressures can help with your braking control”

[@_Tp___]

@@coonepaul agreeing?

[@peterharrington8709]

Perhaps that would depend on the tested speed though? At say 15mph the 140 wouldn't be able to lock up a big MTB wheel, but at an admittedly pedestrian 10mph I'd guess that it would. Clearly in the first case the brakes are a limiting factor, but in the second they're not. However, if you did the test with a much lighter road wheel set, you might find that both types work equally well at 15 mph, and above that, the tyres are breaking traction anyway?

[@coonepaul]

@ there’s a good reason why you don’t see downhill mtb’s running 140mm rotors….at the same speed, same tyres, same rider etc etc a 203mm rotor will stop a bike over a much shorter distance than a smaller one, have more heat dissipation, more mechanical advantage, and if set up correctly will likely offer more modulation too, as there’s less force required at the level to achieve full braking power.

[@MogensRibert-k3z]

Nice Brown bike.

[@makantahi3731]

4:57 these grooves on the rubber are useless

[@savagepro9060]

GCN Tech: “Why Big Brakes Don't Stop You Faster, But Wider Tyres Will” Hmm🤔🤨 Sooo, rim brakes were not bad after all, right?”

[@feedbackzaloop]

Can't fit wide tyres through the caliper. Even cantis are limiting

[@JamesSmith-qs4hx]

Rim brakes are Based as Fcuk.

[@eda2000-r8h]

"always had been, bang"

[@nlfiets]

​@@feedbackzaloopLuckily the width of a tire has no impact on grip in a straight line. So always try to brake before a corner.

[@feedbackzaloop]

@ sorry, what? Not braking in the corner is just redistribution of available grip between lateral and axial components. True for any surface, tyre and brake variant. But if you think grip is abundant no matter the tyre, you never rode steep and rough enough roads.

[@Chris-jc3lr]

Captain Picard meme: Why the f do we need disc brakes then?

[@saltyman37]

wet weather, carbon rims, hand fatigue, absolute braking power from the hoods...

[@PrzemK]

You forgot rotational mas of wheels

[@donnydread7631]

I took the brakes off my bicycle. It turns out, all they did was slow me down. ;)