Which rotor sizes would you prefer to use?

@katcorot

3 жыл бұрын

203F/180R Surly Big Dummy

@Rover200Power

3 жыл бұрын

I find 355mm vented discs works pretty well.

@AnarchoKapital

3 жыл бұрын

Considering that there was already a blocked back wheel, which means reduced brake performance at that wheel, I would go 160 front, 140 back. However I think bike manufacturers could even go smaller in the back. Also application of the bike should be considered: Do you ever ride in conditions in which you need more braking power, e.g. bike packing or very steep descents or in which braking power is reduced by wet or muddy discs, e.g. gravel or CX? That Aeroad is so sweet though.

@somethingreal5042

3 жыл бұрын

160mm

@Pythonassum

3 жыл бұрын

622mm

Also shows the importance of practicing emergency stops.

@frandalzotto7244

3 жыл бұрын

I was able to save my life by training the emergency stops A few hours before he almost collided with a truck And it's probably going to end up under the truck.

@Drago0900

3 жыл бұрын

Nah I commute on my mtb and get brake checked enough by idiots to not need to. Makes me angery when they park in front of my and I can’t lock up my front wheel, while I was getting up to 20mph trying to hit 25.

More impressed at how fast he can unclip

@urh5734

3 жыл бұрын

Gone are the days of Matt

@Garfie1d73

3 жыл бұрын

Matt certainly would agree 😂

Pls appreciate Alex's skills riding on his front wheel😂👍

@Kimberly_Sparkles

3 жыл бұрын

Those were pretty stops.

The next test should be "does price matter for braking performance?" please test for 105, ultegra and durace disc rotor, please thanks you for the test.

@Max__apex

3 жыл бұрын

No it doesn’t .... there all good enough to flip rear wheel up on 160mm rotors from the initial bite point

@Max__apex

3 жыл бұрын

They are but look carefully in the video and see the ease with which he can bring the rear wheel off the ground with 160mm.... getting to maximum braking force earlier when speed is the highest and distance covered more. In braking when travelling at 50m/s in a car if you delay max deceleration by 0.1 sec that’s will impact braking distance by 5 meters. So key is reaching maximum force as earlier as possible and that’s easier with 160mm since lever pressure is less. Also in the video he has to really queeze the levers to reach that point so due to confidence issue 160mm rotor makes it easier to get to that point. Basically 160mm easier to lift rear wheel and slow down :)

@Minecraftrok999

3 жыл бұрын

Yes they are, but your tires probably play a just as - if not even more - important role for stopping you, as you have so little contact to the ground.

@Minecraftrok999

3 жыл бұрын

105 will be good enough.

@joshwilliams6849

3 жыл бұрын

It definitely doesn't, but all I do know is that I have an Ultegra bike and I really want dooss sexy Dura Ace rotors purely for the black paint-job to match my bike ha.

Playing to your strengths, Ollie doing the maths, Alex riding as Ollie wouldn't have reached 40kph

@berthull9333

3 жыл бұрын

Ollie can average nearly 50 kph for over an hour.

Alex's Canyon looks like an absolute weapon. Severe bike envy.

@breitemasse

3 жыл бұрын

but with a damaged Seatpost Like many others

@JustAGlitchFL

3 жыл бұрын

*severe bike enve

main takeaway: learn how to handle emergency brakes

It's interesting on the last one that you started braking waaaaay before the man hole covers!!!

@jerehada

3 жыл бұрын

Did wonder if it was start of end of the man hole and it was consistently hit.

I have 29 inch rotors on my road bike called rim brakes .🤣

@tofadeisastart

3 жыл бұрын

I’m sorry you’re still living in the stone age

@All4Grogg

3 жыл бұрын

Kinda doubt that, since my 622mm 24.49" are the industry standard, for better or worse. One needs decent pads and alloy rims to make them work well, even with the massive advantage in leverage. Disc systems are better at the high end, but rim brakes still get the job done just fine and with less complexity for those not entirely interested in buying into technically faster, but more expensive and less durable tech.

@mgoo1713

3 жыл бұрын

Do you have an anchor on a chain also?

