Interesting! I've a few friends riding fatties on A2s and no issues to speak of. Hayes have a 2yr warranty so the other brake (I think)...
Interesting! I've a few friends riding fatties on A2s and no issues to speak of. Hayes have a 2yr warranty so the other brake (I think) should still be under warranty. I wouldn't think the onus of a rebuild would be on you.
Yes it would also be covered but that would have me out of a brake for maybe 2-3 days while the shop submits warranty claim etc. It took me a short drive and $34 CAD to get the rebuild kit and 1 hour of labour to fix it. Good to know your friends' A2s are going well. Maybe just crappy luck on my end. I'll give them another shot.
The numbers are promising it could possibly be the most powerful brake so far Curious about the aluminum pistons tho, they should transfer lots of heat to...
The numbers are promising it could possibly be the most powerful brake so far
Curious about the aluminum pistons tho, they should transfer lots of heat to the pads 🧐 but I’m sure they know what they’re doing.
Regardless, I’m curious what kind of price and claim they will give us
wouldn't the opposite be true as well? that the pad will be better coupled with the caliper body for better heat dissipation? this could also lead to overheating the fluid i suppose...
The heat in the brakes is coming from the pad/ rotor contact. Aluminum pistons could transfer that heat to the caliper/ fluid. The caliper hopefully is designed to handle/dissipate that heat.
My car has Brembo brakes and they are super easy to work on, I hope that carries over to their MTB brake designs.
Absolutely! That part excites me. I am just eager/optimistic about their take on things and how they may perform. Aluminum pistons will be interesting but at least...
Absolutely! That part excites me. I am just eager/optimistic about their take on things and how they may perform.
Aluminum pistons will be interesting but at least they do have a pretty solid background with high performance brakes so we shall see...
Price has me on my toes however based off their original take 20 ish? years ago.. ha.
But I would assume around the $1,000 realm.
I am excited to try them and hope they become available soon.
The main issue is, regardless of the performance, if they price them at 1k other than to fanboys they’ll be hard to sell, the ugliness is unreal for the brand, compare them to Hope/Intend/Trickstuff and others in the price range, these are in the same aesthetic level of TRPs at best
Aluminium pistons? That's a surprise, I thought manufacturers wanted to isolate the heat from the rotor from the fluid in the caliper (ceramic, steel, phenolic, ...), but with aluminium, that would be kind of the opposite?
But we learn it's a 9mm MC piston and 4x18mm caliper, which should be on the higher end of power (just accounting the hydraulic ratio)
Aluminium pistons? That's a surprise, I thought manufacturers wanted to isolate the heat from the rotor from the fluid in the caliper (ceramic, steel, phenolic, ...)...
Aluminium pistons? That's a surprise, I thought manufacturers wanted to isolate the heat from the rotor from the fluid in the caliper (ceramic, steel, phenolic, ...), but with aluminium, that would be kind of the opposite?
But we learn it's a 9mm MC piston and 4x18mm caliper, which should be on the higher end of power (just accounting the hydraulic ratio)
It’s the highest so far, higher than the mavens. One thing to keep in mind is that regardless of how much heat is being transferred to the fluid, hydraulic fluid, like dot or petroleum based mineral fluid, those fluids have some of the lowest thermal conductivity of any component in the brake system. It’s an order of magnitude lower than that of SS or AL. It’s going to take more BTU’s than one would ever be able generate in a mtb brake system to get any fluid to boil, especially under pressure, when the brake are applied. I can’t remember off the top of my head but DOT fluid at 1500 psi has a boil temperature of well over 800°F, or something similar to that, feel free to fact, check me I could be off. There’s not enough mass in a mountain bike brake system to sustain those system temperatures after someone lets off the brakes when the pressure subsides. Thermal degradation near the boil point is a completely different story, that is one area where DOT fluid has the upper hand compared to mineral oil.
Aluminium pistons? That's a surprise, I thought manufacturers wanted to isolate the heat from the rotor from the fluid in the caliper (ceramic, steel, phenolic, ...)...
Aluminium pistons? That's a surprise, I thought manufacturers wanted to isolate the heat from the rotor from the fluid in the caliper (ceramic, steel, phenolic, ...), but with aluminium, that would be kind of the opposite?
But we learn it's a 9mm MC piston and 4x18mm caliper, which should be on the higher end of power (just accounting the hydraulic ratio)
It’s the highest so far, higher than the mavens. One thing to keep in mind is that regardless of how much heat is being transferred to...
It’s the highest so far, higher than the mavens. One thing to keep in mind is that regardless of how much heat is being transferred to the fluid, hydraulic fluid, like dot or petroleum based mineral fluid, those fluids have some of the lowest thermal conductivity of any component in the brake system. It’s an order of magnitude lower than that of SS or AL. It’s going to take more BTU’s than one would ever be able generate in a mtb brake system to get any fluid to boil, especially under pressure, when the brake are applied. I can’t remember off the top of my head but DOT fluid at 1500 psi has a boil temperature of well over 800°F, or something similar to that, feel free to fact, check me I could be off. There’s not enough mass in a mountain bike brake system to sustain those system temperatures after someone lets off the brakes when the pressure subsides. Thermal degradation near the boil point is a completely different story, that is one area where DOT fluid has the upper hand compared to mineral oil.
