Upgrade Shimano 105 Rear Cassette



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Doug Dempster

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I'm in the process of upgrading my Shimano 105 rear cassette to add some more gear inches. The
original was a 12-24, and I purchased a new 13-34 (as well as a new chain). I also converted from
Ultraglide to Hyperglide. Despite my attempts to get everything adjusted, I can't shift to the 34
ring, and the overall shifting is not clean. Will a longer chain cage help this? Am I just trying to
add too many gear inches?

Thanks for any advice.
 
M

Mike Jacoubowsk

Guest
If you originally had a standard-cage '105 rear derailleur, you're *way* beyond its capabilities
(trying to get it to shift onto a 34t). Even a long-cage '105 will usually have trouble with that,
dependent upon the position of the derailleur hanger.

If you've got a standard-cage derailleur (which is likely, given the gear range of the original
cassette), I'd drop by your LBS and pick up a good-but-inexpensive LX rear derailleur and everything
should work just fine.

--Mike-- Chain Reaction Bicycles http://www.ChainReactionBicycles.com

"Doug Dempster" <[email protected]> wrote in message
news:[email protected]...
> I'm in the process of upgrading my Shimano 105 rear cassette to add some more gear inches. The
> original was a 12-24, and I purchased a new 13-34 (as well as a new chain). I also converted from
> Ultraglide to Hyperglide. Despite my attempts to get everything adjusted, I can't shift to the 34
> ring, and the overall shifting is not clean. Will a longer chain cage help this? Am I just trying
> to add too many gear inches?
>
> Thanks for any advice.
 
M

Mark Boyd

Guest
On Sun, 19 Jan 2003, Doug Dempster wrote:

> I'm in the process of upgrading my Shimano 105 rear cassette to add some more gear inches. The
> original was a 12-24, and I purchased a new 13-34 (as well as a new chain). I also converted from
> Ultraglide to Hyperglide. Despite my attempts to get everything adjusted, I can't shift to the 34
> ring, and the overall shifting is not clean. Will a longer chain cage help this? Am I just trying
> to add too many gear inches?

You need a rear derailleur that will handle a cog that large. Shimano road deraileurs won't do that,
they are rated for 27 tooth biggest cog. I put an 11-30 cassette on a friends road bike and, with
the B screw all the way in, it shifts fine but the derailleur bumps into the cog a little bit on the
30. I'd expect the same problem using a Shimano MTB derailleurs, rated for 32 teeth, with a 34, but
I haven't tried it. Shimano Mega-range derailleurs are rated for 34 tooth biggest cogs and would be
the best solution for you.

It isn't a big deal to switch the rear derailleur since, unlike Shimano front derailleurs, all of
their rear derailleurs use the same amount of cable pull per cog. That means a Mega-range rear
derailleur will work with your 105 shifters.

Mark <http://www.cs.unca.edu/~boyd/bicycling.html
 
G

Grenouil

Guest
"Doug Dempster" <[email protected]> wrote in message
news:[email protected]...
> I'm in the process of upgrading my Shimano 105 rear cassette to add some more gear inches. The
> original was a 12-24, and I purchased a new 13-34 (as well as a new chain). I also converted from
> Ultraglide to Hyperglide. Despite my attempts to get everything adjusted, I can't shift to the 34
> ring, and the overall shifting is not clean. Will a longer chain cage help this? Am I just trying
> to add too many gear inches?
>
> Thanks for any advice.
>

FWIW - you might want to try a smaller set of chainrings rather than bigger rear sprockets. That way
you can keep some fairly close ratios instead of having to spread the cogs to accommodate a 13 to 34
range. I've switched both of my wife's bikes to 46-36-26 compact cranksets, with 12-24 or 12-25 at
the back - works really well.
 
R

Ronald

Guest
> FWIW - you might want to try a smaller set of chainrings rather than
bigger
> rear sprockets. That way you can keep some fairly close ratios instead of having to spread the
> cogs to accommodate a 13 to 34 range.

Yes, and smaller fronts also decreases the gaps in ratio between the existing cogs. Smaller fronts =
closer gears, i always get the smallest chainrings possible for the required max. speed/cadence.

"Grenouil" <[email protected]> wrote in message news:[email protected]...
> "Doug Dempster" <[email protected]> wrote in message
> news:[email protected]...
> > I'm in the process of upgrading my Shimano 105 rear cassette to add some more gear inches. The
> > original was a 12-24, and I purchased a new 13-34 (as well as a new chain). I also converted
> > from Ultraglide to Hyperglide. Despite my attempts to get everything adjusted, I can't shift to
> > the 34 ring, and the overall shifting is not clean. Will a longer chain cage help this? Am I
> > just trying to add too many gear inches?
> >
> > Thanks for any advice.
> >
>
> FWIW - you might want to try a smaller set of chainrings rather than
bigger
> rear sprockets. That way you can keep some fairly close ratios instead of having to spread the
> cogs to accommodate a 13 to 34 range. I've switched both of my wife's bikes to 46-36-26 compact
> cranksets, with 12-24 or 12-25 at the back - works really well.
 
D

Doug Dempster

Guest
This sounds like it might be a good option. From reading some other threads, converting to a triple
in front sounds fairly straightforward/relatively inexpensive. It appears that I might be able to
keep my front derailleur, has anybody upgraded their front 105 to a triple and been able to do that?

DGD

"Grenouil" <[email protected]> wrote in message
> >
>
> FWIW - you might want to try a smaller set of chainrings rather than bigger rear sprockets. That
> way you can keep some fairly close ratios instead of having to spread the cogs to accommodate a 13
> to 34 range. I've switched both of my wife's bikes to 46-36-26 compact cranksets, with 12-24 or
> 12-25 at the back - works really well.
 
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