Another good reason to not adopt disc brakes on road bikes.

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Vantage

Carbon fibre... LMAO!!!
As someone who knows very little about disc brakes: is cable friction really a problem for mechanical disc brakes, as the Sheldon Brown web site claims? Or is the risk of cable friction pretty much the same as for rim brakes?

I don't remember cable friction being an issue when I last had disc brakes and was over 10 years ago. I'm sure things have improved since then.
 

SpokeyDokey

67, & my GP says I will officially be old at 70!
Moderator
I have another question: how long would it typically take to bleed a pair of hydraulic disc brakes? I read this article about it, and was wondering about the time it would take:
https://roadcyclinguk.com/how-to/ma...r785-hydraulic-disc-brake-for-road-bikes.html

Regards & thanks,

--- Victor.

No idea - never had to bleed any of mine.

Doesn't look like a tricky process to me though in the event that you should have to do so.
 

Will Spin

Über Member
You shouldn't need to do it at all. However I did do it on one of my bikes as I don't think the hydraulic fluid had been installed correctly by the bike manufacturer and the brakes were spongy. I bought a brake bleeding kit, took about 1/2 hour to do it and I haven't had to do it again for the last 8 years.
 
It doesn't take long to bleed brakes but you need the kit and you need to be a little organised and careful. Take the pads out and wipe any spills, you don't want to contaminate any part of the braking system, so a bit more effort than normal brakes. The bike needs to be level and so does the reservoir, so a stand helps and you might need to loosen handlebars or levers depending on road or flat bar bike.
 

NorthernDave

Never used Über Member
As someone who knows very little about disc brakes: is cable friction really a problem for mechanical disc brakes, as the Sheldon Brown web site claims? Or is the risk of cable friction pretty much the same as for rim brakes?

No.

I've got mech disks on one bike and they're very similar to the hydraulic ones on my other bikes in everyday performance. Not quite as good, but not by a lot.
 

Shut Up Legs

Down Under Member
Thanks, all. Anyway it's not Sheldon any more, but a guy called John Allen. Also, one thing that lowered my opinion of whoever wrote that web page is that yesterday, when I tried to find a timestamp on the web page, I found some text at its bottom saying "Last Updated: <date/time> by John Allen". The only problem is: the date/time exactly matches the date/time at which I reload the page! Oh, dear...
 

si_c

Guru
Location
Wirral
As someone who knows very little about disc brakes: is cable friction really a problem for mechanical disc brakes, as the Sheldon Brown web site claims? Or is the risk of cable friction pretty much the same as for rim brakes?

Not especially, but cable discs are dependent more on the caliper than the cables in my experience. I use TRP brakes now having tried a couple of brands and they are truly excellent - the Hy/Rd in particular. With compression less outers they are the best cable actuated brakes I've used - far better than any of the Shimano rim brakes I've used too.
 

ColinJ

Puzzle game procrastinator!
I use TRP brakes now having tried a couple of brands and they are truly excellent - the Hy/Rd in particular. With compression less outers they are the best cable actuated brakes I've used - far better than any of the Shimano rim brakes I've used too.
I replaced the dire Promax front brake on my CAADX with a Hy/Rd. Yes, it can be a very effective brake.

The problem that I have with it is that the amount of cable pull needed by the brake is more than my Tiagra brake lever is designed to give. I have to pull the lever 3-4 times as far as normal to start braking and almost to the handlebar to get full braking. Yes - they are correctly adjusted!

I managed to slightly improve performance by relocating the cable to the opposite side of the bolt on the Hy/Rd. I would prefer to reduce cable pull by a factor 2 or 3 but I can't see an obvious (and cheap!) way of doing it.
 

