Could You Stop? Our Brakes Were Useless At This Angle

A lot of us don’t think twice about riding down a ramp or section of trail with a little bit of grade to it. But what if you had to come to a complete stop on it? Could you do it? We wanted to find out how hard it was to stop at what angle, so we built this ramp and did an experiment.
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[@dangalindo5304]

So one issue to consider is that as you increased the angle you also decreased the distance available to come to a stop. That is, you made it harder in two ways. I don’t think this would work, but a fairer approach would be to use the same length ramp each time and attach it to a scissor lift to increase the angle as opposed to cutting the ramp each time. As a side note when you cut the ramp, not only do you decrease the distance available to stop you also decrease the amount of time you have to stop.

[@michaell1026]

Those were my thoughts exactly. Should have read this before I posted.

[@ryanjackson5437]

Could also use a longer ramp with a line closer to the middle (for less steep angles like 25°) and cut ramp length from below the stop line, so that you always have the same distance of stop track but the ramp still gets shorter…just cut below the stop line

[@andreybatashov2183]

nah, they were coming in at such😮 a low speed that length of ramp does not really matter here, IMHO. If they could have stopped, they would.

[@weegaz22]

Yeah i kinda concur with this too, the bermpeak one also had a lip that put the bike itself at a steeper angle before the back tyre then bumped down onto it, the Grip tape on the bermpeak one also looked far more course than the previos setup.

[@esoteridactyl]

I mean this can all be calculated using physics/math anyway lol we did problems like this in high school physics

[@CNYKnifeNut]

I watch so many different genres on KZbin, but the angle cube inevitably shows up in all of them!

[@mads_ittmann1823]

Kevin talbot by any chance?

[@Leo-z6i6u]

I was about to say, Kevin Talbot bro 👍👍👍👍 🤘😎🤘

[@szymonzak6681]

happy to see so many ppl that have the same type of interests as me, was thinking of kev too😂

[@xtincsz]

My parents said if I hit 1k they'd buy me a professional camera begging you guys literally begging!

[@thelifeofjessejames]

Why wouldn’t you just use your iPhone? It’s accurate and you already have one. I’m sure an android phone would be able to do it too with an app

[@PhillipBicknell]

Wasn't expecting the full-on commitment of cutting the ramp shorter to make it steeper - great job!

[@austincheynet9380]

Engineering Student here, I did some calculations on what angle you should be able to reach based on some educated guesses on some factors like coefficient of friction and found a max angle of 41.19°. I feel like your test is fairly accurate depending on the conditions. Thank you Seth for always testing crazy ideas that many of us have had!

[@cantstandthecrap]

after 2 seconds in, I had to think about this. You are absolutely right. Lets watch the next vid, when they put glue on their tires to have a friction coefficient of >1.. bhahaha XD

[@MikeyAntonakakis]

Yup, coefficient of friction (assuming perfect execution of brakes/balance) is equal to the tangent of the max angle achieved.

[@carlosgaspar8447]

why not just under 45 degrees when the coefficient is 1?

[@zaydabbas1609]

@@carlosgaspar8447this is correct, he def didn’t use mu of 1. Bike tires are less grippy than car tires tho

[@gameonyolo1]

​@@zaydabbas1609really? Aren't they supposed to be softer?

[@alecfunes5645]

Hi Seth! Old viewer, 1st comment. IMHO, at your try at home, you were negatively affected by your starting angle. Please take note that you were entering the ramp from a step, and no matter how little it was, I think it added degrees and speed to your test. Have a nice one. Keep it rolling ❤

[@SeanQuinn4]

+1, makes me think of race cars getting unsettled by debris mid-turn when operating on the limit of traction.

[@MichielUrban]

Yeah I thought the same thing, just when your back wheel is coming over the edge the angle is steeper and as soon as you start sliding it's harder to stop.

[@literailly]

Yeah, the back tire contributed zero to the traction, and the angle was perhaps 2-3 degrees more severe. But that's hindsight with video playback ha. Great video!

[@SurrealNonsense]

This was one of the least sketchy 'sketchy' things you have done in the past few years and I would already be out after 35%.

[@RobertSeefeldt-y5m]

Head tube angle

[@xtincsz]

My parents said if I hit 1k they'd buy me a professional camera begging you guys literally begging!

[@MissileGuidance]

​@@xtincsz Subscribed

[@bazhunt8549]

that is bad out

[@prophetzarquon]

Also grip height & arm length: If you can shift yourself farther back, you can descend steeper stuff.

