DH Bike Tech: Super-Sized Brake Rotors

Jul 12, 2019
by Mike Kazimer  

For years, running rotors that measured 200 or 203mm in diameter was the norm for downhill bikes, while 160-180mm was the typical trail bike rotor size. Those dimension are still common, but we're starting to see a shift towards even larger rotors, especially on the World Cup DH circuit. It's partially due to the arrival of 29ers – those big wheels take more power to slow down, especially when the course is super steep.

Just how big can rotors get? Well, SRAM's athletes have had access to 220mm rotors for the last few seasons, and companies like Galfer, Trickstuff, and TRP, among others, have rotors in that size range as well. It's not just the diameter that's increasing – in many cases the actual rotor thickness has been increased in order to improve heat dissipation, and to reduce the likelihood of the rotor getting warped.


Troy Brosnan has shown up to Lourdes with some rather monstrous 220mm disc rotors.
Troy Brosnan showed up with these 220mm rotors at Lourdes in 2017.
223mm laser cut rotors from Trickstuff. These are slightly thicker than the smaller rotors at 2.05mm. Unfortunaly they cost 99 due to being cut instead of stamped and being made in very small volumes.
Trickstuff's 223mm rotor.

Bumping up a rotor size creates more power, which means that riders don't need to expend as much energy pulling on their brake levers. That's an important factor, especially on those near-vertical tracks – arm pump and overall fatigue are directly related to how hard, and how often, a rider needs to grab those levers. Of course, there are limits, and it'd be silly to put a gigantic rotor on an ultralight XC bike, or on a bike that's not ever going to see steep terrain – it's all a matter of picking the right tool for the job. Plus, fork manufacturers typically have a maximum recommended rotor size that's worth keeping in mind.


Want your 29" wheels to look smaller? Try running a bigger rotor - that's Galfer's 246mm prototype pictured here.

All that being said, if 220mm rotors work well, why not go even bigger? That seems to be the route Galfer are taking - Baptiste Pierron was rocking a prototype super-sized 246mm front rotor last week in Vallnord. He's since downsized for Les Gets, where the real challenge is going to be resisting the urge to grab a little brake on the ridiculously high speed, open sections of the course. Val di Sole is the next race on the calendar, a rugged track full of boulders, roots, and plenty of sections where as much stopping power as possible will come in handy – it'll be interesting to see what solutions are employed to find the ideal balance between speed and control.


160 Comments

  • + 199
 I want to see how that 246mm rotor looks on a 26" bike.
  • + 7
 hell yeah
  • + 1
 god i thought the EXACT same thing i swear...lol
  • + 278
 If I do the maths right, I think it would look the same, but the rim would be a bit smaller.
  • + 71
 We could drop a 223mm Galfer rotor on a 26" dirt jumper and see how it looks, could be a sweet little project! What do you think?
  • + 9
 I'm so stoked to see rotors this big in general. More power, better heat dissipation, no BS with lever throws increasing abnormally. It is very much a case where more is more.
  • + 12
 Shhhhhesh, 26 is not dead!
  • + 2
 Time for 30” wheels. 700mm rim diameter.
  • + 5
 Just watch a 24" Trials-Bike with 200mm rotors and you have the looks. kinda.
  • + 1
 @MTBrent: tariffs and duties, all in?
  • + 4
 I wanna see the adapter
  • + 8
 Used to run a Hope 220 on my 26'er
  • + 8
 I'm running 558mm rotors on my 26" bike, gotta be careful making sharp left turns or you'll slice a tire!
  • + 3
 Look at Danny macs trials bike and you’ll get an idea
  • + 1
 @kathwill: same. I went from 200mm IS mount, to a post mount fork in 2009, so had to run the adapter which added 20mm. I think a lot of people wound up doing it when post mount forks became a thing.
  • + 4
 Yeah that's called a rim brake, bud.
  • + 14
 SRAM: We have done with the Eagle Cassettes, it's time for Eagle XX1 Rotor.
  • + 18
 Who remembers Buell motorcycles?
  • + 0
 @galferusa: Make sure you put it up front though. Makes an insta-endo machine.
  • + 0
 A front 246mm rotor would be good on these modern enduro bikes to balance out the satalite dish big cogs they have out back that are bigger than most rotors.
  • + 1
 Track some red Alpine rotor photos, they'll be on 26 wheels. It's quiet assuming. Would of been mid 2000s.
  • + 2
 @zsandstrom: danny mac runs disc brakes, bud.
  • + 1
 @kathwill: I had some 9" rotors on my big hit back in the day. With 24" wheels front and rear.
  • + 9
 Once upon a time, in a forgotten 1990's land that seems far, far away... Shimano had a twin-disc water-cooled prototype brake and Marzocchi Z1 forks had dual caliper lugs. Not saying they should be combined, just saying that MTB tech should take a hard look at moto tech once in a while... Dual-Disc SuperBoost130 front hub spacing, here we come!

