# SRAM road hydraulic?



## pretender (Sep 18, 2007)

Updated: Spy Shots! SRAM Hydraulic Brakes Images Slip Out - Bike Rumor


----------



## krisdrum (Oct 29, 2007)

If true, that would certainly be drawing a line in the sand.


----------



## 88 rex (Mar 18, 2008)

Eh....it'll never catch on.

:14:


----------



## Dan Gerous (Mar 28, 2005)

88 rex said:


> Eh....it'll never catch on.
> 
> :14:


Sure it will, SRAM will force all their sponsored athletes to ride these next year, then everyone will 'need' them.


----------



## 88 rex (Mar 18, 2008)

Dan Gerous said:


> Sure it will, SRAM will force all their sponsored athletes to ride these next year, then everyone will 'need' them.


Don't you worry, I'm not a sponsored SRAM rider and I NEED these!


Very curious on weight though. I only have bikes with disc brakes and plan to keep it that way.


----------



## CabDoctor (Jun 11, 2005)

I'm just looking forward to the hubs. I wish they would release them now. I can run my mini-Vs for now but I'm building up two new sets of wheels and I would hate to have to re-lace these things so I can run disc next season.


----------



## Keski (Sep 25, 2004)

The future is finally becoming now.....


----------



## Hand/of/Midas (Apr 15, 2008)

CabDoctor said:


> I'm just looking forward to the hubs. I wish they would release them now. I can run my mini-Vs for now but I'm building up two new sets of wheels and I would hate to have to re-lace these things so I can run disc next season.


If you are looking for 130mm, White Ind already has some nice hubs for you.
However, the future will go to 135mm, so 240s are going to be the hot ticket.


----------



## CabDoctor (Jun 11, 2005)

Yeah the issue is my current frame and next seasons frame are both 130mm


----------



## foto (Feb 7, 2005)

Hideous shifter...


----------



## holy cromoly (Nov 9, 2008)

If these are for real, I'd consider them for my upcoming fire road bike. I think these have a place on do-all cross bikes that are built for trail riding.


----------



## Killroy (Feb 9, 2006)

88 rex said:


> Eh....it'll never catch on.
> 
> :14:


That is what they said to disc brakes and cross country race bikes....
....and carbon, and clip-less pedals, and integrated headsets, and ect.


----------



## foto (Feb 7, 2005)

and biopace, and tension disks, and 24" rear wheels, and those ugly Scott drop bars, and the 700c road suspension fork (the Marzocchi Paris-Roubaix???), and airport shifting, and Shimano 10mm chain, and Suntour BEAST, and and and


edit: sorry, it wasn't marzocchi, it was Rock Shox.

and suspension stems, and beam bikes, and hideous sun glasses, and and and


----------



## vcnz (Jun 18, 2009)

I would like to know from SRAM how they think this crap is going to be an improvement in terms of performances for racers compared to the standard rim brakes

I see only extra weight, on frame and wheels....we are talking about 400-500 gr I guess


----------



## CabDoctor (Jun 11, 2005)

Not trying to be rude but have you ridden a Cyclocross bike in the muck vs a disc equipped mtb in the muck? The braking is so much better, there's no comparison! Plus you can break way way way later going into corners


----------



## J-K (Nov 5, 2006)

vcnz said:


> I would like to know from SRAM how they think this crap is going to be an improvement in terms of performances for racers compared to the standard rim brakes
> 
> I see only extra weight, on frame and wheels....we are talking about 400-500 gr I guess


Could you put a reminder in your phone to check your own post 3 years from now? Should be fun .

The improvement in performance is what CabDoctor describes. With canti's, I sometimes have to grab a lot of brake right from the start of a descent to keep my bike from speeding up to speeds even 'brake levers to the bars' cannot control in time for a hard corner at the bottom. Way slow... We collectively worked our way around the handicap of cantilever brakes, in many ways.

There will be some extra weight, but that will come down and it will only be at the levers and calipers, not frames and wheels. Remember that with disc braks, rims can become lighter. Frames could be a bit lighter too: Canti bosses need a lot more structure, because they apply bot rotational and outward forces on the seatstay. A seatstay could be really light if it were not for the brake. Disc brakes in the rear triangle enable lighter design solutions. Forks will probably be a little heavier, because of brake force being applied to the end of a long arm instead of the beginning.


