Mechanical Disc Brakes

Discussion in 'Mountain Bikes' started by John Appleby, Sep 23, 2003.

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  1. John Appleby

    John Appleby Guest

    Hi,

    I've just had a nasty blowout at high speed which has left my front rim in shreds. My front
    V-brakes, M950 XTR, are shot (seem to have fallen apart inside). Oh, and my old Pace RC-30 forks are
    succumbing to rust.

    So, I'm considering replacing them with a pair of RC-31s. Carbon doesn't rust...

    The question that remains, and which I'm unsure of, is what to do with the brakes and wheel. I have
    basically two options, I think:

    1) Buy RC-31s with V-brake adapters (£30 more expensive), replace the V-brakes with new ones and
    rebuild the wheel with a new rim.

    2) Buy RC-31s without the V-brake adapters, replace the wheel with a disk brake hub and put a
    mechanical disk brake on. The Avid Ball Bearing one looks nice.

    I'm wondering though whether or not this is likely to be substantially better than the V-brakes. I'm
    not really minded to put a hydraulic disk brake on, because I'm running XTR M951 brake/shifter
    combos which I'm rather partial to. As far as I know, you need the dedicated brake levers on a
    hydraulic shifter.

    The cost is going to be approximately the same (£30-50 more for the disk brake), the weight is
    approximately the same (V-brake adapters for the RC-30 weigh about the same as the weight penalty of
    the disk), so I think the only question is whether or not the mechanical disk is going to be
    substantially better than the V-brake? Oh, and potentially whether the Avid brake will work with the
    M951 lever?

    As an aside, 160mm vs 185mm - is the 185mm necessary? Or just designed for people who are constantly
    on the brakes for DH purposes. I mean, I like going down hills, but I also like going up them...

    Thanks in advamce,

    John
     
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  2. "John Appleby" <[email protected]> wrote in message
    news:[email protected]...
    > Hi,
    >
    > I've just had a nasty blowout at high speed which has left my front rim in shreds. My front
    > V-brakes, M950 XTR, are shot (seem to have fallen apart inside). Oh, and my old Pace RC-30 forks
    > are succumbing to rust.

    John - If you're binning the XTR V's could I trouble you for a spare part? Been looking for the
    thingie that meshes with the wotsit for a good few years without success, no-one seems able to order
    it and its a shame to see the brakes sat doing nothing for want of thingie. Its a round bit that
    sits next to the brake stud and has 6 or so 'teeth'. No problem if you're keeping the brakes as
    spares - just thought I'd ask.

    > So, I'm considering replacing them with a pair of RC-31s. Carbon doesn't rust...

    I owned a pair of these for about 3 months, very nice looking (and nice to ride for the limited
    riding I did on them) but the carbon made me nervous.

    <Snip>

    > I'm wondering though whether or not this is likely to be substantially better than the V-brakes.

    Probably not much difference in overall stopping power but the advantages are with the discs
    reliability as well as increased mud and tyre clearance. I'd vote disc.

    > I'm not really minded to put a hydraulic disk brake on, because I'm running XTR M951 brake/shifter
    > combos which I'm
    rather
    > partial to. As far as I know, you need the dedicated brake levers on a hydraulic shifter.

    Yep. Fair enough.

    > As an aside, 160mm vs 185mm - is the 185mm necessary? Or just designed for people who are
    > constantly on the brakes for DH purposes. I mean, I like going down hills, but I also like going
    > up them...

    I am perfectly happy running a 165mm rotor on both my bikes, but I am not the heaviest bloke in the
    world and I don't drag the brake all the time. As for the Disc/Q.R. issue - I'm not going there...

    > Thanks in advamce, John

    Steve
     
  3. John Appleby wrote:
    > Hi,
    >
    > The cost is going to be approximately the same (£30-50 more for the disk brake), the weight is
    > approximately the same (V-brake adapters for the RC-30 weigh about the same as the weight penalty
    > of the disk), so I think the only question is whether or not the mechanical disk is going to be
    > substantially better than the V-brake? Oh, and potentially whether the Avid brake will work with
    > the M951 lever?
    >
    > As an aside, 160mm vs 185mm - is the 185mm necessary? Or just designed for people who are
    > constantly on the brakes for DH purposes. I mean, I like going down hills, but I also like going
    > up them...
    >
    > Thanks in advamce,
    >
    > John
    >
    >