ep1.pinkbike.org/p4pb17460529/p4pb17460529.jpg

ep1.pinkbike.org/p4pb17460528/p4pb17460528.jpg
  • + 4
 @WAKIdesigns: Come on, 26, 27.5, 29 --> 30.5! Its basic math...
  • + 1
 @vr6ix: I was just thinking about those Shimanos the other day. That whole dual disc with a central pad idea seemed great as it could give you 2x the power with the same lever effort, although I don't really see how you would adjust for wear in the central pad. I remember seeing articles about how pros (mainly Dave Cullinan) at the time were cutting grooves in their pads, or even soaking them in oil, to reduce the power, as they felt those brakes were too strong.
  • + 1
 @galferusa: absolutely !!!!!
  • + 1
 You could also cook a bacon egg and cheese on that rotor, thinking outside my box of eggs.
  • + 1
 @MTBrent: Your intellect is dizzying
  • + 1
 @jfcarrier: no. We must first release 32” wheel so that we then can motivate releasing 30.5” also known as 650mm. First metric wheelsize.
  • + 1
 @DC1988: rim mounted discs?
  • + 2
 Red Raven made 250mm rotors and adapters like 12 years or so ago. This isn't new at all. They were in the 26 inch days. Googling them might turn up some pics.
  • + 2
 @tomwhite1401: Yeah! The front brakes on Buells/EBR look sick.
  • + 127
 Maybe we could make the rotor as large as the wheel? Or even integrate the braking track to the rim itself? Now THAT is the future.
  • + 82
 They could even be cable actuated! No more bleeding!
  • + 6
 There was a trials bike back in the day that had the rotor bolted to the rim, and the brake caliper near the seat tube on the inside of the seat stay.
  • + 7
 That's crazy. Nobody could ever pull that off.
  • + 20
 @Connerv6: Buell motorcycles did it back in the day, I believe they're called perimeter brakes.