[@GumGum393]

Idk if this will get any likes since it's posted so late, butttt I wanna say it. I think me and many fans miss the berm peak trail builds, no pressure if that Era is over for you and you don't want to, but I promise that the fans will watch those to the end of time and we'd love to see them come back. Here's hoping we can get at least few more to test the waters on trail build videos ability to succeed now a days in the algorithm. All the best to Seth. I'll keep watching no matter what you make, but I'd love to see the berm peak trails grow if it's still works on the channel. If you agree and also hope for the trail builds to return drop a like so more can see

[@mattcullen8269]

It's been said many times now and I'm sure Seth knows the trail build vids are most popular. They haven't gone away altogether, but they are no doubt the most labour intensive videos to make. As a recent father I expect he has a lot on his plate. I for one am happy to stick around and look forward to the next trail build whenever that may be.

[@slyfox8953]

@@mattcullen8269stop blowing Seth lol

[@brendoggg_]

I miss when he used to make fun of scooter kids at the skatepark

[@mattcullen8269]

@@slyfox8953 stop being unempathetic lol x

[@slyfox8953]

@@mattcullen8269 1. That’s rude because I wasn’t and 2. You’re CLEARLY just a Seth fan boy who likes anything he does

[@skulpturlamm294]

Track stand on a ramp that is raised with a pully system until you loose tracktion might be an intresting test as well.

[@bigslonker]

yeah, that would be really interesting too, but it’s sort of a different test because you’d be testing the static friction between the tire and grip tape instead of kinetic friction when coming to a stop. since static friction is always higher than kinetic, you’d be able to hold on to a steeper angle than you’d be able to come to a stop on

[@bertkreft9689]

but it would help to find the tippingpoint

[@bigslonker]

@@bertkreft9689 yeah, for sure would, it’s just that it would be slightly steeper than what you could actually come to a stop on. still not a bad way to get a first data point though

[@Sythemn]

Since your failure point is sliding, the two important things are coefficient of friction on the tire / grip tape contact point and brake application on both front and rear to avoid locking either wheel before the other one since static friction (contact point not sliding) is higher than sliding friction.

[@prophetzarquon]

Yeah, & so far as the tire goes, a fat tire low density slick, _covered_ in tiny siping slits, should do best at this.

[@MrMartinSchou]

If you want to test this in an easier way, don't have a drop in but slowly raise the back end while you have a meter on the ramp. You stop raising the ramp when you start slipping, and you'll know the absolute limit. Another interesting test that could be done is just how steep a grade can you climb.

[@Dukhanstmichmal]

Friction is different from a moving or standing start isn't it? By not starting in movement you get "sticking" friction wich can be much much higher than moving friction.

[@CameronDev]

​@@Dukhanstmichmaluntil the wheel is locked and sliding, its all static friction.

[@MrMartinSchou]

@@Dukhanstmichmal I would think so, but that would give you the upper limit. E.g. if you can't stay in place at 45° when raised from 0°, you can't do it by slowing down either.

[@kennyoffhenny]

Good idea, but not sure how you’d stay balanced on the bike. Even if you stop on a flat or low incline surface I’m pretty sure you can only stay on the bike briefly at a full stop.

[@jwalkerXx]

I saw the thumbnail and I thought that's what they were gonna do😭

[@mattnelson5505]

Try using the same bike but put hookworms or thick slick tires on so you have as much grip as possible and lower the tire pressure. I feel like that should work better than the knobby tires with less contact point 10:59

[@gooniesneversaydie27]

1. Cool to see DH geo in effect (though everyone on every bike would be a better test, to remove skill as factor). 2. The importance of weighting front tire (between going otb or losing grip) was made so simple in this test. Weighting the tires appropriately is so important, and the fear is usually of going otb, so really cool to see the balance of the two. Simple, but great video.

[@Filthy_Rich_556]

A lot of youtubers struggle to come up with ideas to create original content. After all, how many mtb related ideas can there be? You do a great job of keeping your audience engaged. At least me....

[@hambernat6444]

10:25 I love that, "It's as just steep as it's flat" 😅

[@colby_rogers]

I recently got into mountain biking. This channel has been a great resource. Thank you for the amazing content

[@Bhdrizzymayne]

I like how Seth's explanation of what would happen when they reach the point is 'essentially we'll be fine cause we're not stupid'

[@spyder027]

That’s how most things are

[@levio1463]

same idea, but put the ramp on its side and ride lengthways, like you are riding an off camber trail. Then see what angle you can make it across at, just walking pace allowed so you cant cheat and just do it really fast. would be a good test for different kind of bikes and headtube angles, I bet it will take a lot of steering effort to keep the bike going straight on something slack vs steep.

