# Disadvantages of disc brakes?



## Fnaar (19 Sep 2012)

I may be buying a new tourer  and I've narrowed it down to 2 potentials. One has discs, one has regular rim brakes. To be used primarily for commute, with light loads, and occasionally for longer tours (nowt drastic) with heavier loads. I've never had discs before, and was wondering about the pros and cons.


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## ColinJ (19 Sep 2012)

Well, watch you don't touch a rotor with your leg after braking on a long descent! (It's a mistake that you will probably only make once ... )

The fluid in the closed hydraulic system on my MTB brakes heats up and expands on long descents and tends to lock the brakes on but I think that is an unusual problem. (Old Hope C2 brakes.)


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## Jmenorton (19 Sep 2012)

I really cant see a disadvantage for discs, weight maybe although not a concern on a tourer. They occasionally squeak in the wet. I think all my future bikes will have discs. Got BB7s on my current Road/CX bike and there fantastic in all conditions.


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## Sara_H (19 Sep 2012)

I've had hydraulic discs for about a year now, and I've found I prefer them, they seem more efficient and less prone to suddenly throwing themselves out of adjustment for no apparent reason!


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## Red Light (19 Sep 2012)

ColinJ said:


> Well, watch you don't touch a rotor with your leg after braking on a long descent! (It's a mistake that you will probably only make once ... )


 
That's why you need a good brand 



> The fluid in the closed hydraulic system on my MTB brakes heats up and expands on long descents and tends to lock the brakes on but I think that is an unusual problem. (Old Hope C2 brakes.)


 
I have those and they are fine, On long descents just twiddle the caps a bit to back them off as they heat up and then in the other direction as they cool down. I marked a couple of black arrows on the caps so I could see how much I had adjusted them and reverse it.


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## GrumpyGregry (19 Sep 2012)

The disc rotors are fairly easily bent, and not so easily straightened again, especially in falls or by clumsy baggage handlers (or the bloke on that train once....)

The disc pads for some calipers are not that commonly available so carry your own spares.

But I wouldn't tour loaded on anything else.

(BB7s (grey road version) since you ask)


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## ianrauk (19 Sep 2012)

Jmenorton said:


> I really cant see a disadvantage for discs, weight maybe although not a concern on a tourer. They occasionally squeak in the wet. I think all my future bikes will have discs. Got BB7s on my current Road/CX bike and there fantastic in all conditions.


 

This.
Have BB7's on my commuter (Kona Honky). Now won't have a commute bike without disc brakes.
They do squeal in the wet.. but I can live with that.

Advantages for me.
No rim wear.
Better stopping in the wet.
No black brake dust gunk.


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## ColinJ (19 Sep 2012)

Red Light said:


> That's why you need a good brand


I get it! In fact, I almost did end up with a permanent scar on one calf. I was amazed at how hot the rotor had got.


Red Light said:


> I have those and they are fine, On long descents just twiddle the caps a bit to back them off as they heat up and then in the other direction as they cool down. I marked a couple of black arrows on the caps so I could see how much I had adjusted them and reverse it.


Well, maybe my descents are a lot longer and steeper than yours because I use the entire range of adjustment and can still end up with the brakes locked hard on until they cool!

I was searching for information on the problem a few minutes ago and one person suggested that bleeding a few drops of hydraulic fluid out of the system might be the answer. I don't mind adjusting the brakes on a descent but it is literally a showstopper when I run out of adjustment.

There is one particular local descent that I get to within 50 metres of the bottom of when the brakes start to overheat. If I'm careful, I can just get to the bottom and carry on.

One thing that has caught me out a few times is forgetting to adjust the brakes back the other way as they cool down. 10 minutes later, I go to brake and nothing happens!


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## Cubist (19 Sep 2012)

I had them on my Boardman commuter, and they were just awesome in any weather. Modern hydraulic brakes are fit and forget, but BB mechanical ones will need a a bit of adjusting, but no more so that rim brakes.


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## MacB (19 Sep 2012)

As per others - you do read of dire warnings if touring in remote parts but then you just make sure you have spare bits. Rotors can get bent but truing them isn't hard and, if beyond that, they can be replaced very easily.

Personally I have stuck with the mechanical BB7s both road and MTB versions because I feel more confident maintaining them. Also it means I have the same spare parts covering the brake systems across 5 bikes.


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## byegad (19 Sep 2012)

If you have a long descent with a full load you need to watch disc temperature. There is an outside possibility that you can warp a disc although I've had no issues even in the North York's Moors where 33% gradients lurk.


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## Red Light (19 Sep 2012)

ColinJ said:


> Well, maybe my descents are a lot longer and steeper than yours because I use the entire range of adjustment and can still end up with the brakes locked hard on until they cool!
> 
> I was searching for information on the problem a few minutes ago and one person suggested that bleeding a few drops of hydraulic fluid out of the system might be the answer. I don't mind adjusting the brakes on a descent but it is literally a showstopper when I run out of adjustment.
> 
> ...


