Nerding out on Brakes shall we? Not another tech deraliment

AndehM
Posts
216
Joined
5/7/2018
Location
El Granada, CA US
1/14/2025 12:04pm

I finally got around to bleeding my brakes using the Canyon / Aaron method that was linked a while back.  The rear brake on one of my sets of my Mavens always felt a bit soft to me, and when I used this method it seemed to firm it up quite a bit.  It was pretty shocking at how many bubbles I was able to draw out using this method of isolating the caliper then the lever (so much that I wondered whether I had a leaky connection but I'm pretty sure that wasn't the case given that I never saw any leaks when pressurizing, and that the amount of bubbles steadily decreased).  I'll definitely be switching to this method from now on.

1
Slavid666
Posts
33
Joined
5/3/2024
Location
Santa Rosa, CA US
1/16/2025 1:15pm
Primoz wrote:
I never said it's a replacement. I said PEEK is used as a counterpart material to steel in gears. Meaning one gear is steel, the other...

I never said it's a replacement. I said PEEK is used as a counterpart material to steel in gears. Meaning one gear is steel, the other is PEEK. I'm not an expert in geartrain design and obviously you don't see PEEK gears in car transmissions and the like, but I did hear a steel/PEEK combo has been used in an eBike drive unit to quite things down, which is the role PEEK plays - use it where you need a quiet geartrain but also need more strength in gear the usual plastic materials give you. COnsidering you don't see aluminium gears, there must be something on PEEK that gives it an advantage, I'd bet it would be surface hardness or something along those lines.

Considering this (PEEK being used to pair to steel gears) while aluminium is neve used for gears, I said PEEK might be a bit hard, i.e. used as a brake master piston it might scratch up the bore too, just like a steel, titannium or probably even aluminium piston would. But I don't have any experience with it and it might be empty worries...

As for CTE, if that is an issue that arises with a master cylinder in the brake, there are bigger issues than CTE itself... With the way seals are done on a master piston, there should be quite a bit of clearance radially between the bore and the piston, shown by pistons being scratched on only one side. One exception here is Sram's piston selling and jamming, but year... In either case, POM is also used as a master piston material from what I've seen and the CTE of it is about twice as big as PEEK's. If CTE was an issue, everybody would be using aluminium pistons anyway...

You are correct, you did say counterpart. In the example that you gave the reason why is correct for certain applications, but I can guarantee that it's not neat PEEK, i.e. unfilled virgin PEEK. Most likely its carbon or glass filled with ETFE or PTFE added as a lubricant, but I would bet that more often than not its PPS, without carbon black added both materials look nearly identical in color, have very similar mechanical and chemical resistance characteristic, but PPS costs 1/2 that of PEEK. 

PEEK is not harder than aluminum. Pulling from my material DB here at work, we have a hardness tested calibrated for Rockwell A and B, 6061-T6 ranges from 56-62B. PEEK doesn't even move the needle on the Rockwell B scale, at all, It's not even close. LOL.

CTE is something that any competent seal designer should take into consideration, especially when designing a seal gland where the seal is being used as a rollback spring, let alone one that can see as aggressive temp swings as I would presume that a disc brake piston would be subjected to. Having to design anything around a moving target is tricky and ends up being an exercise in compromise.

NicoZesty96
Posts
402
Joined
8/21/2014
Location
portogruaro, VE IT
1/18/2025 2:22am

Curiosity, has anyone experimented with different dots?
I was googling the differences between some 5.1 and some 4 and it seems for racing application on motors and cars the 4 series is the one that is most used,

Would a bike brake feel better with a dot with a higher boiling point or a low viscosity one? 
Anyone tried something? 
IMG 5675.jpeg?VersionId=F7iDc7Z0GDkYy62u1w565IMG 5673IMG 5671.jpeg?VersionId=a7TOnkeAvDD2h9HyIfMjVndbvgSI

Primoz
Posts
3712
Joined
8/1/2009
Location
SI
1/19/2025 12:51am

Isn't the general consensus that a lower viscosity for mineral oil brakes makes them feel better?

Interesting though, for the racing fluid it says not to mix it with polyglycol fluids, if I understand it correctly that's off the shelf DOT4 and DOT5.1?