motociclo.endrakor.com/buell-front-brake
  • + 1
 @saminerilohi Hah, you stole my thunder. Rim brakes FTW.
  • + 2
 @NinetySixBikes: yep! Came on all the XBs for sure. Worked well supposedly.
  • + 1
 @NebulousNate: Never had a chance to ride one personally, was a cool looking piece of machinery for sure. But I'm not convinced that this would work equally as well on a MTB. You're putting your rotors very close to the ground and prone to all dirt, grit, rocks and whatnot. I recall riding my Trek 850 through wet grass and mud back in the early 90's and having absolutely no brakes left at the end of a 20 mile ride...
  • + 2
 @seraph: knew I'd seen this before, luckily I saved the post, I'll try to track down more info or a source of the image, but for now heres a shitty instagram repost www.instagram.com/p/BrS7jejh_NR/?igshid=8upqm84km0ir
  • + 1
 @seraph: The Risk. I remember that thing being posted on OTN years and years ago
  • + 30
 Whilst you torque about bigger rotors being better, I spun out the other week and had to be levered out of a ditch. Not after some chav had piston me. I stopped short of braking a bone, but nonetheless I rotor complaint to the manufacturer - I'm not usually an angry guy, but I reached my bite point. As an avid reader of your site, I feel that you pad your articles with compliments and synthetic arguments. I'm not skidding either, I hope that it stops here.
  • + 7
 Ok.
  • + 1
 underrated effort. +1 for mentioning Chav!
  • + 1
 Dude, you left us in the dust!
  • + 6
 bro, u hosed everybody else by taking all the good puns.
  • + 2
 Bro, do you even bleed?
  • + 15
 bring back hydro rim brakes! 29" rotors!
  • + 0
 Back? They've never been away. You just need a fork and frame that accepts them (V-brake mounts, FIRM-tech mounts or direct trials mounts).
  • + 13
 Just run double discs and calipers like on motorbikes.
  • + 3
 Cunningham Hydraulic Engineering, CHE?
The original Marzicchi Z1 had twin disc mounts, remember those?
You could run twin 160mm discs and have a symmetrical front wheel. You do need a different master cylinder though and double brake lines. Probably a bigger ball ache than just machining a new spacer and putting a bigger disc in. It would be cool to see some bespoke double discs though.
How about it @hopetech
  • + 1
 @jaame: Grimeca (with the really cool red brake calipers) also had levers that actuated both brakes. Or actually I think one lever actuated four pots in the rear and two (out of six) pots in the front. Then the other lever actuated the remaining four (out of six) pots in the front.
  • + 1
 Exactly what I was thinking. I've been wondering when this would trickle down to mountain bikes
  • + 1
 @jrcd: But, these were mountainbike disc brakes. Can't find anything about them now though. If I recall correctly, Grimeca also made the first SRAM (branded) four pot disc brakes, so from well before SRAM acquired Avid brakes.
  • + 1
 @vinay: Grimeca didn't do SRAM, they made the original Shimano Deore XT. The only differences were the Grimeca logo was cast into the caliper and used DOT fluid, while the Shimano caliper was machined flat with the logo engraved and used mineral oil. (Source: I ran the Shimanos and my friend liked the red Grimecas because red.)
  • + 1
 Not necessary for the dirt. You only see triple brake setups on street bikes, where high traction necessitate more cooling capacity. Even 450 motocross race bikes only have single front brakes, and with quite small rotors (~260-270mm).
  • + 1
 @CaMKii: I would be interested to see a graph showing the braking power for different sized discs, with single and twin plotted on the same graph.
Mx bikes have only single front discs, but they also have big fat back tyres with a lot of weight on them to slow down.
  • + 10
 One has to wonder what kind of strain that's putting on the brake mounts. Be it the fork post mounts themselves or the adapters.
  • + 8
 Doesn't matter. Locking up a wheel requires the same amount of torque on the mounts, regardless of the length of the lever arm used to achieve it.
  • + 3
 No kidding. I ripped the brake mounts off two frames in a row. (Cough, cough, Intense, cough).
  • + 2
 No more. In fact, possibly less. Bigger rotors don't actually allow more overall force, but instead just offer more cooling:
more material to spread the heat through. Because the lever arm (rotor edge to wheel edge) is smaller with a bigger rotor, less force on the rotor is needed to get the same torque at the rim. That translates to less force needed on the pads, which leads to less lever force needed, which again helps with heat, and greatly helps with arm\hand fatigue.
  • + 5
 Sounds like a job for a new brake mount standard. Unless you're anti progress.
  • + 1
 @just6979: larger rotor = more leverage resulting in greater torque to slow the wheel down with lesser pressure at the lever.
  • + 1
 Well I doubt that like the rest of us they will worry about voiding warranties on their bikes!
  • + 1
 @smuggly: 160mm XC brake in good shape can generate the maximum braking torque you can have. More than that at the rear and the tire lose grip (0.2-0.5 Gs max), more at the front and it's OTB fest (1-2 Gs max). So more powerful brake = less force at the lever, not more at the wheel.
  • + 2
 @faul: its been many years since I studied physics, but from memory the formula is torque = force on the rotor x distance / diameter of the rotor. Make the rotor larger you'll have more braking torque (nm) at the same pressure at the lever, if nothing else changes. Larger rotors make a more powerful brake? An XC brake with a 160mm rotor isn't stopping any one heavy and going hard.