 
You just need to go a bit faster and use the brakes a bit less 

I have never run out of range and I do some fairly technical riding in places like the Lakes, Yorkshire and Peak District to the point where I have blued the rotors a number of times from the length and strength of braking. How many turns of the caps do you have from fully out to where they are clamped on the rotor? If its not many then you might try the following. Dial the cap in one turn, then open the bleed nozzle, let the excess fluid out, then tighten it up again. That will reset the "brakes off" point to one turn in rather than fully out and give you an extra turn of adjustment when they heat up. You can do more than one turn if you want. The only limit is having braking available when you go out and its a cold day - especially with winter coming and leaving some to be able to adjust for pad wear.


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## Peteaud (19 Sep 2012)

My hybrid / commuter / do it all has discs (Shimano Deore) and they have been fantastic.

My Trek MTB has Avid and they are useless. Take a wheel off, and lay the bike on its side for a car trip in the boot and i have to reset them, they bind when hot, ive replaced the domed washers twice due to cracking, hate the things. They will get replaced with Deores when possible.

Road bike - Sora brakes, brill.


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## Fnaar (19 Sep 2012)

Ees gettin compulicated... Rim brake bike is cheaper, so probs go with that. Thanks for your thoughts, peeps!


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## billflat12 (19 Sep 2012)

Using disc brakes is definitely the way to go considering the uk climate , go disc & you,ll never look back ,
Although more expensive hydraulic systems are more reliable as there,s no cable to stretch or clog up.
Think hope,s C2,s are the only closed system( ie.without a reservoir for oil expansion ) , that,s why the inevitable usually happens as they get hot , open systems can suffer brake fade if they overheat though, usually with small rotors and a long descent , main disadvantages is when you grab a handful you can easily lock up , or pad availability ( there.s no common standard like rim brakes)
These Q&A covers most http://www.mtbr.com/discbrakesfaqcrx.aspx#equipment


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## subaqua (19 Sep 2012)

I have hydraulic rim brakes on my commuter (Magura) I still prefer the Hydraulic discs on the MTB for sheer stopping power.


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## byegad (19 Sep 2012)

billflat12 said:


> Only ever experienced brake fade from overheating disc brakes with small rotors ?, main disadvantages are if you grab a handful you can easily lock up , or pad availability while on tour,
> These Q&A covers most http://www.mtbr.com/discbrakesfaqcrx.aspx#equipment


 
Yes pads can be hard to find, but sticking a couple of pairs in your kit adds very little weight.


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## ColinJ (19 Sep 2012)

Red Light said:


> You just need to go a bit faster and use the brakes a bit less
> 
> I have never run out of range and I do some fairly technical riding in places like the Lakes, Yorkshire and Peak District to the point where I have blued the rotors a number of times from the length and strength of braking. How many turns of the caps do you have from fully out to where they are clamped on the rotor? If its not many then you might try the following. Dial the cap in one turn, then open the bleed nozzle, let the excess fluid out, then tighten it up again. That will reset the "brakes off" point to one turn in rather than fully out and give you an extra turn of adjustment when they heat up. You can do more than one turn if you want. The only limit is having braking available when you go out and its a cold day - especially with winter coming and leaving some to be able to adjust for pad wear.


Sounds like a plan! 

I won't be riding the bike again until the Spring because I'm pretty ill. I also don't ride offroad in very cold conditions any more after some heavy crashes on ice in years gone by.

I can't remember exactly how many degrees of movement I can get from the caps. I'll check when I come to look at the bike in the Spring. I'll give it a good fettle in the NY before I start riding again.

I always thought that the problem was a bit more severe than it should have been but never thought that I might have surplus fluid in the system. I basically only get about 250-300 vertical metres of technical descent before the brakes lock up.

As for braking less ... I'm at the limits of my nerve and ability already so I don't want to go any faster!


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## HovR (19 Sep 2012)

ColinJ said:


> I get it! In fact, I almost did end up with a permanent scar on one calf. I was amazed at how hot the rotor had got.


 
I did this when I first got discs after my first long descent on them. "I just need to adjust the brake.." queue rotor shaped scar burnt in to my hand, including the holes in the disc and everything.

Haven't done it again since.


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## Blue Hills (19 Sep 2012)

I asked Paul Hewitt about this when speccing a tourer. He advised against it and said you needed a stronger fork. Not sure how much of an issue that is. I do know that he has built disc-braked tourers for folks - I've seen at least one.
Am currently for slightly complicated reasons using an old hybrid as an occasional tourer - I've been down some pretty steep descents with it's old shimano cantilevers loaded with 4 panniers and a load of junk on the rack and I didn't have any real problems. Of course my rims may have become a bit thinner and cleaning rims can be a a bit of time-consuming - though kind of theraputic.


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## MontyVeda (19 Sep 2012)

personally i can't see the piont of <edit>_upgrading to_</edit> discs. My rim brakes slow down stop the bike perfectly well, I've never had a problem with rim wear, and bearing in mind my front wheel is a good 17 years old... I don't see it as an issue.(back wheel lasted 17 years too, but split at the join a few months back)

I may not clock up tens of thousands of miles a year, but i use my bike daily so do get plenty of miles in (it's a vehicle, not a hobby).

does a brake on the rim have better or worse stoping force due to it being near the outside edge of the wheel as opposed to a small disk near the middle? or does it not matter?


