How Hydraulic Disc Brakes Really Work!

[@45graham45]

You covered all of the obvious stuff that everyone already knows (imho) but you didn't go into stuff that nearly no one knows about - eg; how reservoirs work - feeding the system as pads wear etc, how the pads retract (by the seals or return springs or both?), where air in the system migrates to (reservoir on uplifts etc or lever piston or caliper) & how it enters the system.

[@andyasbestos]

Man, I just wanted to know why the interaction between the mater cylinder and the reservoir seems a bit random at times, especially while bleeding my brakes. I know there's at least a small reservoir in there somewhere, but hell if I know how it's actually connected to the rest of the circuit!

[@ivebeaneverywhere]

reading all these and spending the last three hours trying to find someone who will explain these intricacies has me absolutely set on cables tbh

[@kevinwebb9538]

Great video. Owen is obviously very knowledgeable and presents that knowledge in an easily understandable and entertaining way. More of the same please Owen.

[@OwenBikeNerd]

I'll keep trying to! Thanks for the feedback Cheers Owen

[@rogereheadbyrne4790]

Very interesting! Just yesterday I collected my bike from my local bike shop it was in for the rear brake bleed the front brake was ok or so I thought! Even though the bite point was perfect there was a fault I'm glad the guy checked it as the plunger piston in the brake lever chamber was jammed! A quick disassemble and rebuild sorted it! Thanks to the guy at Wight Mountain Bikes!👏😁

[@raveonum]

Great Video. Im not a mecanic, but over 10 years I used to service/modify brakes on my cars and motorcycles. And I wanna say that the majority of MTB brakes are marketing scam. All those unnecessary complications which force you to buy extra parts. Why don't we have banjo fittings with copper shims for all the hoses? Why use crappy single use olives etc? Bleeding kits is a separate topic which looks completely idiotic to me... Hayabusa brakes are going through hell during brakes, and those brakes are simple and effective without MTB-style super-gizmos.

[@alexkenison]

You need to make a better distinction between 5.1 and 5. 5 is silicone based where 5.1 is glycol based the same as DOT 3 and 4

[@clecss]

You won't believe how much this video helps! Trying to find a good explanation of brakes from physical principles to manufacturing was nearly impossible to do in one video, but not anymore!

[@OwenBikeNerd]

Glad this helps - thanks for the feedback! Cheers Owen

[@antc5010]

Great presentation! It would also be good to mention Dot 3,4&5.1 fluids versus Dot 5 (silicon-based) and their compatibility with different seal materials.

[@glenstruan]

DOT3, DOT4 and DOT5.1 interchangeable, DOT5 is not! Must be a standard system designed in the USA.

[@ivebeaneverywhere]

how does air get into a closed system? how does it automatically adjust for pad wear? why cant i bleed with worn pads in? how the hell do i overfill the system if i want it with no air? how do these people claim to have used their brakes for years on end with no issues? have you been riding uphill the whole time?

[@stx333]

Friction does not depend on surface area. Size of pads is again heat management

[@Surestick88]

That said bigger pads generally require 4 piston calipers which usually means more piston area which means more force for a given pressure from the lever which means more friction.

[@ac-1639]

Some people hate when you have sram brakes and shimano drivetrain or shimano brakes and sram drivetrain...

[@lookwhotalkin]

How about what I run, shimano levers, magura calipers and hope rotors.. 😂

[@sssxxxttt]

I’d say the contrary, it’s really annoying when parts and systems by suppliers don’t work together. If you master compatibility you must be better off making the optimum bike for your purposes

[@rider65]

Because they are stunod? 😅

[@LaurentiusTriarius]

I've never cared about that, these people need to go ride and quit their keyboards. The most annoying to people it seems is unmatchy suspension, I love when I can do it 😂

[@duckey599]

i have shimano saint drivetrain and hope brakes i don't think it matters at all its just preference mate people always pick something jealousy is a nasty thing

[@duckey599]

i once ripped a line out and filled it with olive oil to get home znd it worked tho not very good tho but i could stop atleast abit

[@seigneurchaton]

I wish there were an explanation of how the system adjust itself when the pads are wearing out and become thinner, and why, when there is no pads and no discs to block them, the pistons can be ejected from the caliper, meaning that they don't always go back in as much as they go out when you pull then release the lever.

[@chucktalks63]

The reason they self adjust is because of the square edged seals used on the pistons. When you apply pressure on the pistons the seals slightly move but always want to go back to being square, so they move back to their original place. As the pads wear they can overcome the force from the square edge and move out further to take up the wear.

[@seigneurchaton]

@@chucktalks63 Thanks !

[@rider65]

Good info. 👍 Force, pressure, volume, temp & energy.