I wondered about the temperatures of brake fluid in mtb brakes. It's easy to get DOT fluid with dry boiling points around 600°F, wet boiling point usually drops to mid 400°F. Is the brake fluid (not discs/pads) in MTB disc brakes approaching those temps?
I wondered about the temperatures of brake fluid in mtb brakes. It's easy to get DOT fluid with dry boiling points around 600°F, wet boiling point...
I wondered about the temperatures of brake fluid in mtb brakes. It's easy to get DOT fluid with dry boiling points around 600°F, wet boiling point usually drops to mid 400°F. Is the brake fluid (not discs/pads) in MTB disc brakes approaching those temps?
Well, if they were that hot Magura brakes would be exploding left, right and central. Royal blood has boiling point of 100c or so 🤷🏻
I wondered about the temperatures of brake fluid in mtb brakes. It's easy to get DOT fluid with dry boiling points around 600°F, wet boiling point...
I wondered about the temperatures of brake fluid in mtb brakes. It's easy to get DOT fluid with dry boiling points around 600°F, wet boiling point usually drops to mid 400°F. Is the brake fluid (not discs/pads) in MTB disc brakes approaching those temps?
Aluminium pistons? That's a surprise, I thought manufacturers wanted to isolate the heat from the rotor from the fluid in the caliper (ceramic, steel, phenolic, ...)...
Aluminium pistons? That's a surprise, I thought manufacturers wanted to isolate the heat from the rotor from the fluid in the caliper (ceramic, steel, phenolic, ...), but with aluminium, that would be kind of the opposite?
But we learn it's a 9mm MC piston and 4x18mm caliper, which should be on the higher end of power (just accounting the hydraulic ratio)
It’s the highest so far, higher than the mavens. One thing to keep in mind is that regardless of how much heat is being transferred to...
It’s the highest so far, higher than the mavens. One thing to keep in mind is that regardless of how much heat is being transferred to the fluid, hydraulic fluid, like dot or petroleum based mineral fluid, those fluids have some of the lowest thermal conductivity of any component in the brake system. It’s an order of magnitude lower than that of SS or AL. It’s going to take more BTU’s than one would ever be able generate in a mtb brake system to get any fluid to boil, especially under pressure, when the brake are applied. I can’t remember off the top of my head but DOT fluid at 1500 psi has a boil temperature of well over 800°F, or something similar to that, feel free to fact, check me I could be off. There’s not enough mass in a mountain bike brake system to sustain those system temperatures after someone lets off the brakes when the pressure subsides. Thermal degradation near the boil point is a completely different story, that is one area where DOT fluid has the upper hand compared to mineral oil.
I wondered about the temperatures of brake fluid in mtb brakes. It's easy to get DOT fluid with dry boiling points around 600°F, wet boiling point...
I wondered about the temperatures of brake fluid in mtb brakes. It's easy to get DOT fluid with dry boiling points around 600°F, wet boiling point usually drops to mid 400°F. Is the brake fluid (not discs/pads) in MTB disc brakes approaching those temps?
I don't have any data right now to say one way or another but my gut is telling me no. What I do know is that boiling temp increases pretty significantly based on the pressure that the fluid is it. I have heard engineers in the industry stating that line pressures are over 1000psi for peak braking events, that's 68X more pressure than the atmospheric pressure of 14.7 psi that the boiling point it rated at, but that's all the data that I have to go off of, I don't have extra any inline wireless pressure transducers lying around at the moment to corroborate this
I do have an array of thermal stickers that I was planning on placing on my rotors and calipers this last weekend to see how hot they get doing some practice runs for a DH race coming up later this month, but I got lost in the weekend and forgot to stick them on. Will make sure to do it the Thursday before I pack up for the race.
The way I look at it, even if we took the pressure out of the equation, our brake fluids have thermal conductivities of around .13W/m·K which makes them very good insulators. It will take a lot of sustained heat to actually get the fluid up to the temp of the caliper, which is probably why Brembo has no issue using Al pistons, I would bet that they have not only run the CFD simulations but also performed a significant amount of lab testing to back up their decisions. If I have some time I'll try to setup something simple in comsol to simulate the amount of thermal energy needed to heat a mineral oil to its boiling point, and maybe try to add pressure into the equation, could be a fun thought experiment.
