[Udi]

Oh right, so you just wanted the kevlar ones coz not black?
Yeah that'll work to my knowledge (assuming the fittings look visually the same as yours).
White hoses are hideous though, I'd just rock one black until you have an excuse to get the other too.
Plus that way it doesn't look like you picked white on purpose.

 

[Sandwich]

I picked that one because it was cheap and available, which is not a recurring theme for formula in MERICA. don't care about Kevlar, but matched is better than totally goofy looking, though I agree with you on white v black.

Thanks for the tip though, need to debate Shimano or alternatives...

 

[chris_f]

So my new, shiny, gorgeous Magura MT7s have developed an issue after 3 rides. LMAO

Pistons on one side on the front brake are sticking, so basically what happens is that under hard braking, the pistons on the other side pushes the disc into the caliper, making a loud "clack-clack-clack"-esque sound, and I can feel the vibrations through the levers. Brake power also suffers noticeably while this happens.

It might be a warranty issue, so I'm not really up for tampering too much with them, but does anyone have any suggestions?

 

[Happymtb.fr]

I would suggest that you massage your pistons on the lazy side.

To do so, remove the pads, block the moving pistons in a creative way and actuate the brake lever until the lazy pistons stick quite far out, then push them back and repeat a few times. This should lubricate the pistons and the seals and thus allow them to move evenly with the other side.

 

[chris_f]

Thanks, I'll give that a go today.

 

[Udi]

So my new, shiny, gorgeous Magura MT7s have developed an issue after 3 rides. LMAO

Pistons on one side on the front brake are sticking, so basically what happens is that under hard braking, the pistons on the other side pushes the disc into the caliper, making a loud "clack-clack-clack"

"clack-clack-clack" means "switch to enduro" (i.e. DH @ 2/3 pace) in lizard speak.
MT7 calipers are supposed to be great, clearly user error.

Also, this.

 

[Bike078]

It looks like you were right about my m615 deore @Udi. Despite cleaning and bleeding the rear brake still tends to lock up under extended braking. I will be replacing it with my old slx m665.

 

[spocomptonrider]

I would suggest that you massage your pistons on the lazy side.

To do so, remove the pads, block the moving pistons in a creative way and actuate the brake lever until the lazy pistons stick quite far out, then push them back and repeat a few times. This should lubricate the pistons and the seals and thus allow them to move evenly with the other side.

Thanks, I'll give that a go today.

If this doesn’t work I would also suggest (with the bike in a stand) rotating the lever so it sits level and opening the bleed port, then press the pistons so they are fully retracted into the caliper, once this is done top off the mc with mineral oil give it a few taps and then replace the bleed cover. I was having issues with piston stick as well and this seems to have solved it for me.

 

[Sandwich]

Hey @Udi , can I run saint brake hoses on XT calipers? Is there any difference in the brake lines?

 

[6thElement]

So the Saints on my wifes DH bike have sat since Sept/Oct and currently seem to have less stopping power than Fred Flintstoning it...

Thoughts? Is it likely the calipers have contaminated the pads and nuking the pads or fresh pads should solve it for now?

Levers aren't squishy and only a few bubbles came out with the funnel attached.

 

[Nick]

So the Saints on my wifes DH bike have sat since Sept/Oct and currently seem to have less stopping power than Fred Flintstoning it...

Thoughts? Is it likely the calipers have contaminated the pads and nuking the pads or fresh pads should solve it for now?

Levers aren't squishy and only a few bubbles came out with the funnel attached.

a few hot laps might heat them up and fix everything

or, fix nothing and you have a high-speed out of control wife

I'm helping.

 

[6thElement]

a few hot laps might heat them up and fix everything

or, fix nothing and you have a high-speed out of control wife

I'm helping.

Swapped the rear pads for the only spare set I had, will have to find some more for the front before the weekend.

If I need some Shimano juice can I come steal some?

Anyone want to swap two sets of finned XT for a set of Saint?

 

[Nick]

Swapped the rear pads for the only spare set I had, will have to find some more for the front before the weekend.

If I need some Shimano juice can I come steal some?

Anyone want to swap two sets of finned XT for a set of Saint?

of course on the juice, and I'll check the stash for pads too.
where are you two DH'ing this weekend?

 

[Jm_]

So the Saints on my wifes DH bike have sat since Sept/Oct and currently seem to have less stopping power than Fred Flintstoning it...

Thoughts? Is it likely the calipers have contaminated the pads and nuking the pads or fresh pads should solve it for now?

Levers aren't squishy and only a few bubbles came out with the funnel attached.

Standard fix, pads in oven at 400 for 20, wipe rotors down with 99% rubbing alcohol.

 

[6thElement]

of course on the juice, and I'll check the stash for pads too.
where are you two DH'ing this weekend?