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## andrew_s (19 Sep 2012)

A disc brake will stop the bike much better than a rim brake if it's raining much.
Rim wear can be a problem if you ride a lot on small lanes in all weather, and use the wrong brake pads. My record is about 8 months (6000 miles). Old rims were more substantial than modern lightweight rims are, and so lasted longer.

Hydraulic brakes aren't available for drop handlebars.

On most bikes the front disk is mounted on the rear of the left fork blade. In this position, it is possible for the brake to twist the wheel out of the dropout despite the QR and your weight, and cause a crash (probably nasty).
You have to have lawyer lips on the dropouts, and use a strong QR (i.e. Shimano or Campag ONLY) done up very tight, and check the tightness regularly. It's better to have the QR lever at the disc side too.
Consider this to be the risk equivalent of a worn front wheel rim failing and causing a blowout.

I regard being able to stop on demand in the wet to be my main priority, and therefore my most recent bike has discs (BB7).


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## byegad (19 Sep 2012)

I have BB7s on two of my trikes and love them, but then I also love the SA drums on my QNT.


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## billflat12 (19 Sep 2012)

andrew_s said:


> Hydraulic brakes aren't available for drop handlebars.


There,s the TRP parabox that uses your existing levers
Thankfully since the uci dropped the disc ban in cyclo-cross.momentum for hydraulic is now gathering , we brits do like to stick with tradition so tend to be slower in embracing discs fully.

Fnaar ,can i ask what particular model you had in mind ?

Plenty of traditional drop bar steel tourers available with discs from well under £1k
E.B.C.,s Revolution Country Explorer
Genesis Croix de Fer
Charge Filter Hi
Raleigh Sojourn
Surly disc trucker
Kona sutra


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## Yellow7 (20 Sep 2012)

The disadvantage of rim brakes is they obviously wear down the rim. I’ve just [reluctantly] brought 2 new rims for my tourer (DRC MT19), although the wheels were still running dead true & had never popped a spoke I felt after 18000 miles replacement would best before the next big tour to Singapore. When I built the bike disk brakes were preferable, although [at the time] the SON front hub dynamo was never made with to accept disk brakes.
Hydraulic disk brakes offer excellent breaking power, something required on an off-road trails or down-hill bike, but not really required on a touring bike. Should I ever build another bike I would use & recommend mechanical (cable) disk brakes, this as stated above eliminates the need to replace rims on what is other-wise a good wheel.


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## Nigeyy (20 Sep 2012)

My Top Ten Disadvantages:
i. expense -good discs brakes don't just cost more -it's the disc specific hubs and rims that also can add cost (admittedly assuming you are upgrading not buying new as you are)
ii. weight -more stuff to carry as generally disc brakes will weigh more that a set of cantis or vs
iii. wheel strength -dished wheels necessary for disc hubs inherently make for a weaker wheel
iv. complexity -disc brakes aren't as simple as rim brakes (particularly if they are hydraulics) and of course, the more complex something is.....
v. rack and mudguard issues -on some bikes the disc brake mounts are set on the top side of the seat stay (i.e. as traditional disc mtbs are) and because of this interference this means you need disc specific mounts
vi. limited choice -road style handlebars? Your options are limited.....
vii. compatibility -you can't necessarily just use any old levers with them (i.e. if they are hydraulics).
viii. exposure -discs can be exposed more to dings or when packing the bike.
ix. maintenance cost -hydraulics will cost more to maintain (assuming you pay someone) and pads can be more expensive than their rim brake counterparts
x. accessibility -disc parts aren't usually found in an old hardware store or superstore -rim brakes parts can be, or even found on other bicycles.

Having said that, I have a tourer with Avid BB7 discs on and love them (wouldn't go back). While all the above are disadvantages, realistically and practically, they aren't valid or enough of a reason to give up the advantages I have.


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## Yellow7 (20 Sep 2012)

Nigeyy said:


> My Top Ten Disadvantages:
> iii. wheel strength -dished wheels necessary for disc hubs inherently make for a weaker wheel


 
Any derailleur based wheel is dished, be it disk or rim brakes. This is due to the derailleiur’s cassette mechanism increasing the space from drop-out (where the axle sits on the frame) to the spoke-ring on the hub, relative to the left-hand drop-out, as a result shorter spokes are used on the derailleur side, hence the term 'dished'.

(The more gears on the cassette naturally increasing the gap from drop-out to spoke-ring, shortening the spokes even more, as a result the wheel’s spoke tension (left to right) is not balanced, making the wheel weaker than one with a hub gear)


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## Blue Hills (21 Sep 2012)

Yellow7 said:


> (The more gears on the cassette naturally increasing the gap from drop-out to spoke-ring, shortening the spokes even more, as a result the wheel’s spoke tension (left to right) is not balanced, making the wheel weaker than one with a hub gear)


and as a slight side issue, sometimes the thing has to be dished more than you need - I've got a very solid late 90s steel hybrid I use as a tourer sometimes - 7-speed cassette and it performs just fine with only very occasional walking up the steepest of hills when fully loaded - but because decent 7-speed freehubs can no longer be had, its handbuilt wheels had to be over-dished only for me to then put a spacer on to accommodate the 7-speed cassette. grr, madness I tell you


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## srw (21 Sep 2012)

Yellow7 said:


> Any derailleur based wheel is dished, be it disk or rim brakes.


