replacing center pull brakes with direct pull ones ?

Woland99

Howdy - I am working on friends bike - it is an old MTB with center
pull brakes.
Old brakes seem serviceable. Should I attempt to put direct pull
brakes on it?
What are advantages of such move (if any)? If I understand Sheldon
correctly
I would need new set of levers too?

M-gineering

Woland99 wrote:
> Howdy - I am working on friends bike - it is an old MTB with center
> pull brakes. > Old brakes seem serviceable. Should I attempt to put direct pull
> brakes on it? What are advantages of such move (if any)? If I understand Sheldon
> correctly I would need new set of levers too?

you would need a new frame too, as the pivots are in the wrong place (u
brake pivots are above the rim, V-brake pivots below. Diameter can be
different too)


--
/Marten

info(apestaartje)m-gineering(punt)nl

Woland99

On Jun 20, 1:06 am, M-gineering <ikmotgeens...@m-gineering.nl> wrote:
> Woland99 wrote:
> > Howdy - I am working on friends bike - it is an old MTB with center
> > pull brakes. > Old brakes seem serviceable. Should I attempt to put direct pull
> > brakes on it? What are advantages of such move (if any)? If I understand Sheldon
> > correctly I would need new set of levers too?
>
> you would need a new frame too, as the pivots are in the wrong place (u
> brake pivots are above the rim, V-brake pivots below. Diameter can be
> different too)
>
> --
> /Marten
>
> info(apestaartje)m-gineering(punt)nl

Hmmm... orginal brakes are traditional center pull - not u-brakes
so pivots are below the rims - just like in v-brakes. But i did
not check diameters yet - I assumed those were standarized.

M-gineering

Woland99 wrote:
> On Jun 20, 1:06 am, M-gineering <ikmotgeens...@m-gineering.nl> wrote:
>> Woland99 wrote:
>>> Howdy - I am working on friends bike - it is an old MTB with center
>>> pull brakes. > Old brakes seem serviceable. Should I attempt to put direct pull
>>> brakes on it? What are advantages of such move (if any)? If I understand Sheldon
>>> correctly I would need new set of levers too?
>> you would need a new frame too, as the pivots are in the wrong place (u
>> brake pivots are above the rim, V-brake pivots below. Diameter can be
>> different too)
>>
>> --
>> /Marten
>>
>> info(apestaartje)m-gineering(punt)nl
>
> Hmmm... orginal brakes are traditional center pull - not u-brakes
> so pivots are below the rims - just like in v-brakes. But i did
> not check diameters yet - I assumed those were standarized.


Ah, semantics. It's more usual to call them cantilevers. These are
interchangable

--
/Marten

info(apestaartje)m-gineering(punt)nl

Colin MacDonald

On 20 Jun, 06:12, Woland99 <wolan...@gmail.com> wrote:
> Howdy - I am working on friends bike - it is an old MTB with center
> pull brakes.
> Old brakes seem serviceable. Should I attempt to put direct pull
> brakes on it?
> What are advantages of such move (if any)? *If I understand Sheldon
> correctly
> I would need new set of levers too?

If the existing brakes work then there's no really good reason to
change them - cantilever brakes are fine for most situations. But if
you do change the brakes then yes, you will need to change the levers
as well.

Colin

jim beam

Colin MacDonald wrote:
> On 20 Jun, 06:12, Woland99 <wolan...@gmail.com> wrote:
>> Howdy - I am working on friends bike - it is an old MTB with center
>> pull brakes.
>> Old brakes seem serviceable. Should I attempt to put direct pull
>> brakes on it?
>> What are advantages of such move (if any)? �If I understand Sheldon
>> correctly
>> I would need new set of levers too?
>
> If the existing brakes work then there's no really good reason to
> change them - cantilever brakes are fine for most situations. But if
> you do change the brakes then yes, you will need to change the levers
> as well.

not necessarily - depends on whether they're mtb direct pulls, or road.
they have different leverage ratios.

Woland99

On Jun 20, 8:30 am, jim beam <spamvor...@bad.example.net> wrote:
> Colin MacDonald wrote:
> > On 20 Jun, 06:12, Woland99 <wolan...@gmail.com> wrote:
> >> Howdy - I am working on friends bike - it is an old MTB with center
> >> pull brakes.
> >> Old brakes seem serviceable. Should I attempt to put direct pull
> >> brakes on it?
> >> What are advantages of such move (if any)? �If I understand Sheldon
> >> correctly
> >> I would need new set of levers too?
>
> > If the existing brakes work then there's no really good reason to
> > change them - cantilever brakes are fine for most situations. But if
> > you do change the brakes then yes, you will need to change the levers
> > as well.
>
> not necessarily - depends on whether they're mtb direct pulls, or road.
> they have different leverage ratios.

OK - I should have said "replacing cantilever brakes with direct
pull ones". The reason I thought about doing it is that my friend
was complaining that old brakes did not work very well.
Do I understand it correctly that you can exert more force on rims
using direct pull brakes?