[@jclouse1983]

Nice, for all those times I go for a ride with my inclinometer.

[@elongated_muskrat_is_my_name]

I have often considered logging accelerometer data on my bike. You could do it with a smartphone but might want a decent powerbank too. Especially if you are combining it with gps.

[@5gvaccinator343]

You should try this on a fatbike. More traction and a hard fork should do the trick.

[@shaquilleoatmeal2654]

A fatter tire would provide a larger contact patch which may influence the coefficient of friction due to the compound of the tire being better optimized for a certain load compared to the contact patch but it would be hard to say for sure. Physics would teach us that contact patch would not matter due to it not being a part of the formula for frictional force but it very well may influence grip. Sometimes in the real world there are more effects at play such as tire temperature. Rally cars use thinner tires in the snow for better grip. The effect of a thin tire on the snow is essentially the way way that sipes in a normal road tire prevent the car from hydroplaning. A thin tire digs into the snow and compresses it better allowing it to grip. This is similar to how the water goes into the sipes allowing the tire to contact the actual ground rather than just the water. A fatter tire on snow would float like a snowboard and not compress the snow and the car would be uncontrollable. Just like a tire hydroplaning. I would say the best way to increase grip for this experiment is to use a tire with a lower profile tread and a very very soft compound.

[@SuzukiKid400]

@@shaquilleoatmeal2654sipes allow the tire tread to have compliance, offering micro scale deformations to smoothen out localized accelerations as the tire goes over an inconsistent surface. Grooves in a tire are what channel water flow. Suspension combine with siping is key to providing good traction in low traction environments like on snow and ice. Siping also provides more biting edges to improve gription.

[@tyrellcobb4665]

Go the whole hog: A fat tire quadricycle. More contact points, more traction

[@Harambe_]

@@shaquilleoatmeal2654 That's true, but rubber also has other nonlinear components along with classical friction known as load sensitivity (the friction coefficient changes with load). Soft compound slick would be the best in this case because the surface is flat and grippy.

[@DjDolHaus86]

In this scenario we're looking purely at linear (forward/backwards) traction so we want the maximum amount of vertical load pushing the tyre down into the surface (fixed fork) and the minimum amount of air pressure necessary to stop the tyre ripping off the bead to allow the largest contact patch possible. Tyre choice would be a slick of the softest compound available mounted on the tallest front wheel and smallest rear wheel you can fit.

[@kelvinervin9344]

I love this channel. I grew up riding bikes around my town with all my friends, but now I have kids. And sadly, I don't have the time to ride at the moment, but I can ride vicariously through these videos.

[@DesertCookie]

2:15 Seth does the one thing ChatGPT is known to be terrible at: maths :D. Good to see that it at least got the simplest of calculations right.

[@jamesroscoe7555]

The funny part is it is totally unnecessary and inefficient to use a neural net to solve a problem that is easy to solve through linear programming. Ie using a calculator is better.

[@loscalzo11]

generic AI are not meant to be used to do math! Never trust them to do any kind of calculation task...

[@DavidsTravelWorld]

This setup could be a really cool testing tool for stuff like nosewheelies. Especially if the angle of the ramp was adjustable and not just cut shorter.

[@jeremiahjohnson05]

Seems like you found a fun way to show the friction angle. tan(theta) = mu sub s. The coefficient of friction for a static case (rolling without slip) is catalogued for different materials. Between rubber and dry clean concrete is (mu sub s = 0.9) Solving for theta … tan^-1(0.9) = 41.987 degrees. If the rubber is grippier or the grip paper is more bumpy maybe you could go a bit steeper. The fancy fork might do a better job of keeping deceleration impulse forces lower to keep slip from happening (ie keeping the no-slip condition true so that static coefficient can be used) Nerd out.

[@TheEulerID]

That's what I came up with posted elsewhere. The coefficient of friction is the defining limit. Basically the maximum theoretic angle is the arctan of the coefficient of friction. This is assuming you don't go over the handlebars of course. That's a different issue.

[@ShadowlordDio]

How you add the weight to that equation? Same rubber with a weight on it would increase its grip a lot. Because it gets squashed to the surface.

[@TheEulerID]

@@ShadowlordDio The weight simply cancels out top and bottom when you analyse the forces. The force down the ramp varies linearly with weight, as does the force normal to the ramp. The result is you get the same limit for a given coefficient of static friction whatever the weight. Thus you double the weight, you double the friction force but you also double to force down the ramp.

