hydraulic disc brakes

General cycling advice ( NOT technical ! )
fenmanctc
Posts: 8
Joined: 15 Dec 2013, 10:10am

hydraulic disc brakes

Postby fenmanctc » 22 Feb 2016, 7:29pm

Does anyone know how I can replace the shimano cable disc brakes on my old Trek Soho with hydraulic brakes? The existing brakes have 160mm hub-mounted rotors. Can anyone suggest brakes which will be compatible?

Brucey
Posts: 41390
Joined: 4 Jan 2012, 6:25pm

Re: hydraulic disc brakes

Postby Brucey » 22 Feb 2016, 8:00pm

I'm not quite sure why you would want to do this but hey, its a free world.

Now, when you say 'hub mounted rotors' you mean shimano centrelock, right?

Simplest swap is to use shimano brakes with the appropriate (as recommended in the relevant Shimano techdoc) discs.

NB many shimano centrelock discs are made for 'organic pads only' so look out for that.

The other disc mounting in common use is a 'six bolt' mounting.

160mm discs are a very common size but the swept area varies with the caliper and pad design, thus the width of the disc periphery can vary too. Often you can use 'mismatched' calipers and discs safely, but not always.

Some shimano (and other brands) of hydraulic brake use the same pad design as some shimano mechanical disc calipers; this being the case you ought to be able to use those hydraulic brakes with your extant discs OK, provided you stick with the correct (compatible) pad compounds where necessary.

cheers
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~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~

phil parker
Posts: 1019
Joined: 31 Dec 2009, 5:09pm
Location: Hants/Wilts

Re: hydraulic disc brakes

Postby phil parker » 22 Feb 2016, 8:20pm

You also need to consider the frame braze-ones for the cable routing if they will accept the hydraulic hose, probably not, but how you intend to secure the hydraulic pipes.

blackbike
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Joined: 11 Jul 2009, 3:21pm

Re: hydraulic disc brakes

Postby blackbike » 23 Feb 2016, 7:39pm

In 1979 I bought a Honda motorbike with a cable operated disk brake, and that was enough to stop it from its 60 mph top speed in a reasonable distance. Stopping a pushbike is not nearly as difficult.

Tiberius
Posts: 578
Joined: 31 Dec 2014, 8:45am
Location: North East England

Re: hydraulic disc brakes

Postby Tiberius » 23 Feb 2016, 10:06pm

blackbike wrote:In 1979 I bought a Honda motorbike with a cable operated disk brake, and that was enough to stop it from its 60 mph top speed in a reasonable distance. Stopping a pushbike is not nearly as difficult.


I'm guessing Honda CB100/125cc ????.....Such good brakes that nobody else used them....Utter junk.... :shock:

OP...You really have opened one major can of worms. This place is full of people who will tell you that hydraulic disc brakes are the work of the devil and that they are more complex than the average space shuttle. They will move on to tell you that the heels on their half worn plimsoles will stop you much better than ANYTHING involving hydraulics.

Research if Shimano XT hydraulic disc brakes will fit your bike. One finger mega braking from any speed you can get up to on a push bike (or a Honda CB100/125).......120 quid (ish) for a complete front/rear kit. Dead easy to fit, they even come complete with a little kit to help you shorten the tubes (you WILL have to shorten the tubes unless you have an XXXXXXXXXXXL frame) YouTube will show you how....No bleeding required....

I just KNOW that any minute now I will be dragged away by the massed ranks of the CTC 'Chronic pessimism....what if...what if....what if ??' club....

I like to live dangerously......as long as it doesn't involve crap brakes....... :wink:

Wesh-Laurence
Posts: 372
Joined: 10 May 2009, 8:00am

Re: hydraulic disc brakes

Postby Wesh-Laurence » 24 Feb 2016, 10:01am

Replacing cable operated (mechanical) disc brakes with hydraulic operated disc brakes is fairly easy. You don’t need to change your wheels which already have 160mm diameter disc rotors. There are many makes and models of hydraulic brake that will fit you bike.