[@ilovekale]

Great video An important point of s discussing the caustic / toxic nature of DOT fluid and the effect on longevity of the braking system

[@davidpottage6402]

A factor to consider about brake leavers - are they ambidextrous - Do you have left & right specific levers (eg Shimano) or can the same lever be used on either side like Sram or Magura. Ambidextrous levers simplify buying upgrades and make carrying a spare more reasonable. A few years ago I had a big day at a DH bike park cut short when I broke a brake lever in a fairly minor crash. Considering the total cost of the day (lift tickets, transport there & a hotel), I would in future bring a complete brake with enough hose that it could be mounted front or rear, and an ambidextrous lever so it could be used to replace any broken or faulty brake.

[@JaredNipper]

That was a great overview. Nice work!

[@marcstucki]

What I would have liked to see and understand is how the reservoir works.

[@VicharB]

Thanks. I am new to hydraulics brakes for mountain bikes/XC, and this was informative. Off to your other videos now.

[@William.N]

Brilliant video! Now, can he explain how magnets work?

[@Lee-At-Green-Pheonix-Rc]

I run 203 front and 180 rear hope saw rotors Fr and Rear all steel Tektro Draco big piston brake calipers and pads shimano caliper adaptor with shimano deore derailleurs with alivio shifters and a sram chain 3x9 setup on my custom Dh hybrid changed suspension to longer travel but same geometry and raised the bottom bracket and peddles 2 inches fitted a Rockshox monarch rt3 plus debonair piggyback rear shock 200mmx51mm travel with custom made from DVO suspension USA hardware and a fox 32 float f seiries tapered air fork with a hope straight steer tube to tapered fork adapter with lizzard skinz mini machine grips it's a 2012 jamis Dakar XC sport with beefed up swing arm from jamis replaced on warranty after the weld snapped using a 160mm rotor i had a 5 year factory warranty and happened 1 month before it ran out was sent to Jamis USA for inspection and repairs even emailed me saying i did a good job on modifications and asked my riding styles and build a swing arm accordingly and full bearing replacements to stronger and even rebuilt my suspension while there too

[@Chorge1972]

You have an image of a SRAM brake for a video about how it works?! Shouldn’t it be called „How it NOT works“? 😅😂

[@picassoimpaler3243]

Do NOT mix DOT 5 into any other brake fluid. I repeat do not. There is a chance of brake failure and will either need a complete brake rebuild/new brakes if you do. I know this has been said a lot, but it's a safety thing so the more it's up, the higher chance someone will see it Dot 5 and dot 5.1 are completely different things. You can mix and match dot 3/4/5.1 but dot 5 is a different chemistry altogether and is silicone based. Unfortunately silicone is insoluble in about everything, so you will end up with a gummy mess on your hands.

[@denisdrc5836]

"You cannot refit banjo"??? Maybe I misunderstood something and you talk about a different part, but I literally have the tool for banjo replacement and there are spare part on sale to replace it...

[@darrylduck6356]

You cannot use DOT 5 fluid in brakes designed for 3, 4 and 5.1 Dot 5 is silicon brake fluid and is totally incompatible.

[@LaurentiusTriarius]

Happily DOT 5 is harder to find, 5.1 is just becoming pretty common.

[@davidpottage6402]

I found a 500ml bottle of DOT 4 in my local corner shop! It is also the same grade of brake fluid that my car uses.

[@renzoeltigre]

I was thinking exactly the same. You are the man!

[@kuoasify]

used to own some bikes that had mechanical disc brakes on them for how they were not hard to work on and after getting into a new bike with hydraulic brakes that I haven't noticed a different for how I miss my 11yr old, specialized bike I had from Khs

[@lookwhotalkin]

Hope brakes are fully rebuildable including hose connection to the caliper

[@LaurentiusTriarius]

Pretty much all brakes if you exclude tektro, even then they could be serviced but you can't find replacements parts 😂

[@woduk]

They are just fittted the stainless pistons in my front e4 caliper much better movement and hopefully no brake locking on anymore

[@charlies418]

Do you have a fool-proof way of bleeding brakes? Why can't these bike systems be bled like a car system?

[@Airsofthunter112233]

from what i understand its gravity based. open the valve at the top of the bike to let out any trapped air and push in fluid from the bottom of the bike at the break. of course this assumes your bike is stored in a normal up right postion and not hanging from the garage ceiling or something so that the air bubbles will slowly move to the highest point of the bike over time.

[@YavorM-Yash]

​@@Airsofthunter112233if you hang the bike with front wheel up, which is usually the common way, the levers still be the highest point of the brake system.

