Brakes - Are disc brakes better? and why?

rake

cheese is better than disc brakes if you are hungry.

springtide9

This really is a non discussion item. Disc brakes are far (far) superior on so many levels.

The real question is weight. If the weight penalty isn't that great, then we have a winner... but just like MTBs, the real advantage is only when all components are designed exclusively for discs.

Disc brakes have massively changed over the years, in weight, power and modulation. If you don't understand modulation, you simply don't understand the advantage of disc brakes. It really isn't about whether you can lock out the wheels or not... think most people remember cars of years gone by that had poor brakes that would lock the wheels without any warning.

So yes, SRAM, bring it on. Moving back to non disc brakes feels like stepping into the past. I'm pretty sure disc brakes can be made with very little weight penalty as they have advanced so much over the years, but we also really need all cycle and wheel manufacturers to join the revolution; lets see disc specific components fast; the sooner the better.

dawebbo

I have avid bb7 on my commuting bike and dura ace / sram force on my 2 roads bikes. All are set up properly and well maintained. The bb7 are by far the best, and if I could race with they would be on all my bikes without question.

neeb

It's a pity that disks require specific frame and fork modifications (I assume mounting bosses /eyelets at least?) so that current road frames won't be able to take them.

I wonder if a transitional solution if/when disks start becoming popular on road bikes would be to have them at the front only, in conjunction with a hydraulic rim brake at the rear and different front and rear wheels. It would be feasible to replace the fork with a disk specific one, and it's at the front that the disk advantages would be most useful.

NickintheLakes

neeb wrote:

It's a pity that disks require specific frame and fork modifications (I assume mounting bosses /eyelets at least?) so that current road frames won't be able to take them.

I wonder if a transitional solution if/when disks start becoming popular on road bikes would be to have them at the front only, in conjunction with a hydraulic rim brake at the rear and different front and rear wheels. It would be feasible to replace the fork with a disk specific one, and it's at the front that the disk advantages would be most useful.

That's a very neat thought.

MichaelW

NickintheLakes wrote:

neeb wrote:

It's a pity that disks require specific frame and fork modifications (I assume mounting bosses /eyelets at least?) so that current road frames won't be able to take them.

I wonder if a transitional solution if/when disks start becoming popular on road bikes would be to have them at the front only, in conjunction with a hydraulic rim brake at the rear and different front and rear wheels. It would be feasible to replace the fork with a disk specific one, and it's at the front that the disk advantages would be most useful.

That's a very neat thought.

This is the solution used by entry-level MTBs mainly as a cost-cutting excercise.

springtide9

First photos of the new RED brakes

Article @ http://thedailygrind.robdamanii.com/201 ... ic-brakes/

Trickyh

The other cool thing is that a lot of the r and d has already been done by the mountain bike boys already.. This will save a lot of time going up dead ends and go straight to something which actually works, is light and reliable

il_principe

MattC59 wrote:

If you're comparing the current crop of MTB dick brakes

Says it all really.

dawebbo

I wonder how SRAM will be pricing these. Pressumably will be similar to di2 for the full groupset.

craker

I was recently reading (Sheldon Brown?) about Shimano's attempts to introduce STIs in the '80s.

They started downmarket, putting them on some hybrid at a cutdown price. They were thus viewed as a gimmick by serious cyclists and as they were built cheaply weren't terribly reliable. They failed at this pricepoint and relaunched them as top of the range DA levers, got them ridden on the TDF and ... now everyone uses them.

So it's possible that the cycling tech. companies don't want to be stung by a perception that disk brakes are best found on commuters' bikes when there's top dollar to be earned by putting these things on the best bikes first and letting the technology get accepted and find its way downmarket.

neeb

I wonder if: 1) Campagnolo and Shimano are developing road disk brakes or are planning to 2) SRAM are developing electronic shifting.