ColinJ

Puzzle game procrastinator!
Coming down evil steep descents like the one below, however, means that prolonged heavy braking is the only way to avoid ending up like poor Chris Froome (badly injured in a high speed crash into a wall yesterday).
Oops, I thought this was a new thread. I had already made that point in this one last year! :laugh:
 

mjr

Comfy armchair to one person & a plank to the next
I find it hilarious that people think that their tyres suddenly increase their traction when they use disc brakes.
^^ This. I've only got one bike where the brakes cannot skid a wheel in the wet if told to and that's a vintage bike using leather-flecked pads in sidepull brakes onto steel rims. As others have noted, the slight advantage in lower rim wear mainly seems to mean that other bits of the wheel wear out first. Rim brakes just seem easier and cheaper to me while being good enough for my uses.

The main advantage of more ordinary people using disc brakes is that it makes their braking nice and tuneful for those of us with silent bikes! If only they could hold a note properly, they could get some decent music going. Some of them already have the percussion sorted as they crash through the gears... ;)
 

Slick

Guru
^^ This. I've only got one bike where the brakes cannot skid a wheel in the wet if told to and that's a vintage bike using leather-flecked pads in sidepull brakes onto steel rims. As others have noted, the slight advantage in lower rim wear mainly seems to mean that other bits of the wheel wear out first. Rim brakes just seem easier and cheaper to me while being good enough for my uses.

The main advantage of more ordinary people using disc brakes is that it makes their braking nice and tuneful for those of us with silent bikes! If only they could hold a note properly, they could get some decent music going. Some of them already have the percussion sorted as they crash through the gears... ;)
Actually quite close to the truth for me. I have one disc bike that is silent although it doesn't know what it means to get wet. I have another that does it all and on spending a few quid on a new groupset, the back brake is every bit as silent as the good bike but the front brake that has been treated exactly the same as the rear is like a violin on steroids and in danger of giving me and everyone else around me tinnitus.
 
Location
London
The esteemed brucey in a certain other place, who knows a ton about bikes and mechanicak things reckons that the case for discs is no way as clear cut as some think. Of course in a dastardly plot to try to force us to discs the braking surface of many quality rims is being shaved away not by pads but by the manufacturers.
 

Smokin Joe

Legendary Member
^^ This. I've only got one bike where the brakes cannot skid a wheel in the wet if told to and that's a vintage bike using leather-flecked pads in sidepull brakes onto steel rims. As others have noted, the slight advantage in lower rim wear mainly seems to mean that other bits of the wheel wear out first. Rim brakes just seem easier and cheaper to me while being good enough for my uses.
It isn't about the brakes ability to lock the wheel, it is about control. The more powerful brakes can be applied without much hand force, making it easier regulate your braking.

Anyone who has driven a car with drum brakes will remember that you can easily lock the wheels - the trouble being that the pedal required so much force that you often did so. I cannot remember the last time I made the tyres squeal with discs.
 

lane

Veteran
Not especially, but cable discs are dependent more on the caliper than the cables in my experience. I use TRP brakes now having tried a couple of brands and they are truly excellent - the Hy/Rd in particular. With compression less outers they are the best cable actuated brakes I've used - far better than any of the Shimano rim brakes I've used too.

I have them on my current bike and on my previous bike and am very happy with them.

I replaced the dire Promax front brake on my CAADX with a Hy/Rd. Yes, it can be a very effective brake.

The problem that I have with it is that the amount of cable pull needed by the brake is more than my Tiagra brake lever is designed to give. I have to pull the lever 3-4 times as far as normal to start braking and almost to the handlebar to get full braking. Yes - they are correctly adjusted!

I managed to slightly improve performance by relocating the cable to the opposite side of the bolt on the Hy/Rd. I would prefer to reduce cable pull by a factor 2 or 3 but I can't see an obvious (and cheap!) way of doing it.

This is a frequently reported concern with these. I don't know if it is more an issue on some systems than others, if it is to do with set up or just down to personal preference. Perhaps a bit of all three. I think correct set up is important but even then I have more cable pull than with rim brakes - but I just don't find it an issue.
 
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