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Frankenbrakes and brake improvement discussion

Mo(n)arch

Turbo Monkey
Dec 27, 2010
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Italy/south Tyrol
A buddy of mine rode the TRP and didn't sound impressed, I'll reserve judgement for when I ride them. Reading between the lines on the review gives me this though:


I'd just get Hope V4s for a reliable, high quality option. I am yet to hear from an unhappy owner, and even with the included stainless hoses the V4 is lighter than those TRP Quadiems. The pricing is reasonable these days.

For those without a budget, the best brake I've ridden to date is the Trickstuff Direttissima. The price is completely ridiculous though.

@troy I think the throw will be way too long, but let us know how it goes.

I read the thing with the"give" too and was a little surprised. If I were the engineer, the LAST thing I would consider to have better modulation, is give in the hoses and the lever. That just doesn't make any sense to me.
The best thing you can do is trasmitting the hand force as directly as possible to the caliper, right?
On the other hand, consistency is key and if they go for a few upgrades in the "give" department, we will possibly have a new contender.
Or buy some Saint levers and hoses for it :p
 

Udi

RM Chief Ornithologist
Mar 14, 2005
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Honestly I only read that review because a few people linked it to me now - but as a general rule, I avoid reading reviews from American writers (and basically everywhere outside the EU) because they always try to pass off flaws as features. They are good for pretty pictures though. :)

The reviews from your side of the pond are the only ones worth reading. If you haven't put the brake on a dyno, and you haven't used it for a full bikepark season, then you don't have a review worth reading.

Any reason you wouldn't get V4s btw? Also, I'd much sooner buy Shimano/Magura/Avid than a completely unproven brake with a questionable review.
 

Nick

My name is Nick
Sep 21, 2001
23,822
14,184
where the trails are
has anyone torn into a pair of Cura brakes yet? Now that Formula is running mineral oil, frankenbraking with other MC / calipers should be possible.
 
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Udi

RM Chief Ornithologist
Mar 14, 2005
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Good call, I tried to find the parts list but it doesn't seem to be on the site.
Formula usually run a big MC piston so it's hard to predict if it'd generate enough hydraulic leverage for even the M820/MT7 caliper. I'll add the data whenever it becomes available. Could be a nice lever for @troy 's Julie one day.

Personally I'm hoping this 29er craze drives Formula to bring back their 220mm rotors, they were the lightest available by far and would make it much easier to build a powerful stopping system without crazy long throw or other compromises.
 

Nick

My name is Nick
Sep 21, 2001
23,822
14,184
where the trails are
while you're sleuthing :nerd: see if you can determine the mechanical differences between the Cura and their e-bike version, "designed for the higher average speeds of electric assist bikes".

cura.jpg
cura-e.jpg

 
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kidwoo

Artisanal Tweet Curator
has anyone torn into a pair of Cura brakes yet? Now that Formula is running mineral oil, frankenbraking with other MC / calipers should be possible.
I've got a pair on my trail bike (with metal formula pads) and a pair on my dh bike (with shimano finned roadie pads).

They work well. But I could not for the life of me get a decent bleed on them until I'd rattled them around a bit. Makes me think there are all kinds of little places for voids/bubbles to reside.

I still haven't gotten a completely clean bleed on my dh bike. I don't know if it's the shimano pad spacing making it worse but on some good ass dragging fall line stuff, they do heat up and then drag a bit.....so air.

I've gotten the ones on my trail bike dialed though. Even coming from shimano I'm happy with their braking strength. But right now I don't have any desire to mix and match them with anything else.

If someone wants to send some brake parts I can try it. All I have is shimano stuff.


And to answer your question:

The Cura-E has been designed to accept all major e-bike brake sensors making it a universal e-bike brake. Thanks to this, the Cura-E is ready to use with all existing motors on the market, ones that require a brake sensor and those that are automatic.

curaE.jpg
 
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troy

Turbo Monkey
Dec 3, 2008
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725
@Udi I'm not as skeptical about that as You are, as the Shimano MC piston is almost 45% smaller than the stock one, yet I ended up with much shorter lever stroke and more power (shimano servowave magic link). Julie MC piston is only 17% bigger than the one on the Louise, so it might actually work...:monkeydance:
 

toodles

ridiculously corgi proportioned
Aug 24, 2004
5,420
4,643
Australia
Slightly off-topic but does anyone know how they factory bleed brakes? is it all done by hand or would they use a vacuum pump etc, similar to suspension manufacturing?
 