It could be weird if you have to choose between one or the other in 2 or 3 years time.

rake

MattC59 wrote:

rake wrote:

MattC59 wrote:

rake wrote:

disk will lead to many more broken hip recovery posts and i just had my first crash. i dont want discs. heavy, much more cost and not needed. the line about saving weight on rims is pants, youl need a thicker spoke bed.
why do i want brakes to grip as well in the wet, the tyres wont.

Why more broken hips ? If you're applying sufficient brake force to lose the front or rear wheel, then it doesn't matter what type of brake you have, you need to learn to use the brakes you have and to brake properly.

Why would you need a thicker spoke bed ? Admittedly, the distribution of forces wil lbe different, but you'll not start ripping spokes out of the bed. Oh, and the comment about being able to lose weight from rims was following a conversation with a Shimano development engineer. His words, not mine, but being an engineer, I can understand his comments.

As for the comment about braking in the wet......... really, you didn't think that through did you........

ps, hope your crash wasn't too bad.

i have yet to come off a road bike but thanks for your concern.
if i can lock the wheels in the wet, why need more braking. dont give me any crap about modulation unless you need to learn how to press a lever.
being an engineer then does it not concern you about the leverage ratio using a smaller disc.

My mistake, I thought you had said in your previous post that you had:

rake wrote:

....and i just had my first crash.

I'm not going to give you any crap about modulation, I'll just refer you to all of the brake manufacturers and let them tell you how important it is. You need a combination of power and modulation, simple as that (and knowing that braking isn't just down to pulling a lever.)

When you mention leverage ratios, are you talking about the ratios applied at the lever and thus hte brake on the wheel, or those transmitted through the disk to the fork due to the rotation of the wheel ? Either way, not particularly. Or are you talking about the leverage the rotating wheel has over the smaller disk, thus reducing it's braking performance ? If this is the case, this is why you have a smaller disk, because you don't need the same braking force as you get using a 160mm or 180mm MTB disk.

happy reading
http://www.bikerumor.com/2012/02/14/road-bike-disc-brakes-are-coming-but-will-they-work/
shimano say here wheel rims will be too fragile if braking surface is removed so wont be lighter, 40g will need to be added to rim at least because of front wheel dish.
you say road bikes wont need as large rotors. they will need bigger if the fluid isnt going to boil.
you say better modulation, yet the metalised pads wont work as well till theyve heated up and in the wet they will be cold when first applied.
if you think i believe you spoke to a 'shimano development engineer' and understood him. i dont.
i have a mechanical engineering degree.
oh and if you read my comments on the last thread that came up on this topic, i also spoke about aerodynamics, weight, radial lacing, impact on the frame design and most of the points in the article, which i have only just seen incase you were wondering.

ddraver

Good article - but the conclusion is they re still coming...

(Ashima are also well known for making brakes that are useless on anything other than a flat XC course). Rim brakes still going to be a good stepping stone IMO

rake

ddraver wrote:

Good article - but the conclusion is they re still coming...

where did it say that. i missed it. it was the trp man who said they wanted to make it happen pressumably because of the pay packet involved.
id better stock up now on calipers

ddraver

Read it again - the whole article is "what are you working on," "This will problem can be solved like this"

At not one point do any of the 4 manufacturers say they re not bothering because there is no benefit

TRP is a half way hybrid stopgap - not a hydraulic brake system

rake

remind me what the 'benefit' is. im stumped.
the same problems arise on cars for example, theyve been working on brake fade since time began yet high temperature racing pads dont work well untill heated, road pads do but fade more easily thats the trade off. its not looking good for this modualation.

ddraver

Matt, explains it well above (try and keep up...)

You watch Top Gear right? You see them heating the disks on race cars so much that they glow red dontcha? You think you or I or even Fabian Cancellara will ever require that much stopping power? I think not...

