Replacing cantilevers with v-brakes

[chrisg]

We have an old tandem with mafac type cantilevers. They don't have any
toe-in adjustment on them and it is impossible to get one of the front
pads anywhere near parallel to the rim let alone toed-in properly.
Maybe the boss is slightly skewed although it looks ok.

As I have a spare pair of V-brakes (and lever) I tried fitting them.
The problem is that the pin holes on the bosses where the spring is
inserted seem to be in the wrong position for the v-brakes. Once the
spring has been inserted into the hole the brake has to rotated
through 270 degrees to get it vertical which is impossible. (Looking
from the front the hole is at 9 o'clock position on the left hand fork
and 3 o'clock on the right. The v-brakes have the spring pin at 6
o'clock position).

Has anyone come across this problem? Any suggestions?

 

[Paul Boyd]

chrisg said the following on 30/08/2007 16:22:

> Looking
> from the front the hole is at 9 o'clock position on the left hand fork
> and 3 o'clock on the right. The v-brakes have the spring pin at 6
> o'clock position).

That sounds wrong! The holes should be on the wheel side of the
mounting (inside the fork) rather than outside, which is what it sounds
like you're saying. If the holes really are on the outside, then the
bosses have been fitted incorrectly. V's and cantis should be
interchangeable - I changed to Vs from cantis not so long ago and it was
just a bolt-on job.

--
Paul Boyd
http://www.paul-boyd.co.uk/

 

[chrisg]

On 30 Aug, 16:48, Paul Boyd <usenet.is.worse@plusnet> wrote:
> chrisg said the following on 30/08/2007 16:22:
>
> > Looking
> > from the front the hole is at 9 o'clock position on the left hand fork
> > and 3 o'clock on the right. The v-brakes have the spring pin at 6
> > o'clock position).
>
> That sounds wrong! The holes should be on the wheel side of the
> mounting (inside the fork) rather than outside, which is what it sounds
> like you're saying. If the holes really are on the outside, then the
> bosses have been fitted incorrectly. V's and cantis should be
> interchangeable - I changed to Vs from cantis not so long ago and it was
> just a bolt-on job.
>
> --
> Paul Boydhttp://www.paul-boyd.co.uk/

Yes, the holes are on the outside but are obviously in the correct
position for the mafacs.

It is quite an old tandem, I guess 20-25 years old. Maybe things have
standardised more since then.

Chris

 

[PDannyD]

chrisg wrote:

> As I have a spare pair of V-brakes (and lever) I tried fitting them.
> The problem is that the pin holes on the bosses where the spring is
> inserted seem to be in the wrong position for the v-brakes. Once the
> spring has been inserted into the hole the brake has to rotated
> through 270 degrees to get it vertical which is impossible.

Can you swap the springs around on the V-brakes?

 

[Rob Morley]

In article <[email protected]>,
chrisg
[email protected] says...
> We have an old tandem with mafac type cantilevers. They don't have any
> toe-in adjustment on them and it is impossible to get one of the front
> pads anywhere near parallel to the rim let alone toed-in properly.
> Maybe the boss is slightly skewed although it looks ok.

To toe in Mafacs, place a large screwdriver or similar bar between the
two plates and tweak. Brutal, but it usually works.
>
> As I have a spare pair of V-brakes (and lever) I tried fitting them.
> The problem is that the pin holes on the bosses where the spring is
> inserted seem to be in the wrong position for the v-brakes. Once the
> spring has been inserted into the hole the brake has to rotated
> through 270 degrees to get it vertical which is impossible. (Looking
> from the front the hole is at 9 o'clock position on the left hand fork
> and 3 o'clock on the right. The v-brakes have the spring pin at 6
> o'clock position).
>
> Has anyone come across this problem? Any suggestions?
>
Sounds strange to me - as if the bosses are on the wrong sides. You
might be able to remove the adjusting plates from the brakes and drill
new spring anchor holes in a more appropriate position.

 

[chrisg]

On 31 Aug, 09:44, PDannyD <[email protected]> wrote:
> chrisg wrote:
> > As I have a spare pair of V-brakes (and lever) I tried fitting them.
> > The problem is that the pin holes on the bosses where the spring is
> > inserted seem to be in the wrong position for the v-brakes. Once the
> > spring has been inserted into the hole the brake has to rotated
> > through 270 degrees to get it vertical which is impossible.
>
> Can you swap the springs around on the V-brakes?

The spring prongs are at 12 o'clock (inside) and 6 o'clock (outside)
so swapping or rotating isn't possible.

Chris

 

[chrisg]

On 31 Aug, 11:13, Rob Morley <[email protected]> wrote:
> In article <[email protected]>,
> chrisg
> [email protected] says...
>
> > We have an old tandem with mafac type cantilevers. They don't have any
> > toe-in adjustment on them and it is impossible to get one of the front
> > pads anywhere near parallel to the rim let alone toed-in properly.
> > Maybe the boss is slightly skewed although it looks ok.
>
> To toe in Mafacs, place a large screwdriver or similar bar between the
> two plates and tweak. Brutal, but it usually works.
>
> > As I have a spare pair of V-brakes (and lever) I tried fitting them.
> > The problem is that the pin holes on the bosses where the spring is
> > inserted seem to be in the wrong position for the v-brakes. Once the
> > spring has been inserted into the hole the brake has to rotated
> > through 270 degrees to get it vertical which is impossible. (Looking
> > from the front the hole is at 9 o'clock position on the left hand fork
> > and 3 o'clock on the right. The v-brakes have the spring pin at 6
> > o'clock position).
>
> > Has anyone come across this problem? Any suggestions?
>
> Sounds strange to me - as if the bosses are on the wrong sides. You
> might be able to remove the adjusting plates from the brakes and drill
> new spring anchor holes in a more appropriate position.

Good idea - if I can find a small enough drill bit I'll give it a go.

Cheers,

Chris