Few years ago there was a boiling point chart at epic bleed kits website, where Magura royal blood was measured at 99C with every other fluid measured at well above 200C. They have since changed the formulation I guess, before they weren't even publishing these data at all. Anyway, even for quite steep dh tracks like schladming I wasn't getting caliper temp too hot to touch, so I would be surprised if brake with phenolic pistons or similar would be heating fluid much higher than that 100c point. Brake disc? Sure, those get very hot, pads obviously too. But there doesn't seem to be that much heat transfer to the caliper/ fluid and most heavy lifting is done on disc side. I deleted original comment because the chart that is now published at epic bleed kits used new Magura fluid with boiling point at much more normal value.
My m8000 brake lever on the xt 4 pots (same design as zre/saint) has developed a weird issue since installing the brake on a bike with a complete refill and changing a bent lever.
I bled them multiple times and the bleed seems to be fine but the bite point is somehow too close to the bar. If I push the lever outwards it suddenly shifts into a position where the bite point should be and everything is alright.
Hut when I ride it seem the nite point slowly goes back closer to the bar. Not indefinitely, it feels firm like not like air is inside but it's not far away enough from the bar. When the bike stands the bite point is fine again.
Does this mean some seal is blown? These guys are 6 years old so it might be time to get new brakes but I can't decide.
Dominion A4 sounds like what I want but they won't fit the internal cable routing and I would need to change hoses, switch to dot etc.
Anyone can compare the dominion to the shigura? I'm riding those too.
I don't have any data right now to say one way or another but my gut is telling me no. What I do know is that...
I don't have any data right now to say one way or another but my gut is telling me no. What I do know is that boiling temp increases pretty significantly based on the pressure that the fluid is it. I have heard engineers in the industry stating that line pressures are over 1000psi for peak braking events, that's 68X more pressure than the atmospheric pressure of 14.7 psi that the boiling point it rated at, but that's all the data that I have to go off of, I don't have extra any inline wireless pressure transducers lying around at the moment to corroborate this
I do have an array of thermal stickers that I was planning on placing on my rotors and calipers this last weekend to see how hot they get doing some practice runs for a DH race coming up later this month, but I got lost in the weekend and forgot to stick them on. Will make sure to do it the Thursday before I pack up for the race.
The way I look at it, even if we took the pressure out of the equation, our brake fluids have thermal conductivities of around .13W/m·K which makes them very good insulators. It will take a lot of sustained heat to actually get the fluid up to the temp of the caliper, which is probably why Brembo has no issue using Al pistons, I would bet that they have not only run the CFD simulations but also performed a significant amount of lab testing to back up their decisions. If I have some time I'll try to setup something simple in comsol to simulate the amount of thermal energy needed to heat a mineral oil to its boiling point, and maybe try to add pressure into the equation, could be a fun thought experiment.
We plumbed a pressure gauge in line with some Code RSCs back in the day. You can easily hit 3000 psi yanking on the lever. That would be hard to see on the trail of course, but pressures are definitely higher than most assume.
The bigger limit when it comes to piston temp is more likely to be the seals. The max temp of EPDM isn't that high (about 300F). You could do some fluorinated material like FFKM to get higher temp ratings on your seals, but that's expensive. Brembo refers to their pistons as "isolated" aluminum. What I read into that is some sort of insert to insulate the rest of the caliper. The name of the game usually is keep heat out of the caliper. I've seen plenty of caliper bodies get hot enough to boil water off very quickly even with phenolic or ceramic pistons and rotor temps north of 500F. The fluid volume in the caliper isn't very large so not much heat capacity.
I don't have any data right now to say one way or another but my gut is telling me no. What I do know is that...
I don't have any data right now to say one way or another but my gut is telling me no. What I do know is that boiling temp increases pretty significantly based on the pressure that the fluid is it. I have heard engineers in the industry stating that line pressures are over 1000psi for peak braking events, that's 68X more pressure than the atmospheric pressure of 14.7 psi that the boiling point it rated at, but that's all the data that I have to go off of, I don't have extra any inline wireless pressure transducers lying around at the moment to corroborate this
I do have an array of thermal stickers that I was planning on placing on my rotors and calipers this last weekend to see how hot they get doing some practice runs for a DH race coming up later this month, but I got lost in the weekend and forgot to stick them on. Will make sure to do it the Thursday before I pack up for the race.
The way I look at it, even if we took the pressure out of the equation, our brake fluids have thermal conductivities of around .13W/m·K which makes them very good insulators. It will take a lot of sustained heat to actually get the fluid up to the temp of the caliper, which is probably why Brembo has no issue using Al pistons, I would bet that they have not only run the CFD simulations but also performed a significant amount of lab testing to back up their decisions. If I have some time I'll try to setup something simple in comsol to simulate the amount of thermal energy needed to heat a mineral oil to its boiling point, and maybe try to add pressure into the equation, could be a fun thought experiment.
We plumbed a pressure gauge in line with some Code RSCs back in the day. You can easily hit 3000 psi yanking on the lever. That...
We plumbed a pressure gauge in line with some Code RSCs back in the day. You can easily hit 3000 psi yanking on the lever. That would be hard to see on the trail of course, but pressures are definitely higher than most assume.