[@jrhedman8251]

Highly recommend Engineering Explained’s video from 4 years ago on the G-wagon climbing 100% grade as it talks about the math involved for this. I think another thing is your breaking distance is shrinking as you perform the steeper tests. It might not seem like much but breaking downhill, you’ll need a lot higher friction for your tires in relation to your speed. Really cool test!

[@yoda112358]

Honestly if you could get a 29" slick tire with a really soft compound that might be the trick. Just get maximum surface area on that relatively smooth surface. (or try with a fat bike)

[@Riley880]

but that requires to much effort for a video.

[@flyfishsodak]

Fat bike would be interesting...

[@prophetzarquon]

Exactly this; a fatty mullet with high bars, to maximize front contact area while allowing the rider to shift their weight as far back as possible, running low density soft compound slicks with a _ton_ of tiny siping slits all over them. (Also, it helps to have long arms because you can lean farther back.)

[@miloontheready7814]

I am most impressed that you were able to maintain control going down the ramp, and not falling over at the low speed.

[@repapeti98]

Man, Seth's Revel Ranger looks so good!

[@JohnnyDoeDoeDoe]

You could try and measure the coefficient of friction -- the fact that you topped out at around 45 deg points to a coefficient of around 1. Only road racing rubber for cars and motorcycles goes above a coefficient of 1. You can measure it in your garage with a bit of the rubber placed under a block of wood on an adjustable ramp -- tilt the ramp until the rubber slips and you have your max angle, x. The taninv(x) of this angle is your coefficient of friction. You could also try throwing your bodyweight even farther back, e.g. on a bmx bike, but that's unlikely to change the results much at all. Just my 2 cents as a middling physics student.

[@Fishpizza1212]

The coefficient of friction can't really be above 1. Instead you add additional fundamental forces, like electro-magnetism, chemical bonding, or pure mechanical connections like hooks and loops on Velcro. Drag racing rubber tires have a sticky chemical coating that creates an adhesive chemical bond with the road. Joe never "stopped" on the 46 degree ramp, instead he transferred his forward momentum into rotational momentum about his front tire.

[@Shadow9OO]

Hi Seth! I looked into the subject of tire grip some time ago and found out something interesting: Three things are necessary for maximum grip: 1. soft tire compound 2. large contact area 3. fitting threat pattern The coefficient of friction depends on how well the rubber can interlock with the ground. Softer rubber compounds can adapt better to the roughness of the ground and therefore offer more potential for grip. But to use this potential you need sufficient contact area, otherwise you only shed the rubber of the tires. Last, you need a fitting threat pattern. The harder and smoother the ground, the smoother tire tread is needed.

[@xtincsz]

My parents said if I hit 1k they'd buy me a professional camera begging you guys literally begging!

[@Shadow9OO]

@@xtincsz As much as I like to support aspiring youtubers, I can't approve of your approach here. To be successful on YT, good content is crucial, not begging for Likes or Subs. Especially if it is an unrelated response to a video, that has nothing to do with Fortnite!

[@nekekaminger]

No matter what you do, the coefficient of friction will not go above 1.0, which means 45 degrees is the theoretic maximum. Only way to get beyond that is to use tires that don't need to rely on friction, i.e. use tires with spikes or something like that.

[@speedstyle.]

@@nekekaminger That's not true, the coefficient of friction is unbounded. Rubber on rubber is over 1, they've created artificial surfaces that reach over 5. Friction is just the intermeshing of microscopic surface imperfections, even velcro or gear teeth arguably exhibit 'friction' with very high coefficients.

[@nekekaminger]

@@speedstyle. interesting, back in school I was taught that it can't go above 1.0 but looks like material science has evolved since then^^ Anyway, I think it's unlikely you will encounter surfaces on which bike tires have a coefficient of friction > 1.0 in any situation that resembles real world mountain biking conditions in any way.

[@MichaelRei99]

It is crazy how something so simple and meaningless is so entertaining! I was glued to my seat!

[@Fishpizza1212]

Mechanical Engineer here: 45 degrees is the limit for stopping with friction alone. It's fundamental to mechanics and gravity, as the reaction force coming from the ramp will always be more forward than up. The force of friction from the brakes and tires can only equal the vertical part of the reaction force. So when Joe "stopped" on the 46 degree slope, he didn't stop at all. What happened was that Joe locked up his front brake and tire, then all forward momentum was transformed into rotational momentum, hence his back wheel came up. Had he not let go, his entire bike and body would roll completely over the front tire. The only way to stop on a 46 degree slope or more is to add an additional force, such as magnets, chemical adhesives, or a pure mechanical connection like the hooks and loops in Velcro.