Mo(n)arch

Turbo Monkey
Dec 27, 2010
4,437
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Italy/south Tyrol
Any reason you wouldn't get V4s btw? Also, I'd much sooner buy Shimano/Magura/Avid than a completely unproven brake with a questionable review.
Nah, generally just interested in new stuff. At this point I have some DH-bike in my mind that will hopefully be mine soon(-ish). I am currently working out what I want for braking and suspension, as the stock product is not my cup of tea and or lacking power (Why are people selling DH-bikes with Guides???).
I actually like my Sram brakes. Probably the new Codes will be somethin for me.

So many options but so little reliability...

But, I am totally supporting the 220mm rotor petition as I will be fast™.
 
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troy

Turbo Monkey
Dec 3, 2008
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725
Alright @Udi , so I've connected the Servo-wave lever to Julie caliper and it seems to work fine. Still haven't field tested it, as I have not yet installed a proper, high pressure hose and the pads are probably contaminated and worn (bought an used caliper). Lever is quite firm, and the brake has not even been bled yet, so the lever throw should be shorter than that. #Monsterbrakes :monkeydance:

 
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Udi

RM Chief Ornithologist
Mar 14, 2005
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Looks good in your video. Time will tell though.
It's 2x 28mm right?

The less considered variable after hydraulic then mechanical leverage is the piston rollback, less rollback = shorter throw and can definitely go some way to compensating for increased leverage. I'd have to guess that the Julie has fairly tight rotor clearance, otherwise something doesn't add up.
 
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troy

Turbo Monkey
Dec 3, 2008
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@Udi, Yup, 2 x 28mm pistons.

@Sandwich , Julie brake came in 2 different specifications. HP (high pressure with Louise calipers) and this one with those huge pistons, labeled as low pressure system, like Maguras rim, hydraulic brakes. Hose is not reinforced in any way and on the caliper side they slip onto the connectors instead of using olive/barb threaded combo.
 

Udi

RM Chief Ornithologist
Mar 14, 2005
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Oh right, I thought you meant the Shimano hoses.
That's pretty wild. Makes sense though.

Edit - can you take a video of the caliper showing pad travel to hit rotor as well? Maybe after the brake is finished and bled. Curious.
 
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troy

Turbo Monkey
Dec 3, 2008
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Oh right, I thought you meant the Shimano hoses.
That's pretty wild. Makes sense though.

Edit - can you take a video of the caliper showing pad travel to hit rotor as well? Maybe after the brake is finished and bled. Curious.
There is 2.18mm between the pads (2.2mm on Louise 2x22mm caliper). The Magura Venti rotor is 1.93mm thick (after ~3 seasons of use).
 

Nick

My name is Nick
Sep 21, 2001
23,822
14,184
where the trails are
shhh shhh shhh shhh shhh shhh shhh shhh shhh shhh shhh shhh shhh shhh shhh shhh shhh shhh shhh shhh shhh shhh shhh shhh shhh shhh shhh shhh shhh shhh shhh shhh shhh shhh shhh shhh shhh shhh shhh shhh shhh shhh shhh shhh shhh shhh shhh shhh shhh shhh shhh shhh shhh shhh ......
 

troy

Turbo Monkey
Dec 3, 2008
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And to see if/how much the caliper flexes. :D
It doesn't, It is HUGE as fuck, 1 piece caliper (black one, the silver one is from Louise <shimano piston size>)
Justo so You can compare:
calipers.png


shhh shhh shhh shhh shhh shhh shhh shhh shhh shhh shhh shhh shhh shhh shhh shhh shhh shhh shhh shhh shhh shhh shhh shhh shhh shhh shhh shhh shhh shhh shhh shhh shhh shhh shhh shhh shhh shhh shhh shhh shhh shhh shhh shhh shhh shhh shhh shhh shhh shhh shhh shhh shhh shhh ......
Louise calipers do not rub the rotor, so I highly doubt that 0.01mm (0.0004") on each side will make any difference.
 
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StiHacka

Compensating for something
Jan 4, 2013
21,560
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In hell. Welcome!
It doesn't, It is HUGE as fuck, 1 piece caliper (black one, the silver one is from Louise <shimano piston size>)
Good. I had a pair of MT-8, one piece caliper, it flexed several mms when applying force to a Shimano lever (something you could not easily do with the flexy original plastic lever). MT-6 and MT-S are much better in that regard, they have more meat.
 

troy

Turbo Monkey
Dec 3, 2008
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Good. I had a pair of MT-8, one piece caliper, it flexed several mms when applying force to a Shimano lever (something you could not easily do with the flexy original plastic lever). MT-6 and MT-S are much better in that regard, they have more meat.
Yeah, that's why I bought the one from the post above nstead of those ones (28mm pistons as well)

 

troy

Turbo Monkey
Dec 3, 2008
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Goddammit, I knew something was going to happen. It was going waaay to easy. I've installed the high pressure hose and bled the system, but the caliper is made for 190 or 210mm magura specific rotors. #teh_standardzz
:bonk:
For now I've used some fancy SHIMZZZ between the lowers and the caliper, but pads are contaminated with oil, so can't check its power. No cash for some new ones this month...
 

