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Disc brakes versus V brakes...

Discussion in 'Cycling Components' started by amelia-jane, 1 Nov 2009.

  1. amelia-jane

    amelia-jane Active Member

    Location:
    Birmingham
    Can anyone help me out with the pros and cons of each?

    What sort of cyclist/cycling is suited to each?

    Thanks.
     
  2. Norm

    Norm Guest

    The way it was explained to me is that road bikes use rim brakes, off-roaders use disk brakes.

    There's a couple of reasons for this.

    Disk brakes need stronger wheels because they apply the braking force to the hub, whereas rim brakes apply their force on the rim (duh ;) ). Disk brakes, therefore, need stronger spokes to handle this. Off road bikes have stronger wheels, for other reasons, so this is not an issue.

    Rim brakes are also more susceptible to bad conditions, riding through muck and puddles affects the rim much more than it does a disk, which is something like 10 inches higher.

    Disks can also be made from good braking material, whereas rims have to also be made from good wheel material.

    All of which generally puts disk brakes in the hands of the MTBers and rim mounted blocks on the road. :bicycle:
     
  3. Piemaster

    Piemaster Veteran

    Location:
    Hull or Brazil
    I'd say there are an increasing amount of road orientated bikes have disc brakes now. My Giant Escape, sons Carrera Gryphon (most definitely a flat barred road bike). The Boardman hybrids come with discs too. I suspect at some time in the future there drop bar levers for discs will appear.
    I really discs, even in the dry I can lock both wheels and skid with them and don't seem to be effected in the wet at all. Braking is limited by road/tyre combination not by the discs.. They are entry level Avid juicy 3 and have never needed touching, no fiddling with cables at all.
     
  4. BalkanExpress

    BalkanExpress Über Member

    Location:
    Balkans
    Agree with Norm on the princple, but would add that an increasing number of hybrid and road bikes (touring not racing) are being fitted with disc brakes.

    This is in part being led by MTB specialist broadening their ranges, Kona being the prime example.

    There are arguments for and against and no doubt others who post after me will give you chapter and verse on this (not as heated as the helmet no helmet debate but still some strong view;)) .

    My own personal experience is a recent switch to discs on my Kona Sutra. I had a couple of initial issues on set up, caused in large part by the pads sticking together when I took the wheels out to transport it, however on the whole I am happy with them, good stopping power, easy adjustment (Avid BB7). Just do n't ask what they are like in the wet as the paintwork is far too pretty to mess up:biggrin:
     
  5. GrasB

    GrasB Veteran

    Location:
    Nr Cambridge
    Off the top of my head...
    Pros:
    * less liable to getting water/dirt contamination on the friction material to start with then...
    * less effected by weather/road. I've never had soaking wet discs have bite problems, unlike rim brakes
    * there's no worry when tanking down long hills heavily loaded about rim temps, leading to over-pressure blowouts
    * remove the stress from the rim under braking, which seems to translate into wheels staying true for longer.
    * your wheels will last longer as there's no wear on the rim

    Cons:
    * discs setups are heaver
    * more stress is placed on the spokes
    * can be fiddly to get just right
    * try to pull the wheel out of the dropouts (it's a moment of torque thing)

    As for what they're suitable for, it doesn't really matter it's more what performance compromises you want to make. I'll be putting a front disc on the Marin in the near future as the extra weight won't be any problem & I'm fed up with killing off rims, with that said discs won't be going anywhere near my fixie racer which is for fast riding.
     
  6. Norm

    Norm Guest

    Sorry, I should have said that I was just giving the principles. Just like you can commute on a racer or tour on a folder, it is possible to compromise and use either as a solution in sub-optimal circumances. :smile:
     
  7. P.H

    P.H Über Member

    Not yet mentioned is the apparent need to strengthen the forks for disc brakes. Much of the comfort on my tourer comes from the bit of flex in the fork, would this still be possible with a fork designed for discs?
    I'm presently running carbide coated Rigida rims with V and canti brakes. Does away with many of the arguments againt rim brakes, better wet weather braking, clean and much longer lasting.
     
  8. Crankarm

    Crankarm Veteran

    Location:
    Nr Cambridge
    Disc brakes systems are heavier than rim brake sytems. It is far easier to lock a wheel with a disc brake system than with rim brakes although good rim brakes such as top end road race DuraAce or SuperRecord calipers or XTR V brakes can easily lock a wheel. Typically tyres on disc brakes wheels are much fatter - MTB and have a much greater contact with the riding surface therefore a much greater area to generate friction to stop. A 23C road tyre has a comparatively very small contact area with the road. Applying a disc brake system would mean the road wheel/tyre if it suddenly locked could immediately mean your bike would drop you on the tarmac. There don't tend to be too many big holes full of water and mud or rocks, roots and trees that road bikes have to negotiate where their rims are likely to get submerged in mud or water compromising braking efficiency. MTBs have inboard discs so they can be ridden along muddy trails through pools of mud, water and rocks without the braking surface becoming contaminated. Also MTBs tend to be much heavier than road bikes to withstand all the shocks and vibrations from hard riding, manouevring and jumping. Road bikes have to be strong, light and aerodynamic.

    I suppose a touring/expedition bike which will carry a considerable load and be ridden in adverse conditions would benefit from dsic brakes. Many world touring bikes use MTB based frames and are built for strength rather than out and out lightness. Going down a steep mountain pass in the Himalayas or a non existant road in Africa you might prefer disc brakes. Mind if they go wrong you are less likely to be able to get them repaired as say a conventional rim brake system.

    Modern rim V brakes are pretty good if you've got decent rims and brake pads. Even copious amounts of water and muck don't seem to faze them too much. Of course if you get neat wet mud mixed with grit on your rims and blocks then you're going to have to clean them thoroughly but how often does this happen? Thankfully, not often for me anyway.

    HTH.