@All4Grogg

3 жыл бұрын

@@mgoo1713 Alloy rims are less aero for the same weight, not heavier in most cases. Also, rim brakes absolutely do work just fine on grippier brake surfaces as found on alloy wheels. Unless you are severely lacking hand strength the tire will skid before the limits of the brakes are reached. Disc brakes are superior, but that doesn't make rim brakes dangerous.

@TheObeseDuathlete

3 жыл бұрын

And then it rained

160 on the front, 140 on the rear.

@markhaneklaus282

3 жыл бұрын

seems they get limited exchange with their mtb collegues

@TheSpinnerfish

3 жыл бұрын

This, if only because the adapter on the rear looks shite.

@antonpeterson1245

3 жыл бұрын

Would have been good to see the mixed setup as Alex was locking up with the 160 rear

Ollie was spot on with getting better at emergency stops being a factor

i love to see how Ollie is walking when he measure the distance :D

Those are some impressive graphics, GCN has come a long way

"bigger rotors* *Mountain bikers have left the chat*

@bjoe385

3 жыл бұрын

Big ol’ 203s all round.

@JustAGlitchFL

3 жыл бұрын

@@bjoe385 I run 200s on my trail/all mountain bike with SRAM codes. I love it.

Brilliant pair presenting together! Ollie's love of the data combined with his facial expressions...👌

and it gets more important when you do descents after big mountain climbs in the alps for example, your speed is very high there and a bigger disc cools better as well. the reason why mtb's also have very big discs, if they would have small discs they would overheat all the time.

@DeKempster

2 жыл бұрын

And on road bike the descent speed are much higher than mtb. Requiring more cooling. So yes size does matter

I would be interested to see a Disc VS Rim brake science experiment. Keep up the great content!

I tried this experiment out on mountain bikes when they went to disc's, and on Motorbikes, and i found the hole braking system and the rider combined Wil respond differently to any minor changing of components. Simply moving your hand to a position so you grab the leavers at their ends, means you can apply more power (longer leaver). How you feel or perseive mod's has to be taken into consideration, sometimes it's the rider not the bike that makes the difference.

@grahamelliott6041

3 жыл бұрын

Nice spelling

@mbal4052

3 жыл бұрын

@@grahamelliott6041 don’t be that guy

@grahamelliott6041

3 жыл бұрын

@@mbal4052 which guy is that ?

@ginti4725

3 жыл бұрын

@@grahamelliott6041 sorry, we all can't be geniuses. Some of us people have dyslexia.

@grahamelliott6041

3 жыл бұрын

@@ginti4725 you don’t have to be a genius to spell correctly or to use a spell checker

I'm sorry to be that person... But Force X distance give a moment in Fmm not in F/mm. Gcn does science needs a scientist on board. I'm free if you're hiring?

@rezoanalom9732

3 жыл бұрын

Ollie has a PhD lol. Granted it's in chemistry and not in physics, but still 😅

@hiddenSeeker

3 жыл бұрын

@@rezoanalom9732 Ah wow, didn't know that. Now it makes sense that he fixed their explanation in the 'Critical mass' video

@keithmaclure9101

3 жыл бұрын

@@rezoanalom9732 being an expert in one chemical niche does not qualify you to pronounce on every science/ engineering topic thereafter...🤦

@rezoanalom9732

3 жыл бұрын

@@keithmaclure9101 no, but the physics in the video is high school-level. I'd expect a PhD in chemistry to be familiar with that level of physics. However, I'm sure it was just a small mistake.

@keithmaclure9101

3 жыл бұрын

@@rezoanalom9732 limited RAM filled up with chemistry knowledge?! 🤪🤣

Love u Olie, u're always so interesting. U'll always be our favorite presenter.

Meanwhile over at #GMBN we've been switching up from 160 to 180 and 200's now! When you are going downhill at speed, you need that extra stopping power!

@thedownunderverse

2 жыл бұрын

soon you'll be up to 700c brakes....... oh wait

There is literally no point in Ollie being in kit in this shoot, Is it the only clothing he owns?