2
boozed
Posts
339
Joined
6/11/2019
Location
AU
1/19/2025 3:37am Edited Date/Time 1/19/2025 10:43pm
Primoz wrote:
Isn't the general consensus that a lower viscosity for mineral oil brakes makes them feel better?Interesting though, for the racing fluid it says not to mix...

Isn't the general consensus that a lower viscosity for mineral oil brakes makes them feel better?

Interesting though, for the racing fluid it says not to mix it with polyglycol fluids, if I understand it correctly that's off the shelf DOT4 and DOT5.1?

The only ingredient listed in the MSDS for RBF 700 is "diamines", so that wasn't much help.

But it is polyglycol based.  Presumably it shouldn't be mixed because that would degrade its performance.

1
NicoZesty96
Posts
402
Joined
8/21/2014
Location
portogruaro, VE IT
1/19/2025 10:14am
Primoz wrote:
Isn't the general consensus that a lower viscosity for mineral oil brakes makes them feel better?Interesting though, for the racing fluid it says not to mix...

Isn't the general consensus that a lower viscosity for mineral oil brakes makes them feel better?

Interesting though, for the racing fluid it says not to mix it with polyglycol fluids, if I understand it correctly that's off the shelf DOT4 and DOT5.1?

they're all Motul racing dots, so should be high quality but yeah they do have different viscosity in colder temperatures and different dry/wet boiling points

1
Placek
Posts
3
Joined
1/16/2015
Location
Chicago, IL US
1/24/2025 11:26am

Awesome thread

Plenty of valuable tips and tricks.

I’ve battled with my Shimano XTR Trail brakes many times, but I’ve never managed to eliminate that spongy feel after the initial piston engagement.
On top of that, I had the impression that air kept getting into the system, so I ended up bleeding them multiple times each season.
I’m done with Shimano.

Now, faced with the dilemma of choosing a single brake set for an enduro bike, if price wasn’t an issue, which would you go for?

They don’t need to have insane power (like Maven).
What matters to me:

 - Minimal dead zone and smooth lever action.

 - Mineral oil compatibility.

 - High-quality craftsmanship—no sketchy screws (like MT7) or poor assembly tolerances (e.g., what I’ve heard about Dominion from Dale).

I’m fine with maintenance, as long as it’s not something I have to do every few rides.

1
Eae903
Posts
147
Joined
10/20/2023
Location
Laramie, WY US
1/24/2025 12:52pm Edited Date/Time 1/24/2025 12:55pm
Placek wrote:
Awesome threadPlenty of valuable tips and tricks.I’ve battled with my Shimano XTR Trail brakes many times, but I’ve never managed to eliminate that spongy feel after...

Awesome thread

Plenty of valuable tips and tricks.

I’ve battled with my Shimano XTR Trail brakes many times, but I’ve never managed to eliminate that spongy feel after the initial piston engagement.
On top of that, I had the impression that air kept getting into the system, so I ended up bleeding them multiple times each season.
I’m done with Shimano.

Now, faced with the dilemma of choosing a single brake set for an enduro bike, if price wasn’t an issue, which would you go for?

They don’t need to have insane power (like Maven).
What matters to me:

 - Minimal dead zone and smooth lever action.

 - Mineral oil compatibility.

 - High-quality craftsmanship—no sketchy screws (like MT7) or poor assembly tolerances (e.g., what I’ve heard about Dominion from Dale).

I’m fine with maintenance, as long as it’s not something I have to do every few rides.

Dominions are out due to them being dot fluid by your requirements anyways. The construction and tolerances are totally fine on them, it's the finish that dale had an issue with. I would probably do the Formula Cura 4s since you seem to not want Shimano. I absolutely loved the set I tried, very similar to the Dominions in feel IMO, just not quite as powerful. 

2
jasbushey
Posts
79
Joined
10/6/2015
Location
Durango, CO US
1/24/2025 1:58pm Edited Date/Time 1/24/2025 1:59pm
Placek wrote:
Awesome threadPlenty of valuable tips and tricks.I’ve battled with my Shimano XTR Trail brakes many times, but I’ve never managed to eliminate that spongy feel after...

Awesome thread

Plenty of valuable tips and tricks.

