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Frankenbrakes and brake improvement discussion

Udi

RM Chief Ornithologist: “I Brake for Birds”
Mar 14, 2005
4,886
1,138
Are the pads on the a4 not tall enough for the braking surface of the discs or are those washers below the caliper a little too thick? I ask because of the untouched strip at the base of the braking surface on the rotors
The guy is a n00b, obviously set up his caliper wrong and glazed his rotors
 

buckoW

Turbo Monkey
Mar 1, 2007
2,513
2,087
Champery, Switzerland
The 220mm rotor does not need the washers for the 220mm adapter, haha. You guys are right. Thanks for keeping an eye on me.


32754FFB-4146-4FB2-A042-FE7B276AE8BF.jpeg


Ah, that’s better.
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Lap before work.
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Getting some good color. Panic braking art!
299B4984-D297-4103-BBF8-B001D1396B8A.jpeg
 
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kidwoo

Artisanal Tweet Curator
Aug 25, 2003
30,559
6,542
The old timey times
speaking of hope and frankenbrakes

ran this on my dirtbike most of the summer, even checked udi's spreadsheet for an mc piston size to verify feasibility

brakelevers.jpg


front and rear brake off a hope duo, no footbrake


works like a fuckin champ
 

Jm_

sled dog's bollocks
Jan 14, 2002
14,198
5,762
AK
speaking of hope and frankenbrakes

ran this on my dirtbike most of the summer, even checked udi's spreadsheet for an mc piston size to verify feasibility

View attachment 166233

front and rear brake off a hope duo, no footbrake


works like a fuckin champ
That's gotta be the most F-ed up bleeding process ever.
 

kidwoo

Artisanal Tweet Curator
Aug 25, 2003
30,559
6,542
The old timey times
That's gotta be the most F-ed up bleeding process ever.
as far as the lever goes, it's just two brakes, one on each side. The rest is just like bleeding a mix of mtb stuff at the lever and big dumb motor stuff at the caliper ;)




.....yeah it took me a while

I had to drill and tap my own adapters to get the mtb lines into the calipers.

I have a certain standard of minimum speed going downhill from years and years of bikes and a footbrake just wasn't cutting it on the screechpig.
 
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buckoW

Turbo Monkey
Mar 1, 2007
2,513
2,087
Champery, Switzerland
speaking of hope and frankenbrakes

ran this on my dirtbike most of the summer, even checked udi's spreadsheet for an mc piston size to verify feasibility

View attachment 166233

front and rear brake off a hope duo, no footbrake


works like a fuckin champ
Oh sick! I was wondering if that could work? Can I see a better pic of the levers? You could keep the foot brake if you wanted it. It’s pretty tiring to use the levers all day, imo.

Where did you order that lever from?
 

kidwoo

Artisanal Tweet Curator
Aug 25, 2003
30,559
6,542
The old timey times
Oh sick! I was wondering if that could work? Can I see a better pic of the levers? You could keep the foot brake if you wanted it. It’s pretty tiring to use the levers all day, imo.

Where did you order that lever from?
I've actually got two, that one I found randomly on facebook marketplace after everything sold out this summer. The other one I found on some german backcountry(dot)com looking place.

Literally the only reason to keep a foot brake is wheelies IMO. I bought an adapter to run the footbrake too but 5 months in I don't miss it at all. And I don't accidentally hit it sometimes scrambling and moving my foot around.

I've done 5k descents on all kinds of shale and rocky shit. It's better. It's much less tiring because you can use both brakes much more effectively. You're not over-relying on the front. Moto levers get tiring because they're made for the 1960s. Get a nice ergonomic mtb setup and it's not tiring at all because you can adjust them with much more precision to engage close the bar with one finger.

It's kinda tough to take pics with that handguard in the way but it's just one of these


The adapters I had to make are the more interesting end
 

kidwoo

Artisanal Tweet Curator
Aug 25, 2003
30,559
6,542
The old timey times
There are also thumb brake options for the left hand, although probably sized for street bikes.