Tyre grip is a separate issue, relating to surface area and friction.
  • + 0
 @smuggly: You can't have more braking force than you have friction or OTB limit.
Better brakes= less efforts at the lever, more heat resistance, but you can't have a more powerful brake than one making you do an OTB.
Any brake has to stop a 100kg mass with 1G deceleration, even V brakes, to be alowed in europe, so any brake can generate enough power if you pull enough the lever. more than 1G is enough for an OTB in many case, 2Gs is the maximum you can obtain with a really good braking technique, during less than a second.
  • + 1
 @faul: I agree with you don't have more friction with a larger rotor, in the equation friction = force, that remains constant for the same caliper, pads and rotor material/surface. I also agree that larger rotors with more mass tolerate sustained heavy braking better - heat is managed better.

However, if you increase the distance (rotor size) torque will increase in a linear relationship to the increase in rotor size, ie, 20% larger rotor will roughly equal 20% more braking torque - if you have the same level of force (friction) further from the rotation of axis, you have more braking torque.

Its exactly the same reason why riders are using bigger rotors in this article on 29'ers, more mass further from the axis of rotation requires more torque to decelerate it, hence a larger rotor does this as it provides greater torque with all other factors remaining the same.
  • + 3
 @faul:
Peer reviewed engineering paper highlighting rotor size and brake power.

www.sensorprod.com/news/white-papers/2010-03_ctb/wp_ctb-2010-03.pdf

Larger the rotor, the greater the braking force.

Larger rotors (203mm) will also provide the same braking force as a 160mm rotor at less than half less lever pressure.
  • + 1
 @smuggly:
You don't understand.
If you brake harder than 1G (9.81m/s) more than a few tenth of a second, you crash. It's the ultimate limit of physics you can't best. The first graph of your link shows accelerations under 10m/s except for a small peak.
More powerful brake = you pull less hard to obtain the same braking force. you won't ever have more braking force.
If a brake can't generate the torque for a 1G deceleation of a 100kg mass, it can't be sold in europe Norm should be around the same values in the rest of the world. Any brake you can buy is powerfull enough if you pull the lever enough, to make an OTB at every corners. Only difference is lever feel and consistency.
  • + 1
 @faul: Agree with you, the limit is the force that can be transmitted between the tire and the ground.
What I don't get in the article is the "bigger wheels need bigger rotors"
  • + 4
 @Whipperman: If you used the radius ow the wheel as one arm of a lever and the radius of the rotor as the other arm, you'd have a fairly simple lever. By increasing the radius of the wheel, you change the leverage ratio. To achieve the same lever feel, you'd need a bigger rotor to match the leverage.
  • + 2
 @smuggly: the lever isn't rotor to axle, it's rotor to tire. A bigger rotors on a 29er is helpful because the tire is further from the rotor, thus increasing the force needed at the rotors, thus increasing force needed at the lever, given same size rotor as a smaller wheel. The extra mass of a 29er wheel and tire is less significant than the longer lever.
  • + 1
 @smuggly: that xc brake with a 160 rotor will stop anybody, it will just require more lever force to do it.
  • + 1
 @just6979: No, its rotor to axle, ^ see above for the formula. Wheel size relates to the moment of inertia (I = Σ miri2) the greater the mass and the further that mass is from the AXLE increases the moment of inertia. Therefore you need a larger rotor, which has a longer moment arm from the axle, to create greater breaking torque. A 160mm XC will not stop anyone in a timely manner, who is heavy, going hard, Heavy DH casings on a large wheel.
  • + 2
 @smuggly: socratic.org/questions/how-do-you-increase-the-mechanical-advantage-of-a-third-class-lever

"Answer: By decreasing the distance between the Effort and Load Points."

axle = fulcrum
brake = effort
tire = load

bigger rotor = shorter distance between brake (effort) and load (tire)

Rim brakes are almost 1:1, since the brake is very close to the tire, making the effort to load distance very small. That's why that even though the mechanical advantage of hydraulics isn't there*, Rim brakes don't require super human lever forces (if the rim is clean, but that's another story).