It's like watching the same thing that MTBers went through around the turn of the millennium! The basic lesson is that you should use the disc size that best manages the brake temperatures you experience during your normal riding. That doesn't mean bigger = better, you need a big enough disc to cope with peak temperatures but not so big that it is too hard to heat up and generate the best pad grip on the disc. That usually means a bigger disc on the front to the rear. But you can also change the disc size to improve feel and reduce 'arm pump' on long descents. Basically small rotors for flat terrain, bigger for hilly areas. If you want a grabbier brake go up a size and smaller for more modulation. For the vast majority of people a 160mm up front and a 140mm out back would be a good starting point, that way you get decent power on the front (where the majority of braking is done) and better modulation on the rear (where grip is less as your mass moves forward, allowing you to reduce locking up). For newcomers to discs there is also the matter of braking technique too but that's probably another whole video in itself as it is subtly different to rim brake technique.

Should have tested the mix option too, I suspect because you were doing endos, the stopping would be similar. To answer what do you get for more money, mainly weight savings. One set I have fitted at the lower end didn't have automatic pad advance, but back in the heady days of stock availability I frequently swapped the OEM levers for series ones. This is despite the inline connection not being sold after market - which is mad because it's useful

This is the greatest video on braking; full-stop.

Great video and more fun, interesting and USEFUL content. Impressive stopping skills we should all practice. Can you get the GTN boys on the tri bikes in the next brake video? :)

I run a 160 on front and a 140 on the rear. Having ridden racing motorcycles I know you can’t have to much front brake and the rear as little as possible due to the weight transfer during braking.

@flightbyrd

Жыл бұрын

Yes! Rear wheel lock up and regaining traction causes high sides on road motorcycles. In this test on the bike, the rear wheel is providing limited braking and none at all when it is in the air.

@mlee6050

9 ай бұрын

I think someone did that way or other way round to sort of balance out braking

Thank you so much for this comparison, and thank you Ollie for insisting on retrying the test, because I agreed with your observation, and you were right. At a difference of 14%, as a non competitive average cyclist, I'll stick to the 140s that came on my Giant Fastroad Advanced 1 for the weight benefits.

@AlexSquared

Жыл бұрын

yeah that 2 grams you saved will make a HUGE difference....lmao

Next time you encounter a recent generation tandem, check out the disc brake rotors. They’re usually quite large, 200mm or larger. It takes a lot of breaking power to bring two riders and massive frame to a stop.

Perfect video! Thanks!

160mm both front & rear for me - always have stuck 160's on

Please do a similar test, changing from resin over semi-metallic to metallic brake pads! 👏👍

Great video guys. And to the point of new bikes with larger rotors on the front, I just looked at my new Orbea and it has a 160 on the front and a 140 on the back. Go figure. Thanks for pointing that out!! 👍🙏

i’m building a gravel bike with campag ekar. interestingly the brake manual recommends larger rotators as rider/bike weight increases.

An interesting control would have been to also compare to rim brakes on a similar bike

@prestachuck2867

3 жыл бұрын

Yes! And use alloy rims with Dura-Ace integrated rim brakes!

@lucabravi4332

3 жыл бұрын

Check GCN italia for that similar compare

@brendonnoble5227

3 жыл бұрын

@@prestachuck2867 yes and in the wet.

@rossdavies2343

3 жыл бұрын

Been done I’m sure?

@hernendezsanchez7646

3 жыл бұрын

Oh there will be some tears, tantrums and long comments and posts if that happens. Lets just leave the rim blokes to themselves playing with their crayons

Worth pointing out the logic in increasing rotor sizes for heavier riders, or those likely to be carrying luggage etc. When weight increases is when the braking performance of the disc becomes most important. As we saw, he was closer to going over the bars on the 160's so bigger isn't necessarily better for the same weight.

Wow, interesting findings! Changed my mind as well.

Like this, and just moving to discs make scenes in UK weather and been 90kg need 160mm rotors.