I’ve battled with my Shimano XTR Trail brakes many times, but I’ve never managed to eliminate that spongy feel after the initial piston engagement.
On top of that, I had the impression that air kept getting into the system, so I ended up bleeding them multiple times each season.
I’m done with Shimano.

Now, faced with the dilemma of choosing a single brake set for an enduro bike, if price wasn’t an issue, which would you go for?

They don’t need to have insane power (like Maven).
What matters to me:

 - Minimal dead zone and smooth lever action.

 - Mineral oil compatibility.

 - High-quality craftsmanship—no sketchy screws (like MT7) or poor assembly tolerances (e.g., what I’ve heard about Dominion from Dale).

I’m fine with maintenance, as long as it’s not something I have to do every few rides.

Eae903 wrote:
Dominions are out due to them being dot fluid by your requirements anyways. The construction and tolerances are totally fine on them, it's the finish that...

Dominions are out due to them being dot fluid by your requirements anyways. The construction and tolerances are totally fine on them, it's the finish that dale had an issue with. I would probably do the Formula Cura 4s since you seem to not want Shimano. I absolutely loved the set I tried, very similar to the Dominions in feel IMO, just not quite as powerful. 

Seconded for the Cura 4s.  Also the FCS upgrade is noticeable improvement in overall performance.  I prefer the lever shape and it allows a lot of tweak to the power delivery.  My biggest issue with them is that I can't run as close to the bar as I prefer.  I like my full pull to be ~1cm to the bar and these are closer to 1.5-1.75cm (I can go measure if needed) so they are a bit further out than I like.  Without FCS I could run them closer, but I like the feel and delivery I get more with the FCS. 

If you don't run your levers really close to the bar, I'd say those are an excellent option.  

SilentG
Posts
11
Joined
8/5/2019
Location
Prescott, AZ US
1/24/2025 3:24pm
Placek wrote:
Awesome threadPlenty of valuable tips and tricks.I’ve battled with my Shimano XTR Trail brakes many times, but I’ve never managed to eliminate that spongy feel after...

Awesome thread

Plenty of valuable tips and tricks.

I’ve battled with my Shimano XTR Trail brakes many times, but I’ve never managed to eliminate that spongy feel after the initial piston engagement.
On top of that, I had the impression that air kept getting into the system, so I ended up bleeding them multiple times each season.
I’m done with Shimano.

Now, faced with the dilemma of choosing a single brake set for an enduro bike, if price wasn’t an issue, which would you go for?

They don’t need to have insane power (like Maven).
What matters to me:

 - Minimal dead zone and smooth lever action.

 - Mineral oil compatibility.

 - High-quality craftsmanship—no sketchy screws (like MT7) or poor assembly tolerances (e.g., what I’ve heard about Dominion from Dale).

I’m fine with maintenance, as long as it’s not something I have to do every few rides.

Thirded for Cura 4s.

Had multiple sets on several bikes over several years and the only thing they needed was pads when it was time and a bleed if I moved them to/from a frame with internal routing.

Hope Tech 4 is like a Cura 4 for maintenance, can find spares and exploded view drawings of parts. Hope use DOT where Formula is mineral oil (used Formula and Pentosin CHF), even more modulation in feel vs Cura, longer levers than Formula (may or may not be a pro/con).

Hope has more adjustable levers than Formula which may or may not be a pro/con depending on what you like (one of my beefs with Magura is I don't like the feel of some of the levers as I'm a 1.5-2 finger braking person).

I liked the Hope enough to rotate out my Cura fleet over the past year or two.

1
NicoZesty96
Posts
402
Joined
8/21/2014
Location
portogruaro, VE IT
1/24/2025 10:19pm
Placek wrote:
Awesome threadPlenty of valuable tips and tricks.I’ve battled with my Shimano XTR Trail brakes many times, but I’ve never managed to eliminate that spongy feel after...

Awesome thread

Plenty of valuable tips and tricks.

I’ve battled with my Shimano XTR Trail brakes many times, but I’ve never managed to eliminate that spongy feel after the initial piston engagement.
On top of that, I had the impression that air kept getting into the system, so I ended up bleeding them multiple times each season.
I’m done with Shimano.

Now, faced with the dilemma of choosing a single brake set for an enduro bike, if price wasn’t an issue, which would you go for?

They don’t need to have insane power (like Maven).
What matters to me:

 - Minimal dead zone and smooth lever action.