A 160mm XC brake can certainly stop any rider, it's just a matter of lever input, and with the mechanical advantage of the hydraulics almost anyone can squeeze even something like a SRAM Level hard enough to lock the wheel. The problem would be that pulling the lever that hard for long periods of time would cause enormous arm pump, and the smaller rotor area would heat up faster and cool down slower. A bigger rotor (shorter effort to load distance) requires less brake force (AKA effort), which leads to less lever force needed, which means less arm pump from braking. And larger rotor area can better handle the heat.

* (except of course with hydraulic rim brakes, which any trials rider would tell you are still the most powerful type of brakes as long as the rim is clean)

** And yes, rotational inertia of the wheel itself is greater, but that's still a relatively small bit of the total inertia of the entire bike and rider.
  • + 8
 What..... what do you mean, when you say we do not have a standard for disk brakes?!?
Wait until Stam hears about it. They will dub the 203.9 rotor size as the new trend on stiffness and braking power.
We are doomed....
  • + 0
 Sram* I mean
  • + 33
 @pellegrinimtb: I prefer Stam
  • + 2
 Careful what you wish for
  • + 1
 they already have the 200 vs 203mm nonsense
  • + 19
 @hamncheez: that's your countries fault with your illogical refusal to adopt the superior metric system.
  • + 3
 @inked-up-metalhead: check out the big brain on Brett!
  • + 6
 What's up with the stupid sizes: 223, 246? 223 is 20 more than 203, but 246 is 23 more than 223. Unless they're going 23 more than 200, but 200 is only 20 more than 180. And then there is 185, which was the old inch-fraction approximation of 7-1/4 inches ) to go with 203's 8 inches.

Actually have to hand it to SRAM here for just switching to even 20mm jumps (though there also was 170mm for a hot minute) across the range: 140, 160, 180, 200, 220; and just ignoring the old inch-approxiamations. And not making a big fanfair about it.
  • + 3
 Maybe they can now use the same adaptor that's being used for running a 203mm rotor with a fork with 6" PM mounts. Probably if you'd bolt these to a fork with 8" PM, you can fit a 246mm rotor. These are not radial mounts like Hope uses on their own frame (for the rear brake) so the geometry is slightly different and you can't stack as if it were a radial mount.
  • + 12
 If you guys did away with your imperial System we could all be fine with even numbers.
  • + 9
 Just remember buell motorcycles
  • + 6
 I've been saying it for years, but no one listens. Brakes are overrated! All they do is slow you down.
  • + 0
 So why did Gwin lose World Champs when his brakes failed?
  • + 6
 I like big rotors and I cannot lie.
  • + 2
 The mounting of any rotor diameter can be derived quickly and easily. Teams are using some pretty silly adapters here.

www.peterverdone.com/wp-content/uploads/2018/06/2018-07-13-PVD-Shimano-PM-System.png

www.peterverdone.com/disc-brake-mounting-systems
  • + 2
 Having maximum braking power requiring least amount of finger strength is just a no brainer. And the more you brake ( like we amateurs tend to do) the bigger the benefits are via less arm pump. It's so hard for us humans to be open minded for new ideas.
  • + 1
 I think you mean frame manufacturers, not fork, have a max rotor size, and that's due to frame clearances, not brake forces. Again, even a 140 rotor can lock up a wheel under the biggest riders out there, it just takes more lever force, and in fact puts _more_ force through the caliper and mounts, because the lever arm from rotor to tire is much bigger.
  • + 2
 I remember back when I went to les gets many many years ago. Hope 6ti brakes, 40's with 225 rotor and high rise bars on my vpfree. Minions too and mallet dh pedals and an air shock. Some things come full circle.
  • + 1
 I would be totally into buying bigger thicker rotors! Hand/arm pump is one of the biggest limiting factors to riding long fast steep rough trails for me.

Anyone do the math? How much additional brake power does 220mm and 240mm offer over 203mm?
  • + 3
 Torque is a linear funktion of leverage, so the same amount as 223 is bigger than 203: about 11% stronger + more heat capacity and -transfer which is harder to calculate.
  • + 2
 Using the macdonalds system or metric?
  • + 1
 That galfer rotor looks to be just an enlarged version of already existing designs, and the brake pad height is now too small to use the whole braking surface?