I definitely thought about those but bracing yourself against the bars while running into things seemed like the wrong place to put a brake lever. I'd been kind of obsessing over this for like a year and checked out all kinds of shit like that. What I've got is basically just a poor mans (and brake version) of this. Which I think is still too big and weird, and requires a hydraulic clutch, which I don't have and didn't like when using an adapter to get it. The hope levers I got for 200 each, these are more like 900

clake2.JPG
 
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Westy

the teste
Nov 22, 2002
46,241
11,804
Sleazattle
I definitely thought about those but bracing yourself against the bars while running into things seemed like the wrong place to put a brake lever. I'd been kind of obsessing over this for like a year and checked out all kinds of shit like that. What I've got is basically just a poor mans (and brake version) of this. Which I think is still too big and weird, and requires a hydraulic clutch, which I don't have and didn't like when using an adapter to get it. The hope levers I got for 200 each, these are more like 900

View attachment 166257
Although it was a direct replacment for the cable system, I put a hydraulic clutch on my motorcycle and loved it. The level of control was amazing. I could stop on a steep hill, hold position in idle by feathering the clutch, give'er a bit of gas with out moving then just feather the clutch to control initial acceleration and speed. Was never able to do that with the cable mechanism.
 

kidwoo

Artisanal Tweet Curator
Aug 25, 2003
30,559
6,542
The old timey times
Although it was a direct replacment for the cable system, I put a hydraulic clutch on my motorcycle and loved it. The level of control was amazing. I could stop on a steep hill, hold position in idle by feathering the clutch, give'er a bit of gas with out moving then just feather the clutch to control initial acceleration and speed. Was never able to do that with the cable mechanism.
Was it one of the magura hymec things? I tried one of those and took it off. I've got a streetbike stunt lever on both bikes. They're two strokes I ride almost exclusively on singletrack so I'm constantly feathering to do what you're describing......I just couldn't get the hydro thing to bracket the engagement range very well. I liked the hydro clutch I had on a KTM but that's a complete real hydraulic system.
 

Westy

the teste
Nov 22, 2002
46,241
11,804
Sleazattle
Was it one of the magura hymec things? I tried one of those and took it off. I've got a streetbike stunt lever on both bikes. They're two strokes I ride almost exclusively on singletrack so I'm constantly feathering to do what you're describing......I just couldn't get the hydro thing to bracket the engagement range very well.
Yup, the Hymec. I can't remember the details but I fumbled around with the installation without getting it to work well at first, even tried making my own mount before kicking myself and realizing I was doing it wrong. I think the instructions were missing some details, of course now I can't remember what I was doing wrong. Something about the throw and engagement point being off. But once I got it setup properly it worked great.
 

kidwoo

Artisanal Tweet Curator
Aug 25, 2003
30,559
6,542
The old timey times
I could get it to work fine, I just got the cable with a real lever (IE not the stock neanderthal shit) to work a little better.

that's my contribution to dirtbikes: absolute minimum lever throw possible to avoid arm pump but still function :D
 

Boozzz

Chimp
Sep 12, 2019
30
38
Interesting stuff, I saw 9.15mm too, probably same source. Not having a dig at your beautiful website but to be honest it detracts from the original intention of the spreadsheet (creating combination brakes) and instead focuses on ordering the brakes in a method which amplifies the largest inaccuracy in our calculations - the mechanical leverage - thus total leverage is likely very wrong for many brakes in the list. We are only calculating 1 lever arm, but this leverage is applied through an angle to the MC piston which drastically changes the final mechanical leverage (at least to my understanding). On some brakes this means the leverage we calculate becomes lower as the lever moves, for others it can become significantly higher (particularly for SRAM/avid and trickstuff with intentionally close-to-bar main pivots). It wouldn't be hard to correct this (especially for people like flo / troy / happymtbfr / hab) but I'm happy with my brakes and lazy. If someone wants to get involved with this I'll help incorporate the changes. Ultimately though, the issue with DH brakes (at least since the M820) was never peak force.

Yours is the 2nd report of quality control issues in this thread with the Dominion A4.
I rode them recently and thought they felt great (on all fronts - light lever action, good punchy stopping), but I guessed early on that the build quality wouldn't compete with some others. They're also damn heavy. I own the previous gen of Hayes brake (Prime Pro) and it's a cast alloy monstrosity, I'm running the calipers with some nicer Formula levers. It'd be cool if they made a more expensive version with better materials and lower weight one day, there would definitely be a market.

