Rear deraillers

Quoted message said:

There's also the possibility you're considering putting a megarange
cassette on, which won't work with some mechs because of the large jump to
the lowest cog, but I'm speculating now.

If you specify manufacturer and model of mech, you may find someone has
some specific experience which may help you.

The Alivio rear mech works OK with a megarange cassette. It never ceases to
amaze me how the mech copes with the big jump though recently I've rarely
used the megarange sprocket must be a sign that i'm fitter.

Neil Smith said:

Dear All,
is a rear mech likely to burst apart if it is used on to large a
freewheel. Specifically, if the top spec for the mech is 30t and the
freewheel goes up to 32 or 34t

You can break a rear mech if the chain is too short to go around both
big cogs and you try and change into that gear combination, but the
scenario you're proposing has got a lot of uncertain variables. Some
manufacturers go for safe specs so they can be used beyond them if you
don't care about warranty. If you're considering putting a bigger than
spec cassette on, also consider lengthening the chain (or getting a new
one if you're changing it because it's worn out). There's also the
possibility you're considering putting a megarange cassette on, which
won't work with some mechs because of the large jump to the lowest cog,
but I'm speculating now.

If you specify manufacturer and model of mech, you may find someone has
some specific experience which may help you.

JimP

--
Let's think the unthinkable, let's do the undoable, let's prepare to
grapple with the ineffable itself, and see if we may not eff it after
all. - DNA

Jim Price said:

If you're considering putting a bigger than
spec cassette on, also consider lengthening the chain (or getting a
new one if you're changing it because it's worn out).

Neil, A longer chain may not be necessary if the existing chain happens
to be longer than necessary for the existing gears (common). In fact the
shorter the chain, the more the mech will be pulled away from the
sprockets. So when pushing the mech's specifications, have the chain as
short as possible to work with the largest chainring + largest rear cog
combination*. Also adjust the b-tension screw to taste (see
www.sheldonbrown.com)

* Doesn't matter if performance in this gear is [censored] because chain is on
the short side, just as long as it's selectable without busting anything,
in case you ever select it by accident. The manufacturers expect you to
use a slightly longer chain than this, and also to be able to use the
small-small combination, hence the conservative specs they come out with.
+2 a couple of teeth is doable.

~PB

vernon levy said:

Quoted message said:

There's also the possibility you're considering putting a megarange
cassette on, which won't work with some mechs because of the large jump to
the lowest cog, but I'm speculating now.

If you specify manufacturer and model of mech, you may find someone has
some specific experience which may help you.

The Alivio rear mech works OK with a megarange cassette. It never ceases to
amaze me how the mech copes with the big jump though recently I've rarely
used the megarange sprocket must be a sign that i'm fitter.

Current Alivio yes. Ancient Shimano stuff scrapes against 1st gear when
in second. I can't stand the enormous jump myself.

Fitness wise, I'm suffering at the moment because my teeth need fixing
(appointment booked but not for ages) and a bike ride makes it worse.

JimP

--
Let's think the unthinkable, let's do the undoable, let's prepare to
grapple with the ineffable itself, and see if we may not eff it after
all. - DNA

Neil Smith said:

Dear All,
is a rear mech likely to burst apart if it is used on to large a
freewheel. Specifically, if the top spec for the mech is 30t and the
freewheel goes up to 32 or 34t
Thanks
Neil

They usually cope with a little more than specified. 2T should be OK,
but you'll have to adjust the B-tension screw carefully to ensure the
top jockey doesn't bump on the largest sprocket.

It is Shimano Alvio and the range 13-32t
"Zog The Undeniable" <[email hidden]> wrote in message
news:4470196a.0@entanet...

Quoted message said:

Neil Smith said:

Dear All,
is a rear mech likely to burst apart if it is used on to large a
freewheel. Specifically, if the top spec for the mech is 30t and the
freewheel goes up to 32 or 34t
Thanks
Neil

They usually cope with a little more than specified. 2T should be OK, but
you'll have to adjust the B-tension screw carefully to ensure the top
jockey doesn't bump on the largest sprocket.

In article <4470196a.0@entanet>, Zog The Undeniable (hrothgar19

@yahoo.com) said:

Neil Smith said:

Dear All,
is a rear mech likely to burst apart if it is used on to large a
freewheel. Specifically, if the top spec for the mech is 30t and the
freewheel goes up to 32 or 34t
Thanks
Neil

They usually cope with a little more than specified. 2T should be OK,
but you'll have to adjust the B-tension screw carefully to ensure the
top jockey doesn't bump on the largest sprocket.

If it still does, take the B-tension screw out and re-insert it at the
other end of its hole. This provides a bit more B-tension (whatever
that may be) and ought to prevent unwanted chain/cassette
fraternisation.

--
Dave Larrington - <http://www.legslarry.beerdrinkers.co.uk/>
Never trust a man with more than one moustache.