why cable operated discs?

[Gumstabber]

Ok, so I've really got in to this whole cycling to work thing over the last 3 months. Rain or shine I'm on my bike. I promised myself at the beginning of this whole escapade that if I kept it up all through the winter I would reward myself with a nice bike to continue with next year.

I've come to hate the rim brakes on my current hybrid though, when it's wet and dirty they howl loudly and grind away on the rims so I'm thinking that for my new bike I'd like disc brakes. Discs are what I have on my MTB powered by Hope hydraulic levers and calipers. Nice, they stop me no matter what the weather, and in Wales they really get tested.

Looking around though and most of the cyclocross/fast urban bikes seem to run with mechanical discs Avid BB5's mostly. They don't really weigh that much more than cable and when I'm spending £1000 on a bike I'd like the best please.

So that led me to wonder why don't they have hydraulic discs? Can anyone answer this? Do I need hydraulics?

[anonymous-user]

most likely convenience, its quite easy to replace a cable but I would imagine its because the stopping power required isnt as great although you would assume that bikes intended for use on the road would require greater stopping capability!

dealing with brake fluid is quite messy and bleeding some hydraulic brakes is a complete pita!

[Batfink]

Cables are not so susceptible to heat. Important if you regularly reach high speeds

[Jimbo.]

Cost. Pure and simple.

re. cables, hydraulics and heat. Non-issue.

[The Surveyor]

Easy answer, it's cost.

Check the range of bikes and the cheaper MTB's will have cable disks, the more expensive will have the hydraulic ones.

Paul

[Beyond Rational]

Above a certain price point, on drop bar bikes at least, I think it is because no-one makes a shifter that works with hydraulic brakes. It's a bit of a catch 22 situation, unlike during the introduction of the technology in MTBing where the brake and shifter were (for the most) independent.

At least to the home purchaser, Shimano M596 hydros are cheaper, taking into account levers, cables etc, than complete BB5/BB7 setup of decent quality.

[Comfortably Dumb]

I'm guessing the lack of availability of affordable hydraulic STI road style leavers is an issue as well.

Edited by Comfortably Dumb on Tuesday 13th November 20:10

[sjg]

For anything with drop bars (like the cross bikes) there is an incredibly small pool of hydraulic brake levers to choose from - especially as the brake lever is usually also the shifter. There's things like the Hope V-Twin which allows a cable lever to work a hydraulic brake, but that's extra complexity and weight.

Avid BB5 & BB7 are actually really nice brakes. There's a lot of snobbery about hydraulic over cable (mostly because there are some really cheap and nasty cable discs on budget bikes) but actually the latter work fine for most people, have fewer maintenance headaches (try shortening a hydraulic hose!) and are easy to adjust. Any minor difference in stopping power makes little difference on thinner wheeled bikes where you've got enough power to lock up regardless.

Have a test ride of a bike with them, you might change your mind.

[RobDickinson]

Disk brakes are going to be making inroads into high end road bikes soon though arnt they? I assume that will be hydraulics...

[Batfink]

RobDickinson said:

Disk brakes are going to be making inroads into high end road bikes soon though arnt they? I assume that will be hydraulics...

maybe but i'm not convinced its really out of necessity. Its good for cyclocross and mountain bikes where mud and debris can affect braking, but would they cope with the high speeds of downhill road bikes?

[RobDickinson]

Batfink said:

RobDickinson said:

Disk brakes are going to be making inroads into high end road bikes soon though arnt they? I assume that will be hydraulics...

maybe but i'm not convinced its really out of necessity. Its good for cyclocross and mountain bikes where mud and debris can affect braking, but would they cope with the high speeds of downhill road bikes?

You think disk brakes would cope poorer than rim brakes? They'll allow racers to brake later and harder I think..?

[Jimbo.]

RobDickinson said:

You think disk brakes would cope poorer than rim brakes? They'll allow racers to brake later and harder I think..?

A well set-up rim brake can damn-near overwhelm the front tyre as it is, so more power is irrelevant. The supposed advantage of discs is more consistent braking in poor weather, more predictable braking with carbon rims, and less heat build-up on said rim (with its effects upon tyres/tubs etc).

There are hydraulic discs for road bikes/cross bikes, but they're more of a stop-gap until Shimano/SRAM/Campagnolo sort a fully hydraulic system. For now you'll have to do with cable-actuated hydraulic brakes. IIRC Magura have something, but it's TT brakes only.