On the other hand, at least the situation has improved. The two big S brands are getting crushed by the small guys who are slowly fixing the issues at various price points.
I should get my secondary school physics book out for this, but yeah, the leverage could change if the distance between cam and master cylinder changes, which can happen if the angle from cam to MC changes. On the Hayes Dominion and the Hope Tech 3, this doesn't seem to happen though: the rod that connects directly to the cam and pushes the MC remains perpendicular to the MC at all times. Perhaps a bit so on the Magura MTs, as the MC gets pressed directly by a triangular protrusion fixed to the lever, which sort of rotates right on top of the MC when you press the lever. But the difference will be very minimal. I also have a Guide RS here in a box somewhere, will have a look at how that lever works with the swing link, which could very much change the leverage. I'm definitely willing to help make the data better, but only have a few brakes at my disposal unfortunately. I reckon the way the spreadsheet is setup, with a min and max distance from pivot to cam is a good start. What would be a good way to incorporate possible angle variations?

As far as the Hayes Dominion goes, yeah, it's a similar cast aluminium monstrosity as the Stroker Trail I still have somewhere. Apart from the big functional issue with uneven pad retraction, the surface finish is just really bad, paint uneven, tooling marks everywhere on the caliper, caliper halves that don't really match up, screws that come pre-scored. And the weight is the same as Hope V4s with stainless steel braided hoses.

I've did ride the Dominion for a week or so on my trials bike, as a back brake (the main brake with trials). I used the caliper with almost no pad clearance (which I discoverd only later), so the lever had almost no free stroke. As far as lever feel, it did feel good, super light action. Bite point was a quite vague, though it felt better on the caliper with more pad clearance. Power was very good, pretty grabby too. Where my Magura MT5s tended to slip when just under-jumping a ledge (full weight on back wheel, brake locked, slammed at speed into top of a wall, just below the edge), the Hayes just held. Pretty impressive. This was with the stock semi-metal pads (sintered don't get warm enough for trials I find).

Since I've sent back my Hayes, I figured I'd give some Hope Tech3 V4s I also had lying around a shot on the same bike. Lever action is super heavy compared to the Dominions. The V4s do modulate better (not good per se for trials) but actual peak power doesn't seem that far below the Dominions, very similar to the MT5s I would say, perhaps even a bit better. But that might also be because of me having put in fresh pads and given the rotors a thorough clean (pads are Discobrake Kevlar cheapo's, same as in the Magura's). What I like about the Hopes is that the levers hardly flex and that they are completely silent. Magura's had massive pad rock and knocking sounds all the time, Hayes a bit, Hope zero.

I got 9.08mm for the Dominion A4 MC. The other numbers in the spreadsheet look right.
Sounds good! I think we can put this in the spreadsheet now?
 

Jm_

sled dog's bollocks
Jan 14, 2002
14,198
5,762
AK
Since I've sent back my Hayes, I figured I'd give some Hope Tech3 V4s I also had lying around a shot on the same bike. Lever action is super heavy compared to the Dominions. The V4s do modulate better (not good per se for trials) but actual peak power doesn't seem that far below the Dominions, very similar to the MT5s I would say, perhaps even a bit better. But that might also be because of me having put in fresh pads and given the rotors a thorough clean (pads are Discobrake Kevlar cheapo's, same as in the Magura's). What I like about the Hopes is that the levers hardly flex and that they are completely silent. Magura's had massive pad rock and knocking sounds all the time, Hayes a bit, Hope zero.

Sounds good! I think we can put this in the spreadsheet now?
My V4s came with 3 sets of pads. Great. One set was resin and I thought I'd burn those up first just to get rid of them. Bad idea. Completely worthless. Made the brakes feel like shitty 180mm brakes. The E-brake pads I've been running have been great though (one of the three). The other pads are also sintered, not sure how they'll be different than the sintered e-brake pads, but whatever, go for max I say. Over-rotor the hopes for comparable power. I like how the lever positively snaps back, that's a nice feeling, feels solid too, not like flexing plastic. Don't notice them being heavier action, but they are a little different to get your finger around, I always play with the reach/bite point after bleeding to get it just right.
 

toodles

ridiculously corgi proportioned
Aug 24, 2004
3,878
2,434
Australia
Don't notice them being heavier action, but they are a little different to get your finger around, I always play with the reach/bite point after bleeding to get it just right.
The Hayes I tried had a ridiculously light action. Felt like pulling on a normal brake that had no fluid in it.