Nice stoppies, Alex! Use a nice big rotor on front. Dig a 180 or 203 out of the MTB parts bin. Then, you can go 140 on the rear. Every disc brake vehicle has a similar disparity in front vs rear rotor size and capability.

From my perspective the best reason for bigger rotors is heat transmission. I had never problems that my disc brakes stops the wheel. My bigger problem is that my wheel tires (GP 5000) are slipping on the road surface (even if it is dry) or that I am afraid that they overheat. I have seen that Bosch has developed an ABS system like from cars for E bikes (I don't want all these electrical stuff on my bike, but there are innovations to solve this road surface slipping problems)

Very impressive wheely! It is a pitty, that you missed considering a 180 mm rotor, which might be a valuable upgrade for some of us.

@iangannon8543

2 жыл бұрын

The benefit of 180s are heat dissipation, larger riders or lower grip strength.

@myscreen2urs

2 жыл бұрын

@@iangannon8543 and performing somersaults🙃

I made a presumption before starting the video. Wasnt expecting basically any difference. Result is surprising - considering the braking performance is a sum of many factors.

I'm trundelin' , I' trundelin'.... Ollie during their 4v1 race :D ANyway, its good to see him inthese kind of videos, because he seems to be the only one who actually gets the technicalities. I loved his part in Hanks heavy hillclimb

nice to know that the gcn Guys got the Same Seatpost issue with the aeroad

The larger rotors may also provide better feedback for modulation, which could help explain why they performed disproportionately better. I'm not sure of this, but it's a thought I've had for some time.

@ayowser01

Жыл бұрын

That would be up to the master cylinder.

My bike has two different rotor sizes and I was gonna swap everything to 160mm anyways. I already figured that there'd be better stopping performance, but I'm surprised that it's that much. Good thing I just got my new work stand.

Kudos for not chaning more than break rotors and changing back to the first ones in the end. A proper way to test!

8:49 My BMC came OEM with 160F and 140R Shimano Ultegra. I recently (yesterday) upgraded the rear to a 160 rotor due to brake fade on steep descents. I had a scare in overshooting a hairpin when my rear lost its grip. Other than descending I have no issue with the stopping dependability of the 140. Time will tell.

Would be interesting to see 160F and 140R as a comparison.

Can GCN do a tutorial on emergency stopping? I don't know how to do them and want to learn

Makes sense to have 140mm at the back and 160mm on the front. Would suspect performance to match 160mm test results, because the back wheel was airborne during each proper stop. The back rotor played no part when it mattered. Would be great if you could run the test with this variation as well.

I think the heat transfer is the most important thing - I was descending a 15 percent climb reaching about 45mph freewheeling and the 140mm faded on me, very close to ending up in the ditch, only managed to cut my speed in half before they had nothing left. I don’t know if 160 would have eliminated that altogether but it would have helped.

One key part of this decision is on display in the torque equation: the "N" part. If you are a heavier rider, you need more applied torque to stop. Therefore, the larger diameter rotor is the way to go. I am 88kg and run a 160 out back, only just recently upping from 140. Noticeable difference, especially since I like the downhills, which, in New England, invariably end at a junction. Note: Offroad, I run 180 on my trail bike and 200 on my enduro. I like being able to feather my rear brake with a bit more finesse to scrub speed while keeping going,.

I was hoping you guys would have further explained the 160 front/140 rear setup. Cars and motorcycles run this setup because it helps with brake bias. You want your front brake to be stronger so that with equal brake force applied at the calipers (generally people don't squeeze one brake any harder than the other) your rear brake has much less of a chance of locking up given the weight distribution on a bike. I started running 160/140 and my back wheel has been locking up a lot less. Just purely anecdotally.

Can you do a video for brake pads too? Which is best for what use (wet, dry, rider weight, etc)?

Nice to see that you use the metric system :) !

I don't get why there would be a difference. Maximum braking deceleration is achieved when enough braking pressure is applied just before the moment that the wheels would start to skid. Different rotor diameters and therefore different lever distances mean that less hand squeezing force is needed for the same brake pressure, but still even with the smallest rotors, it should still be possible to lock the brakes. As long as you're able to lock the brakes, it should also be possible to achieve maximum braking. The only reason I could think of is that the travel length of the brake lever with wider discs offers more control, but in that case, Ollie is right, it's Alex's (lack of) control that decreases the performance of the smaller rotors.