You appear to have very little knowledge of bicycle mechanics and therefore I would suggest you get a good bicycle mechanic to make the change for you. You need a 3mm and a 5mm hex allen spanner to fit the levers to the handlebars and the disc calipers to the frame.

You simply need to buy a front and rear hydraulic operated disc brake which come complete with levers and hydraulic hoses already attached. Buy brakes with the correct length of hydraulic hoses which do not need shortening or lengthening. In the UK the front brake will have a short hose and be operated on the right hand lever, the rear brake will have a longer hose and be operated on the left hand lever.

An issue you may have is if the brake/gear shifter levers you currently have are combined in a single “pod” on your handlebars. If this is the case you will have to buy new separate gear shifter levers as well as the new hydraulic disc brake set.

The hydraulic calipers will simply replace the cable operated calipers (you will already have the correct mount adaptors for use with 160mm diameter disc rotors).

Use cable ties to secure the brake hoses to the bicycle frame.

blackbike
Posts: 2492
Joined: 11 Jul 2009, 3:21pm

Re: hydraulic disc brakes

Postby blackbike » 24 Feb 2016, 10:30am

Tiberius wrote:
blackbike wrote:In 1979 I bought a Honda motorbike with a cable operated disk brake, and that was enough to stop it from its 60 mph top speed in a reasonable distance. Stopping a pushbike is not nearly as difficult.


I'm guessing Honda CB100/125cc ????.....Such good brakes that nobody else used them....Utter junk.... :shock:



Honda CB100N, V registered.

Such junk that my nephew is still riding the same bike with the same cable operated disk brake.

Brucey
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Joined: 4 Jan 2012, 6:25pm

Re: hydraulic disc brakes

Postby Brucey » 24 Feb 2016, 11:05am

Tiberius wrote: ....is full of people who will tell you that hydraulic disc brakes are the work of the devil and that they are more complex than the average space shuttle. They will move on to tell you that the heels on their half worn plimsoles will stop you much better ....

I just KNOW that any minute now I will be dragged away by the massed ranks of the CTC 'Chronic pessimism....what if...what if....what if ??' club....


you have to ask yourself

a) 'how likely are they to fail?' and
b)' can you fix them?' and
c) 'how much 'benefit' do you accrue in the meantime?'

There isn't a hydraulic system built yet that won't (eventually) fail to a leak.

This mightn't matter in except that for most folk the answer to 'b)' is a resounding 'NO' and for c) the answer is that the benefits are not enormous vs other forms of brake.

So it is a judgement call really. It is a bit like choosing tyres; for some the ride quality/speed of lightweight tyres is worth the increased risk of a puncture, and for others it isn't.

IMHO if you are outside of the realms of 'performance cycling', and have a normally strong grasp etc, choosing hydraulic brakes is usually a bit like choosing lightweight tyres, even though you don't care how fast you go exactly and can't fix a puncture, i.e. it is a bit daft.

BTW happily I own and use hydraulic brakes, but they are certainly not for everyone and every bike.

cheers
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~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~

pete75
Posts: 13413
Joined: 24 Jul 2007, 2:37pm

Re: hydraulic disc brakes

Postby pete75 » 24 Feb 2016, 12:10pm

Brucey wrote:you have to ask yourself

a) 'how likely are they to fail?' and
b)' can you fix them?' and
c) 'how much 'benefit' do you accrue in the meantime?'

There isn't a hydraulic system built yet that won't (eventually) fail to a leak.

This mightn't matter in except that for most folk the answer to 'b)' is a resounding 'NO' and for c) the answer is that the benefits are not enormous vs other forms of brake.



Strange then isn't it that motor vehicles abandoned the apparent advantages of cable and rod actuated brakes for hydraulic many, many years ago. They're usually one of the most reliable bits of car or motorbike. Yes they may eventually leak , after much usage, but then they're simple and easy to fix mostly just a matter of replacing seals and/or worn pistons and then bleeding the system.

Whether or not bikes actually need the power of hydraulic brakes is another matter.