The bigger limit when it comes to piston temp is more likely to be the seals. The max temp of EPDM isn't that high (about 300F). You could do some fluorinated material like FFKM to get higher temp ratings on your seals, but that's expensive. Brembo refers to their pistons as "isolated" aluminum. What I read into that is some sort of insert to insulate the rest of the caliper. The name of the game usually is keep heat out of the caliper. I've seen plenty of caliper bodies get hot enough to boil water off very quickly even with phenolic or ceramic pistons and rotor temps north of 500F. The fluid volume in the caliper isn't very large so not much heat capacity.
Great to know! Thats a good point about seal temp, EPDM does have a very low melt temp depending on the amount of polymeric cross-linking. As someone who has designed brakes, have you spent much time using seals in DOT applications outside of the run-of-the-mill mcmaster epdm? I have worked with o-ring molders that had some interesting grades of EPDM and FKM as well with much higher Tg temps than typical commodity grade materials.
Kalrez is guccci stuff, you get the compliance of EPDM, chemical resistance of PTFE and the gas permeability of ETFE all for the low price of $60 an o-ring
Figured this would be the place to ask. Hope I don't derail the brake fluid/pressure bit you guys are on.
Looking at the new unreleased shimano brakes a few people are running got me thinking. I know some of you are running shiguras, but has anyone done a mavano setup? XT/XTR levers to a maven caliper? My bike came with the base as Maven bronze brakes and they feel great. But others have stated that these levers are easier to pull then the silver / ultimate levers. So just wondering if anyone has done any tinkering.
You mean the maven bronze levers are easier to pull or the new shimano levers?
Never saw a shimano/maven combo but on the german forum someone is already using the new xtr lever for a shigura setup. He's saying that the new levers have a bigger oil reservoir so they are better suited for the shigura mod. He's running them with Bionol and says they have a light lever feel.
The new xt levers come with a du bushing and no bearing in the lever though. I'm also interested in the new shimano brakes but complete shimano sounds a bit underwhelming from the reviews.
Great to know! Thats a good point about seal temp, EPDM does have a very low melt temp depending on the amount of polymeric cross-linking. As...
Great to know! Thats a good point about seal temp, EPDM does have a very low melt temp depending on the amount of polymeric cross-linking. As someone who has designed brakes, have you spent much time using seals in DOT applications outside of the run-of-the-mill mcmaster epdm? I have worked with o-ring molders that had some interesting grades of EPDM and FKM as well with much higher Tg temps than typical commodity grade materials.
Kalrez is guccci stuff, you get the compliance of EPDM, chemical resistance of PTFE and the gas permeability of ETFE all for the low price of $60 an o-ring
Run of the mill McMaster stuff is 250F I believe. 300F is cured a little differently. That's what we were using. Did variation of FKM in the mineral oil brakes that was supposed to be compatible with DOT as well, but it swelled just enough to cause issues unfortunately.
You mean the maven bronze levers are easier to pull or the new shimano levers? Never saw a shimano/maven combo but on the german forum someone is...
You mean the maven bronze levers are easier to pull or the new shimano levers?
Never saw a shimano/maven combo but on the german forum someone is already using the new xtr lever for a shigura setup. He's saying that the new levers have a bigger oil reservoir so they are better suited for the shigura mod. He's running them with Bionol and says they have a light lever feel.
The new xt levers come with a du bushing and no bearing in the lever though. I'm also interested in the new shimano brakes but complete shimano sounds a bit underwhelming from the reviews.
Supposedly the bronze levers are easier to pull the the silver/ultimate versions. It seems like the biggest criticism the mavens have received is that the levers are too hard to pull. So I was wondering if anyone had played with mixing levers now that SRAM is all mineral oil at this point. That said my bronze ones are fine and I doubt the ultimates are that much harder to pull.
They all got updated, The bases are excellent in this regard aswell. Bases are very underrated, excellent brake, using 220 F and 200R on my DH bike an im 100kg. love it.💪
Hey all, can anyone help with a huge dilemma I’m having? I currently run code rsc with 223mm galfer wave and galfer purple pads. These work...
Hey all, can anyone help with a huge dilemma I’m having? I currently run code rsc with 223mm galfer wave and galfer purple pads. These work great and tend to not over heat too badly for me, I also really like the lever feel. However I’m a big guy at 6’4” and 250lbs so have been looking at either some maven ultimates or hope T4V4 for more power, hopefully keeping a similar lever feel in terms of modulation. I’m UK based, but do a fair amount of uplifted riding in the UK and Europe. At this point I’m going round in circles trying to decide which way to go, hope or sram. Can anyone help me out who has tried both brakes? thanks
Why change brakes if they're working great? From your post: "These work great and tend to not over heat too badly for me, I also really like the lever feel." Seems like they're perfect for you.
Hey all, can anyone help with a huge dilemma I’m having? I currently run code rsc with 223mm galfer wave and galfer purple pads. These work...