 Not strictly true. One of our tandems has an undished derailleur rear, with a disc. I agree it's rare.


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## Yellow7 (21 Sep 2012)

srw said:


> Not strictly true. One of our tandems has an undished derailleur rear, with a disc. I agree it's rare.


 
OK, the manufacturer obviously took into account the additional weight of the stoker, a well designed bike then.


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## Nigeyy (21 Sep 2012)

To be fair, I wasn't clear. I meant to say that the inclusion of a disc will cause the spokes to be further to the inside of the hub than they would be otherwise if no disc was there. That will -all things being equal -make for a weaker wheel. Almost all rear wheels and front disc wheels are dished to some extent.

Having said that, I believe a wheel well built with the appropriate number of spokes, good quality rim, hubs, etc will negate that. Think of it this way: if discs caused weak wheels, the mtb community would be in big trouble!

I personally think this "disadvantage" is specious (but the op asked for disadvantages!).


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## SatNavSaysStraightOn (21 Sep 2012)

I've toured on both and I prefer my rim brakes over the disc brakes. But I am not comparing like with like. Simply what I have toured on.

I did a 800 mile tour on my mountain bike with hydraulic disc brakes. They were whatever came as standard on the Scott Scale 40 (2010 model), not exactly a bike designed to be tourer on (I also used it on mtb trails as well, complete with pannier rack!).

I've done a 8,700 mile tour on my off-road touring bike (designed for remote areas of the world) which has Rigida Andra 30 26" (559) MTB CSS Rim's combined with Swissstop Blue Brake Pads for Deore / LX / XT / XTR Brakes - for Ceramic & Carbide CSS Rims, neither the rims nor the pads are cheap). (sorry direct copy from the invoice made life easier for me)

Why - well part way into 2 week tour (thankfully in Denmark, somwhere with plenty of bikes, bike shops and very helpful cyclists) my disc brakes seized up completely. Denmark is not exactly mountainous... so no major decents or anything like that. The brake dust had built up so much (somehow) that it had effectively applied my brakes permanately on for me and the front wheel would no longer rotate. Perhaps I should have known this was an issue? maybe. But I have had no issues whatsoever with my rim brakes in 8,700miles on tour and more off-tour. I have not had to do anything except change the pads once and we have covered some long descents fully laden at speed (one in particular that comes to mind was upto 60kph fully laden for 2.5km and another which had a 700m vertical descent again fully laden in winter conditions (kit is generally heavier in winter)). We have never had to deal with brakes overheating, rubbing or squealing, only wearing out after 4,500 miles for the first set, the second set will last much longer and are already at 4,200 miles and don't even look worn.

But like I said, I'm not comparing like with like and both of those setups would stop on a six pence. Would I have disc brakes for a bike staying in the UK or even western Europe/USA or somewhere that is not that remote? Yes, happily, but not for anywhere else in the world. Its the same reason I have a steel tourer - ability to repair in remote parts.

So it comes down to the age old issue - personal preference and what the bike is going to be used for.


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## Ticktockmy (21 Sep 2012)

I find it hard to make comparisons between disk or rim brakes, I have bikes with both types, and have toured with both types and never had problems, I have in the last few years got a preference for the disk brake system mine are Hope X2, and have had no problems at all, I change to sintered pads during the winter month, and back to standard pads once the weather get dryer. With rim pads, I have found that different makes have different braking performance, some seem to wear the rims more so than others. I must say that I have never known anyone who has had their front wheel pull out of the front forks due to excessive braking using disk brakes. I think one has to think about what use the bike will be used for then purchase a bike or bike parts suitable for that use.


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## Crankarm (21 Sep 2012)

Well I've been commuting on my Kona MTB which has cheap Hayes disc brakes which have been pretty good apart from occasional rubbing and squealing which I have to say has at times driven me mental. But on balance I prefer them to traditonal rim brakes as stopping power is superieur on a loaded bike and brake dust and gloop on the wheels is far less so less time spent cleaning the bike which is a major advantage.


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## MontyVeda (21 Sep 2012)

what's all this 'stopping power'?

Both rim brakes and disk brakes, when set up correctly are more than capable of_ locking the wheel_ in both wet and dry conditions (unless you have a vintage bike with old chrome plated steel rims)... the most efficient point of braking is just before the wheel locks.

So what's all this 'stopping power'?


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## Bodhbh (21 Sep 2012)

Suppose with hydrolics if the cable gets ripped or something, you're pretty buggered. But they are just so damn maintenence free. I started touring on a converted MTB 5-6 years ago, so I've had deore hydrolics since the git-go and apart from changing the pads, they've needed nothing doing to them, nada. I use the bike for the commute and off-roading too so they get it all. I bled them, but they didn't need it as they were the same after. Now they're the only remaining thing left from the orginal bike, everything else including the frame is replaced.

If I was building a tourer up from scratch I would probably go for cable discs, especially if I was planning on going anywhere remote, but fairly happy to leave the hydrolics on till they go kaput.