----------



## pretender (Sep 18, 2007)

vcnz said:


> I see only extra weight, on frame and wheels....we are talking about 400-500 gr I guess


Stu Thorne says about half a pound (230g) on a pretty vanilla swap-out (BB7s, standard hubs, etc).

Below is a photo on TRP's web site but IMO speaks to the advantages of discs, especially for us weekend warriors who don't have a multi-bike quiver nor a mechanic in the pits. Do you see a spare half pound here?


----------



## T0mi (Mar 2, 2011)

CabDoctor said:


> Not trying to be rude but have you ridden a Cyclocross bike in the muck vs a disc equipped mtb in the muck? The braking is so much better, there's no comparison! Plus you can break way way way later going into corners


Imho the interest in disc brake is more about clearance than braking power.


----------



## robdamanii (Feb 13, 2006)

I am mostly saddened that my cross bike doesn't have disc tabs....

I can't imagine how much better these will be in the gooey northeast early season races.


----------



## kbiker3111 (Nov 7, 2006)

> I would like to know from SRAM how they think this crap is going to be an improvement in terms of performances for racers compared to the standard rim brakes
> 
> I see only extra weight, on frame and wheels....we are talking about 400-500 gr I guess


Why would it be 4-500 grams when the weight penalty is considerably less than that on mountain bike discs over mtb rim brakes? The hubs only increase in weight about ~50g, seat stays and fork legs can actually be made lighter because they don't resist canti forces. Hydro lines are generally lighter than cables and the brakes themselves are svelte enough to be lightweight. 

Back in the day, Cannondale actually made the CAAD 5 mtb lighter than the CAAD4 by going disc only.


----------



## David Kirk (Mar 6, 2005)

I for one am excited by the change. I think we will see a few things happen in the next few years - 

* any serious racing cross bike will have discs.

* pro-tour road bikes will move toward discs to to make for safer and faster bikes in the high mountain descents while not melting the tubular glue. The bikes will be faster and safer - a very rare combo IMO.

* both road and cross bikes will move to 135 mm rear spacing. It will allow for stronger wheels with better spoke angles and less dish with little to no real downside. Some will say that this move to 135 is bad because it will result in a wider Q factor but the reality is that if any change needs to be made it will be very small - about 2 mm or so.

* wheel design will slowly change in response to the differing needs of a disc set up. Rim weight will drop slightly and disc hub designs will get slimmer and lighter. In a short period of time I thunk we will see the net weight gain caused by using discs to be minimal or go away altogether.

* finally - braking will be better and it will be more fun to ride in the goo or rain. Better control of the speed of the bike is always a good thing.

Just my 2 cents.

Dave


----------



## atpjunkie (Mar 23, 2002)

*that pic*



pretender said:


> Stu Thorne says about half a pound (230g) on a pretty vanilla swap-out (BB7s, standard hubs, etc).
> 
> Below is a photo on TRP's web site but IMO speaks to the advantages of discs, especially for us weekend warriors who don't have a multi-bike quiver nor a mechanic in the pits. Do you see a spare half pound here?


is more an example of why mini vees aren't the best choice


----------



## atpjunkie (Mar 23, 2002)

*the 135 will happen anyhow*



David Kirk said:


> I for one am excited by the change. I think we will see a few things happen in the next few years -
> 
> * any serious racing cross bike will have discs.
> 
> ...


with 11 and 12 speed drive trains yes? Seems the 2 are destined for each other


----------



## David Kirk (Mar 6, 2005)

atpjunkie said:


> with 11 and 12 speed drive trains yes? Seems the 2 are destined for each other



I agree - 135 will be the new norm soon regardless of brake system used.

Dave


----------



## foto (Feb 7, 2005)

Great, looking forward to all these hubs I got being obsolete.

At some point, wouldn't it be nice if people just stopped messin with stuff? How many different headset "standards" are there now? Bottom bracket "standards"? Frankly I think given they way every frame pretty much needs its own headset it would be stupid to go to 135. Something weird and proprietary would make more sense, like 142, so that no one will be tempted to maybe use some nice XT hubs they happen to have laying around. That would be consistent with the new standard of making sure there are no standards in component fitment.