 - Mineral oil compatibility.

 - High-quality craftsmanship—no sketchy screws (like MT7) or poor assembly tolerances (e.g., what I’ve heard about Dominion from Dale).

I’m fine with maintenance, as long as it’s not something I have to do every few rides.

if money is not a problem then of course, Intend Trinity and Trickstuff Maxima must be at the top of the list, although the latter might nor have the shortest stroke, look at the Radic Kaha for that, all more powerful and of course higher quality than shimano, not sure about the 612 die bremse but they have the same size pistons and master as the maxima

2
Dasf
Posts
1
Joined
1/25/2025
Location
Berlin, AR US
1/25/2025 6:53am

Maybe this helps:

About 13mm-14mm of lever throw on the 612 to the bitepoint.


IMG 2590.jpeg?VersionId=26LnmSCSLCuvMp8pMhLsV

1
Placek
Posts
3
Joined
1/16/2015
Location
Chicago, IL US
1/25/2025 12:05pm

Eae903 jasbushey SilentG

Gentlemen,
I didn’t expect so much consensus on Formula. I admit that this setup wasn’t on my radar due to its relatively low popularity, actually very little popularity - wondering why?.
I prefer the brake lever to sit relatively far from the handlebars, so that shouldn’t be an issue here. However, I’m curious about the braking power you’ve mentioned as being moderate—will they be weaker than Shimano?
Additionally, how would you rate their performance in terms of lever smoothness, ease of operation, and maintenance?

 

jasbushey
Posts
79
Joined
10/6/2015
Location
Durango, CO US
1/26/2025 5:51am Edited Date/Time 1/26/2025 5:53am

It is better in all regards for me? I had two bikes last year. One with an XT 4 pot and another with the Cura4s.  Curas have more power, better modulation.  I think the tests typically show 20% more power than XTs.  Lever feel is hard for me to describe but I like it and only rode Shimano prior. Power comes on earlier and more linear than Shimano but delivery can be adjusted quite a bit with the fcs.  Only had to bleed once after 2 years. Bleed is easy, similar to sram. A top bleed is easier on Shimano, but full bleed better on formula. 

I and many others swapped the organic pads that come with them out. I use MTX red. I never used the originals but I hear the power isn’t stellar. 


NSMB and Enduro mag have a good write up on them that can explain the feel more descriptively than me. 

1
Aksel_Lfft
Posts
105
Joined
4/21/2016
Location
Plaisance-du-Touch FR
1/26/2025 12:19pm Edited Date/Time 1/26/2025 12:20pm
Placek wrote:
Eae903 jasbushey SilentGGentlemen,I didn’t expect so much consensus on Formula. I admit that this setup wasn’t on my radar due to its relatively low...

Eae903 jasbushey SilentG

Gentlemen,
I didn’t expect so much consensus on Formula. I admit that this setup wasn’t on my radar due to its relatively low popularity, actually very little popularity - wondering why?.
I prefer the brake lever to sit relatively far from the handlebars, so that shouldn’t be an issue here. However, I’m curious about the braking power you’ve mentioned as being moderate—will they be weaker than Shimano?
Additionally, how would you rate their performance in terms of lever smoothness, ease of operation, and maintenance?

 

I have not a wide experience in different brakes (only shimano and few srams) but I for sure would recommend the cura 4s. I have them for a couple of years now and they are really great ! I love the feel, the power and the robustness of the set. they helped me greatly with arm pumps on long and steep downhills and are basically maintenance free. I would love to try the FCS lever though to see the fine tuning they offer. On the power side, it's enough for me but I can't tell how precisely they compare to the competition

P.S: I use them with the formula mineral oil (I'd like to test the bionol one though) and I run currently Galfer advanced pads that I think provide a bit more bite than the standard ones (planning on testing the standard trickstuff also)

1
j0lsrud
Posts
32
Joined
7/20/2021
Location
NO
1/26/2025 12:50pm
Placek wrote:
Awesome threadPlenty of valuable tips and tricks.I’ve battled with my Shimano XTR Trail brakes many times, but I’ve never managed to eliminate that spongy feel after...

Awesome thread

Plenty of valuable tips and tricks.