Hey all, can anyone help with a huge dilemma I’m having? I currently run code rsc with 223mm galfer wave and galfer purple pads. These work great and tend to not over heat too badly for me, I also really like the lever feel. However I’m a big guy at 6’4” and 250lbs so have been looking at either some maven ultimates or hope T4V4 for more power, hopefully keeping a similar lever feel in terms of modulation. I’m UK based, but do a fair amount of uplifted riding in the UK and Europe. At this point I’m going round in circles trying to decide which way to go, hope or sram. Can anyone help me out who has tried both brakes? thanks
Why change brakes if they're working great? From your post: "These work great and tend to not over heat too badly for me, I also really...
Why change brakes if they're working great? From your post: "These work great and tend to not over heat too badly for me, I also really like the lever feel." Seems like they're perfect for you.
That is a very fair question! I think I’m just aware that when I got the codes, they were about the most powerful brakes I could easily find, but things have moved on, and being a larger guy I’m very curious to try something new. Also codes were originally on a sentinel, I’m now on a spire and riding a chunk faster
Hey all, can anyone help with a huge dilemma I’m having? I currently run code rsc with 223mm galfer wave and galfer purple pads. These work...
Hey all, can anyone help with a huge dilemma I’m having? I currently run code rsc with 223mm galfer wave and galfer purple pads. These work great and tend to not over heat too badly for me, I also really like the lever feel. However I’m a big guy at 6’4” and 250lbs so have been looking at either some maven ultimates or hope T4V4 for more power, hopefully keeping a similar lever feel in terms of modulation. I’m UK based, but do a fair amount of uplifted riding in the UK and Europe. At this point I’m going round in circles trying to decide which way to go, hope or sram. Can anyone help me out who has tried both brakes? thanks
Why change brakes if they're working great? From your post: "These work great and tend to not over heat too badly for me, I also really...
Why change brakes if they're working great? From your post: "These work great and tend to not over heat too badly for me, I also really like the lever feel." Seems like they're perfect for you.
That is a very fair question! I think I’m just aware that when I got the codes, they were about the most powerful brakes I could...
That is a very fair question! I think I’m just aware that when I got the codes, they were about the most powerful brakes I could easily find, but things have moved on, and being a larger guy I’m very curious to try something new. Also codes were originally on a sentinel, I’m now on a spire and riding a chunk faster
Being 175lbs riding weight myself I feel I can benefit from stronger brakes than the codes, so it’s definitely worth it to get something more powerful.
A colleague of mine always thought his guides ultimate were enough at 230lbs
They all got updated, The bases are excellent in this regard aswell. Bases are very underrated, excellent brake, using 220 F and 200R on my DH bike...
They all got updated, The bases are excellent in this regard aswell. Bases are very underrated, excellent brake, using 220 F and 200R on my DH bike an im 100kg. love it.💪
You mean there was a running change and the levers now can be pulled easier?
They all got updated, The bases are excellent in this regard aswell. Bases are very underrated, excellent brake, using 220 F and 200R on my DH bike...
They all got updated, The bases are excellent in this regard aswell. Bases are very underrated, excellent brake, using 220 F and 200R on my DH bike an im 100kg. love it.💪
You mean there was a running change and the levers now can be pulled easier?
it was reported on the other site at some point that other than the initial release they made the lever lighter(it might have been in a bike review), I cant seem to find that quote now though but With direct link in the base its even easier.
in a Modern Everyday road car, that should not happen unless something is loose etc causing the same as below.However in race cars, especially such as...
in a Modern Everyday road car, that should not happen unless something is loose etc causing the same as below.
However in race cars, especially such as 'supercars' in Australia, Drivers will tap the Brake pedal at the end of a long straight before brake zone to ensure the Pads are close to the rotor/disc, This is often because of the lead up corners putting side stress/flex though the carrier/hub pushing the pistons back.
Alright this is getting a little off topic - just trying to add color to a guys comment about crappy lever feel on some shimanos. Hope...
Alright this is getting a little off topic - just trying to add color to a guys comment about crappy lever feel on some shimanos. Hope you find a solution, please let us know what works incase my shimanos decide to start acting up on me.
Any car with ABS will give you a different pedal feel when you prime the brakes before a braking event. It's especially noticeable in pickup trucks. Try it on your way home.
It's been a while since this thread has gotten derailed. Maybe we're overdue :D I'm curious what the discovery is too. I got hypercritical of brakes a...
It's been a while since this thread has gotten derailed. Maybe we're overdue :D
I'm curious what the discovery is too. I got hypercritical of brakes a long time ago and thought going with Shimano would end my search. And it did until they started developing all sorts of issues. I am cautiously optimistic on their new lineup but as it seems they're still using plastic MC pistons, at least on the high-end wares, they're still off my braking diet.
Alright this is getting a little off topic - just trying to add color to a guys comment about crappy lever feel on some shimanos. Hope...