----------



## pretender (Sep 18, 2007)

atpjunkie said:


> is more an example of why mini vees aren't the best choice


I think Mafac-style brakes would still get packed up with weedy, sticky mud like that. Maybe not quite as bad as those mini-Vs.


----------



## foto (Feb 7, 2005)

My point exactly, from this article...

"As of now, the caliper will use a regular post mount, but Becker hinted that SRAM is working with frame manufacturers to develop a road-specific mount"

SRAM Hydraulic brake images leaked

We need a road specific caliper mount why? Only so that all those thousands of disc calipers that are floating around out there won't work, that's why. What a bunch of crap. This creates a great niche for a brand to come out with a "future proof" line of bikes that uses pressfit 11/8" headsets, BSA bottom brackets, 27.2 seatposts, and 130 spacing. Oh wait, that would be surly.


----------



## GeoKrpan (Feb 3, 2008)

I recently built a monstercross with 135mm rear spacing, Avid BB5s Road 160/140mm front/rear, and Dura Ace STI.
The BB5s work perfectly with the Dura Ace levers and they are better than any rim brake that I've used. (I had Magura hydraulic rim brakes on my MTB back in the day, before disks.)
I've abandoned hydraulic disks on my MTBs. I found that they are not materially stronger than cable disks and cable disks do not require much more effort from the hands. Cable disks are easier to set up and easier to live with.

The difference between 130 and 135mm is 2/10s of an inch, not much. I'm currently using 29er wheels and 700x28 tires on the monstercross. The wide rims really make a difference in the ride quality.


----------



## David Kirk (Mar 6, 2005)

foto said:


> Great, looking forward to all these hubs I got being obsolete.
> 
> At some point, wouldn't it be nice if people just stopped messin with stuff? How many different headset "standards" are there now? Bottom bracket "standards"? Frankly I think given they way every frame pretty much needs its own headset it would be stupid to go to 135. Something weird and proprietary would make more sense, like 142, so that no one will be tempted to maybe use some nice XT hubs they happen to have laying around. That would be consistent with the new standard of making sure there are no standards in component fitment.


I hear you loud and clear and feel your frustration. I hear this a lot - let's draw a line in the sand and call it a day. The tough part is deciding where to draw that line.

Bikes today are heads and shoulders better (safer, more durable, lighter, better riding, and maybe even faster) than what was available just 15 years ago and most of us enjoy the new stuff. It just works better. What if we'd drawn the line when hubs were 126 and 6 speeds? How about DT shifters? How about friction? - draw that line in 1986 or so and say that there is no need to think about new and better ways to make stuff because this is good enough.

And of course it was good enough. We enjoyed riding that stuff and I have bikes of that era hanging on hooks in my basement. But they stay on the hooks because my new bikes are better. When better stuff becomes available that makes for a more fun riding experience who will turn that down?

The saving grace on this is that 130 mm hubs will not go away any time soon. 126 hubs lasted for a very long time and you can still get them if you want. The same with threaded headsets, English BB's. The thing to remember is that the word 'standards' in regards to things like rear spacing, BB's and headsets are is a very loose term. There are lots of 'standards' (kind of flies in the face of the term but there you go) out there and most will be around for a very long time. Certainly long enough that the bike you are using now, the one where you are worried about the new wheels fitting, will be old and in the way by the time its rear spacing become antiquated and it will be some retro bike hanging on a hook in your basement to remind you of the old days.

Change is good IMO - vive la difference.

dave


----------



## foto (Feb 7, 2005)

David Kirk said:


> I hear you loud and clear and feel your frustration. I hear this a lot - let's draw a line in the sand and call it a day. The tough part is deciding where to draw that line.
> 
> Bikes today are heads and shoulders better (safer, more durable, lighter, better riding, and maybe even faster) than what was available just 15 years ago and most of us enjoy the new stuff. It just works better. What if we'd drawn the line when hubs were 126 and 6 speeds? How about DT shifters? How about friction? - draw that line in 1986 or so and say that there is no need to think about new and better ways to make stuff because this is good enough.
> 
> ...