I’ve battled with my Shimano XTR Trail brakes many times, but I’ve never managed to eliminate that spongy feel after the initial piston engagement.
On top of that, I had the impression that air kept getting into the system, so I ended up bleeding them multiple times each season.
I’m done with Shimano.

Now, faced with the dilemma of choosing a single brake set for an enduro bike, if price wasn’t an issue, which would you go for?

They don’t need to have insane power (like Maven).
What matters to me:

 - Minimal dead zone and smooth lever action.

 - Mineral oil compatibility.

 - High-quality craftsmanship—no sketchy screws (like MT7) or poor assembly tolerances (e.g., what I’ve heard about Dominion from Dale).

I’m fine with maintenance, as long as it’s not something I have to do every few rides.

How about the new Magura Gustav?

They look very promising. Maybe not got the absolute power, but it will have basically all the power aviable whatever you throw at it.

1/26/2025 3:06pm
Aksel_Lfft wrote:
I have not a wide experience in different brakes (only shimano and few srams) but I for sure would recommend the cura 4s. I have them...

I have not a wide experience in different brakes (only shimano and few srams) but I for sure would recommend the cura 4s. I have them for a couple of years now and they are really great ! I love the feel, the power and the robustness of the set. they helped me greatly with arm pumps on long and steep downhills and are basically maintenance free. I would love to try the FCS lever though to see the fine tuning they offer. On the power side, it's enough for me but I can't tell how precisely they compare to the competition

P.S: I use them with the formula mineral oil (I'd like to test the bionol one though) and I run currently Galfer advanced pads that I think provide a bit more bite than the standard ones (planning on testing the standard trickstuff also)

Try the Trickstuff Power pads, I’d say.

Placek
Posts
3
Joined
1/16/2015
Location
Chicago, IL US
1/27/2025 5:03am
Placek wrote:
Awesome threadPlenty of valuable tips and tricks.I’ve battled with my Shimano XTR Trail brakes many times, but I’ve never managed to eliminate that spongy feel after...

Awesome thread

Plenty of valuable tips and tricks.

I’ve battled with my Shimano XTR Trail brakes many times, but I’ve never managed to eliminate that spongy feel after the initial piston engagement.
On top of that, I had the impression that air kept getting into the system, so I ended up bleeding them multiple times each season.
I’m done with Shimano.

Now, faced with the dilemma of choosing a single brake set for an enduro bike, if price wasn’t an issue, which would you go for?

They don’t need to have insane power (like Maven).
What matters to me:

 - Minimal dead zone and smooth lever action.

 - Mineral oil compatibility.

 - High-quality craftsmanship—no sketchy screws (like MT7) or poor assembly tolerances (e.g., what I’ve heard about Dominion from Dale).

I’m fine with maintenance, as long as it’s not something I have to do every few rides.

j0lsrud wrote:
How about the new Magura Gustav?They look very promising. Maybe not got the absolute power, but it will have basically all the power aviable whatever you...

How about the new Magura Gustav?

They look very promising. Maybe not got the absolute power, but it will have basically all the power aviable whatever you throw at it.

Well, there is not much info about them, tests neither.

First impressions suggests they fit better eMTB which is not my story yet. 

Primoz
Posts
3712
Joined
8/1/2009
Location
SI
1/29/2025 12:58am Edited Date/Time 1/29/2025 1:00am

New or not, it shouldn't be granted. Formula did oval pistons years ago. 

2
1/29/2025 3:32am
sspomer wrote:
i'll delete if already posted, but sram non-circular brake piston patent? is this new? https://patents.google.com/patent/DE102024102985A1/en?assignee=Sram%2c+Llc&before=priority:20250101&after=priority:20230101&sort=new

i'll delete if already posted, but sram non-circular brake piston patent? is this new? 

https://patents.google.com/patent/DE102024102985A1/en?assignee=Sram%2c+Llc&before=priority:20250101&after=priority:20230101&sort=new

Screen Shot 2025-01-28 at 4.30.10 PM.png?VersionId=r

There has to be a reason pretty much all brake calipers use round pistons. 

Primoz
Posts
3712
Joined
8/1/2009
Location
SI
1/29/2025 3:44am

It's easy to get seals. And round pegs in round holes seal the best as the pressure is constant around the perimeter. 