(FYI on Messages #1 & #2) If you're wondering, this is why hyper fast cars have massive disc rotors that are almost the same diameter as the wheel so as to give all four wheels as much leverage stopping power as possible, to keep heat down and extend pad wear. Now these brakes are truly like on & off light switches with absolutely little or ǹo modulatioǹ. To over come this problem they use computerized anti lock brake systems to give the driver a normal brake pedal feel. If you think about it, regular caliper brakes and the wheel is actually a giant 700c size disc rotor.disc brake. The first to realize this fact was HONDA in the late 50s as they were searching for a more powerful brake system for their roadraciǹg motorcycles besides the traditional hub drum brake. Incredibly they developed first V Brake with a fair amount of succes, exactly like the V brake on mountain bikes today! Hard to believe but this is what inspired British race car engineers to develop the first Lt/Wt disc brakes for cars. I might be wrong on this history but I read it in a Honda authorized history book 30+ years ago. I love it, Dan ( :

@paullinnitt5450

3 жыл бұрын

Suzuki ran a rim mounted disk in some GP RG500s in the 80s for maximum rotor size. Calliper was inside the disk. Search Ciba Geigy Suzuki. They also had a honeycomb composite chassis

@dansotelo228

3 жыл бұрын

Ahhh, those crazy Japaǹese they come up with great and crazy solutioǹs, lots to learn there.

@dansotelo228

3 жыл бұрын

I think it was Buel who ran those rim discs for a while on There sport bikes. When I was at Shimaǹo we looked into that same rim disc idea but it was not practical.

08:00 This is the main point: rotor heat accumulation and dissipation. The 160mm rotor has more surface area and has higher relative speed vs wind for heat dissipation, and more weight for heat accumulation. This will help tremendously while descending big climbs.

did that same exact pads has done the bedding in process for both rotor size before test?

What tires/size/pressure were used for this experiment? I found (I'm ok) that traction of my gp5000tl is a limiting factor, not braking force of rotors. In fact moving from rim brakes, I had to learn to take it easier on the brakes, so I don't lock wheels and skid.

It's been so dam long since I've seen/used/thought about a trundle wheel. Absolute scenes, absolute truth. Can I get a GCN trundle wheel of truth in the GCN shop?

Great video guys thanks!! I’d like to know about the weight difference between running 140s and the 160 because I would change to 160s for both!!! OR using the MTB discs like the pros???

@tomeklubomir

3 жыл бұрын

Dura Ace (as used in the video) 140s are 96g each or 192g for pair and 160s are 119g each or 238g for a pair. So a weight difference of approx 46g, not a lot really.

"I didn't expect that..." As a mountain biker who has ridden discs since the Naughties, I absolutely expected that. It's called Physics...

both wheels do completely different jobs, so for me it makes sense to give each one its own specific properties: disc brakes: 160mm front, 140mm back wheel depth: 40mm front, 50mm back (for example...) tire size: 25mm front, 28mm back tire pressure: 90psi front, 100psi back...

It's good that Alex did this, if hank would do this, he would make salto's every run

I have 160F/R and after cracking the ceramic piston on the rear I installed a hope RX4. Maybe do a 2 pot vs 4 pot test.

As you can see on the video and this is also confirmed on motorbikes, the rearbrake is almost useless in an emergency braking as all the weight is on the front. On my racing motorcycle I had 2 x200mm on the front and 1x120 mm on the back. You save a bit of weight on the back disc.

breaking performance is determined by the area of the disk that is swept by the pad(s) not just rotor diameter. Assuming a 10 mm2 break pad for each rotor the 160 has 2100 mm2 more swept area per side than the 140. A larger break pad/caliper( think quad piston calipers) on the smaller disk would have the same effect but at a weight penalty.

That Canyon looks mega. I want one with those deep wheels.