Thanks, I feel much better now. I had forgotten that "standards" is a loose term in these last 20 minutes.

Actually, I think you are just slighlty missing what I am getting at. Right now, because of actually somewhat standard standards, you can build an old frame with new junk, or a new frame with old junk. Observe, I have a pile of old frames in my house. They can all get built up with just about any random crap (to a degree). Furthermore, back when these "loose standards" were a little more standard, I could buy a new frame, and build it up with any random crap. Call me a curmudgeon, but I don't think proprietary standards that are not standard at all does anything to improve my ride quality or experience. 

I swear to GOD I do not notice the difference between a 41 or a 42 integrated headset, or an integrated headset on a stiff frame vs a pressfit headset on a stiff frame.

When STI came out, did you have to buy a new frame to accomidate it?

Ugh, I hate spelling.


----------



## 88 rex (Mar 18, 2008)

foto said:


> Thanks, I feel much better now. I had forgotten that "standards" is a loose term in these last 20 minutes.
> 
> Actually, I think you are just slighlty missing what I am getting at. Right now, because of actually somewhat standard standards, you can build an old frame with new junk, or a new frame with old junk. Observe, I have a pile of old frames in my house. They can all get built up with just about any random crap (to a degree). Furthermore, back when these "loose standards" were a little more standard, I could buy a new frame, and build it up with any random crap. Call me a curmudgeon, but I don't think proprietary standards that are not standard at all does anything to improve my ride quality or experience.
> 
> ...


I guess I don't totally get what you're getting at also, because I thought Dave was addressing your concerns about past, present and future "standards."

At this stage in the game, almost any frame can be built with any variety of parts with the correct adapters. BB30 may be the most flexible system out there. With the right adpater you can run any crank. Same thing with tapered headtubes. You can run any threadless fork out there. 

I really think the industry is at a great stage right now. I've had very little compatability issues with any parts, and it's almost never difficult to find the parts you need.


----------



## foto (Feb 7, 2005)

88 rex said:


> I guess I don't totally get what you're getting at also, because I thought Dave was addressing your concerns about past, present and future "standards."
> 
> At this stage in the game, almost any frame can be built with any variety of parts with the correct adapters. BB30 may be the most flexible system out there. With the right adpater you can run any crank. Same thing with tapered headtubes. You can run any threadless fork out there.
> 
> I really think the industry is at a great stage right now. I've had very little compatability issues with any parts, and it's almost never difficult to find the parts you need.


Um, before BB30 came out, I could "run" any crank I wanted without any adapters. (of course, I haven't owned an italian frame in a while, which is plenty fine)

You can't use a BB30 crank in any frame though. You can't use a tapered fork in any frame either. Things are _less_ cross compatible, not more. My favorite is integrated "seat masts". Good luck selling that thing once you cut it to fit you...


----------



## 88 rex (Mar 18, 2008)

foto said:


> My favorite is integrated "seat masts". Good luck selling that thing once you cut it to fit you...



Either this is a funny coincidence or you read my blog.


----------



## vcnz (Jun 18, 2009)

pretender said:


> Stu Thorne says about half a pound (230g) on a pretty vanilla swap-out (BB7s, standard hubs, etc).
> 
> Below is a photo on TRP's web site but IMO speaks to the advantages of discs, especially for us weekend warriors who don't have a multi-bike quiver nor a mechanic in the pits. Do you see a spare half pound here?


There is nothing wrong with the brakes, the frame would get clogged up with mud anyway with those tires. 
Concering the weight, a disk brake (only one disk with screws) has the same weight as a TRP Mag (only one brake including hardware) on my scale, so all the rest of crap is extra weight:
caliper with hardware, heavier hubs, oil, heavier shifting levers etc.....and last but not least, the cable for disk brakes are much longer since they have to reach the hub....and we are talking about a meter
The guy says 230gr.....good luck then 

Besides, even the disk brakes setup would have the same weight, you are going to add 150gr per wheel, so 300gr per wheel set (hubs, disks and screws) anyway. It's a downgrade and it makes no sense


----------



## cda 455 (Aug 9, 2010)

pretender said:


> Stu Thorne says about half a pound (230g) on a pretty vanilla swap-out (BB7s, standard hubs, etc).
> 
> Below is a photo on TRP's web site but IMO speaks to the advantages of discs, especially for us weekend warriors who don't have a multi-bike quiver nor a mechanic in the pits. Do you see a spare half pound here?