[@Gruwg2024]

Engineers and engineering students look for a chance to say “engineer here” or “engineering student here”. Is it a confidence?

[@roachwerks3043]

@@Gruwg2024they just want you to know they are about to drop some nerd knowledge I’m a civil engineer lol

[@Karpaahh_]

Cool video! I could not ride down that angle I think. For my automotive Engineering background I remember that a 45deg angle is the theoretical maximum angle you can ride up or down. This had everything to do with the tire compound. If the friction coëfficiënt of the tire is 1, then you have equal the force that lets you stay on that angle as the force that pulls you down from that angle. This is due to the gravitational force decomposition.

[@randomc1949]

yeah 45 is the max if you're looking at static friction with 2 smooth rigid bodies. rubber and grip tape bring in adhesion and tearing that will get you a bit more but it's not going to be much I wouldn't think. as others have said going with soft compound slicks would be an option to increase contact patch and therefore that adhesion.

[@Durwood71]

I wouldn't have a problem riding down that, but I would have a problem with trying to come to a complete stop in the middle!

[@awkragt]

Getting past a friction coefficient of 1 is probably difficult. I wonder if hot sticky Moab rock is better?

[@MikeyAntonakakis]

@@awkragt not difficult to get to much higher than 1. Racing slicks can be 1.5-2 when heated up. But mountain bike tires have a lot of factors to balance (wear, puncture resistance/durability, knobbies, etc).

[@Fishpizza1212]

@@MikeyAntonakakis Drag racing tires DO NOT have a coefficient of friction above 1. They instead introduce a new force in the form of chemical bonding through adhesives. The tire compound melts and turns into a chemical adhesive, which is an additional force beyond rigid body friction.

[@ryanhooper4660]

I learned I need to dial in my front brakes better... amazing skill there!

[@prophetzarquon]

I have hated a bike that was otherwise identical to one I loved, except for soft brakes. In fact, I have one I'm not riding right now, because it needs better brakes.

[@MikeyAntonakakis]

This is a very good test of coefficient of friction of the tires involved. Friction coefficient = 1 if tire slip happens at 45deg (since tangent of 45 is 1).

[@Uncle_pepsi]

Steepest trail in my area has a short section of around 50 degrees. Was only able to brake down to a certain speed no matter how much I pull the brakes

[@brandonthurmond]

I really wondered if this one would be worth watching. You have done this video so well. I couldn't stop watching. Great job as always making interesting and new content. This sounds like something fun to do with the crew

[@davepapineau]

It's also interesting to think about these angles in terms of skiing for those who also ski in the winter. For perspective a 30° slope is about what a black diamond ski run is at most ski resorts. A lot of double blacks are 35-40° with maybe a handful of the steepest runs tipping > 45°. 30° is also the slope angle where it's steep enough for a slope to avalanche.

[@colophon2377]

For reference the steepest pisted run in the Alps is Harakiri in Mayrhofen at 78%, which is only 38 degrees. 45 degrees would be seriously steep, I think only the top lips of a few bowls would exceed that.

[@happy_run]

@@colophon2377 NA there are more > 45 degree runs

[@truefoxtrot2884]

you could try with a reverse(? mullet (bigger front wheel, smaller rear) it woud mitigate the OTB risk a little , however, a smaller wheel has less surface area in contact with the ground (if everything else is equal) than a rear wheel, fat tyres would be pretty beneficial, and just in case you could put a couple mats at the side of the ramp ;) hoping for the next video, cheers!

[@cordite7207]

Im guessing that head angle helps too, having the wheel further ahead of your centre of gravity will drop it too

[@prophetzarquon]

Also grip height, & arm length: The farther back you can shift your weight, the steeper you can descend.

[@TheEulerID]

The only thing that matters in this test is the coefficient of friction and making sure both wheels are braked to their limit without skidding, which takes a bit of skill. That's assuming you don't go over the handlebars. As I and others have calculated, the maximum theoretical angle is simply the arctangent of the coefficient of friction.

[@Juicehucks]

This is my favorite type of Seth content!

[@audiofile8311]

oh boy! ChatGPT is NOT good at trigonometry

[@TheEulerID]

In general, it's absolutely lousy at mathematics in general. That's not surprising; ChatGPT doesn't actually use a mathematical model. It's answers are essentially a statistical analysis of the learning material it is fed.

[@thoscommando]

Everyone here seems to be talking about increasing the coefficient of friction, but I think it is interesting how this is so similar to aircraft and their bank angles. The required lift to maintain level flight in a turn increases in the same way. Really interesting video!