I don't mind the Hope resins (red backing). I think they're made by Galfer? I tend to stick to their sintereds for all weather riding but have tried a few different options from Trickstuff and Galfer. FWIW, the Shimano pads fit the V4s as well so you can run the Saint pads if you wish/get stuck somewhere.
 

Jm_

sled dog's bollocks
Jan 14, 2002
14,198
5,762
AK
Current Saints? I'll have to try that. I remember back in the day MonoM4s could run shimano pads...but I could never get them to run well. Maybe I was using resin back then though...
 

HAB

Chelsea from Seattle
Apr 28, 2007
11,319
1,704
Seattle
The Hayes I tried had a ridiculously light action. Felt like pulling on a normal brake that had no fluid in it.
Yup, the Dominions have the lightest action of anything I've tried yet. I'm into it but YMMV.

I'm definitely in agreement with the criticism above of their fit and finish from a cosmetic perspective, but my pair has been excellent from a performance/reliably standpoint. Not doubting anybody who has had issues, just another data point.
 

buckoW

Turbo Monkey
Mar 1, 2007
2,513
2,087
Champery, Switzerland
I was just guessing, is that actually what you were riding? :rofl:


an eroded switchback with a pocket is still a switchback ;)
Yeah, that is our main track behind our house and me wife and I ride it all the time. There are alternate lines and another section a 100 meters away. 3000 vertical foot runs.

These we’re the last of the tight turns which were awkward and hard to carry speed. Now they are “Bermkakke’d” as they say here.

1634780586956.jpeg




*Eroded switchbacks with pockets.

1634780992535.jpeg


I still have 2 trail builders working on the track. It’s running real good currently but these photos are from last spring, btw.
 
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buckoW

Turbo Monkey
Mar 1, 2007
2,513
2,087
Champery, Switzerland
you know damn well that ain't the parts I'm talkin about!!

bet I could jump that vert wall left turn straight to the bar down the hill......
I know what you are talking about and I changed a lot of stuff to make it more rideable. That is the section with all the janky switchbacks. I have been in charge of the maintenance and building on this track since 2006. I changed some stuff. It’s fast as fuck.

I bet you could get stood up nicely and just high side it in one of those with a sweet 29er.
 

kidwoo

Artisanal Tweet Curator
Aug 25, 2003
30,559
6,542
The old timey times
the section with all the janky switchbacks.
see? you knew exactly what I was talking about the whole time

Honestly though that whole course looked like endless switchbacks on the teeveee


I get high sided just getting out of bed these days

I was waiting for some cut D3 commentary
oh shit is that straight ronnie mac style?

respect!
 
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buckoW

Turbo Monkey
Mar 1, 2007
2,513
2,087
Champery, Switzerland
see? you knew exactly what I was talking about the whole time

Honestly though that whole course looked like endless switchbacks on the teeveee


I get high sided just getting out of bed these days



oh shit is that straight ronnie mac style?

respect!
2007 and 2011 was a long time ago.
After I realized we weren’t going to do more World Cups, I had to make it more fun and less “Death or Glory.”

It’s proper DH. If you like DH bikes then I would be surprised if you didn’t enjoy the track. Just ignore the low sides.
 