3
Finkill
Posts
69
Joined
9/2/2015
Location
GB
1/29/2025 4:06am

I think Formula started that they had issues with the oval pistons not moving evenly (wonky) due to the seal force not being even all the way around the piston. Round seals have even force. 

I have a set of Formula RO brakes that I inherited, which have the oval pistons. I need to find the time to rebuild them and see how they perform. 

3
HexonJuan
Posts
175
Joined
6/10/2015
Location
WI US
1/29/2025 6:55am
sspomer wrote:
i'll delete if already posted, but sram non-circular brake piston patent? is this new? https://patents.google.com/patent/DE102024102985A1/en?assignee=Sram%2c+Llc&before=priority:20250101&after=priority:20230101&sort=new

i'll delete if already posted, but sram non-circular brake piston patent? is this new? 

https://patents.google.com/patent/DE102024102985A1/en?assignee=Sram%2c+Llc&before=priority:20250101&after=priority:20230101&sort=new

Screen Shot 2025-01-28 at 4.30.10 PM.png?VersionId=r

There has to be a reason pretty much all brake calipers use round pistons. 

Yup, manufacturability. I'll also wager that a square seal won't roll quite uniformly so retraction and leakage may be real issues. 

Eae903
Posts
147
Joined
10/20/2023
Location
Laramie, WY US
1/29/2025 8:32am
Placek wrote:
Eae903 jasbushey SilentGGentlemen,I didn’t expect so much consensus on Formula. I admit that this setup wasn’t on my radar due to its relatively low...

Eae903 jasbushey SilentG

Gentlemen,
I didn’t expect so much consensus on Formula. I admit that this setup wasn’t on my radar due to its relatively low popularity, actually very little popularity - wondering why?.
I prefer the brake lever to sit relatively far from the handlebars, so that shouldn’t be an issue here. However, I’m curious about the braking power you’ve mentioned as being moderate—will they be weaker than Shimano?
Additionally, how would you rate their performance in terms of lever smoothness, ease of operation, and maintenance?

 

I don't find them weaker than Shimano at all, and in Europe, they are a lot more popular. The US brake market is a lot more limited then Europe, we don't really see anything OEM other than Sram or Shimano, with trp/tektro thrown on some lower end bikes occasionally. They bleed easily, and are very consistent. They just have a different feel than Shimano, I think they sit between the Hayes Dominions and Sram codes in terms of feel, more positive contact than the Sram, and less squishy once there is contact, but a slightly heavier free stroke than the Dominions. It was a brake that I jumped on and immediately got along with. I definitely don't feel that way about most brakes, I can't ride Sram G2s or Level 4 pistons at all, just hate the way they feel, and then brakes like the Codes, or Magura MT5s took getting used to, but I could use them. If I were to buy a set of the Formulas, I would also get a small stock of brake pads at the same time just in case I'm out traveling somewhere because they're not going to be in every shop, but I run into that problem with my Dominions anyways. 

Primoz
Posts
3712
Joined
8/1/2009
Location
SI
18 minutes ago

For bleeding brakes, has anyone thought of doing it with a vacuum machine? Setting the vacuum low enough (for example 0,9 bar absolute pressure or something like that) and connecting both sides of the brake to the same reservoir (Y connection) and vacuuming the reservoir, theoretically you could pull out all the bubbles and with the reservoir they could easily be replaced by oil flowing in from either side.

Eae903
Posts
147
Joined
10/20/2023
Location
Laramie, WY US
5 minutes ago
Primoz wrote:
For bleeding brakes, has anyone thought of doing it with a vacuum machine? Setting the vacuum low enough (for example 0,9 bar absolute pressure or something...

For bleeding brakes, has anyone thought of doing it with a vacuum machine? Setting the vacuum low enough (for example 0,9 bar absolute pressure or something like that) and connecting both sides of the brake to the same reservoir (Y connection) and vacuuming the reservoir, theoretically you could pull out all the bubbles and with the reservoir they could easily be replaced by oil flowing in from either side.

My shop is getting a Vaccum fill machine to work on suspension with, specially cane Creek stuff, and if I can I'll see if I can get it to work with brakes, but I have a feeling it's not going to be worth the time and effort. 

Post a reply to: Nerding out on Brakes shall we? Not another tech deraliment

The Latest