[@AzizBike]

Dot 5 is a silicone fluid and is not compatible with the other DOT fluids. You want DOT 5.1.

[@westinthewest]

It sounds like you said 'hydroscopic' instead of 'hygroscopic'.

[@stephen-wy1ej]

Never changed the oil in mine in 10 year still as good as day 1 if it works dont mess

[@Mike-fh1qp]

EXCELLENT INFO. Really well presented. Perfect. Cheers

[@mitch_smith]

Every Owen video gives me the feeling he has forgotten more about the topics he's talking about than I will ever know! He's like a biking encyclopedia!

[@OwenBikeNerd]

ooft thats high praise indeed - thank you - but yep theres always more to know on most topics! Cheers for the kind words! Owen

[@melibaut]

Thanks for the interesting and informative video!

[@OwenBikeNerd]

Thanks for the great feedback - glad the video works - do let us know what other topics you'd like us to cover here at GMBN Tech! Cheers Owen

[@meteturhan3505]

In case of Sram, they do not work 🥳

[@nonamewithname9045]

Hello, i have 1 question and that is that i have a sram level brake system that takes dot liquid right? Could i put the same dot fluid thats in cars or i have to buy specific sram branded dot fluid? Thanks

[@YavorM-Yash]

It has to be a DOT 5.1.

[@dcv9460]

AWESOME DETAILED VID! 😎💯👍

[@zukzworld]

Great video, thanks! ❤

[@SloanRanger61]

Great video, Owen. I didn't think I would learn much, but I learned a lot!

[@OwenBikeNerd]

Cheers - thank you! Owen

[@duckey599]

god i miss doddy no offence at all you are a great guy equal as doddy but i just miss doddy unique character as we all have unique characters🤜🤛 love the channel y'all ❤️

[@ellerybice3787]

It's doddy's hair that you miss eh? 👶🏻

[@alfrednOObel2]

When talking about both levers and calipers you didn't explain why does it matter, which is the hydraulic equation: F1D1 = F2D2. It literally tells us that the force applied on the one end, multiplied by the distance is equal to the force on the other end by it's distance. So oyou can move the large pistons at the caliper with huge force, but small distance, by applying small force for the larger distance with small pistons at the levers (and even increasing it with the leverage ratio of the levers themselves). You haven't explained also how do floating rotors help with heat management. And it's kind of advanced management at trhis point as it is not designed to dissipate heat better or anything like this. The floating rotors role is to isolate the hot rotor surface from the colder spider. As metals increase their volume when heated, the rotors want to expand. But the cold spiders prevents them from it, so traditional rotors warp when they are heated. Floating rotors allow them to expand equally on their circumference to prevent warping. As for the difference betwen pad matrial, the main one that you have not mentioned is their characteristics with heat. Resin pads work very well when cold, but fade quicker when heated. So they are good for someone who doesn't go on long downhills, but wants sharp brakes available instantly. Metallic pads do not offer full power when cold, but will work really well on long descends as they will not fade as quickly. I also dubt the part about adding the brake pad material to the rotors. Such thing could happen, but to do so, you would have to spin the wheel around 10 000 RPM to generate enough heat to achieve that.

[@charlies418]

DOT brake fluid strips paint in seconds. Do yourself a favour and use AUTOMECH brake fluid the same as used by the military. Better than DOT fluids as it does NOT strip paint AND it does NOT absorb moisture (you can mix it with DOT fluids if you have to). I've used it in my kit-car for years - I used to have to bleed the brakes every year and replace corroded brake slave cylinders - I've not had to do either for years because this fluid is designed to be used in military vehicles that stand for a long time. It isn't cheap but if you want the best!

[@sidneisoarescm]

For some tires (such as Continental "X" King), when I put the rolling direction inverted (on the front tire), I notice more grip in curves, precisely because there are intermediate (and lateral) studs in the way the tire Scorpion "XC M" is manufactured - it's difficult to try to explain this..., but it's something like that, the side of the intermediate and lateral spikes, when you turn the handlebars, are more perpendicular to the movement (and not in the direction of movement of the recommended rotation), providing, in my perception, a feeling that these studs are more "ready" and enter the terrain more, giving a greater feeling of predictability and safety in the curves. Of course, I imagine there will be some loss of roll with this, but, up front, I prefer predictability in curves. In fact, this would be a better suggestion for a video theme to be more illustrative, perhaps drawing on opinions from riders not sponsored by tire companies, independent studies and even companies that manufacture tires with side stud patterns like the Pirelli Scorpion "XC M" .

[@johndef5075]

Sram uses dot AND they suck. 2 big +'s for Shimano....