    Mr. Appleby, I don't think that anyone can tell you that the Avids are substantianlly better than
    V's, that is probably a matter of opinion. I can tell you this, I recently made the switch from
    V's to Avid mechanicals and for my application I like the Avids better. It was not an issues of
    braking power for me, but loss of power and feel on long downhills. It is not uncommon here to
    have a 3-5 mile downhill with constant braking. I felt the V pads became soft and hot and had
    some loss of control. I do not get that feeling with the Avids (160 mm rotors). They may get
    hot, but the feel of the brake is the same at mile one as it is at mile 5. Plus, I will move the
    old V's to my fully rigid bike and replace the cantis (I like the cantis, but are more difficult
    to set up), so it is no real loss. BTW, you can always replace the Avids on the front wheel and
    see how you like that before you fully commit. Good luck.
    --
    Craig Brossman, Durango Colorado (remove ".nospam" to reply)
     
  4. Philthy

    Philthy Guest

    > 2) Buy RC-31s without the V-brake adapters, replace the wheel with a disk brake hub and put a
    > mechanical disk brake on. The Avid Ball Bearing one looks nice.
    Avid Mech disks are by far the best mech disk (Not juts my opinion user and mag reviews seem to
    think the same) , they have very good stopping power once bedded in. For me they perform far better
    than the V's they replaced. Set up is easy due to the fact that they have a system for compensating
    for badly faced mounts, fit and forget as long as you use a good set of cables. As for price I
    bought both of mine from
    http://www.chainreactioncycles.com/viewproduct.asp?category=Brakes+Disc&ModelID=2617 The don't come
    in a box as they appear to be ex OEM, but since the real retail is supposed to be 40 quid more each,
    who cares. always get nice next day delivery from Chainreaction too no bother.

    > As an aside, 160mm vs 185mm - is the 185mm necessary? Or just designed for people who are
    > constantly on the brakes for DH purposes. I mean, I like going down hills, but I also like going
    > up them...

    I stuck with the 160 as I vary between 11.5 and 12 stone depending on how much cake and Chocolate I
    can eat ;-) No bother stopping at all.

    Phil
     
  5. David Kunz

    David Kunz Guest

    John Appleby wrote:

    > Hi,
    >
    > I've just had a nasty blowout at high speed which has left my front rim in shreds. My front
    > V-brakes, M950 XTR, are shot (seem to have fallen apart inside). Oh, and my old Pace RC-30 forks
    > are succumbing to rust.
    >
    > So, I'm considering replacing them with a pair of RC-31s. Carbon doesn't rust...
    >
    > The question that remains, and which I'm unsure of, is what to do with the brakes and wheel. I
    > have basically two options, I think:
    ...
    > 2) Buy RC-31s without the V-brake adapters, replace the wheel with a disk brake hub and put a
    > mechanical disk brake on. The Avid Ball Bearing one looks nice.

    I have Hayes mechanicals with XTR integrated shifter/V-levers -- for a similar reason. These work
    great. Not considerably better at normal braking than Vs; but mud, wet, and long downhills are
    dramtically improved. I've heard and read enough good stuff about Avid's that I'd expect the same.

    The down side is that you'll have disc in the front and V in the rear. Many claim that this is not
    problem. I did it for a while and found that it wasn't a problem, but it was annoying -- I couldn't
    get the balance between front and back braking as well as when the brakes were the same. Within 3
    or 4 months, I had a new rear hub and another Hayes mechanical as father's day and birthday
    presents :).

    > As an aside, 160mm vs 185mm - is the 185mm necessary? Or just designed for people who are
    > constantly on the brakes for DH purposes. I mean, I like going down hills, but I also like going
    > up them...

    I'm pretty sure that the 185 is for downhill. The only times that I'm even remotely worried is
    when I'm hauling down a steep mountain road (on the way home :)) and I come around a bend and
    find a car driven by a little wizzened old lady/man, hugging the steering wheel for dear life,
    going 10 MPH... :)

    David
     
  6. Sdc

    Sdc Guest

    "John Appleby" <[email protected]> wrote in message
    news:[email protected]...
    > Hi,
    >
    > 2) Buy RC-31s without the V-brake adapters, replace the wheel with a disk brake hub and put a
    > mechanical disk brake on. The Avid Ball Bearing one looks nice.
    >
    I just bought 160 mm avid mech's to replace avid v's that I will use with my existing LX levers. I
    should be riding them by the weekend after next I hope. I'll let you know...oh I am keeping my v's
    on the back.