Wow; That's muck :lol: !


----------



## foto (Feb 7, 2005)

88 rex said:


> Either this is a funny coincidence or you read my blog.


Or neither.


----------



## tednugent (Apr 26, 2010)

it's really not about breaking power... since discs have less leverage than rim brakes. It's all about modulation of the available (less) braking power.


----------



## davidka (Dec 12, 2001)

foto said:


> My point exactly, from this article...
> 
> "As of now, the caliper will use a regular post mount, but Becker hinted that SRAM is working with frame manufacturers to develop a road-specific mount"
> 
> ...


To better optimize the component for it's use.If a road caliper can be made smaller and lighter than an MTB caliper, why tie it to an unnecessarily bulky mount? The calipers can be neatly tucked into the frame and fork. If SRAM offers a clean solution that's well designed, nobody will have any interest in re-purposing a disc caliper from an MTB onto a road bike besides, it would require that SRAM's hydraulic lever have the correct fluid ratio to drive the caliper, which it likely won't.

FWIW, it does say SRAM is working with manufacturers (plural), which I hope means that they're working towards a single standard for road so it's settled quickly.


----------



## David Kirk (Mar 6, 2005)

foto said:


> Um, before BB30 came out, I could "run" any crank I wanted without any adapters. (of course, I haven't owned an italian frame in a while, which is plenty fine)
> 
> You can't use a BB30 crank in any frame though. You can't use a tapered fork in any frame either. Things are _less_ cross compatible, not more. My favorite is integrated "seat masts". Good luck selling that thing once you cut it to fit you...


Again I hear you.

In my mind I see the constant stream of changes falling into one of two distinct categories - those that improve the riding experience and those that are done for other reasons.

Integrated headsets are a perfect example of a change that was not made with the aim of making the bike better/more fun to ride but instead it was done to make the bike easier for the builder to make. There is nothing wrong with this of course but I'm personally not interested in this type of change. I would put BB30 and it's ilk in the same pile. Nothing wrong with them but one needs to recognize why they exist - to reduce labor and increase profit for big bike companies. If I was designing for a big company I might head that way too. But I don't so I'm able to just offer stuff that, IMHO, makes the bike in some way better not just different...........and I feel strongly that for many riders that disc brakes will be worth the change.

I do see your point about having a pile of stuff and a pile of frames and all the stuff will fit on all the frames. It would be nice if that was the case at this point (as long as we weren't setting aside real progress for the sake of having a new BB fit a 20 year old frame) but I think this ship sailed long ago. I've been a full time guy in the bike biz for over 30 years now and have seen so many things come and go in that time. I doubt many want to use down tube shifter at this point and that's a good thing because you can't mount them to most bikes made in the last 10 years. I can't screw my 5 speed regina oro freewheel to anything commonly available now. Quill stems? Can'y really use them in most cases. So unless you want to draw that line in the sand at a time when all of your parts/frames are compatible and eschew anything made after that time I'd think you're going to have to adapt ........................... or not. eBay is full of stuff that will fit the need.

One last bit of perspective. I'm a framebuilder who builds lugged and fillet brazed steel frames. All my frames use regular seat posts, threaded BB's and standard press in headsets (many of them 1"). I'm hardly what most would consider on the bleeding edge of new design. I only change things when the end result is better and never change for the sake of change. I'm a pragmatist to a fault. At the same time I've got 20 years of racing experience and some things are just plain better because they work better and are safer when used at the limit. Disc brakes are one of those things. I will never offer a frame with an ISP but will happily offer road and cross bikes with discs.

dave

P.S. - one last prediction. We will have this same conversation again in about 5 years when the next new brake comes along and there will be guys who say "I've been riding with disc brakes for years and they have always been good enough and no one needs better brakes" in response to the next new/better system to come out. These guys will look at old rim brakes as antiquated, the discs they are using at that moment to be 'right' and anything newer than that to be silly. Sort of a Goldie locks deal. One can't effectively stop time or true progress.