Granby Ranch, free day on our mtbparks pass as a warmup before Winter Park and Keystone get going.

 

[slyfink]

Vital having trouble with the Magura MT Trail carbons?

the rear brake was often inconsistent and needed a bleed after a short time

(Maybe a 2-pot caliper is undersized for a bike of that heft?)

 

[slimshady]

Vital having trouble with the Magura MT Trail carbons?

(Maybe a 2-pot caliper is undersized for a bike of that heft?)

That has nothing to do with it being 2-pot, but with a stupid design decision by Magura. Their MCs have a venting hole in the handlebar clamp area, and given enough time the diaphragm blocking it will start letting air into the circuit. Down here, where spare parts are scarce, most of the guys opt for either selling them and buying Shimano (only to land in the same boat with regards of leaky MCs) or plugging the venting hole with some silicone glue.

 

[StiHacka]

That has nothing to do with it being 2-pot, but with a stupid design decision by Magura. Their MCs have a venting hole in the handlebar clamp area, and given enough time the diaphragm blocking it will start letting air into the circuit. Down here, where spare parts are scarce, most of the guys opt for either selling them and buying Shimano (only to land in the same boat with regards of leaky MCs) or plugging the venting hole with some silicone glue.

Next time, make them try Shimano levers.

 

[toodles]

Measurements for interest.

Hope Evo main pivot to piston

Tech 3 lever

Hope tech 3 lever pivot to plunger

Tech 3 master piston

Hope Evo lever length

Tech 3 master cylinder seals

 

[Udi]

I've now added all that to the spreadsheet.
https://docs.google.com/spreadsheets/d/1sjPSmOYbhjDBFxcvXVw1ufKfowEBu1AKh8sB6T8e24Y/edit#gid=0

With big thanks to toodles, troy, and a few lurkers, we've got reasonably complete data on many current brakes now:
Hope Tech3 E4, Tech3 V4, Trickstuff Direttissima, Magura MT5, MT7

If between @Flo33, @HAB, @kidwoo you guys could measure your Formula brakes, I could fill out some common options there also. Refer to toodles' pics for the measurements, first one is "center of braking finger to lever pivot center" and second is "lever pivot center to cam center".

I know MC measurements are harder, but even the lever geometry would be great for now.

 

[HAB]

@Udi I'm out of town through the weekend but I can take some next week.

 

[Flo33]

I'll see what I can do. External measurements are no problem, MC would be. Brake is working flawless.

 

[slyfink]

I've now added all that to the spreadsheet.
https://docs.google.com/spreadsheets/d/1sjPSmOYbhjDBFxcvXVw1ufKfowEBu1AKh8sB6T8e24Y/edit#gid=0

With big thanks to toodles, troy, and a few lurkers, we've got reasonably complete data on many current brakes now:
Hope Tech3 E4, Tech3 V4, Trickstuff Direttissima, Magura MT5, MT7

If between @Flo33, @HAB, @kidwoo you guys could measure your Formula brakes, I could fill out some common options there also. Refer to toodles' pics for the measurements, first one is "center of braking finger to lever pivot center" and second is "lever pivot center to cam center".

I know MC measurements are harder, but even the lever geometry would be great for now.

Hey Udi, on another thread somewhere, someone mentioned the Hope Trials brake. I hadn't heard of that before, so I went on their site to have a look. It seems the caliper piston is 25mm. It's not on your chart, but the V2 is, and it has 25mm pistons too. I'm not particularly good with math/excel, and don't want to fuck anything up by playing in your spreadsheet (sounds dirrrrty!), but I copied the values from the V2 caliper and Tech3 lever that I think apply... but I'd suggest reviewing it caus' like I said, I really suck at that shit...

All this to say... I still don't know how any of that would translate into a real world application. I'm surprised that the slave area of the single 25mm piston is bigger than that of the V4. They hydraulic leverage rate is also way up there (if my assumptions and math are correct of course).

 

[Udi]

@slyfink - yes your reasoning all seems correct, I can check it later.
I haven't seen the brake in question, but the V2 brake actually came with the Tech-Evo lever which has a larger MC piston, so the peak force is slightly lower than the T3V4. The problem is that Hope run fairly large slave piston rollback, so you'd tend to get very long lever throw by running the T3 / V2 combo, even though it looks good on paper. The only way that'd change is if the 25mm slave caliper you mention has lower rollback than the V2.

 

[Flo33]

I've now added all that to the spreadsheet.
https://docs.google.com/spreadsheets/d/1sjPSmOYbhjDBFxcvXVw1ufKfowEBu1AKh8sB6T8e24Y/edit#gid=0

With big thanks to toodles, troy, and a few lurkers, we've got reasonably complete data on many current brakes now:
Hope Tech3 E4, Tech3 V4, Trickstuff Direttissima, Magura MT5, MT7

If between @Flo33, @HAB, @kidwoo you guys could measure your Formula brakes, I could fill out some common options there also. Refer to toodles' pics for the measurements, first one is "center of braking finger to lever pivot center" and second is "lever pivot center to cam center".