Otherwise, good idea before experimenting with Shigura combinations or shelling out $$$ for a Trickstuff brake.
  • + 1
 It is all getting back to the roots. Next stop is
re-inventing V-brakes (this time oil-runned calliper surrounding the tyre) but insted of rubber we will use resin or metal discs/rim pads... in this case the disc diameter will be astonishing 29' or 27.5'
  • + 1
 Bought Clark's floating rotors as an upgrade............IDK, they look nice, but the back one often seems to be rubbing, which I thought was the whole point of floating rotors.
  • + 4
 Only a bit of real world experience with them on my end but, I think truly floating rotors, which actually have side to side play between the inner stricture and outer friction ring, are guaranteed to drag lightly somewhat frequently, but won't drag hard much at all. In contrast, non floating rotors can be set up to run drag free most of the time, but when they get really hot they can drag much harder than the equivalent floating model will.

The situation is further complicated by some companies that make rotors that they call "floating" but which have very little play between the inner spider and outer friction ring.
  • + 2
 we need a dual rotor, quad caliper setup! 1 rotor on each side of the wheel, as well as a caliper on both the front and back of the forks for maximum braking performance
  • + 1
 There was a picture of a bike with Dual Zee calipers on the front in pb, from a cycle Show if i remember correctly.
  • + 4
 Or they could bring back the caliper, Vbrakes and call it a day!
  • + 2
 Gustav M with 210mm disc, it was in 2007 and still running... Nothing new about bigger disc, but forks ans frames, can they handle it ????
  • + 1
 All Magura forks (even the lightest XC forks) were designed to accept brake rotors up to 210mm. And that wasn't just the Gustav brake. You could use a regular rear brake IS caliper and mount it in the front with the appropriate adaptor (adaptor 16 if iirc) you could also run the 210mm rotor. Magura Louse FR was sold as such. They quit doing this when PM took over simply because most other fork manufacturers wouldn't accept 210mm rotors. 203mm was the max for most, often even smaller for XC. I wonder now whether other fork manufacturers have dropped this size limit. If the audience sees their SRAM sponsored hero run 246mm rotors on the Boxxer forks, they'll want this too. And it won't be long until other third party component manufacturers start making after market adaptors and rotors in even bigger sizes. If you've got access to a CNC machine and a laser cutter, it doesn't take much to make them bigger and thicker. "We're making the stuff that allows you and other progressive riders to push the limits of the sport. Join the revolution!" Alright, I'm progressive and all that, take my money. Helmet manufacturers will step up with even bigger chin bars.
  • + 3
 Hope has had 225 rotors and their 203 double wide vented rotors for years now.
  • + 2
 As a kid, I saw a prototype bike where the rim had a just under 26" rotor attached to it. Everything else looked tiny since...
  • + 4
 Nice innovation SRAM...*slow clap while watching squirrel eating nuts*
  • + 0
 The caliper in the first picture is horribly misaligned. Looks like maybe a 220mm rotor with a 225 mount. That combo probably isn't going to be very helpful. Especially when the pads wear enough that the parts not touching the rotor can touch each other. Then no matter how hard you squeeze, you ain't slowing down.
  • + 1
 Disc says 246mm.
  • + 2
 Maybe the SRAM brakes are shit?!