----------



## foto (Feb 7, 2005)

Thanks for your perspective, I appreciate it.

I'll just add that I have no experience in the industry at all, and I am simply a curmudgeon ranting on the internet.


----------



## davidka (Dec 12, 2001)

David Kirk said:


> Integrated headsets are a perfect example of a change that was not made with the aim of making the bike better/more fun to ride but instead it was done to make the bike easier for the builder to make. There is nothing wrong with this of course but I'm personally not interested in this type of change. I would put BB30 and it's ilk in the same pile. Nothing wrong with them but one needs to recognize why they exist - to reduce labor and increase profit for big bike companies. If I was designing for a big company I might head that way too. But I don't so I'm able to just offer stuff that, IMHO, makes the bike in some way better not just different...........and I feel strongly that for many riders that disc brakes will be worth the change.
> 
> .


 Do you believe they were easy and cheap to develop and manufacture? An integrated headset system requires higher precision and finish than facing a conventional head tube. 

Both of the above innovations reduce weight, increase stiffness and reduce part count. Simplified assembly is a nice perk for you and me but it's not important on low volume, high dollar bikes as far as the manufacturer is concerned.

The real reason they exist is because they do improve the bike's performance and innovation attracts customers.


----------



## David Kirk (Mar 6, 2005)

davidka said:


> Do you believe they were easy and cheap to develop and manufacture? An integrated headset system requires higher precision and finish than facing a conventional head tube.
> 
> Both of the above innovations reduce weight, increase stiffness and reduce part count. Simplified assembly is a nice perk for you and me but it's not important on low volume, high dollar bikes as far as the manufacturer is concerned.
> 
> The real reason they exist is because they do improve the bike's performance and innovation attracts customers.


I would disagree with you on this. The cost of CNC turning a integrated head tube in volume is silly low - much lower cost than the labor of post welding head tube reaming and facing. A CNS lathe spits them out like popcorn. If you price it out there is no comparison. Couple that with the fact that it also reduces the labor to assemble the bike at the factory without the need to press in cups and it's a no brainer. And this is all good for cost reduction. It does not make the bike stiffer (assuming making it stiffer is a good thing), stronger, or better riding in any way. It does however mean that if the head tube ends are in any way damaged that the frame needs to be replaced instead of pressing a new headset in.

BB30 is much the same way. They can be stiffer than some external cup threaded BB's but they aren't all stiffer. And with the loads they see the extra stiffness is almost never utilized.........unless you weight 250 pounds and can sprint. So making it stiffer than a standard BB is moot for the most part.

A BB30 does a good job of allowing for bigger tubes to attach to the shell and that is important with carbon not not so much with any metal. The biggest thing a BB30 (and all it''s new cousins) has going for it is that it's easy to make a carbon BB shell with out threads and it's easy to install the bearings into the frame at the factory. If you measure the stiffness of the assembled unit there is often little to no difference between pre and post BB30. Again - ease and cost savings are a good thing but they don't' improve the ride at all.

The subject of this thread, disc brakes, do improve the experience for many and the difference is easy to measure.

Dinner time here - gotta run.

Thanks for reading.

Dave


----------



## davidka (Dec 12, 2001)

Most of your points are accurate if referring to a frame made of steel but very few production bikes are made of steel these days, even fewer with BB30/IhS. Build with aluminum and/or carbon and it becomes a very different picture.


----------



## johnnyrev (Oct 1, 2009)

What are the differences between the hydraulics and my Avid BB7s? I've heard its response versus ease of use.


----------



## johnnyrev (Oct 1, 2009)

I love my discs, but I know almost nothing about the topic - other than that they rock! Love to hear the gritty, geeky details...


----------



## davidka (Dec 12, 2001)

johnnyrev said:


> What are the differences between the hydraulics and my Avid BB7s? I've heard its response versus ease of use.


