Changing Cassette

[Ian]

I have been following the thread about the gears, however it went all over
the place.

Anyway my question is, if I change my cassette from a 12 - 25 to a 12 - 27,
will it cause any problems with smooth changing.
Is it just a simple changeover that won't cause any other problems ?

Ian

 

[ritcho]

I have been following the thread about the gears, however it went all over
the place.

Anyway my question is, if I change my cassette from a 12 - 25 to a 12 - 27,
will it cause any problems with smooth changing.
Is it just a simple changeover that won't cause any other problems ?

Ian

It should change fine. The only concern is whether your chain is long enough. A 27T rear cog takes up more chain. If the chain is not long enough, it will destroy your rear derailer. Check to ensure there is just enough chain in the big-big combination and you'll be fine. Not that you'll ever want to use the big-big combo, but it's nice to have enough chain to prevent yourself from accidentally wrecking your derailer.

Cheers,
Ritch

 

[adam]

"Ian" <[email protected]> wrote in message
news:[email protected]...
>I have been following the thread about the gears, however it went all over
> the place.
>
> Anyway my question is, if I change my cassette from a 12 - 25 to a 12 -
> 27,
> will it cause any problems with smooth changing.

Nope, just check the chain is long enough but you should be ok. Check out:
http://www.sheldonbrown.com/derailer-adjustment.html#chain

> Is it just a simple changeover that won't cause any other problems ?

Yep

Adam

 

[Geoff]

"Ian" <[email protected]> wrote in message
news:[email protected]...
>I have been following the thread about the gears, however it went all over
> the place.
>
> Anyway my question is, if I change my cassette from a 12 - 25 to a 12 -
> 27,
> will it cause any problems with smooth changing.
> Is it just a simple changeover that won't cause any other problems ?
>
> Ian
>
>

Shouldn't be a problem. Assuming you are running a double on the front and
a standard short cage derailleur. You may need a small adjustment to the
rear mech to stop it from hitting the bigger 27T sprocket and depending on
your current chain length you might need to add a couple of links.
Personally I've only had experience changing between cassettes with a 19T,
23T or 25T top end but I know a couple of people that run a 27T with a short
cage. Anything bigger than a 27T may need a different derailleur with a
longer cage.

Flyingdutch may be able to give you a better qualified answer when it comes
to the jump from 25T to 27T but I think he's currently running a long cage
derailleur.

Geoff

 

[stu]

"Ian" <[email protected]> wrote in message
news:[email protected]...
> I have been following the thread about the gears, however it went all over
> the place.
>
> Anyway my question is, if I change my cassette from a 12 - 25 to a 12 -
27,
> will it cause any problems with smooth changing.
> Is it just a simple changeover that won't cause any other problems ?
>
> Ian
its a simple enough changeover if you have the tools.
its is a cassette right??? http://www.sheldonbrown.com/free-k7.html
the 2 biggest worries i can think of are, how old is the chain? it might be
to worn to fit a new cassette.
if it isn't worn, is the chain long enough to go big-big?
http://www.sheldonbrown.com/derailer-adjustment.html#chain
hope this helps

stu

 

[Random Data]

"Geoff" <[email protected]> wrote in message news:<[email protected]>...

> Anything bigger than a 27T may need a different derailleur with a
> longer cage.

I've run either a 12-32 or an 11-30 cluster with an XT short cage, and
been able to use 22/32/42 chainrings with it. You can't go big-big and
still have usable tension in the lower gears, but unless you're really
mashing the shifter you can feel that the derailleur doesn't want to
go into a gear, and stop before you break it.

However, the XT short cage may have been the equivalent of a road
"medium cage". It's been so long since that derailleur went to the
parts bin I can't remember just how long the cage was.

Dave - who had about a year span of breaking a derailleur between
every 4 and 6 weeks. That was expensive.

 

[Marty]

Random Data wrote:
> "Geoff" <[email protected]> wrote in message news:<[email protected]>...
>
>
>>Anything bigger than a 27T may need a different derailleur with a
>>longer cage.
>
>
> I've run either a 12-32 or an 11-30 cluster with an XT short cage, and
> been able to use 22/32/42 chainrings with it. You can't go big-big and
> still have usable tension in the lower gears, but unless you're really
> mashing the shifter you can feel that the derailleur doesn't want to
> go into a gear, and stop before you break it.
>
> However, the XT short cage may have been the equivalent of a road
> "medium cage". It's been so long since that derailleur went to the
> parts bin I can't remember just how long the cage was.
>
> Dave - who had about a year span of breaking a derailleur between
> every 4 and 6 weeks. That was expensive.

The instructions that come with Shimano derailluers tell you what sort
of gear sizes you can run. There's a little formula you have to work it
out.

I also had a bad run on derailluers and have a box with three brand new
ones on standby. Yes it is expensive. Since getting the spares a few
months ago I haven't had any failures, Touch Wood! (Touches head).

Marty

 

[Ian]

Thanks guys , much appreciatted.
"stu" <[email protected]> wrote in message
news:[email protected]...
>
> "Ian" <[email protected]> wrote in message
> news:[email protected]...
> > I have been following the thread about the gears, however it went all
over
> > the place.
> >
> > Anyway my question is, if I change my cassette from a 12 - 25 to a 12 -
> 27,
> > will it cause any problems with smooth changing.
> > Is it just a simple changeover that won't cause any other problems ?
> >
> > Ian
> its a simple enough changeover if you have the tools.
> its is a cassette right??? http://www.sheldonbrown.com/free-k7.html
> the 2 biggest worries i can think of are, how old is the chain? it might
be
> to worn to fit a new cassette.
> if it isn't worn, is the chain long enough to go big-big?
> http://www.sheldonbrown.com/derailer-adjustment.html#chain
> hope this helps
>
> stu
>
>