The Shimano riders seems to don't need bigger Rotors
  • + 1
 Agreed, Sram is fine for a lot of pedal trails, but once your start riding lift stuff, you'll pull tendons and get overuse injuries in your hands.... as you'll find yourself not stopping and the adrenalin is making you pull harder then you should be.
  • + 1
 Maybe shimano brakes are hard to control with bigger rotors?
  • + 1
 All sram brakes I have ever owned or tried have been less than impressive or shit. And the centreline discs they w*nk on about are awful, they dont have stopping power, put a groove in the pads and squeal in the wet, sorry, that is just the way it is.
  • + 3
 Where's Friday Fails?????
  • + 8
 in les gets
  • + 14
 in yer pants
  • + 1
 @endlessblockades: still hurt that I didn't have an erection on you?
  • + 3
 @ilyamaksimov: My comment was a reply to foolcyclist, but I cause no men to experience a boner.
  • + 1
 @endlessblockades: We Don't Do That Here
  • + 1
 Hurry up and make these available to the public (at a mass market level). I am 220lbs and would love some more powerful braking without having to upgrade my calipers!
  • + 3
 You can already order the 223 Galfers from their website. As long as you have 180 post mounts, the 160-203 adapter is all you need.
  • + 1
 Right. Hope 225mm work well with a Galfer adapter and two washers too.
  • - 1
 Just get saints, you'll never look back. Im around 250lbs and can stop from around 20mph in about 30ft. Good pads and 200mm rotors help but it's definitely the saints that get the credit.
  • + 3
 They won't give you more power unless there is something limiting the force you can put into the levers. Big rotors don't increase overall braking power, but do decrease input force needed for the same overall braking power.
  • + 0
 @inked-up-metalhead: on flat ground. Good job, but people are worried about the steeps.
  • + 1
 @Muckal: they're still some of the most powerful brakes on the market so yeah...
  • + 1
 @inked-up-metalhead: no doubt about that. Still, in my mind people are worried about not being able to stop in any situation there might be. Most people, like me, do not have a problem with their brakes being so weak but with their braking being executed poorly.
  • + 2
 @inked-up-metalhead: it also depends quite a lot on wheel size. On 26" i'm fine with XTs on 203 rotors, on the 29" i'll go with V4s on 203 rotors. I'm 185-190lbs.
  • + 1
 @inked-up-metalhead: I was fine with 200mm rotors on 26" wheels for many years.

Only now with the higher rotational momentum (don't know if that is the right term) of the 29er wheels with heavy tires I found the 225mm rotor to be beneficial.
  • + 2
 Almost 15 years ago galfer sold 10inch rotors and adapters nothing new here. Just hype
  • + 4
 I want Dual brake rotors
  • + 1
 If I had a Hub-discs factory I'll made special mount hubs for 203 (and larger) discs, still can't get 203 discs had the same mount for 140 sized discs
  • + 4
 What makes Dan so Dirty?
  • + 1
 Dirt.
  • + 1
 Running Formula's new 220mm Monolithic rotors... the brakeing power with the 2-pot Cura's is massive.
  • + 1
 Have you ever seen a Buell? The rotor is almost the size of the rim. What's next mixed Wheels like the MX world LOL
  • + 1
 Why are there both 200 and 203mm rotor sizes? Why doesn't the bike industry choose one?
  • + 1
 203 because 8 inches, 200 because metric is superior, but some people refuse to change to the superior system.
  • + 1
 @Pavel-Repak: Ah... but why is Sram using 200 and Shimano using 203, while Sram is American and Shimano is Japanese? I would expect it to be the other way around, with Sram sticking to 203 because they're American.
  • + 1
 @cedrico: because the grass is always greener on the other side. My German Magura’s are 203 on the front, 180 on the rear. It doesn’t even bother me a bit.
  • + 1
 From what I learned from phub, there's no such thing as the right tool(s) for the job.
  • + 1
 I had my first 220mm hope rotor in 2005. It was the only way to mount hope m4’s on a first gen fox 40.
  • + 1
 Like big brakes are new..... Fox 40‘s had it down with hope‘s years ago on 26“ wheels.
  • + 1
 I’ve found rotors that the Tandem riders are using as big as 250mm!
  • + 1
 Brakes only slow you down
  • + 1
 Formula and hope have had 220 mm rotors for about 10 years.....
  • + 1
 Until they got to 2 piece floating rotors that size, I'll stick with 203s
  • + 1
 soon enough their going to start putting calipers on the rims! -oh wait.
  • + 1
 Is it safe to put a 220mm Rotor on a Fox 49?
  • + 7
 Course not! it will explode and release radioactive particles all over the place

Smile
  • + 1
 yes a 10mm Adapter wont break it. Wink I might give it a try.
  • + 1
 radial mount disc brakes are next
  • + 1
 Hope already showed them on their HB bike. Neeeext...
  • + 1
 My pussy fingers say not big enough
  • - 1
 Big rotors equals better modulation BTW not less.

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