Hydraulics are pretty much set and forget (there are quality issues out there but this is the norm), once bled they hold the setting indefinitely. The system is sealed so response is perfectly accurate and consistent in bad conditions, there is no cable/housing to foul, cable/housing is heavier than hydro line/fluid and has many more routing limitations, hydro calipers are smaller and lighter than cable driven brakes. 

If you get the chance, try an mtb with good, high-end hydraulic discs on it. BB7's are the gold standard of cable driven brakes but I think you'll experience a big difference.


----------



## kbiker3111 (Nov 7, 2006)

johnnyrev said:


> What are the differences between the hydraulics and my Avid BB7s? I've heard its response versus ease of use.


Basically, your BB7's are good but good hydro's are better. BB7's are heaaaavy, at least for discs. Hydro's get rid of most friction, making lever feel and modulation better. By varying the psi in the fluid vs master and slave cylinder size, hydros can get better modulation and power. 

Its not that BB7's are bad or even worth replacing, they're just an imperfect solution.


----------



## atpjunkie (Mar 23, 2002)

*look down at the chainrings / crank*



pretender said:


> I think Mafac-style brakes would still get packed up with weedy, sticky mud like that. Maybe not quite as bad as those mini-Vs.


in that style mud I imagine the rotor would be caked as well


----------



## CabDoctor (Jun 11, 2005)

tednugent said:


> it's really not about breaking power... since discs have less leverage than rim brakes. It's all about modulation of the available (less) braking power.


This is semi-true

It is about modulation, but mechanical leverage really has a small portion to do with it. Braking is all about turning kinetic energy into heat and dissipating that heat. With rim brakes and disc brakes, the goal is to create as much friction as possible to create as much heat as possible and then to remove that heat as quickly as possible, allowing the brake to create and suck out more heat. Leverage really doesn't have that much to do with it because once you lock up the wheels(with to much leverage), all your friction is coming from the tire/road and no longer your brakes (which is why when you lock up, you skid for days). Because disc use a metal on metal or metal on organic compound systems, they are far more efficient at transferring heat and dissipating heat. This is why disc are used in every other racing discipline. 

Here's the problem with rim brakes. They lock up the wheels to early in the lever travel. So you have a very small area of lever travel to try and modulate. This gives the appearance of a powerful brake. HOLY CRAP DID YOU SEE HOW I LOCKED UP THE WHEEL WITH MY PINKY! But its actually not because you end up either breaking long because of poor modulation or you lock up your wheels and skid long because of poor modulation. Not a very powerful or usable brake when you look at the numbers.

Ideally, any brake, should only lockup the wheel at the last possible millimeter of lever travel. Leaving all that lever movement to operator for modulation adjustment.


----------



## johnnyrev (Oct 1, 2009)

Thanks.


----------



## WTFcyclist (Jan 17, 2012)

Does anybody has any problem with MTB hydraulic disc brake at low temperature. Can brake fluid freeze?


----------



## davidka (Dec 12, 2001)

The short answer is no, you can't freeze brake fluids in any temperature you'd be able to cycle in.

Freezing point for DOT 4 is -75f(-59C)

Freezing point for mineral oil: -30C(-22F)


----------



## rydbyk (Feb 17, 2010)

Killroy said:


> That is what they said to disc brakes and cross country race bikes....
> ....and carbon, and clip-less pedals, and integrated headsets, and ect.


...and 29er wheels and..


----------



## foto (Feb 7, 2005)

rydbyk said:


> ...and 29er wheels and..


and 1.25" headsets, and softtails, and elastomers, and slingshots, and roller-cams, and and and


----------



## vcnz (Jun 18, 2009)

davidka said:


> Hydraulics are pretty much set and forget (there are quality issues out there but this is the norm), once bled they hold the setting indefinitely. The system is sealed so response is perfectly accurate and consistent in bad conditions......


If you buy a new brake set, the cables are much longer than needed to fit different fork length, frame size etc. and you need to cut them to fir your bike. You need to detach the cable, cut it and install new olive and attach it back. If you're not accurate/lucky and some air goes into the hydraulic circuit, you need a service kit to take all the oil out. You need to have some spare oil (so buy oil etc...). Of course if you buy a bike already equipped with disk brakes it's a different story, but this is how it works on mtb where disks are popular and I changed brake sets many times


----------