I'm just about to order 160mm for my front to replace 140mm, so the timing of this video is just about perfect 👍

@spikev5842

3 жыл бұрын

check the warranty on your forks

Great video. Just had a thinking would larger disks have increased brake drag when compared the smaller disks.

@Wildschwein_Jaeger

3 жыл бұрын

Yes

Curious, how much wiggle room do you have to change the size of your rotors? My gravel bike, takes a 180mm and 160mm (or maybe it's a 160mm and 140mm). I can't go any bigger or smaller with the current setup

Mixed. 160 front, 140 rear---better modulation. Braking only works with the wheel on the ground. Like with cars/motorbikes if you have too much bite in the rears it will upset the balance and handling.

great video, what's going on with alex's seat angle on this canyon

Why does ur saddle pointing upwards? Anyway there’s a feel difference on the lever between 140 and 160 anyway on Norma riding conditioning. Tested it personally on the front rotor.

140mm likely brake similar to (relatively) rim brakes. That is a test I would like to see. I always found them weak on a mountain bike.

I put a 180mm on the front of my gravel/bikepacking bike. It's there if I need it!

@wayslow

3 жыл бұрын

Don't. Unless your fork is rated for 180. Brakes put a lot of force on fork and it needs to have proper strength to handle those forces. I learned it the hard way.

@samuelchap

3 жыл бұрын

@@wayslow I believe it is, the current version comes stock with 180mm at least and mine appears to have the same overbuilt fork. I didn't change it to shorten my braking distance but rather to avoid brake fade when rolling down Devonshire hills while carrying (too much!) kit. I'm also running Sram Force which has a lot of modulation, you'd need to quite determined to lock the wheel from the hoods and I could easily exert the same torque by braking at speed from the drops with 140mm rotors.

@dariuslankarian3282

3 жыл бұрын

@@wayslow I believe thats only for carbon forks. For steel fork you should be able to upgrade from 160 to 180 with no issues.

@wayslow

3 жыл бұрын

@@dariuslankarian3282 I've seen aluminum rear triangles break on mountain bikes after switching from 160 to 180mm. While steel should be more resistant to those forces, they are applied to a different area with a bigger leverage. And the fork failing isn't anything you want to witness - there is no warning, you plummet to ground with your face first.

@dariuslankarian3282

3 жыл бұрын

@@wayslow i agree but with steel it would bend significantly before breaking carbon and aluminum have no give they snap when under heavy load.

Personally bigger rotors are more of a heat dissipation thing than absolute power for me. As a heavier rider who likes to decent fast, I’d love to run a 180mm front if my fork would allow. I wish you guys would test brake fade down a long decent, but still a very interesting video.

And now we know what size Alex should use under these conditions. What about rotor weight and aero drag over the course of a longer ride? Sprinter versus climber. Is it possible a smaller rider would do fine with 140's front and rear? A larger rider with 160s and more average size with a 160 front/140 rear? And what about a test where Hank has to stop with different size rotors before hitting an obstacle?

Most of that test looked pretty good, but that 5.6m stop was suspicious. The rear wheel was in the air before the front wheel had passed the sewer cover, so I think the brakes may have been applied too early. Still a cool video.

I think im sold. Been thinking to upgrade to 160 on the mountain bike awhile. Didn't know if there would be much of a difference though.

@gcntech - best method to clean brakelevers/hoods (Di2) after a winter of indoor riding, full of sweat and salt? Remove the rubber and clean off with a wet rag or??

I have also seen the professional teams use mountain bike rotors because supposedly they are better at dissipating heat than the ones normally used in road bikes

Surely we need a comparison now with 160mm on the front and 140mm on the back!

@robertredziak6461

3 жыл бұрын

I believe difference will be insignificant as during hard braking rear wheel barely or even doesn’t touch the road.