Tell me how much experience you have had with hydraulic disks vs cable brakes, sounds like you ve not had much...

rake

i know they glow red hot why is that relevant, the point was they dont work well ie no feel when theyre cold like those metal bike pads. this counteracts seemingly the whole point of better modulation.

end of thread. the answer is no. :!:

ddraver

No as in you ve never used disk brakes - clearly you have nt as otherwise you would well know that they have plenty of modulation when they re cold, as do the vast majority if car brakes. So you can't take the same system off of a Porsche and put it on your bike, ergo all disk brakes are rubbish?

No, of course not. You re just being silly now.

rake

ddraver wrote:

No as in you ve never used disk brakes - clearly you have nt as otherwise you would well know that they have plenty of modulation when they re cold, as do the vast majority if car brakes. So you can't take the same system off of a Porsche and put it on your bike, ergo all disk brakes are rubbish?

No, of course not. You re just being silly now.

it cant be that clear i havent used disk brake, ive driven a car and suffered brake fade when they got too hot for the road pads either faded or boiled or both. it didnt want to stop and it happens suddenly without warning.disc glowing and clouds of dust shot out from the wheels. ive also owned a few motorcycles with disc brakes which have more in common to bicycles. ever wondered why a lot of bikes have twin discs at the front, its to manage the heat better. you dont seem to understand there is a trade off, brakes that work well when hot dont when cold and vice versa. car brakes work cold but fade at a lower max temperature which is what happened to that bike.
the no answer was to the question of discs brakes being simply 'better' on a push bile.
stick to raving, you dont have much grasp of science.

ddraver

I really hope you re just being silly - otherwise you are a total idiot...

You are seriously comparing the braking system needed to bring a 1 tonne plus object to a halt versus one to stop a 80kg guy on a 10kg bike? You seriously think they re the same? They need to generate the same stopping power? they will generate the same heat?

Please...

I ve used Cable brakes and disk brakes (on a bicycle, a real actual bicycle) on long alpine descents on and off road and I can't emphasise enough how much better the disks are, even ignoring modulation (which is massively improved), being able to stop the bike using one finger is so much better.

Yeah so there are a few small challenges for road bikes that have nt been solved on MTBs yet - Big Whup, this is what R&D is for. Personally think having the combined R&D budgets or road and MTB working on problems can only lead to better performing, more reliable and...yes...lighter systems for all disciplines - It's win win!

rake

no it wont generate the same heat on a bike, but bike brakes are smaller so the same can happen.its a scale thing.your expecting a small light as possible brake to handle too much power. heat engergy and temperature are not the same things, it can still overheat. you missed your thermodynamics lectures didnt you.

ddraver

So you make them so they don't.....They ve been doing that on MTB's for years? Again, where is the problem?

rake

shimano tells you in the previous article. to solve it you need bigger heavier discs than mtb not smaller. yes they sure can be made to work very well, but they wont be lighter or able to compete on size and aerodynamics or integrity of the front wheel. calipers are mounted centrally, a single disc will be one sided, this causes the fork to bend more on one side while braking which can cause the bike to steer off line. that would be unpleasant down hill. mtb get around it because they have much more solid larger heavier forks.

ddraver

^ All problems that are solvable...

rake

yes, with more weight,more size and more drag. That doesnt always equal better on a pushbile. Its the best indicator as to why they have not yet materialised. they would have been out for a long time if they were simply better. they havent missed a trick they just weighed up the pro's and con's.

ddraver

I disagree...there I think we ll have to leave it....

rake

drop shimano a line, get disc's to market faster, you'll have the full market to play with.
all the best.

andrewjoseph

I put bb7's on our touring bikes, after using hydraulics on mtb's for years, not really liking the (admittedly cheap) calipers on my boardman comp, I decIded on disks for the tourers, 160mm front and back, I even bought thicker heavier ones as i didn't like the avid ones that warped too easily.

Yes, disks can get hot, but I have never experienced brake fade even when the disks are hot enough so you can smell them. i have 203mm floating rotors on the front of my mtb, not for pure power, but for better cooling and modulation. i would have no problem putting them on my tourer if I thought it needed them.

I prefer decent braking to light weight and good looks. poor braking can result in bent bits.