My mate who I tour with has a Thorn Sherpa and it gives me a good benchmark to see how my homebrewed thing stands against a traditional tourer, and the brakes on either are pretty much equal underload - until it gets wet or you ride thru alot of crap then the discs shine. Which is I suppose stating the bleeding (excuse the pun) obvious as that's why they're on MTBs.


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## andrew_s (23 Sep 2012)

Ticktockmy said:


> I must say that I have never known anyone who has had their front wheel pull out of the front forks due to excessive braking using disk brakes.


I have - a companion on a camping tour round the alps.
Fortunately it was at low speed in the most convenient location possible (just pulling up at Briancon campsite), and the only casualty was a pair of written off forks. A short while earlier and it would have been half way down the Galibier, and a great deal more serious. 
The problem was no lawyer lips and the allen key skewer in a SON dynohub.




MontyVeda said:


> what's all this 'stopping power'?
> Both rim brakes and disk brakes, when set up correctly are more than capable of_ locking the wheel_ in both wet and dry conditions (unless you have a vintage bike with old chrome plated steel rims)


a) You get your stopping or speed control done with less hand pressure. This is significant with heavy bikes, big hills, wet conditions or if you are somewhat less than Charles Atlas. Also, if you aren't squeezing so hard you have better control.
b) I'd have to disagree about rim brakes working well in wet conditions. There's the delay whilst the brake wipes the water off the rim, which you can allow for normally, but not when it's something unexpected such as a car pulling out in front of you, and if it's properly wet rather than merely a bit damp the rims get wet again as fast as the brake wipes the water off and you never get decent braking.


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## MontyVeda (23 Sep 2012)

andrew_s said:


> ...
> a) You get your stopping or speed control done with less hand pressure. This is significant with heavy bikes, big hills, wet conditions or *if you are somewhat less than Charles Atlas*. Also, if you aren't *squeezing so hard* you have better control.


what a crock of crap


andrew_s said:


> b) I'd have to disagree about rim brakes working well in wet conditions. There's the delay whilst the brake wipes the water off the rim, which you can allow for normally, but not when it's something unexpected such as a car pulling out in front of you, and if it's properly wet rather than merely a bit damp the rims get wet again as fast as the brake wipes the water off and *you never get decent braking*.


more crap

...but if it helps you justify your purchase


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## Red Light (23 Sep 2012)

andrew_s said:


> Hydraulic brakes aren't available for drop handlebars.


 
Yes they are and I have some. Hope V-Twin hydraulic adapter for drop bar levers. Magura used to do an HS66 hydraulic drop bar lever but it wasn't a brifter and therefore limited appeal. The V-Twin will adapt any drop bar lever for hydraulic brakes though.


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## Davidc (23 Sep 2012)

In my thinking the big advantage of discs is keeping the braking away from the rims. The big disadvantages are complication and flimsiness. Put together this comes to a don't care balance. Unless steel rims reappear, then it's discs all the way.

I have not yet replaced a wheel because the brakes have worn the rim away. I have replaced one because it was worn out (as in small fatigue cracks visible at the bike's annual service) That wheel would otherwise have been replaced soon afterwards because of rim wear from braking. On more expensive rims than I use, which are often softer I can see there's a problem. Rims normally get replaced because I've bent them.

I have ridden a MTB with discs. They are good brakes. However. With decent pads fitted (not the manufacturers original ones) I get as much braking as can be used on both my tourer (cantilevers) and my town MTB (V or linear pull). Both front brakes can start to lift my 13 1/2 stone + bike if I have to do an emergency stop.

I am not superman, but find that on both bikes braking only takes a sensible amount of effort. I can fully apply the brakes with no difficulty..

I think disc brakes are a better solution to brake design than rim brakes, but not enough to make changing an existing bike to them a sensible option. One day I may but a bike that has the m fitted. I will find out how to service and maintain them, and happily use them.

I really don't understand the fuss or strong feelings on this one. Hydraulics seem a good idea, but why can't we have that with cantilever or caliper rim brakes if it's such an improvement?


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## Davidc (23 Sep 2012)

Red Light said:


> Yes they are and I have some. Hope V-Twin hydraulic adapter for drop bar levers. Magura used to do an HS66 hydraulic drop bar lever but it wasn't a brifter and therefore limited appeal. The V-Twin will adapt any drop bar lever for hydraulic brakes though.


 
Including STIs? And as above, can hydraulic cantilevers, calipers or linear pull be bought?


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## Red Light (23 Sep 2012)

Davidc said:


> Hydraulics seem a good idea, but why can't we have that with cantilever or caliper rim brakes if it's such an improvement?


 
Cough... Magura!

Magura hydraulic rim brakes are far superior to cable rim brakes IMO - almost as good as discs.


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## Davidc (23 Sep 2012)

I'll have a look, but I can get as much braking as I can use with cables already so there'd need to be a big improvement in control and feel to justify any change.

Edit: Had a look, will look again when the price comes down by 90%.


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## Red Light (23 Sep 2012)

Davidc said:


> Including STIs? And as above, can hydraulic cantilevers, calipers or linear pull be bought?