I think that the new ones I got are MTB direct pulls. These are
Avid Single Digit 5.

Booker Bense

In article <f9d4aa2b-1769-43ec-aa16-237ef2e03e44@e53g2000hsa.googlegroups.com>,
Woland99 <woland99@gmail.com> wrote:
>On Jun 20, 8:30 am, jim beam <spamvor...@bad.example.net> wrote:
>> Colin MacDonald wrote:
>> they have different leverage ratios.
>
>OK - I should have said "replacing cantilever brakes with direct
>pull ones". The reason I thought about doing it is that my friend
>was complaining that old brakes did not work very well.

Cantilever brakes take more work to setup properly, but once
that's done they work as well as any in my experience. See
Sheldon Brown's page on cantilever brakes.

>Do I understand it correctly that you can exert more force on rims
>using direct pull brakes?

No, they are just a lot easier to setup.

_ Booker C. Bense

Werehatrack

On Thu, 19 Jun 2008 22:12:18 -0700 (PDT), Woland99
<woland99@gmail.com> may have said:

>Howdy - I am working on friends bike - it is an old MTB with center
>pull brakes.
>Old brakes seem serviceable. Should I attempt to put direct pull
>brakes on it?
>What are advantages of such move (if any)? If I understand Sheldon
>correctly
>I would need new set of levers too?

It's very likely that a new set of pads and a little attention to
adjustment will make the existing brakes as effective as they need to
be. Although you can mount direct-pull brakes in place of cantis,
unless you replace the levers at the same time, you'll find that the
brake adjustment gets very touchy, the need for proper wheel truing
gets even more critical, the hand lever travel gets quite long, and it
may become distressingly easy to unintentionally lock the brakes.

Before doing all that, I'd try swapping to a new set of brake pads.
Make sure that you check the rims for wear first, though. If the bike
has a lot of miles, and the rims are aluminum, then the sidewalls of
the rims may be worn enough that it may be new wheel time. Steel rims
generally don't wear enough to worry about, but braking is nowhere
near as effective in wet conditions with a steel rim, either.

--
My email address is antispammed; pull WEEDS if replying via e-mail.
Typoes are not a bug, they're a feature.
Words processed in a facility that contains nuts.

landotter

On Jun 20, 10:38Â*am, Woland99 <wolan...@gmail.com> wrote:
> On Jun 20, 8:30 am, jim beam <spamvor...@bad.example.net> wrote:
>
>
>
> > Colin MacDonald wrote:
> > > On 20 Jun, 06:12, Woland99 <wolan...@gmail.com> wrote:
> > >> Howdy - I am working on friends bike - it is an old MTB with center
> > >> pull brakes.
> > >> Old brakes seem serviceable. Should I attempt to put direct pull
> > >> brakes on it?
> > >> What are advantages of such move (if any)? �If I understand Sheldon
> > >> correctly
> > >> I would need new set of levers too?
>
> > > If the existing brakes work then there's no really good reason to
> > > change them - cantilever brakes are fine for most situations. Â*But if
> > > you do change the brakes then yes, you will need to change the levers
> > > as well.
>
> > not necessarily - depends on whether they're mtb direct pulls, or road.
> > Â* they have different leverage ratios.
>
> OK - I should have said "replacing cantilever brakes with direct
> pull ones". The reason I thought about doing it is that my friend
> was complaining that old brakes did not work very well.
> Do I understand it correctly that you can exert more force on rims
> using direct pull brakes?

AFAIK, you lose mechanical advantage with cantis as the lever is
pulled towards the handlebars. That said--they can be set up to brake
nicely. The high mechanical advantage of linear pull brakes comes at
the disadvantage of needing to keep the brake pads very close to the
rim and thus the wheels very true.

>
> I think that the new ones I got are MTB direct pulls. These are
> Avid Single Digit 5.

You'll need new levers that pull the appropriate amount of cable.
About $15USD for some decent models by Tektro or a suitable
equivalent.

Tim McNamara

In article
<f9d4aa2b-1769-43ec-aa16-237ef2e03e44@e53g2000hsa.googlegroups.com>,
Woland99 <woland99@gmail.com> wrote:

> On Jun 20, 8:30 am, jim beam <spamvor...@bad.example.net> wrote:
> > Colin MacDonald wrote:
> > > On 20 Jun, 06:12, Woland99 <wolan...@gmail.com> wrote:
> > >> Howdy - I am working on friends bike - it is an old MTB with
> > >> center pull brakes. Old brakes seem serviceable. Should I
> > >> attempt to put direct pull brakes on it? What are advantages of
> > >> such move (if any)? ?If I understand Sheldon correctly I would
> > >> need new set of levers too?
> >
> > > If the existing brakes work then there's no really good reason to
> > > change them - cantilever brakes are fine for most situations.
> > > But if you do change the brakes then yes, you will need to change
> > > the levers as well.
> >
> > not necessarily - depends on whether they're mtb direct pulls, or
> > road. they have different leverage ratios.
>
> OK - I should have said "replacing cantilever brakes with direct pull
> ones". The reason I thought about doing it is that my friend was
> complaining that old brakes did not work very well. Do I understand
> it correctly that you can exert more force on rims using direct pull
> brakes?