Balgaroth

Chimp
Oct 22, 2021
33
21
Alsace (FR)
Hi guys,
I’ve discovered a week ago that I wasn’t alone Frankenbraking and being a terrible bike nerd myself discovering 58 pages of nerding (and whining lol) was pretty exciting. I have some data to share but I guess from a different perspective which is performance/price rather than ultimate performance. Since there is 3+ years of experimenting this write-up might be long, you’ve been warned.
As a quick background, I’ve been riding DH since 2004 and have owned HFX Mags, Codes, Oros, M810, Codes R. More recently I’ve been Enduroing where I live and Bikeparking in the Alps, trying to make use of Slates and M745 which I found to be massively underpowered (some numbers at the end).
So when I got delivery of my 2019 bikes both were setup with Slate T4, after a few sessions I realised that these were definitely too weak. I had some leftover Servowave levers and decided to experiment with them on the endure bike first. This worked fine, gave more bite which retrospectively hid the fact that they weren’t really more powerful (same MC diam.) but I got on ok ad did the same with the DH bike. Fast forward to 2021, this time only one bike, setup with M745 which visually seem very similar to the Slate, I took the same old Shim levers but this time it was very clear that despite having more initial bite, the final power wasn’t there and were requiring a lot of finger pull. Once you factor the inconsistent bite point it wasn’t worth it and I reverted to the M745 lever which is agricultural but doesn’t skip a beat. Now even in the Bike Park I got on ok, only over-heating problem I had over the summer was in Tignes on the “Black Metal” track which is stupidly steep with no place to let your brakes cool down. Otherwise it was fine since you take breaks on the bike park. Later this season I decided to restart racing some Enduros which restarted my bake tinkering. On steep and long stages I got harm pump from having to pull super hard on these levers with no option to stop every 1 or 2min or ride, not acceptable. First step was going 223mm front and 203mm back, I ride a 297 bike. It helped but it surely wasn’t night and day. I also noticed that the standard hoses are very flexy so I went with Shimano BH90 which helped but clearly not enough. Interestingly this is now a standard modification for TRP evo brakes. Season is now over and my next bike will have Slates again but I plan to race more so I am tinkering now to be able to have a somewhat usable setup next season. In the tinkering process I started to explore the hydro leverage ratio and ultimately ended-up on this thread.
One big surprise was fitting some Elixir R SL on my partner’s bike, good bite, good modulation, good power despite them being 10 years older than my TRP/Tektro. Since I had good memories of Oros I decided to dig out an old pair that was in my old parts box. Classic sticky MC made me dismantle the lever, measure the piston (9.99) and poor man’s lathe it to 9.95mm, the lever now feels perfect. Interestingly these old brakes didn’t feel any worse that my Slates or M745, once you actually do the math they are more powerful with respectively 32 vs 27 vs 30 total leverage ratio in stock form (numbers below). Additionally the M745 in form stock (High Mech, Low Hydro) yields the same total leverage than the Slate lever with M810 calliper (Low mech, High hydro) and having used both, the Slate/M810 combo felt much more powerful than the M745. Additionally the M745 lever combined with M810 calliper is more powerful but the difference isn’t as massive as expected when looking at numbers. Ultimately all this is anecdotal evident and it is hard to compare since they have been tried with different pads/discs/bikes but it seems that hydro leverage is somewhat more important than mechanical leverage, maybe because hydro ratio isn’t influenced by friction whereas mechanical leverage has increasing friction as you pull harder on the lever which somewhat cancel your mechanical advantage? Maybe someone with formal education in engineering or physics can figure this one out?
For now the Oros will be on my 27.5 hardtail until they decide to give up the ghost. After this I went full-on need with lever and calliper measuring, calculation and combination. I had some old M810 callipers that were also in my toolbox so I fitted them with the M745, same pads and same disc, all else equal maths says a jump from 30 to 39.5 in total leverage which is a 30% increase in power. Lever throw is barely worse that it was with the original calliper, which is a surprise. Power is good and really easy to manage, having none of the traits Shimano brakes are know for.
If all goes well I still have one problem, being that the Slate lever has less mechanical advantage compared to the M745. M745 and TRP levers are no compatible which could have been an easy tweak. If someone who have the new TRP lever blade that could be interesting to see the mechanical leverage they offer. Otherwise sourcing some MT5-7 calipers should allow me to remain within a decent leverage range (34.8) without costing me a fortune. One added benefit is that the Tektro/TRP levers are consistent and reliable so it might be a better option than going with Shigura none-servowave levers.
Here are some of the measurements I took:
  • Oro: MC 10mm / SC 22mm / Lever 66-10mm
  • Slate T4: MC 10mm / SC 16-14mm / Lever 72-12mm
  • M745 : MC 10mm / SC 14-14mm / Lever 77-10mm
I initially tried to measure with the lever blades on but wasn’t happy with it. I took some time to remove them from the MC and while the difference in finger-pivot wasn’t massive, the pivot-pivot was proportionally more important which has a bigger influence in the lever ratio calculation.
I checked and aside from the brand new DH-Evo, all TRP use the same lever blade, and 10mm MC so those numbers are applicable. Once factoring the SC of Slate, Quadiem and DH-R it is no wonder those have good modulation and a massive lack of actual power.
I hope this is somewhat helpful.
 

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