 
Yes, I have a V-Twin on STI set up on one of my road bikes. And I have Magura hydraulic cantilever brakes on the tandems and my hardtail mountain bike. What I don't have is the Magura hydraulic caliper brakes although you can get them on e-bay still (Magura HS11 or HS66 from memory). They have a dedicated drop bar lever though so you need to go to bar-end or down-tube shifters with them.


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## Red Light (23 Sep 2012)

Davidc said:


> I'll have a look, but I can get as much braking as I can use with cables already so there'd need to be a big improvement in control and feel to justify any change.


 
There is, trust me. Its not the quantity of the braking, its the quality - steady, progressive and very consistent and predictable giving much greater confidence you can stop where and when you need to.


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## Red Light (23 Sep 2012)

Davidc said:


> In my thinking the big advantage of discs is keeping the braking away from the rims. The big disadvantages are complication and flimsiness.


 
I replaced the pads on my mountain bike Hope discs a couple of weeks ago. Apart from that I haven't touched them in years. They just work. No worrying about lubricating and replacing cables, cables rusting, breaking, stretching, brake pads wearing etc. They just sit there maintenance free and just work. And they continue to work if a spoke breaks or the rim gets dented or buckled and through the worst conditions. If you ride off-road in gritstone areas you can easily get through two sets of rim brake pads in a single ride and I've demolished a couple of pairs over a weekend downhilling in the US.


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## Davidc (23 Sep 2012)

Interesting RL. certainly if I was looking for a MTB for offroad/ downhill/ XC use I'd buy one with hydraulic discs as original equipment.

With the prices I saw in a quick lookup I won't be fitting hydraulics as a modification at present. In days gone by, when I toured with heavy kit and/or went a lot faster than now I'd have considered it. I understand what you're saying and if I see lower prices might think about hydraulic rim brakes, if for no better reason than liking working on bikes!

At some stage I may get another new bike, and by then we may see changes in road technology so discs &/or hydraulics may be OEM fitted. This depends partly on UCI making new technologies legal in the events they control.

One change I'd like to see now would be road frames (Toring and Audax in particular) being equipped with the mountings for discs. The cheap bike I use as a utility bike came with standard V brakes but has mountings for discs if I choose to use them, that's what I'd like to see on real road bikes.


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## Red Light (23 Sep 2012)

Davidc said:


> One change I'd like to see now would be road frames (Toring and Audax in particular) being equipped with the mountings for discs. The cheap bike I use as a utility bike came with standard V brakes but has mountings for discs if I choose to use them, that's what I'd like to see on real road bikes.


 
Cross frames, yes, road frames unlikely. The forks need to be built quite a bit stronger to handle disc brakes so most manufacturers will stick with lightweight forks and no discs on road bikes.


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## ColinJ (23 Sep 2012)

Red Light said:


> I replaced the pads on my mountain bike Hope discs a couple of weeks ago. Apart from that I haven't touched them in years. They just work. No worrying about lubricating and replacing cables, cables rusting, breaking, stretching, brake pads wearing etc. They just sit there maintenance free and just work. And they continue to work if a spoke breaks or the rim gets dented or buckled and through the worst conditions. If you ride off-road in gritstone areas you can easily get through two sets of rim brake pads in a single ride ...


That is my experience too. I was trashing rims and brake blocks at an alarming rate on winter MTB rides up here in Calderdale so I made sure that I had disk brakes on my upgrade MTB. They have been totally reliable for 11 years and I am still riding on the same rims which have a couple of minor dents from hitting big rocks, but are otherwise good as new..

(I wore out a pair of brake blocks on a steep technical descent on my first MTB but had to carry on braking and destroyed the rim.)


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## byegad (23 Sep 2012)

ColinJ said:


> I get it! In fact, I almost did end up with a permanent scar on one calf. I was amazed at how hot the rotor had got.
> 
> Well, maybe my descents are a lot longer and steeper than yours because I use the entire range of adjustment and can still end up with the brakes locked hard on until they cool!
> 
> ...


 
I'm using cable operated Avid BB7s. You are talking about hydraulic lock, caused by brake fluid boiling.
So maybe you'd be better off with cable operated brakes. No hydraulic lock and easier to repair, what's to lose?


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## ColinJ (23 Sep 2012)

byegad said:


> I'm using cable operated Avid BB7s. You are talking about hydraulic lock, caused by brake fluid boiling.
> So maybe you'd be better off with cable operated brakes. No hydraulic lock and easier to repair, what's to lose?


The cost of a new set of brakes! 

I reckon that slightly reducing the amount of hydraulic fluid in my brakes sounds like a viable plan. I'll try that in the New Year when I start cycling again.


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## byegad (23 Sep 2012)

No it won't. You'll boil the fluid just the same and the brakes will still lock on. That is the major disadvantage on hydraulic discs.
IF You are using metallic pads an organic set will reduce the heat transfer top the fluid, but the fundamental issue heat transfer to the fluid.


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## Crankarm (23 Sep 2012)

byegad said:


> No it won't. You'll boil the fluid just the same and the brakes will still lock on. That is the major disadvantage on hydraulic discs.
> IF You are using metallic pads an organic set will reduce the heat transfer top the fluid, but the fundamental issue heat transfer to the fluid.