Udi

RM Chief Ornithologist
Mar 14, 2005
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Did you build a rear as well? It's always the rear throw that breaks the deal after a month in the bike park, that's the real test.

Acetone (100%) works best for contaminated pads. Fire helps.
 

troy

Turbo Monkey
Dec 3, 2008
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Did you build a rear as well? It's always the rear throw that breaks the deal after a month in the bike park, that's the real test.

Acetone (100%) works best for contaminated pads. Fire helps.
Naaah, why would I need such a powerful brake for a rear? Lever throw is 2mm (0.078") more (tip of the lever to the grip) than on the XT servo brakes on my other bike. 17mm vs 15mm on XTs (0.67" vs 0.59").
 

Sandwich

Pig my fish!
Staff member
May 23, 2002
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so wait, what's the point of such massive calipers? how do you apply the power to the rotor? bigger pads? wider rotor? i'm confused.

dual pistons make sense, but i'm struggling to understand the fluidics here.
 

troy

Turbo Monkey
Dec 3, 2008
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@Sandwich - Hydraulic leverage. Just like Saints or Formula ROs are so powerful because of the master cylinder/piston area ratio. I'm doing the same with Julie caliper, that has huge pistons. They give me a bigger piston area than on Saints, while i'm using the same lever - bigger ratio. Check out the spreadsheet that @Udi made.
 
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Udi

RM Chief Ornithologist
Mar 14, 2005
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@Sandwich to add to what troy said, it's a mix of the mechanical leverage (which is a curve, not constant) and hydraulic leverage that defines the braking force. If you use the same lever then you'll maintain the same mechanical leverage curve, so by changing only the hydraulic leverage (like troy did) you can guarantee an increase in force. There's also a likely increase in throw - it would be a guaranteed increase if we only considered leverage but there are some other variables like piston rollback which can change the outcome a little, which is why we were discussing it.

Using more pistons doesn't actually mean more power, it's just the total increase in slave piston area that matters - you can also achieve the same leverage change by using a smaller MC piston. Too far in any direction and it won't work, but plenty of workable options exist.

Naaah, why would I need such a powerful brake for a rear? Lever throw is 2mm (0.078") more (tip of the lever to the grip) than on the XT servo brakes on my other bike. 17mm vs 15mm on XTs (0.67" vs 0.59").
IMO testing lever throw on the front doesn't mean a lot coz it's the rear where it's always longer and problems occur, but fair enough if you're only using it on the front. Just not the most stringent test.

More potential for success though. Maybe it's not a bad idea in general to run a more risky/powerful setup on the front and a more reliable/consistent setup on the rear.
 

shirk007

Monkey
Apr 14, 2009
499
354
Someone want to remind me again why all this faffing with frankenbrakes?

My Magura MT5's have been great. Loads of power and great modulation. No issues with heat fade.
 

Sandwich

Pig my fish!
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May 23, 2002
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Using more pistons doesn't actually mean more power, it's just the total increase in slave piston area that matters - you can also achieve the same leverage change by using a sm
I get that, but I guess more pistons makes sense to me, as all of that power is translated through the pad to the rotor. Having a single piston with the same overall diameter suggests equivalent power but concentrated on one pad over the piston face, rather than "two" pads over the two pistons. I'm not going to bother with the math but I guess if there is a hydraulic advantage then that makes sense. I just had a hard time seeing why you would want a bigger piston unless you were putting a bigger pad and bigger rotor and increasing the contact area, like how quad piston brakes work.

My Magura MT5's have been great. Loads of power and great modulation. No issues with heat fade.
My mt5s have been just OK. Power on tap, but you have to work for it. Not like some other brakes that have power in spades without needing a solid squeeze. Certainly weaker than my 810s and possibly my 785s, but stronger than a hayes mag or formula T1s.

So, more power = better.
 

troy

Turbo Monkey
Dec 3, 2008
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IMO testing lever throw on the front doesn't mean a lot coz it's the rear where it's always longer and problems occur, but fair enough if you're only using it on the front. Just not the most stringent test.
Well, if I ended up with the same lever throw as on Louise calipers with a front brake, my guess something would be that similar would happen with a rear brake.

Btw it weights 310g (0.68lbs), so basically the same as a Saint brake.
 

kidwoo

Artisanal Tweet Curator
Man I don't even think most brakes out there are shitty. But once you've felt the awesomeness that is a fully functional shimano level brake, of course you're going to try and duplicate that but add in some reliability.


If anyone knows where I can get some cura hoses domestically I'll try some shimano levers with those calipers. I can't cut my hoses any more.