V-Brake bosses differences?

[f.c...@gmail.com]

Hello,
today I tried to replace my old, no-brand V-brakes with the latest
Deore Lx v-brakes (BR-M580).
I found out that the bosses on the frame are too short for the new
brakes. While the width is perfect, the length is a few millimeters
shorter. Actually, if I compare the old v-brakes with the new, the new
ones are a few millimeters thicker.

My frame is a few years old and I think it was designed for cantilever
brakes (it has the cable stop in the rear triangle).
Are cantilever bosses slightly different from v-brake bosses?
Or do new Shimano v-brakes require special bosses?

Thanks in advance,
Federico

[othyj...@gmail.com]

No, no, and no. You should just install those brakes and ride. Canti
and V bosses are the same thing, they even mount the same distance
from the axle. Minor changes in modles od brake may look slightly
diffrent, but they still function the same.
-Tim

[Chalo]

f.c...@gmail.com wrote:
>
> today I tried to replace my old, no-brand V-brakes with the latest
> Deore Lx v-brakes (BR-M580).
> I found out that the bosses on the frame are too short for the new
> brakes. While the width is perfect, the length is a few millimeters
> shorter. Actually, if I compare the old v-brakes with the new, the new
> ones are a few millimeters thicker.

I don't know about the particulars of your brakes, but many
parallelogram-pivot linear-pull brakes don't pivot on the boss itself,
instead having a bushing pivot built into the brake. The inner bushing
components must be longer than the brake bosses so that they will be
fixed in place by the pivot bolts.

Chalo Colina

[Zog The Undeniable]

f.c...@gmail.com wrote:

In theory they should be the same, but I've also had tolerance issues
where the boss has been too short, causing the brake to bind when the
bolt is fully tightened.

Are the bosses on your frame removable? Many are.

[Michael Press]

In article
<1140388946.3...@g44g2000cwa.googlegroups.com>,
"othyj...@gmail.com" <othyj...@gmail.com> wrote:

What are you talking about?

--
Michael Press

[A Muzi]

f.c...@gmail.com wrote:

I'm not sure I understand the problem but there are two
common compaints on installing linear brakes:
1. If the brake shoe is so long as to interfere with
clearance between rim and fork blade, simply cut off the
back edge of the brake shoe. (Braking effectiveness is all
about swept area, puck size is virtually irrelevant)
2. If your brakes still stick way out to the side when they
hit the rim, look closer at the brake pad spacers. There are
both thick and thin spacers supplied - simply reverse them
so the big one is outside the arm.

If it is some other variant please write again.
--
Andrew Muzi
www.yellowjersey.org
Open every day since 1 April, 1971

[Nate Knutson]

Like Chalo, I don't know about these brakes, but what he suggests is
almost certainly what's going on. Many cantis and v-brakes, especially
cheaper and/or older ones, have one bushing per brake arm and it pivots
on the boss itself, with the pivot bolt holding the arm in place by
bottoming out on the end of the boss. Other cantis and v-brakes have a
center pivot piece that sticks out past the end of the post and is
secured in place by the pivot bolt tightening against it, and then a
bushing that pivots around that. This is better because it allows the
brake maker more control over sealing, slop, etc. It also eliminates
the risk of mushrooming the end of a canti post by overtightening the
pivot bolt, which is really easy, as well as eliminating the
accompanying issue of an arguable need for using threadlocker and only
a minimal amount of torque on pivot bolts.