Tiberius
Posts: 578
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Location: North East England

Re: hydraulic disc brakes

Postby Tiberius » 24 Feb 2016, 1:39pm


Honda CB100N, V registered.

Such junk that my nephew is still riding the same bike with the same cable operated disk brake.



Yup....THEN, Honda dropped it and nobody else took it up.....Wonder why eh ??

Nice little bikes though those old CB100's.....sort of a 'real' motorbike in miniature.

i remember the 'Merchants of doom' back in the day saying the Jap' stuff would never last. Keep on top of the oil changes and that little Honda will last forever.... :D

pete75
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Joined: 24 Jul 2007, 2:37pm

Re: hydraulic disc brakes

Postby pete75 » 24 Feb 2016, 1:52pm

Tiberius wrote:

Honda CB100N, V registered.

Such junk that my nephew is still riding the same bike with the same cable operated disk brake.



Yup....THEN, Honda dropped it and nobody else took it up.....Wonder why eh ??

Nice little bikes though those old CB100's.....sort of a 'real' motorbike in miniature.

i remember the 'Merchants of doom' back in the day saying the Jap' stuff would never last. Keep on top of the oil changes and that little Honda will last forever.... :D


Lambretta started using cable operated disk brakes on the Tv175 in about 1963. They used the same system on their larger machines for a long time after.

User avatar
[XAP]Bob
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Joined: 26 Sep 2008, 4:12pm

Re: hydraulic disc brakes

Postby [XAP]Bob » 24 Feb 2016, 2:12pm

pete75 wrote:
Brucey wrote:you have to ask yourself

a) 'how likely are they to fail?' and
b)' can you fix them?' and
c) 'how much 'benefit' do you accrue in the meantime?'

There isn't a hydraulic system built yet that won't (eventually) fail to a leak.

This mightn't matter in except that for most folk the answer to 'b)' is a resounding 'NO' and for c) the answer is that the benefits are not enormous vs other forms of brake.



Strange then isn't it that motor vehicles abandoned the apparent advantages of cable and rod actuated brakes for hydraulic many, many years ago. They're usually one of the most reliable bits of car or motorbike. Yes they may eventually leak , after much usage, but then they're simple and easy to fix mostly just a matter of replacing seals and/or worn pistons and then bleeding the system.

Whether or not bikes actually need the power of hydraulic brakes is another matter.


But car braking systems are far heavier, and have rather different modes of operation to their cycle counterparts.

We tend to have one hand squeezing one lever, which operates one caliper, on one disc.

Cars have one foot pushing on one pedal operating at least 4 calipers on four discs.

There is an innate requirement to balance force and automatically adjust for uneven pad wear that simply doesn't exist on a cycle.
Additionally the weight of a car base hydraulic system is significantly higher than that on a bike, and much of that mass will be on things like over engineered seals etc...
A shortcut has to be a challenge, otherwise it would just be the way. No situation is so dire that panic cannot make it worse.
There are two kinds of people in this world: those can extrapolate from incomplete data.

Tiberius
Posts: 578
Joined: 31 Dec 2014, 8:45am
Location: North East England

Re: hydraulic disc brakes

Postby Tiberius » 24 Feb 2016, 4:19pm

pete75 wrote:
Lambretta started using cable operated disk brakes on the Tv175 in about 1963. They used the same system on their larger
machines for a long time after.



Indeed they did (my series 3 GP200 had one).....until they went down the pan in 1971 (IIRC) and flogged all the machine tools/old frames etc to the Indians

My mate bought one of the new Indian GP200s three years ago. They are imported with a cable disc brake and the importer (Arthur Francis RaySpeed) changes that to a hydraulic disc brake BEFORE it even hits the roads..... (Thank God... :mrgreen: )...

pete75
Posts: 13413
Joined: 24 Jul 2007, 2:37pm

Re: hydraulic disc brakes

Postby pete75 » 24 Feb 2016, 4:41pm

[XAP]Bob wrote:
pete75 wrote:
Brucey wrote:you have to ask yourself

a) 'how likely are they to fail?' and
b)' can you fix them?' and
c) 'how much 'benefit' do you accrue in the meantime?'

