usable gear/cog question

I have a Trek 1500 with a 53 X 39 double with a 12 X 26 nine speed
casette. The front derailler is a 105 double, rear is ultegra,
shifters are 105.

While in the big ring I can only use the 4-5 smallest cogs in the rear
without chain rub. While in the smaller front ring, I can use the
seven largest cogs with no problem and, if riding easy, eight of the
nine. Does this seem normal? It leaves me with no overlap between the
two rings.

Dave

wrote:
I have a Trek 1500 with a 53 X 39 double with a 12 X 26 nine speed
casette. The front derailler is a 105 double, rear is ultegra,
shifters are 105.

While in the big ring I can only use the 4-5 smallest cogs in the rear
without chain rub. While in the smaller front ring, I can use the
seven largest cogs with no problem and, if riding easy, eight of the
nine. Does this seem normal? It leaves me with no overlap between the
two rings.

Dave

Check if your outer chainring limit screw on the front derailleur is
allowing the front derailleur cage to go too far out, towards the crank
arm. Your gap between the outside side of the chain and the outer
plate of the front derailleur cage may be too large. Check when the
chain is on the outer chainring and the smallest cog in back. If so
then when you are shifted onto the large chainring, you have less space
in between the front derailleur plates to allow the chain to move over
the rear cogs.

Your front derailleur inner limit screw is probably correct. It is set
so there is barely any space between the inside side of the chain and
the inner front derailleur plate when in the largest cog in back and
small chainring in front. So you have the full space between the front
derailleur plates to allow the chain to move over lots of cogs before
rubbing.

On Mon, 08 May 2006 07:16:34 -0700, mayokiely wrote:

While in the big ring I can only use the 4-5 smallest cogs in the rear
without chain rub. While in the smaller front ring, I can use the
seven largest cogs with no problem and, if riding easy, eight of the
nine. Does this seem normal? It leaves me with no overlap between the
two rings.

The inner ring seems normal. the small-small combinations tend to get
chain rub on the inside of the big ring, so you should avoid those. But
on the big ring you should be able to use all but the biggest sprocket in
back. Sounds like the front derailleur is too far out. I don't suppose
your shifter has "trim" adjustments -- click a little and move it a bit to
not run on the chain. If not, you need to take more time getting the
front adjusted. IMO this is a slight problem with Shimano shifters.
Campy has lots of trim adjustment; only the higher-priced Shimano do.

--

David L. Johnson

__o | When you are up to your ass in alligators, it's hard to remember
_`\(,_ | that your initial objective was to drain the swamp. -- LBJ
(_)/ (_) |

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In article ,
David L. Johnson wrote:
On Mon, 08 May 2006 07:16:34 -0700, mayokiely wrote:

While in the big ring I can only use the 4-5 smallest cogs in the rear
without chain rub. While in the smaller front ring, I can use the
seven largest cogs with no problem and, if riding easy, eight of the
nine. Does this seem normal? It leaves me with no overlap between the
two rings.

The inner ring seems normal. the small-small combinations tend to get
chain rub on the inside of the big ring, so you should avoid those. But
on the big ring you should be able to use all but the biggest sprocket in
back. Sounds like the front derailleur is too far out. I don't suppose
your shifter has "trim" adjustments -- click a little and move it a bit to
not run on the chain. If not, you need to take more time getting the
front adjusted. IMO this is a slight problem with Shimano shifters.
Campy has lots of trim adjustment; only the higher-priced Shimano do.


_ I don't know about his 105 brifters, but mine have one "click"
of trim available if you look for it. It takes a bit of practice,
since it's easy to overclick and end up shifting. If you didn't
know or expect it to be there you might realize that it was
available to use.

_ Booker C. Bense

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