upgrading an old Dawes Galaxy - help needed !!

[Pete A]

Dont know if anyone can help/advise - Im upgrading an old Dawes Galaxy
at moment. Have had a 22/32/42 older Deore LX chainset fitted with
110mm bb. Also, had rear wheel dished to accomodate a 7speed freewheel
(OLD is 126mm). As a result the chainline is not brill. Ive just
fitted the front mech - a Shimano Nexave, but when the chain is on the
small chainwheel & largest rear sprocket the chain rubs on the inside
face of the front mech. I cant adjust the mech over any more cos it is
already touching the chainstay, and I cant move it upwards cos that
would totally mess up the positioning for the largest chainwheel. Any
suggestions ???

I know Im trying to use an early 80's touring frame with a 1996
chainset & a more modern front mech, but Im tearing m'hair out at
moment trying to think of different solutions. Only one I can think of
is to have the bike sent to a frame builder, and have the rear stays
properly repositioned to improve the overall chainline, but I think
this could get costly !!

 

[Pete Biggs]

Pete A wrote:
> Dont know if anyone can help/advise - Im upgrading an old Dawes Galaxy
> at moment. Have had a 22/32/42 older Deore LX chainset fitted with
> 110mm bb. Also, had rear wheel dished to accomodate a 7speed freewheel
> (OLD is 126mm). As a result the chainline is not brill.

Do you mean you're having to have the chainrings further inboard than
ideal? Otherwise a longer BB should fix all the problems.

> Ive just
> fitted the front mech - a Shimano Nexave, but when the chain is on the
> small chainwheel & largest rear sprocket the chain rubs on the inside
> face of the front mech. I cant adjust the mech over any more cos it is
> already touching the chainstay, and I cant move it upwards cos that
> would totally mess up the positioning for the largest chainwheel. Any
> suggestions ???

I filed a bit off my Campag front mech body to allow it move closer to the
seat tube--saved getting a longer BB, the chainline of which I didn't
want. Don't know if anything like that is applicable to your mech & setup
(or any other suitable mech)?

> I know Im trying to use an early 80's touring frame with a 1996
> chainset & a more modern front mech,

It should be doable one way or the other.......

> but Im tearing m'hair out at
> moment trying to think of different solutions. Only one I can think of
> is to have the bike sent to a frame builder, and have the rear stays
> properly repositioned to improve the overall chainline,

....without that!

~PB

 

[James Thomson]

"Pete A" <[email protected]> wrote:

> Dont know if anyone can help/advise - Im upgrading an old Dawes
> Galaxy at moment. Have had a 22/32/42 older Deore LX chainset
> fitted with 110mm bb. Also, had rear wheel dished to accomodate
> a 7speed freewheel (OLD is 126mm). As a result the chainline is
> not brill.

What does the chainline (from the centre line of the seat tube to the
middle ring)? measure at the moment? I would've thought a 107mm BB would be
a better choice for your bike if the crankset is the one I'm thinking of,
but 110 shouldn't be too bad.

> Ive just fitted the front mech - a Shimano Nexave, but when the chain
> is on the small chainwheel & largest rear sprocket the chain rubs on
> the inside face of the front mech. I cant adjust the mech over any
> more cos it is already touching the chainstay, and I cant move it
> upwards cos that would totally mess up the positioning for the
> largest chainwheel. Any suggestions ???

If you're not using an indexed front gear shifter, I would try adjusting
the derailleur upward to clear the chainstay. With careful setup (pay
particular attention to setting the outer stop as close in as possible, and
adjust the clamp angle so that the inner plate is parallel to the
chainrings), you should still be able to get reliable shifting to the big
ring without risking dropping the chain over the top.

It does sound as though your derailleur isn't the best possible for the job
though. As well as being made for different sizes of chainwheel, there are
also different Shimano derailleurs which correspond to different
seattube-chainstay angles (63-66 or 66-69 degrees). It's rare to fall foul
of this, but check the documentation that came with your derailleur (if
any) and see which you have. It may also be stamped on the rear of the
cage. Most road/touring bikes do better with a 63-66 degree model.

If you do decide to replace the derailleur, look for one that better
corresponds to your chainrings. Anything intended for Compact Drive (i.e. a
large chainring in the 40-44t range) should do the job, as long as you
don't want it to index with Shimano road-type STI levers. Suitable models
would include most Shimano MTB derailleurs from the mid nineties onward.
Your Galaxy needs one with a 28.6mm clamp.

> I know Im trying to use an early 80's touring frame with a 1996
> chainset & a more modern front mech, but Im tearing m'hair out at
> moment trying to think of different solutions. Only one I can think of
> is to have the bike sent to a frame builder, and have the rear stays
> properly repositioned to improve the overall chainline, but I think
> this could get costly!!

I suspect chainline isn't the problem - at least, not a major one, but If
you did decide to have the rear end realigned, you could consider having it
spread to accept more modern hubs (130 or 135mm). Frame alignments tend to
be fairly inexpensive, but you'ld probably need to strip all the components
from the frame before taking it to the builder.

James Thomson