[@jamesmincher3435]

I hate dot fluid had avid juicy three they were terrible always losing power shimano mineral fluid system much better

[@bjornfongern4850]

Re DOT brakefluids: There are DOT 3, 4 and confusingly 5.1. These are all similar glycol based brake fluids (you shouldn´t mix but you can interchange them). The higher the number the higher the boiling point (roughly) There´s also a DOT 5 which is something entirely different and is silicone based. This one is NOT interchangeable with the other DOT types so beware what you buy. All the DOT bicycle brakes I am aware of use DOT 4 or 5.1

[@gammamarino8487]

How does it work on sti

[@bluemootang3239]

2:57 haha "flavors"

[@FOTB407]

I was hoping he’d mention something abt steel braided hoses when he talked abt stiffness

[@LaurentiusTriarius]

Owen they are full floating MTB rotors, even the Chinese crap on ali has advertised float of 1° to 2° They can rattle yes but it isn't affecting performance. Shimano and galfer are NOT floating rotors they are riveted tight

[@duckey599]

hope too floating rotors can rattle but it is not a anoying rattle to me and imo they rattle when they get heated up or somehow very high speeds too

[@АлександрДорофеев-ь6р]

Спасибо за детальное соотношение качества подачи информации в видео про тормоза и их разновидность. Моги бы вы более подробно рассказать о том как регулировки на ручках влияют на колодки во время движения. Разновидность и скорость сжатия в разных местах и погодных условиях. Спасибо 🙏

[@corkErist]

A bigger pad size does not result in more friction. The friction is independent of the area.

[@MattRose30000]

It does convert kinetic energy into heat faster though, and steel has a lower coefficient of friction at higher temperatures. That's probably why they work?

[@kwennemar]

Thanks!

[@Airsofthunter112233]

I have recently ran into an issue after purchasing a used mountain bike where i noticed when replacing the rear pads that they are not fully covered by the surface of the rotor. basically the pad's surface is wider than the rotor. any ideas on how to go about fixing this? would it be better to replace the rotor to a wider version if such a thing exists? or would it be better to replace the caliper and pads to a smaller size?

[@OwenBikeNerd]

Great Question - we do an Ask tech show where you can send in your question and we try and answer them - so I'll add your question but if you've got more details about the bike, the rotor sizes and brake model - we'll try and help as much as we can! Cheers Owen

[@Airsofthunter112233]

@@OwenBikeNerd I think you just helped me answer my own question. I'm relatively new to the mountain biking world so I didn't even think to check the brake and rotor model against what the bike would have originally come with. Turns out the previous owner swapped the rear rotor to one with the same diameter but a 4 millimeter narrower surface area.

[@prusak26]

You likely have a wrong adapter, or it's installed up side down (fork), or back to front (frame).

[@Airsofthunter112233]

@@prusak26 the wrong rotor was installed

[@alfy364]

Why are ceramic pads never mentioned 🤔

[@woduk]

Not commonly used, was actually wanting to try some out

[@alfy364]

I have been using them for the last couple of years, they’re awesome. I wouldn’t go back.

[@grahamleach4101]

I know my brakes are 4 pot and use mineral oil 203mm rotors

[@ninjazzrhythm400]

I'm glad that someone did mention that both DOT and mineral oil are toxic. I hate these channels giving misinformation about mineral oil and saying its safer. They're all toxic and there is a website that talks about the danger of mineral oil that noone is aware off. I advise anyone who works one any chemicals, and it doesnt matter if its environmentally friendly, dont trust anyone with your health.

[@hectorlmges]

Bought two new bikes recently, sadly equipped with SRAM G2s brakes (and DOT fluid) get rid of them and installed Maguras + Galfer metallic pads. Never looked back.

[@Slazmoservicing4209]

Wait till a ABS type function or brake bias comes into the mix...

[@nealwright5622]

How are you going to have a bias function when each brake is operated independently? That's why you usually have a different rotor size front and rear.

[@kuchenblechmafiagmbh1381]

Seems like some motorcycles have CBS (=Combined Braking System) and that or ABS (some also combine that) are mandatory in a lot of countries nowadays. However, for ABS you need some electronic control AFAIK and most bicycles don't have a permanent power source - [hub] dynamos for lighting aren't common on MTBs/road bikes and only deliver a few watts (I guess proper lighting already uses most of that). Maybe on Pedelecs but of course with a safety margin (traction gets cut off at 5%(?) so it can still power lighting and ABS system), maybe with Di2 but IMHO that would overcomplicate the braking system and sometimes intelligent simplicity (fewer points of failure) isn't wrong but you remember Mercedes-Benz with their SBC in early to mid-2000s? It had a huge recall and they went back to "conventional" braking after that.