[@MICUTO]

How about you fixate your front wheel onto the ramp and test out at which angle you can hold your balance? Like at what point couldn't you shift your weight back enough anymore and go over the handlebars? Needs a soft landing tho.

[@sweatyRL]

this was the first vid I watched of Seth😂 now I watch him every day

[@kgenkov]

Try to find the critical angle for a block that has a bike tire stuck on it. The tan of that angle will give you the friction coefficient. Also, try to avoid skidding. The friction coefficient is lower when the two surfaces move against each other. Also, I think that tire pressure doesn't affect the result here too much if at all. Actually in this exact scenario my prediction is that higher pressure would yield better results for multi-compound tyres. The smaller patch will ensure that only the soft central part will be in contact while for lower pressures you also get friction from the side knobs which are made of a harder, less grippy material. That'll effectively reduce the friction coefficient of the tyre as a whole.

[@bermchasin]

that works in textbooks but in practice the friction coefficient will vary a little bit as different loads are applied and the tire deforms/complys.

[@owlclaw]

Pretty cool to see this done on a bike and not a block of wood like in school. Interestingly, the equation for sliding friction does not depend on surface area only compound and normal force, so a flatter tire just helps to grab more area averaging out inconsistencies; grabbing features like rocks is different. Also according to this equation the bike should not matter at all if you’re balanced like a unicycle on the front tire!

[@Policepigeon]

Its impressive that even the relatively small contact patch of a MTB can hold on at that steep an angle

[@peglor]

Not really - friction force is independent of contact area on dry clean surfaces. In wet conditions it is a lot more important because water is a very effective lubricant, so the hysteresis in the rubber is where almost all the grip comes from. It's why there's such a dramatic drop in traction in wet conditions.

[@alexanderauer637]

How to improve this to learn something ?? I think I learned tons by watching and a contraption like this should be part of every mtb skills school. Seeing how you can control grip and braking power with weight distribution depending on the slope is really helpful. I ride lots of techy steep stuff on loose terrain and front/back weight distribution and braking power vs. grip for steering is such an important skill. I always had the feeling that the technique (or your focus on how you brake and how far back you go) has to change a bit as it becomes steeper, and you have just made that 100% clear, intuitive and even quantifiable - awesome job !! Thanks Seth and greetings from across the pond ;-)

[@moriskehl5991]

Joe swerved a bit left and right so its less steep

[@davidbrown8888]

Thanks for asking! I had visions of a competition early in the video. You played with the basic concept via air pressure and tire compounds. The competition is to build a bike specifically to win a competition of increasing grades. Tread, compound, pressure, bar changes for altering CoG, suspension pressures, frame and anything else you can think of.

[@WorldwideHistoryProductions]

Would be interesting to see this test performed backwards, rolling down rear wheel first. Would be quite scary, but I feel like your weight disttibution would be even better.

[@andreasw5925]

I love how much effort was in this video :D Great drivers, good vibes video! Regards from Germany!

[@Matthew_709]

i mean even 10 degrees i still cant stop need new brakes i recon

[@Danielkarpenkoflight_]

Hey Seth this is Daniel Karpenko, i enjoyed the video can’t wait for the next ones coming 😊

[@manosadj]

man i miss old berm peak

[@herculesmclovin]

You asked what could you do that's useful.. firstly thanks for the video I enjoyed it (reminiscence of your older sbh videos) I think what would be useful is forgetting about adding slick tyres and all that, instead stick with what we are actually going to face on the trails.. what's the steepest 'safe angle' on a 3 metre rock face, then what about when it's raining too? What about loose rock/gravel instead of bedrock? What about going down loam, then with roots, then wet? It's fun seeing what's the most extreme angle possible by making modifications and changing tyres etc.. but *useful* would be what we are likely to encounter on the trail 👍🏽 also it's an opportunity to share the skillset for escaping these gradients when things go wrong/slip. Cheers Seth and Team 🙏

[@PSBeard]

Your test setup is somewhat flawed in the immediate transition from flat to angle is itself causing you to loose traction, if it was purely to find the maximum angle then smooth curved entry from flat to the angle would work better and allow the rider to find the balance point between tires and also not upset the bike with traction breaking bounce.

[@MarshallAcosta]

Your flaw is still not knowing lose and loose

[@HelloKittyFanMan]

Cool video, including our giant protractor, ha! Happy Father's Day!

[@johnsonjay60]

🤙

[@ironmaiden5658]

This was pretty interesting. Mastering angles like these on the trails are definitely something you can only learn by trial and error then knowing what you're capable of. Fall and get back up and do it again.