    I think that normally the v-brake stopping power is fine and 160mm is definately ok for x-coutry.
    Disks must be nice for the UK weather, no? especially in the fall, winter and spring....and summer
    too I guess.

    I never felt the need for disks but I'm getting a great deal on the brakes and wheel and I hope to
    ride more over the upcoming wet and muddy months. Maybe get something other than XTR v-brakes? it
    doesn't surprise me to see flimsy, overpriced XTR stuff breaking down. I have el cheapo avid v's
    that I never had trouble with.

    SDC
     
  7. Andy Chequer

    Andy Chequer Guest

    > Carbon doesn't rust...

    Steel doesn't delaminate.....

    Andy Chequer just a thought
     
  8. John Appleby

    John Appleby Guest

    > John - If you're binning the XTR V's could I trouble you for a spare part? Been looking for the
    > thingie that meshes with the wotsit for a good few years without success, no-one seems able to
    > order it and its a shame to
    see
    > the brakes sat doing nothing for want of thingie. Its a round bit that
    sits
    > next to the brake stud and has 6 or so 'teeth'. No problem if you're
    keeping
    > the brakes as spares - just thought I'd ask.

    I think that's the part that's broken. It fell off the inner piece some time back and I can't get it
    to mesh back correctly (I have to bolt it on very carefully). As a result one half of the brake is
    pulling harder than the other and I have to compensate with the screws. The brakes aren't pulling
    together quite as well as they should as a result and so braking power is reduced, plus pads wear
    too much on one side.

    > > So, I'm considering replacing them with a pair of RC-31s. Carbon doesn't rust...
    >
    > I owned a pair of these for about 3 months, very nice looking (and nice to ride for the limited
    > riding I did on them) but the carbon made me nervous.

    Well I've been riding a Trek 9900 carbon frame for coming on 7 years now. I'm past the point of
    nervous there i guess :)

    > I am perfectly happy running a 165mm rotor on both my bikes, but I am not the heaviest bloke in
    > the world and I don't drag the brake all the time.
    As
    > for the Disc/Q.R. issue - I'm not going there...

    Yeah hmm I'm left wondering whether the increased power of a correctly setup V-brake might actually
    be all I need. I don't have a problem with clearance and I've never had a problem with fading on
    the XTR pads.

    The only problem is on the rear where I need a booster to stop frame flex, but since my frame won't
    take a disc brake on the rear anyhow, I'm not sure if I'll bother.

    Thanks for the reply, it's given me food for thought.

    Regards,

    John
     
  9. John Appleby

    John Appleby Guest

    > I just bought 160 mm avid mech's to replace avid v's that I will use with
    my
    > existing LX levers. I should be riding them by the weekend after next I hope. I'll let you
    > know...oh I am keeping my v's on the back.

    Your feedback would be interesting. I shan't be buying just yet, because I have spent too much on my
    bike already this month :)

    > I think that normally the v-brake stopping power is fine and 160mm is definately ok for x-coutry.
    > Disks must be nice for the UK weather, no? especially in the fall, winter and spring....and summer
    > too I guess.

    Perhaps; I've never found a problem with V-Brakes myself. I find it's mostly a question of picking
    the right tyres for the conditions.

    > I never felt the need for disks but I'm getting a great deal on the brakes and wheel and I hope to
    > ride more over the upcoming wet and muddy months. Maybe get something other than XTR v-brakes? it
    > doesn't surprise me to
    see
    > flimsy, overpriced XTR stuff breaking down. I have el cheapo avid v's
    that
    > I never had trouble with.

    Well to be fair, they are the original M950s from when they first came out in 1996 (I think, or was
    it early 1997). Anyhow, I can't complain.

    I've not got a bad word to say against XTR; I've got some M900, some M950 and some M960. Some 1994
    M900 hubs that have never been serviced and still run sweet as anything. The only question in my
    mind is this new Hollowform II crankset. I can't really be dealing with £75 for an outer ring when
    I can buy a full RaceFace set for £65. Plus the reported poor BB bearing life in early models. But
    then I always did think that Shimano were a ripoff on the chainset. So I bought the RaceFace
    turbine set and I'm very happy with it so far. Moreover, ISIS looks like it's a good technology
    that's here to stay.

    Regards,

    John
     
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