[anonymous-user]

RobDickinson said:

Batfink said:

RobDickinson said:

Disk brakes are going to be making inroads into high end road bikes soon though arnt they? I assume that will be hydraulics...

maybe but i'm not convinced its really out of necessity. Its good for cyclocross and mountain bikes where mud and debris can affect braking, but would they cope with the high speeds of downhill road bikes?

You think disk brakes would cope poorer than rim brakes? They'll allow racers to brake later and harder I think..?

its going to be interesting though because when do they need to brakelater and harder? on long alpine descents, you could argue that the last thing the likes of the pro tour peloton want is good brakes that grab and stop in an instant!... I would suspect they run the pads as close to the rims as it is so they can descend, feather the levers and brake as little as required to maintain speed. Something like discs which could be too good are also going to be a fair bit heavier than the likes of dura-ace, record and red.

[dudleybloke]

my xc bike has tektra draco hydraulics, my dh bike has hope m4's.
iv rode a few bikes with cable disks and dont like the feel of them. (could have been the set-up/maintainence though)

pad choice makes a difference too.
the standard sintered pads worked almost binary in nature but since swapping to kevlar pads i can precisely modulate and feather the brakes mid corner with confidence that im not going to lock up. (unless i want to of course!)

Edited by dudleybloke on Tuesday 13th November 21:08

[BadgerBenji]

As has been said above there is no drop bar hydraulic lever from the main players at present just a few people making cable actuated to hydraulic disc, but in my opinion it's not a pleasant thing to look at. But there is hope, Cannondale was spotted on a bike with Tim Johnson testing a SRAM Red/Avid hydraulic drop bar lever at the latest USGP round, it was seen but as of yet no one has any photographs. It's probably only a question of time till Shimano joins in as they also have the technology but whether they chose to develop it is a different question. Fortunately SRAM sees cyclocross as a big market, which it is in the USA at present.

The biggest pain with cable operated discs is the readjustment they need as only one side of the caliper in most is acctuated so as the pads wear they need fettling.

[walm]

I just swapped my mechanicals for hydraulic on my MTB.
No reason. Just fettling.
They do appear easier to apply though.
In the mud for the mechanicals to get close to lock-up took nearly three digits.
These hydraulics get full power with just one!

Not looking forward to this bleeding malarky.

[P-Jay]

I can't add a lot here, but price certainly plays a part, certainly where drop bars are concerned, disc brakes on road bikes is really a new thing and even the Hope hydraulic one look a bit 'shed designed' and on a £1000 bike would probably amount to 40% or more the cost of it.

Plus you can't use anything like the same amount of braking force on a narrow, high pressure road tyre so the simpler, easier to maintain and less powerful cable version makes more sense.

If it's a deal breaker for you, buy a cheaper hybrid with cable discs and retro fit some hydraulics, they should swap straight over if you buy the right ones.

Edited by P-Jay on Wednesday 14th November 14:28

[P-Jay]

Batfink said:

RobDickinson said:

Disk brakes are going to be making inroads into high end road bikes soon though arnt they? I assume that will be hydraulics...

maybe but i'm not convinced its really out of necessity. Its good for cyclocross and mountain bikes where mud and debris can affect braking, but would they cope with the high speeds of downhill road bikes?

"Cope" as in would Hydraulics 'survive' the rigors of road bikes?

Oh, I'm sure they'd be ok, some of the big DH Mtb hydraulic brakes can put up with some insane 'treatment' and heat, whilst they're being pounded to crap. I'm sure then the time comes (I hear it's the UCI putting a stop to it) they'll make some tiny, lightweight hydraulics for road racers, but if you mounted a decent MTB brake system on a road bike and went out of your way to try to abuse them, the wheel would collapse or the frame snap before the brakes gave up.

[RobDickinson]

AFIK the issue on high end road bikes at the moment is the spoke lacing patterns used cant cope with the torque from the brakes at the hub.

[BadgerBenji]

RobDickinson said:

AFIK the issue on high end road bikes at the moment is the spoke lacing patterns used cant cope with the torque from the brakes at the hub.

I wonder if they have thought of using the same spoke lacing as on top end mountain bike wheels, it's not rocket science and not the reason there isn't hydraulic discs on road bikes. To lock the wheel with a cable operated disc will exert the same forces as locking it with a hydraulic disk.