Alright this is getting a little off topic - just trying to add color to a guys comment about crappy lever feel on some shimanos. Hope you find a solution, please let us know what works incase my shimanos decide to start acting up on me.
Any car with ABS will give you a different pedal feel when you prime the brakes before a braking event. It's especially noticeable in pickup trucks. Try it on your way home.
It's been a while since this thread has gotten derailed. Maybe we're overdue :D I'm curious what the discovery is too. I got hypercritical of brakes a...
It's been a while since this thread has gotten derailed. Maybe we're overdue :D
I'm curious what the discovery is too. I got hypercritical of brakes a long time ago and thought going with Shimano would end my search. And it did until they started developing all sorts of issues. I am cautiously optimistic on their new lineup but as it seems they're still using plastic MC pistons, at least on the high-end wares, they're still off my braking diet.
It's been a while since this thread has gotten derailed. Maybe we're overdue :D I'm curious what the discovery is too. I got hypercritical of brakes a...
It's been a while since this thread has gotten derailed. Maybe we're overdue :D
I'm curious what the discovery is too. I got hypercritical of brakes a long time ago and thought going with Shimano would end my search. And it did until they started developing all sorts of issues. I am cautiously optimistic on their new lineup but as it seems they're still using plastic MC pistons, at least on the high-end wares, they're still off my braking diet.
Other than aliexpress special replacements this is the only aluminium master that I have seen up to this point...
Trickstuff is using plastic (something from Igus at one point), Intend is, obviously Shimano and Sram, probably most others.
You only gain expense and complexity (you have to use a glide ring) by using an aluminium master piston... And dimensional stability and resistance against in ingesting water and expanding, but that would be useful only for Sram... And you can probably handle that with tolerances anyway.
Other than aliexpress special replacements this is the only aluminium master that I have seen up to this point... Trickstuff is using plastic (something from Igus at...
Other than aliexpress special replacements this is the only aluminium master that I have seen up to this point...
Trickstuff is using plastic (something from Igus at one point), Intend is, obviously Shimano and Sram, probably most others.
You only gain expense and complexity (you have to use a glide ring) by using an aluminium master piston... And dimensional stability and resistance against in ingesting water and expanding, but that would be useful only for Sram... And you can probably handle that with tolerances anyway.
Btw Aliexpress sram replacement pistons don't use glide rings either, not sure how many brakes create high enough side loading to need glide rings tbh, dominion uses alloy master piston with glide rings I think?
Pull apart any Sram brake (I have experience with those, not with any others sadly) and you can see the piston is scratched on one side.
That's also the reason the fluid comes out gray on non RSC brakes as the master body and caliper is painted, not anodized, which means the bore is raw aluminium. This gets scratched and worn a bit and thus the grey fluid - even old fluid in an RSC brake is still clear.
As the plastic piston is softer than the aluminium, even though there are some wear particles, it still seals. With an aluminium piston I bet the bore would get scratched enough for the seals not to seal (and the lever dropping to the bar). Technically the seal can carry the sideloads if it is stiff enough, but I can assure you with Sram the piston hits the bore.
Aliexpress replacement pistons not using glide rings is the exact problem I used "aliexpress special" term for. For the love of God, don't use them.
As for Formula, the white ring carrying the spring is probably acting as a glide ring as well. And hope does use glide rings.
Remember, the primary function of the bore wall is to provide a smooth surface for the seal to seal against. If anything will be sliding along it, besides the seal itself, it has to be softer than the bore. If you have a steel bore, no problems. As most mtb brakes have aluminium masters, there's a bit of a problem with aluminium pistons.
Yes it would also be covered but that would have me out of a brake for maybe 2-3 days while the shop submits warranty claim etc. It took me a short drive and $34 CAD to get the rebuild kit and 1 hour of labour to fix it. Good to know your friends' A2s are going well. Maybe just crappy luck on my end. I'll give them another shot.
wouldn't the opposite be true as well? that the pad will be better coupled with the caliper body for better heat dissipation? this could also lead to overheating the fluid i suppose...
The heat in the brakes is coming from the pad/ rotor contact. Aluminum pistons could transfer that heat to the caliper/ fluid. The caliper hopefully is designed to handle/dissipate that heat.
My car has Brembo brakes and they are super easy to work on, I hope that carries over to their MTB brake designs.
The main issue is, regardless of the performance, if they price them at 1k other than to fanboys they’ll be hard to sell, the ugliness is unreal for the brand, compare them to Hope/Intend/Trickstuff and others in the price range, these are in the same aesthetic level of TRPs at best
https://www.instagram.com/reel/DLzNdUqsUkf/?igsh=ZWdmNm44cHQwYmFh
Aluminium pistons? That's a surprise, I thought manufacturers wanted to isolate the heat from the rotor from the fluid in the caliper (ceramic, steel, phenolic, ...), but with aluminium, that would be kind of the opposite?
