Should I dish some more?

I put a 145 mm dropout 48 spoke Suzue tandem-drum equipped rear onto a
Peugot (originally 124 mm droppouts for compact French 6 speed) steel
framed bike I'm making into a robust commuter.
My chainline with this substitution is such that I can't use the
smaller sprockets at all without throwing the chain from the big
sprocket or without rubbing the chain on the big ring as a guide if I'm
on the smaller rings (I'm currently running a 5 speed Shimano freewheel,
but was intending to switch to a 7 speed later).

I have the tire dished with the tire center about 10 mm closer to the
right side flange than the left. The tire is perfectly centered with
respect to the brakes.

Should I continue dishing the wheel and respacing the axle or am I
getting too much dish and should refrain from going further or consider
bending the stays to solve the chainline issues?

Are there other options I haven't considered?


--
meb

meb Wrote:
I put a 145 mm dropout 48 spoke Suzue tandem-drum equipped rear onto a
Peugot (originally 124 mm droppouts for compact French 6 speed) steel
framed bike I'm making into a robust commuter.
My chainline with this substitution is such that I can't use the
smaller sprockets at all without throwing the chain from the big
sprocket or without rubbing the chain on the big ring as a guide if I'm
on the smaller rings (I'm currently running a 5 speed Shimano freewheel,
but was intending to switch to a 7 speed later).

I have the tire dished with the tire center about 10 mm closer to the
right side flange than the left. The tire is perfectly centered with
respect to the brakes.

Should I continue dishing the wheel and respacing the axle or am I
getting too much dish and should refrain from going further or consider
bending the stays to solve the chainline issues?

Are there other options I haven't considered?

On once instance I said sprocket when I meant ring.

First paragraph should have read:

I put a 145 mm dropout 48 spoke Suzue tandem-drum equipped rear onto a
Peugot (originally 124 mm droppouts for compact French 6 speed) steel
framed bike I'm making into a robust commuter.
My chainline with this substitution is such that I can't use the
smaller sprockets at all without throwing the chain from the big
chainring or without rubbing the chain on the big ring as a guide if I'm
on the smaller rings (I'm currently running a 5 speed Shimano freewheel,
but was intending to switch to a 7 speed later).

Sorry about the confusion and thanks for any thoughts.


--
meb

meb wrote:
I put a 145 mm dropout 48 spoke Suzue tandem-drum equipped rear onto a
Peugot (originally 124 mm droppouts for compact French 6 speed) steel
framed bike I'm making into a robust commuter.
My chainline with this substitution is such that I can't use the
smaller sprockets at all without throwing the chain from the big
sprocket or without rubbing the chain on the big ring as a guide if I'm
on the smaller rings (I'm currently running a 5 speed Shimano freewheel,
but was intending to switch to a 7 speed later).

I have the tire dished with the tire center about 10 mm closer to the
right side flange than the left. The tire is perfectly centered with
respect to the brakes.

Should I continue dishing the wheel and respacing the axle or am I
getting too much dish and should refrain from going further or consider
bending the stays to solve the chainline issues?

Are there other options I haven't considered?

You've demonstrated one beautiful aspect of long chainstays!

Get the hub as narrow as you reasonably can and center both the rim over
your locknuts and the frame itself (at whatever width that is).

I'm assuming here that you have more axle spacers which can be removed.
On a Shimano tandem (145mm) hub, for examplem, 134 is about the limit.

Failing other solutions, a longer spindle for a wider chainline could
help but I'd work at the rear end first.
--
Andrew Muzi
www.yellowjersey.org
Open every day since 1 April, 1971

On 2008-02-07, meb wrote:

I put a 145 mm dropout 48 spoke Suzue tandem-drum equipped rear onto a
Peugot (originally 124 mm droppouts for compact French 6 speed) steel
framed bike I'm making into a robust commuter.
My chainline with this substitution is such that I can't use the
smaller sprockets at all without throwing the chain from the big
sprocket or without rubbing the chain on the big ring as a guide if I'm
on the smaller rings (I'm currently running a 5 speed Shimano freewheel,
but was intending to switch to a 7 speed later).

I have the tire dished with the tire center about 10 mm closer to the
right side flange than the left. The tire is perfectly centered with
respect to the brakes.

10mm doesn't sound like excessive dish-- a Campag 9/10 speed hub has a
20mm difference in distance from centre line to the left and right
flanges.

But then it's not for robust commuters I suppose.

Should I continue dishing the wheel and respacing the axle or am I
getting too much dish and should refrain from going further or consider
bending the stays to solve the chainline issues?

Your small sprockets are too far to the right. However you bring them
left, whether by axle re-spacing or by bending the frame, won't you
still always need more dish to keep the rim in the right place with
respect to the brakes?

Also asymmetric frame spacing will result in the back wheel steering
slightly to the right, although I suppose you can adjust it in the
dropouts a bit.

Are there other options I haven't considered?

What about a BB axle that projects the chainrings a bit further out to
the right?

Or use a 130mm wheel unless you've really set your heart on this
tandem-drum thing.

A Muzi Wrote:
meb wrote:
I put a 145 mm dropout 48 spoke Suzue tandem-drum equipped rear onto
a
Peugot (originally 124 mm droppouts for compact French 6 speed)
steel
framed bike I'm making into a robust commuter.
My chainline with this substitution is such that I can't use the
smaller sprockets at all without throwing the chain from the big
sprocket or without rubbing the chain on the big ring as a guide if
I'm
on the smaller rings (I'm currently running a 5 speed Shimano
freewheel,
but was intending to switch to a 7 speed later).

I have the tire dished with the tire center about 10 mm closer to
the
right side flange than the left. The tire is perfectly centered
with
respect to the brakes.

Should I continue dishing the wheel and respacing the axle or am I
getting too much dish and should refrain from going further or
consider
bending the stays to solve the chainline issues?

Are there other options I haven't considered?

You've demonstrated one beautiful aspect of long chainstays!

Get the hub as narrow as you reasonably can and center both the rim
over
your locknuts and the frame itself (at whatever width that is).

I'm assuming here that you have more axle spacers which can be
removed.
On a Shimano tandem (145mm) hub, for examplem, 134 is about the limit.

Failing other solutions, a longer spindle for a wider chainline could
help but I'd work at the rear end first.
--
Andrew Muzi
www.yellowjersey.org
Open every day since 1 April, 1971

No spacer removable to the left, although there is a nut holding the
drum on that might be replaceable with a thinner one or possibly moved
outboard the dropout.

The bottom bracket may be the option I need pursue.
The current bracket and crankset are unusually narrow with a large
accomdation recess in the chainstay that the 52 ring still occaisionally
brushes. This bike has a mix of French and English thread components,
so not sure where the BB fits in this scheme.


--
meb