That's a definite "maybe." We should all bear in mind that V brakes
were designed manufacturing efficiency- they eliminate the need for a
cable housing stop above the brake, therefore making it easier to build
suspension forks and full suspension mountain bikes. They were not
designed to make braking better. Any benefits for the rider are
accidental. Unfortunately the bike rags didn't understand this and
blathered on about better braking so that it is now part of the lore and
myth of bicycling.

(Other things that fall into the same situation are cassette hubs,
cartridge bottom brackets, threadless headsets- all of which reduce
labor at the factory and save money, allowing greater profit margins or
cheaper price points).

Tom Kunich

"Tim McNamara" <timmcn@bitstream.net> wrote in message
news:timmcn-490191.17031020062008@news.iphouse.com...
>
> (Other things that fall into the same situation are cassette hubs,
> cartridge bottom brackets, threadless headsets- all of which reduce
> labor at the factory and save money, allowing greater profit margins or
> cheaper price points).

Cassette hubs greatly increased the reliability of the rear axles on bike
with more than 7 speeds. Probably even for 7-speed bikes as well. You almost
never see a broken axle any more.

It isn't clear to me how to accept cartridge bottom brackets. Certainly the
lowest quality bearings are better than most of the crappy cone bearings
that were misadjusted most of the time. Though there probably was no
advantage to properly lubricated and adjusted bearings.

As I pointed out - I came off very hard a month ago (first time in 20 years
of riding). Somehow my foot popped out of the inside pedal on a 30 mph
downhill ride and went into the front wheel breaking off the fork. I was in
the hospital all day while they waited to see if I had any symptoms of head
injury - which I didn't.

The next day I recovered my bike from a friend's garage, took it home and in
30 minutes (I had a spare carbon fork) I had totally replaced the fork and
the bike was ready to ride again. I've put in 500 miles on that bike since
then. So while I LIKE the old fashion threaded headsets I can see certain
advantages to a threadless.

jim beam

Tim McNamara wrote:
> In article
> <f9d4aa2b-1769-43ec-aa16-237ef2e03e44@e53g2000hsa.googlegroups.com>,
> Woland99 <woland99@gmail.com> wrote:
>
>> On Jun 20, 8:30 am, jim beam <spamvor...@bad.example.net> wrote:
>>> Colin MacDonald wrote:
>>>> On 20 Jun, 06:12, Woland99 <wolan...@gmail.com> wrote:
>>>>> Howdy - I am working on friends bike - it is an old MTB with
>>>>> center pull brakes. Old brakes seem serviceable. Should I
>>>>> attempt to put direct pull brakes on it? What are advantages of
>>>>> such move (if any)? ?If I understand Sheldon correctly I would
>>>>> need new set of levers too?
>>>> If the existing brakes work then there's no really good reason to
>>>> change them - cantilever brakes are fine for most situations.
>>>> But if you do change the brakes then yes, you will need to change
>>>> the levers as well.
>>> not necessarily - depends on whether they're mtb direct pulls, or
>>> road. they have different leverage ratios.
>> OK - I should have said "replacing cantilever brakes with direct pull
>> ones". The reason I thought about doing it is that my friend was
>> complaining that old brakes did not work very well. Do I understand
>> it correctly that you can exert more force on rims using direct pull
>> brakes?
>
> That's a definite "maybe." We should all bear in mind that V brakes
> were designed manufacturing efficiency- they eliminate the need for a
> cable housing stop above the brake, therefore making it easier to build
> suspension forks and full suspension mountain bikes. They were not
> designed to make braking better. Any benefits for the rider are
> accidental. Unfortunately the bike rags didn't understand this and
> blathered on about better braking so that it is now part of the lore and
> myth of bicycling.

no timmy, you're just mathematically challenged. "linear pull" brakes
are an improvement because the mechanical advantage stays essentially
the same during operation, unlike cantilevers where the m.a. drops. we
went all through this just a few weeks ago.


>
> (Other things that fall into the same situation are cassette hubs,
> cartridge bottom brackets, threadless headsets- all of which reduce
> labor at the factory and save money, allowing greater profit margins or
> cheaper price points).

paranoid bull.

Tom Kunich

"jim beam" <spamvortex@bad.example.net> wrote in message
news4GdnZ9LDJWv-8HVnZ2dnUVZ_tninZ2d@speakeasy.net...
>
> no timmy, you're just mathematically challenged. "linear pull" brakes are
> an improvement because the mechanical advantage stays essentially the same
> during operation, unlike cantilevers where the m.a. drops. we went all
> through this just a few weeks ago.

Cantilevers work so badly I just don't see how anyone ever was able to use
them.