 
Brake fluid that does not boil? You would have to be doing some seriously hard braking on your bike to get brake fluid to boil. What fluid do downhill racers use or don't they use brakes ...................?


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## Nigeyy (24 Sep 2012)

Monty:

while I don't think I'd be as blunt  , I agree with your posts. All things equal (i.e. good quality examples of both) I do think one of the advantages of disc brakes is the ability to modulate and wet weather performance. After much experimentation, I find v-brake style brakes to be very digital on braking -but certainly as powerful as discs -though I do think discs outperform rim brakes in the wet -you get more consistent and predictable braking.

In fact, I've never found a really good setup with v-brake style brakes; I can't seem to find a brake lever with a lever shape I like plus a short enough pull to give the kind of modulation I like. On the other hand, I love some cantis I have for the exact opposite reason -the modulation and power they provide is outstanding -and is only let down in the wet weather. Just my opinion, but I certainly don't share the love of v-brake styles brakes (I really don't want my wheels to lock easily, thanks!). Anyway, the reason I love my discs is down to 3 basic facts: i. they are more than powerful enough, ii. they modulate excellently, and iii. they provide -so far -the best wet weather performance I've had on a bike brake. Having said that, are they that much better? To be honest, no. If I was building a touring bike again and was on a budget, discs wouldn't be a necessity that's for sure. However, if budget wasn't a big deal, I'd definitely get them! To summarize: I just don't think discs offer the best bang for the buck. If you have the money, I'd say get them, otherwise don't worry if you can't.

Actually, this leads on to a big belief of mine -when we talk about brakes, I think we should be talking about the whole of the system including the brake levers as they are also essential to the essence of the brake performance. It's truly amazing how much of a different feel you get to a brake simply by having a different cable pull of literally 3 mm. I've heard people slag off cantis in the belief they are inherently a bad brake design -it may be some people have some poor quality flexible cantis, but overall I can't help but think oftentimes it's the poor or mismatched brake lever that is more the cause of the issue (assuming they are set up appropriately). In fact, I really wish brake lever manufacturers would post their cable pulls (it really would seem to something that would be very handy to know!).

Oops, I've digressed from the original question..... yeah, as other people have posted, it's down to personal choice. I think it's safe to say none of the common brake system designs out there are bad.



MontyVeda said:


> what a crock of crap
> 
> more crap
> 
> ...but if it helps you justify your purchase


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## stewie griffin (24 Sep 2012)

I don't have a disc equipped bike & I'm neither for nor against discs, but surely a disc equipped bike stresses the wheels more than a rim braked bike?

Discs must have the same effect as the rear wheels drive "hub twist" in the opposite direction & at a much much greater force (can you accelerate in the same distance you can stop?) so I expect spokes have to be stronger (& wheels relatively heavier), the front forks beefier as well as the weight of calipers, etc.

Rim brakes don't twist the hub in the rim, the braking forces on a rim braked wheel are similar to just putting more weight on the bike, but no twisting forces.

I can understand the advantages on a MTB where rims are subjected to more dirt & can be ground down quickly, & how nice it must be to be able to run bucked wheels without issue.

What I don't get is where any of this is useful on a road bike, where over & over again simplicity has proven to be the best bet for trouble free cheap cycling. So MTB yes, road bike no.

But I'm happy to have my opinion changed


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## Nigeyy (24 Sep 2012)

Yes, they do. But I think the real question to ask is "does this really make a difference?"

I haven't had a disc wheel fail yet. I really think this is along the lines of a disc wheel being inherently weaker, or disc brakes being more complex and hence more likely to suffer a mechanical breakdown. Theoretically it is, but practically a good quality well built disc wheel or good quality disc brake will be fine.

Admittedly anecdotal -but as I said,I haven't suffered a disc wheel failure yet after many, many miles (as well as my friends who ride with disc wheels) and I've actually had more trouble with traditional rim brakes (tension spring breaking) than on my disc brakes. Course, YMMV.



stewie griffin said:


> I don't have a disc equipped bike & I'm neither for nor against discs, but surely a disc equipped bike stresses the wheels more than a rim braked bike?
> But I'm happy to have my opinion changed


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## byegad (24 Sep 2012)

Crankarm said:


> Brake fluid that does not boil? You would have to be doing some seriously hard braking on your bike to get brake fluid to boil. What fluid do downhill racers use or don't they use brakes ...................?


 
Or more likely you will boil moisture absorbed by the fluid.

Any locking on in a hydraulic system that self releases when cooled down is due to this.


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## ColinJ (24 Sep 2012)

byegad said:


> Or more likely you will boil moisture absorbed by the fluid.
> 
> Any locking on in a hydraulic system that self releases when cooled down is due to this.


The fluid can expand without actually boiling!

As mentioned in previous posts above, the Hope C2s have controls to compensate for this fluid expansion. My problem is that I get to the end of the range of control after about 250-300 vertical metres of descent. That happens to be towards the top end of what I have to descend round here so enough extra control to back off the brakes for another 100 metres worth and I'd be happy. Removing a small amount of hydraulic fluid might do the trick. I'll try it when I get back on the MTB next Spring.