But we learn it's a 9mm MC piston and 4x18mm caliper, which should be on the higher end of power (just accounting the hydraulic ratio)
It’s the highest so far, higher than the mavens. One thing to keep in mind is that regardless of how much heat is being transferred to the fluid, hydraulic fluid, like dot or petroleum based mineral fluid, those fluids have some of the lowest thermal conductivity of any component in the brake system. It’s an order of magnitude lower than that of SS or AL. It’s going to take more BTU’s than one would ever be able generate in a mtb brake system to get any fluid to boil, especially under pressure, when the brake are applied. I can’t remember off the top of my head but DOT fluid at 1500 psi has a boil temperature of well over 800°F, or something similar to that, feel free to fact, check me I could be off. There’s not enough mass in a mountain bike brake system to sustain those system temperatures after someone lets off the brakes when the pressure subsides. Thermal degradation near the boil point is a completely different story, that is one area where DOT fluid has the upper hand compared to mineral oil.
I wondered about the temperatures of brake fluid in mtb brakes. It's easy to get DOT fluid with dry boiling points around 600°F, wet boiling point usually drops to mid 400°F. Is the brake fluid (not discs/pads) in MTB disc brakes approaching those temps?
Well, if they were that hot Magura brakes would be exploding left, right and central. Royal blood has boiling point of 100c or so 🤷🏻
It's 250c (around 480f), not 100c
I don't have any data right now to say one way or another but my gut is telling me no. What I do know is that boiling temp increases pretty significantly based on the pressure that the fluid is it. I have heard engineers in the industry stating that line pressures are over 1000psi for peak braking events, that's 68X more pressure than the atmospheric pressure of 14.7 psi that the boiling point it rated at, but that's all the data that I have to go off of, I don't have extra any inline wireless pressure transducers lying around at the moment to corroborate this
I do have an array of thermal stickers that I was planning on placing on my rotors and calipers this last weekend to see how hot they get doing some practice runs for a DH race coming up later this month, but I got lost in the weekend and forgot to stick them on. Will make sure to do it the Thursday before I pack up for the race.
The way I look at it, even if we took the pressure out of the equation, our brake fluids have thermal conductivities of around .13W/m·K which makes them very good insulators. It will take a lot of sustained heat to actually get the fluid up to the temp of the caliper, which is probably why Brembo has no issue using Al pistons, I would bet that they have not only run the CFD simulations but also performed a significant amount of lab testing to back up their decisions. If I have some time I'll try to setup something simple in comsol to simulate the amount of thermal energy needed to heat a mineral oil to its boiling point, and maybe try to add pressure into the equation, could be a fun thought experiment.
Few years ago there was a boiling point chart at epic bleed kits website, where Magura royal blood was measured at 99C with every other fluid measured at well above 200C. They have since changed the formulation I guess, before they weren't even publishing these data at all. Anyway, even for quite steep dh tracks like schladming I wasn't getting caliper temp too hot to touch, so I would be surprised if brake with phenolic pistons or similar would be heating fluid much higher than that 100c point. Brake disc? Sure, those get very hot, pads obviously too. But there doesn't seem to be that much heat transfer to the caliper/ fluid and most heavy lifting is done on disc side. I deleted original comment because the chart that is now published at epic bleed kits used new Magura fluid with boiling point at much more normal value.
My m8000 brake lever on the xt 4 pots (same design as zre/saint) has developed a weird issue since installing the brake on a bike with a complete refill and changing a bent lever.
I bled them multiple times and the bleed seems to be fine but the bite point is somehow too close to the bar. If I push the lever outwards it suddenly shifts into a position where the bite point should be and everything is alright.
Hut when I ride it seem the nite point slowly goes back closer to the bar. Not indefinitely, it feels firm like not like air is inside but it's not far away enough from the bar. When the bike stands the bite point is fine again.
Does this mean some seal is blown? These guys are 6 years old so it might be time to get new brakes but I can't decide.
Dominion A4 sounds like what I want but they won't fit the internal cable routing and I would need to change hoses, switch to dot etc.
Anyone can compare the dominion to the shigura? I'm riding those too.
We plumbed a pressure gauge in line with some Code RSCs back in the day. You can easily hit 3000 psi yanking on the lever. That would be hard to see on the trail of course, but pressures are definitely higher than most assume.
The bigger limit when it comes to piston temp is more likely to be the seals. The max temp of EPDM isn't that high (about 300F). You could do some fluorinated material like FFKM to get higher temp ratings on your seals, but that's expensive. Brembo refers to their pistons as "isolated" aluminum. What I read into that is some sort of insert to insulate the rest of the caliper. The name of the game usually is keep heat out of the caliper. I've seen plenty of caliper bodies get hot enough to boil water off very quickly even with phenolic or ceramic pistons and rotor temps north of 500F. The fluid volume in the caliper isn't very large so not much heat capacity.