[@Jaqob_DHR]

HIIIII

[@billincolumbia]

Super fun experiment! Gotta get your tire pressure wayyyy down, like 8 psi. More rubber in contact with the surface. Take the saddle off the bike. Get your weight as far back as possible. Lock the back brakes, and then squeeze the fronts until you either stop or skid.

[@ykjockey]

Hi

[@andrewpeterson5882]

"There's something kinda sketchy about this but I can't put my finger on it" he says as he pedals his bike onto a steep ramp with a potential full-on faceplant waiting not 5 feet below xD Seth is the best.

[@techguydilan]

I think you did learn something valuable: Stopping angle depends on a variety of factors, some of which aren't reliably predictable.

Brings back memories of sitting on the bike rack flying down a Santa Cruz range paved mountain road. It was difficult to stop without going over the handlebars and was easier to just keep going.

[@corbinscott2143]

It’s important to remember that once you lose traction you aren’t gonna get it back since static friction is much greater than dynamic friction. That being said I think the approach is super important, it’s gotta be smooth so you never have to lose traction and then regain it before the line. In the set up at the end you were forced to let your tire go airborne as you dropped onto the slant. I think you should retry with a smooth entrance onto the ramp

[@debbiegrooman5800]

I both learned something and was entertained!. I swear next Boulder roll, I am NOT stopping! Thanks Seth! 😂

[@davidf.8497]

I won't be braking the same, down hills above 42° now :). Just love your videos. Keep up!

[@MissMtnLife]

What about comparing tire compounds across different brands? Like specialized T9 vs maxxis max grip? Or just showing the difference different tire types and compounds have with all other elements being control. You could do the same for general riding speed. So many riders don’t think twice about rubber compound, thread count, tread pattern... It would be cool to see how they all affect one’s riding.

[@rustii-h3x]

You know it’s a good day when Seth posts

[@andyk3643]

I'm thinking a less aggressive tread may help. Either way. I love these types of videos. It's fun, compared to the typical "how to" videos.

[@yuribr84]

Joe was not going straight, but on a diagonal. That reduces the effective angle and makes braking easier.

[@e36z32]

“Recklessly low” 😂 Fun video Seth!

[@dsp4392]

I think a lot of Joe's success comes down to brake modulation. Maybe he has better brakes, maybe he has better control, but looking at the video, he slows down a lot more progressively and does a lot to avoid locking his wheels. The whole time he seemed to get right under the stiction point. Kind of like manual ABS.

[@jacklougheed4561]

For boring testing: drag weighted sections of tires over grip tape with a fish scale to find compounds that are not going to tear away, but bite really well, and tread patterns that work well. Then try again and sag your suspension out on the bikes. With the rear end lower it will make it take much easier to use yourself to balance the bike.

[@57boomer44]

Proper kudos on that ramp construction my dude.

[@micha3777]

Thanks for the great video, it's an interesting experiment. I think the main reason why you couldn't stop on the later experiment was the lip of the porch onto the ramp. you had to fall a small distance with the back wheel, picking up too much speed in the process I wouldn't be surprised that it would comfortably make a difference of a few degrees. (the bump is quite visible on 9:21 soon after the statement "that bump down to the ramp does not help"). you could compare that to 7:14 where the back wheel very smoothly rolls over the edge, never leaving the ramp edge in the process, where in this case, the part of the breaking force was not possible due to the tearing of the tape, this could possibly have kept down the entrance speed even more.

[@Zeldon567]

Glue a piece of tire to the bottom of a heavy object with a low center of gravity. Put grip tape on a board or other flat object and attach an angle gauge to it. Slowly raise one end of the flat object until the heavy object with a piece of tire glued to the bottom of it loses traction. Then you have your answer for the theoretical limit at which you'd lose traction. For further experimentation, you could make the height of the center of mass for the heavy object adjustable and experiment from there.

[@athiftsabit1208]

This kind of experiment is what make bikes interesting

[@furleyforever]

Very cool experiment. When I finally learned how to efficiently brake on slippery descents was the day that my riding progressed exponentially.

[@mattyltd]

I would be very interested in seeing a sequel to this, but with different tires. My assumption is that with some very good soft compound, low pressure, and tires half worn, genuinely worn, not cut, it would be possible to go even steeper. For example addix purple or black chili. I remember riding black chili a few years ago and always always always having issues with otb, never slipped. And definitely don't do it on new tires, I find the finish layer to take away a lot of the grip.