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## willem (24 Sep 2012)

There are obvious advantages in terms of braking quality. The principal disadvantages on a tourer are that they are more vulnerable, and that they require a stiffer and thus less comfortable fork. My personal preference on a loaded tourer is for Magura hydraulic rim brakes. But if budget is a concern, I think nothing beats a pair of Deore v brakes, particularly if used with Koolstop Salmon pads.
Willem


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## Red Light (24 Sep 2012)

byegad said:


> No it won't. You'll boil the fluid just the same and the brakes will still lock on. That is the major disadvantage on hydraulic discs.
> IF You are using metallic pads an organic set will reduce the heat transfer top the fluid, but the fundamental issue heat transfer to the fluid.


 
I've done some pretty serious hard braking on long runs on my brakes and have never had a fluid boiling problem. I've even blued the discs a few times they got that hot. 

What ColinJ is talking about is something completely different. Hope make closed and open hydraulic brake systems. With the closed ones there is no compensation for the expansion and contraction of the braking fluid temperature with volume so as the brakes heat up the fluid expands and eventually locks the brakes on with the lever released if it gets hot enough. There are adjustment caps on top of the brake levers to allow you to adjust for this on the fly and for ambient temperature changes. 

All that has happened is CJ has set his brakes up so they are in the right position in ambient with the adjusters fully out so he cannot back them off further. He just needs to reset it with the adjusters turned in a few turns so that now when the brakes heat up he has a few turns of adjustment left to compensate.


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## Red Light (24 Sep 2012)

willem said:


> There are obvious advantages in terms of braking quality. The principal disadvantages on a tourer are that they are more vulnerable, and that they require a stiffer and thus less comfortable fork. My personal preference on a loaded tourer is for Magura hydraulic rim brakes. But if budget is a concern, I think nothing beats a pair of Deore v brakes, particularly if used with Koolstop Salmon pads.
> Willem


 
I would say from my experience that rims are more vulnerable (dings and dents) than discs and when they are dinged they can compromise the braking quite a lot. With a disc its easy to take an adjustable spanner to it and bend it back straight but they are pretty tough and hard to damage. Have had to rebuild wheels to replace damaged rims on tour a few times but never discs.


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## Flying Dodo (24 Sep 2012)

stewie griffin said:


> I don't have a disc equipped bike & I'm neither for nor against discs, but surely a disc equipped bike stresses the wheels more than a rim braked bike?
> 
> Discs must have the same effect as the rear wheels drive "hub twist" in the opposite direction & at a much much greater force (can you accelerate in the same distance you can stop?) so I expect spokes have to be stronger (& wheels relatively heavier), the front forks beefier as well as the weight of calipers, etc.
> 
> ...


 
I've been test riding a number of disc equipped road bikes recently, to replace my old commuter bike. Although most of them are nominally cyclocross bikes, they're all pretty light. The main reason I'm looking at discs is that having a rural commute, I don't want another winter of snow jamming up the brakes, plus I know the discs will stop me quicker in the wet.


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## Blue Hills (25 Sep 2012)

Red Light said:


> There is, trust me. Its not the quantity of the braking, its the quality - steady, progressive and very consistent and predictable giving much greater confidence you can stop where and when you need to.


I'd agree about Magura hydraulic rim brakes. I have a set of pretty old HS11s on my Cannondale - what you might best describe as a flat-bar fast city bike.
I've never touched them at all in years and years apart from replacing brake blocks. Blocks are decent value, cheaper than many more "normal blocks" in fact, and are an absolute doddle to replace - just pop them in. This also makes cleaning the blocks/checking them for debris a doddle - pop them out, clean them, pop them back.

Initial set-up of the mounts on the cantilever bosses can be a bit of a fiddle but once that's done you are sorted. I particularly like the way the blocks come at the rims at a 90 degree angle - straight on - none of the arching or swing movement you get with normal cantilevers or V brakes.

I'm a bit surprised that they aren't supplied as original equipment on more bikes but suppose it's cost/the fact that the bikes would then bust price points seen as competitive-critical by bike manufacturers. For something like a fast city bike or a bike used for day rides I'd encourage anyone after nicer breaking to consider them. Red Light is exactly right - it's not just the strength of the braking, it's the modulation and sheer confidence of them. And the fit and forget. I wouldn't put them on a tourer though - although the lack of faff and the sheer bloody ease of changing brake blocks would be great, I'd be too concerned about the hudraulics getting messed up by some accident or daft individual interfering with them. And then getting them sorted on tour would be a pain. But I stress that in normal use you can usually just forget about them - for years and years.


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## AndyPeace (25 Sep 2012)

ColinJ said:


> Well, watch you don't touch a rotor with your leg after braking on a long descent! (It's a mistake that you will probably only make once ... )


 
There's got to be limited circumstances where this would happen, go on tell us how you ended up doing this?


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## ColinJ (25 Sep 2012)

AndyPeace said:


> There's got to be limited circumstances where this would happen, go on tell us how you ended up doing this?


Brake on descent, heating up rotor, come to narrow gate across bridleway (there was a big gate but the small one was nearer!), squeeze through gate with MTB, smell burning, pain in leg ...


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