There isn't a hydraulic system built yet that won't (eventually) fail to a leak.

This mightn't matter in except that for most folk the answer to 'b)' is a resounding 'NO' and for c) the answer is that the benefits are not enormous vs other forms of brake.



Strange then isn't it that motor vehicles abandoned the apparent advantages of cable and rod actuated brakes for hydraulic many, many years ago. They're usually one of the most reliable bits of car or motorbike. Yes they may eventually leak , after much usage, but then they're simple and easy to fix mostly just a matter of replacing seals and/or worn pistons and then bleeding the system.

Whether or not bikes actually need the power of hydraulic brakes is another matter.


But car braking systems are far heavier, and have rather different modes of operation to their cycle counterparts.

We tend to have one hand squeezing one lever, which operates one caliper, on one disc.

Cars have one foot pushing on one pedal operating at least 4 calipers on four discs.

There is an innate requirement to balance force and automatically adjust for uneven pad wear that simply doesn't exist on a cycle.
Additionally the weight of a car base hydraulic system is significantly higher than that on a bike, and much of that mass will be on things like over engineered seals etc...


Seperately operated just like on a motorbike unless it's a Moto Guzzi. I suppose someone has never ridden a motorbike they won't know front and rear brakes are usually operated independently.

I'm not saying that cycles need a hydraulic system but I do take issue with the idea they are difficult to fix if they wear or that they are less reliable than cable systems.

Over engineer a seal - how? The part that bears on a piston either wears or it doesn't. Wear will depend on the material used and the cleanliness of the operating environment. There's no reason why seals on bike brakes need to be made of inferior materials to those used in cars.

Brucey
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Joined: 4 Jan 2012, 6:25pm

Re: hydraulic disc brakes

Postby Brucey » 24 Feb 2016, 5:03pm

Tiberius wrote: ..... bought one of the new Indian GP200s three years ago. They are imported with a cable disc brake and the importer (Arthur Francis RaySpeed) changes that to a hydraulic disc brake BEFORE it even hits the roads..... (Thank God... :mrgreen: )...[/b]


but that could be as much (or more) to do with execution rather than conception.

There are undoubtedly lots of other shonky parts on those machines too, the difference being that the other ones are slightly less likely to kill you when they go wrong.

pete75 wrote: ....I'm not saying that cycles need a hydraulic system but I do take issue with the idea they are difficult to fix if they wear or that they are less reliable than cable systems. Over engineer a seal - how? The part that bears on a piston either wears or it doesn't. Wear will depend on the material used and the cleanliness of the operating environment. There's no reason why seals on bike brakes need to be made of inferior materials to those used in cars.


The seals wear, the bores corrode, the fluid goes off, guide bushings swell up when they get contaminated, the boots fail; there is an endless list of things that go wrong with hydraulic systems. If you are competent enough you can fix a lot of this stuff but no-one can say for sure that when they fit new seals to a used hydraulic brake part that it will be 100% functional afterwards; that is proven (or not) when the parts are tested. These days seal kits are increasingly difficult to find for car brake systems because they are in essence only attractive to the home mechanic; at workshop rates there is no mileage in trying to fit seal kits to potentially knackered cylinders, it is more cost effective to replace them. This is also what many bike shops do with bicycle brakes, and for similar reasons.

So when people say 'oh my hydraulic brakes cost XYZ' I can't help thinking that 'the repair cost' in the event of trouble will also be 'XYZ' too, because unless someone is prepared to take a punt on it, the most likely outcome is that the whole lot will go in the bin when it starts to leak.

In point of fact I think that the mean time to failure might be a lot less for hydraulics than cables on bicycle brakes, but a cable can be quickly and economically replaced, whereas a failing hydraulic system is a different prospect. It is no accident that most hydraulic bike brakes are sold as pre-bled units that just get bolted on; doing much else rapidly becomes non-cost effective in a workshop.

BTW it isn't just Moto Guzzis that have linked brakes, some Hondas have them too.

cheers
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~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~