I know MC measurements are harder, but even the lever geometry would be great for now.

Formula ROR
Finger contact point to lever pivot 7 cm
Pivot to cam center 1 cm

 

[HAB]

I get the following for the ROR lever

72mm
10.5mm

 

[Flo33]

I'll go and check again in daylight today.

 

[Udi]

Thanks guys, I've added it to the spreadsheet.
Good to have verification - those numbers work out roughly the same as a ratio anyway.

Does anyone know if the RO-R MC piston diameter would be the same as the previous T1 / RO lever?

 

[Flo33]

Can confirm 10.5 mm for the pivot to cam.
The 72 mm for the finger contact point would be at the middle of the bend at the end of the lever, as far as my measurement skills go. I for one am only quite touching that point with the outer part of my finger. I don't think that's the force center.

No info on the MC. Will ask the official Formula rep I got some info earlier.

 

[Happymtb.fr]

I remember reading on PB that the Cura and Cura4 share the same lever assembly from a comment of a Formula representative. Hopefully he/she knows what he/she talks about...?
If right, with the slave area around 11% bigger for the 4's, it would result in 11% increase in leverage!
Then I don't know if Formula went for longer throw and similar roll back as the simple Cura, same throw and less roll back or something in between...

 

[slyfink]

Cura tear-down. with pictures. https://nsmb.com/articles/formula-cura-brakes-teardown/

 

[Udi]

I don't think that's the force center.

I agree with you.
I measured my own and I think 69mm is closer to the truth, still generous even. I'll use that for now.

If right, with the slave area around 30% bigger

Where are you getting 30% bigger slave area from? My calcs say 11%.

 

[Happymtb.fr]

Where are you getting 30% bigger slave area from? My calcs say 11%.

Oops! Something went wrong somewhere obviously... thanks for putting that straight!

 

[Flo33]

Formula rep responded. The 25.4 mm on the ROR is the equivalent circle's diameter with the same piston area. But I'm not 100% sure if that's correct. He has to dig deeper for the MC diameter.

As the topic of F1 brakes was brought up here, formula1.com posted some info on the teams efforts to cope with the brake killing course of Montreal last weekend. Not that it's super insightful, but nonetheless interesting.

 

[Udi]

Interesting stuff there Flo, the reason I mentioned it is because we're running much closer to material limits than most people realise - particularly evident with how quickly sintered pads lose their peak friction permanently due to heat effects. It's not surprising that heat management and rotor sizing are the key issues they are discussing too.

The balance of weight and performance (which they bring up constantly) is also a key issue which I don't think many appreciate, because even a "heavy" MTB brake (eg. a 300g Saint / MT7) is ridiculously light by motocross or road-automobile standards. The fact that so many brakes fail in some way under hard usage might be partially fuelled by people not being willing to pay for the level of materials and technology actually required for the application.

Of course there's plenty of small problems that could be solved in the design phase (without much additional mass or cost), but knowing what to do and applying the knowledge... well that's worth money in itself.

 

[profro]

The fact that so many brakes fail in some way under hard usage might be partially fuelled by people not being willing to pay for the level of materials and technology actually required for the application.

So true. I can't help believe this is why my 10 year old Formulas are still working as they were $250/wheel back in the day.

 

[HardtailHack]

Pretty cool thread, I have nothing current to measure that isn't already listed, just some ancient Hope Motos and Moto V2.
Still seems like a good enough reason to buy a ball type bore gauge set.

 

[Udi]

Trickstuff have updated their brake encyclopedia, funnily it covers many of the things I've posted recently.
http://www.trickstuff.de/en/know-how/index.php

I'll post some of the interesting parts, as they bust some common myths and re-state some facts which have been argued here recently:

 

[Flo33]

Trickstuff have updated their brake encyclopedia, funnily it covers many of the things I've posted recently.
http://www.trickstuff.de/en/know-how/index.php

I'll post some of the interesting parts, as they bust some common myths and re-state some facts which have been argued here recently:

View attachment 129151

View attachment 129152

View attachment 129155

View attachment 129153

View attachment 129154

Saw it too. Was sure you'll bring it up

Another interesting bit of motor brakes info.

 

[Sandwich]

That one piece commentary is interesting. In theory, we will never know whether a monobloc caliper matters, at least in cycling, until somebody carefully designs and optimizes two calipers with the same piston size and lever. It's easy to say "monobloc is stiffer", but it's just as likely that the entire system is different and therefore not accurately measurable.

anybody got access to a cnc machine? imma start machining some brakes and charging you suckers a mortgage for them