@chris_tyson

3 жыл бұрын

@@robertredziak6461 undoubtedly, but it would be interesting to put numbers to it as guidance to equipping/optimising bike set-up

@robertredziak6461

3 жыл бұрын

@@chris_tyson I think you may go for such mixed setup except some strange cases like mine: an oversized, almost 20 stones big MAMIL ;)

I have a Shand Stoater Rohloff which is a gravel bike and I use 160 on the front and 140 on the back. I find a 160 on the back just locks up too easily. I'm an automotive engineer by trade and most cars and motorbikes have a smaller disc on the rear for this reason. The back wheel naturally has less grip as the weight is transferred forward during braking, even if one moves their body backwards.

I thought you'll end up trying 180mm to 203mm rotors. For Science of course.

@Digi20

2 жыл бұрын

that is not possible for flatmount road bikes. 160 is max. there are some gravel bikes/forks appearing that accept 180mm in the front though.

Possibly an effect of Alex having more control over the braking force with the lower force needed at the lever? Better modulation of the brake so could hold the stoppie better

@spikev5842

3 жыл бұрын

I don't think the physics supports that there will be lower force at the brake lever if it needs to deal with increased torque

Changing the rotors and also the brake pads too.. Since both of them had grove marks..

another very important aspect is that larger rotors cool off a little bit faster. Not important in the UK I assume, but try and descend the 48 hairpins of the Stelvio in 35°C and you know what I'm talking about ;)

Yes. Archimedes said it best about being able to lift the earth with a long enough lever. Larger rotors have greater leverage. More mass & surface area as well, thus better cooling. And this is why tandems run 180-200mm rotors in front.

3:28: „Boom.“ - Alex Paton 😉

Now try the same with 25 vs 28 mm tyres as well as tubeless, running recommended lower pressures, and tubed tyres at the recommended higher pressures.

I wonder what the stopping distance would be with the 140 in the rear and 160 in the front and if it would stop faster because of the reduced chance of the rear brake locking up and not skidding as much.

Very interesting, as always. I prefer rim brakes, nice and easy.

@svenw1507

3 жыл бұрын

Ever rode a hydraulic disc brake? Once set up you forget it! Breaking performance is a lot better!

lessons learned: 1 - 160mm in front and 140mm in rear. 2- practice emergency stops!

I think there are four main arguments for the 160mm rotor, one of which was discussed in the video (heat dissipation). Another argument is that a 160mm rotor has a larger swept area (the area that the pad runs over the disc) and so should wear out slightly slower than a 140. The other two reasons I can come up with for a 160 are directly related to the stopping distances achieved in the video: 1) By having 14% more torque on the 160mm rotor, that means that you’ll reach maximum breaking on the front wheel that much faster in terms of lever stroke. It takes less time to travel less distance, and since you can only pull your fingers so quickly, the more torque you have on a given wheel, the more quickly you’ll be able to lock up the wheels - just because you don’t have to pull the lever as far to do so, assuming that the pads and rotors have the same clearance. 2) This kind of relates to above, but I think the other reason the 160mm rotor stopped faster is that it requires less force overall to go into the lever in order to reach maximum braking. Fingers are incredibly sensitive, especially when it comes to lower levels of force. I think that the 160mm rotor will give you more feel because you don’t have to pull as hard, so you can ramp right up to the edge of grip/control more easily, and you can more easily modulate the brakes. For instance, I can much more quickly and easily squeeze something with about 50% of the force I’m capable of than I can with 80% or 100% force. I have a much lower cycle time with lower exertion, so I would more easily be able to handle the fine tuning needed to stop on a 160mm rotor as quickly as possible. A bit of a digression: for most of those emergency stops, the back wheel was lifting off the ground. That means that 100% of the braking force was going through the front wheel as soon as the rear lifted off the ground. I’d bet you’d be able to stop just as fast with a 140mm in back as you could with the 160 front and back because of this.

very interesting thanks, so my hack bike is safer than my new one. would also be good to compare against rim brakes too

There are two independent rotors, each offering up to 14% improvement. If both brakes take on an equal force, that should give you about a 29% improvement. (1.14*1.14 = 1.29) If all the stopping force came from one brake, you would be stuck with a 14% improvement. So the 22% improvement is within the range. I think trying out 140/160 and 160/140 in addition to 140/140 and 160/160 will answer the question of how much stopping force comes from each brake.