[@jasonburgroff6893]

Love seeing @manglermixer we need another Pisgah Podcast

[@emilPlaysGames]

2 Things: Try a mullet with either a 27.5 or even a 26" Inch in the rear and a either a 29er or 27.5 er up front. go use some " slicker " Tires with shorter and or more studs like the Schwalbe Thunder Burt (Since Gravel Semi Slicks dont come in a great enough width for this kind of tests yet..)

[@scottconley8001]

This was such an entertaining video!!!!!! Loved it

[@trialshawaii]

An international pro trials rider using a trials specific bike on this ramp would definitely be the ultimate test. They're the masters of balance, braking and control.

[@brandonmtb3767]

You have invented a new personal best challenge. Now we all have to go see the sharpest angle we can stop on with our bikes

[@davidcroxton8306]

The bicycle tipping point is about when a vertical line from your belly button/center of mass is in front of the center of effort of the front tyre. Braking force swings that line forward.

[@pimbeweegt]

always a good video when you ride and test a bike or just a crazy experiment

[@MichaelBylehn]

If you still have the ramp you should try to make it flush with the platform. It definitely added difficulty which isn't what you want when you're testing absolute limits. Very interesting video!

[@elbob1491]

In college physics class, Prof. pulled a 2x4 piece on the small face and large face. Friction force was not affected. Literally, the center of mass rearward is your limiting factor. Hence, why your rear wheel lifts. Get some funky rear swept handlebars so you can put your CoG further rearward. Psi adjustments won't keep the rear wheel down. Lowering Psi just means the tire needs a larger contact patch to put all the pounds across more square inches, if you will.

[@leroybishop2245]

No knobby tires. Slick tires made from softer rubber. But, you’ve already achieved the goal. 👏🏻

[@TheEulerID]

As the slope gets steeper, there are two effects coming into play. Firstly force acting down the slope increases in proportion to the sine of the angle with respect to the horizontal. So at 30 degrees, there's about 50% of your weight acting down the slope. However, simultaneously, the force normal to the surface, and pressing the wheels into the slope, is proportion to the cosine of the angle. Thus the force down the slope is increasing, whilst the friction level is decreasing. What couples the friction force with with the force applied normal to the surface is the coefficient of friction. One the ratio of the force down the slope exceeds the normal force multiplied by the coefficient of friction, then the wheel will slide. Thus the maximum angle you can stop at is the arc tangent of the angle (which I will call theta) is equal to the coefficient of friction. Thus if the coefficient of friction between rubber tyres and grip tape was 1, then the absolute maximum angle you could stop at is arctan(1) = 45 degrees. If it's 0.8 (which is reasonable for rubber on grippy tarmac), then it's arctan(0.8)= 39 degrees. Note that it doesn't matter if there's some force normal to the surface on both wheels assuming the coefficient of friction is linear with respect to load and both wheels are being braked to the limit of their traction. Note, I haven't watched past the start of the video yet, but I will predict that a maximum angle around the 40 degrees region will be possible. Note that in this calculation the height and weight of the riders is irrelevant, neither does the bike's geometry. The only thing that matters is that coefficient of friction. This all assumes that you don't go over the top of the handlebars. If you do, that's a different game entirely. Then you have to take account the centre of mass position of the bike/rider combination in terms of both height above the surface and how far back from the front wheel contact patch you are (note, it's that contact patch that matters - not where the position of the axle). Of course riders can change that a lot by moving back and lowering their body. The more you can do that, the less likely to go over the handlebars. That is where height of the rider, and the geometry of the bike matters. Now I've watch this, 42.6 degrees corresponds to a coefficient of friction of 0.92. That seems highly plausible. nb. none of the calculations are difficult; well within the scope of physics at High School, certainly where I come from, and I might even have been taught it before the age of 16.

[@cesarrlozanol]

Hi Seth, great video. I learned a lot. Thanks from Venezuela

[@SnowRaver-p2v]

I love that y'all had the TINIEST roller to do that ramp.

[@JayDubster]

Well impressed how Joe made that look easy!

[@ek715]

Watching this from a skier (and mtber) perspective whos obsessed with slope angles and gradients was interesting

[@ridingwithreggie]

That was some very helpful information. I have one double black diamond trail section that I've been trying to wrap my head around because it's so steep. I believe I can do it.

[@bighammer3464]

Finding the length of the ramp is super easy and you don’t need ai. Just divide 7ft/ sin(angle). Easy

[@YorkyPudinz]

Smooth curve over the peak. And by shortening the ramp, you've also given less time/distance to actually stop so the ramp length needs to stay the same