Great to know! Thats a good point about seal temp, EPDM does have a very low melt temp depending on the amount of polymeric cross-linking. As someone who has designed brakes, have you spent much time using seals in DOT applications outside of the run-of-the-mill mcmaster epdm? I have worked with o-ring molders that had some interesting grades of EPDM and FKM as well with much higher Tg temps than typical commodity grade materials.
Kalrez is guccci stuff, you get the compliance of EPDM, chemical resistance of PTFE and the gas permeability of ETFE all for the low price of $60 an o-ring
Figured this would be the place to ask. Hope I don't derail the brake fluid/pressure bit you guys are on.
Looking at the new unreleased shimano brakes a few people are running got me thinking. I know some of you are running shiguras, but has anyone done a mavano setup? XT/XTR levers to a maven caliper? My bike came with the base as Maven bronze brakes and they feel great. But others have stated that these levers are easier to pull then the silver / ultimate levers. So just wondering if anyone has done any tinkering.
You mean the maven bronze levers are easier to pull or the new shimano levers?
Never saw a shimano/maven combo but on the german forum someone is already using the new xtr lever for a shigura setup. He's saying that the new levers have a bigger oil reservoir so they are better suited for the shigura mod. He's running them with Bionol and says they have a light lever feel.
The new xt levers come with a du bushing and no bearing in the lever though. I'm also interested in the new shimano brakes but complete shimano sounds a bit underwhelming from the reviews.
Run of the mill McMaster stuff is 250F I believe. 300F is cured a little differently. That's what we were using. Did variation of FKM in the mineral oil brakes that was supposed to be compatible with DOT as well, but it swelled just enough to cause issues unfortunately.
Supposedly the bronze levers are easier to pull the the silver/ultimate versions. It seems like the biggest criticism the mavens have received is that the levers are too hard to pull. So I was wondering if anyone had played with mixing levers now that SRAM is all mineral oil at this point. That said my bronze ones are fine and I doubt the ultimates are that much harder to pull.
They all got updated, The bases are excellent in this regard aswell.
Bases are very underrated, excellent brake, using 220 F and 200R on my DH bike an im 100kg. love it.💪
Why change brakes if they're working great? From your post: "These work great and tend to not over heat too badly for me, I also really like the lever feel." Seems like they're perfect for you.
That is a very fair question! I think I’m just aware that when I got the codes, they were about the most powerful brakes I could easily find, but things have moved on, and being a larger guy I’m very curious to try something new.
Also codes were originally on a sentinel, I’m now on a spire and riding a chunk faster
Being 175lbs riding weight myself I feel I can benefit from stronger brakes than the codes, so it’s definitely worth it to get something more powerful.
A colleague of mine always thought his guides ultimate were enough at 230lbs
Now on mavens he knows he was wrong
You mean there was a running change and the levers now can be pulled easier?
it was reported on the other site at some point that other than the initial release they made the lever lighter(it might have been in a bike review), I cant seem to find that quote now though
but With direct link in the base its even easier.
Um... Who doesn't use plastic master pistons??
Hope for sure not
Other than aliexpress special replacements this is the only aluminium master that I have seen up to this point...
Trickstuff is using plastic (something from Igus at one point), Intend is, obviously Shimano and Sram, probably most others.
You only gain expense and complexity (you have to use a glide ring) by using an aluminium master piston... And dimensional stability and resistance against in ingesting water and expanding, but that would be useful only for Sram... And you can probably handle that with tolerances anyway.
Old formula brakes used to use hard anodized pistons. No glide rings, just right tolerances where they should be https://images.app.goo.gl/TntETbWcq6Kgnygf8
Btw Aliexpress sram replacement pistons don't use glide rings either, not sure how many brakes create high enough side loading to need glide rings tbh, dominion uses alloy master piston with glide rings I think?
Pull apart any Sram brake (I have experience with those, not with any others sadly) and you can see the piston is scratched on one side.
That's also the reason the fluid comes out gray on non RSC brakes as the master body and caliper is painted, not anodized, which means the bore is raw aluminium. This gets scratched and worn a bit and thus the grey fluid - even old fluid in an RSC brake is still clear.
As the plastic piston is softer than the aluminium, even though there are some wear particles, it still seals. With an aluminium piston I bet the bore would get scratched enough for the seals not to seal (and the lever dropping to the bar). Technically the seal can carry the sideloads if it is stiff enough, but I can assure you with Sram the piston hits the bore.
Aliexpress replacement pistons not using glide rings is the exact problem I used "aliexpress special" term for. For the love of God, don't use them.
As for Formula, the white ring carrying the spring is probably acting as a glide ring as well. And hope does use glide rings.
Remember, the primary function of the bore wall is to provide a smooth surface for the seal to seal against. If anything will be sliding along it, besides the seal itself, it has to be softer than the bore. If you have a steel bore, no problems. As most mtb brakes have aluminium masters, there's a bit of a problem with aluminium pistons.
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