Down shifting FD under load impossible or Brand S to rescue?

In article <[email hidden]>,

Wayne said:

My wife and I ride a Comotion Speedster with FSA 30/42/54 crank and
Shimano triple FD and shifters. The system shifts well, but of course
I want it to do something extra, down shift into the granny under some
load. Currently we soft pedal and it shifts down first time - every
time. Of course with a tandem the added rider coordination takes a
little longer than on a single and the loss of momentum is more
severe. Usually a little planning solves the problem and we can take
the correct approach, but every once in a while it would bail us out
of trouble if we could just pedal through the shift.

Both Sheldon's and Peter White's web sites mention that after market
chain wheels do not shift quite as well as Shimano's originals. How
do they shift better?

I dunno, I'm not seeing how the chainrings could make much
difference for the downshift, upshift yes, downshift ???

Quoted message said:

If we are willing to give up the 54 would a
Shimano 30/39/52 help this problem at all? Also if we went this route
would changing to a smaller granny put us back in the same
situation?

If you change the 39 to a 42, you'll likely need a different
front derailler if you want to use Shimano indexing. The
derailler cage needs to match the middle chainring for best
shifting, (i.e. I had a 105 derailler that was meant for a
30-42-52 triple, I switched to a 26-39-52 and the shifting
didn't really work right until I got an Ultegra Triple front
which is designed for a 30-39-52 triple.

I'd suggest

1. Get and install a chain watcher if you don't have it already.
Cheap insurance.

2. Figure out whether your front derailler is meant for a 42 or
39t middle ring. Get the one that matches.

With my 105 brifters, an ultegra triple FD, I can generally shift
from middle to lower under moderate pressure. If I could live
with a 30t inner I'm sure it would all work better.

_ Booker C. Bense

Yes, using a Shimano crank with a Shimano FD and shifter will work better than using another brand of crank. It's always a good idea to let up on the pressure a bit when shifting, especially on the front where the shift takes place under chain tension.

Booker C. Bense said:

In article <[email hidden]>,

Wayne said:

My wife and I ride a Comotion Speedster with FSA 30/42/54 crank and
Shimano triple FD and shifters. The system shifts well, but of course
I want it to do something extra, down shift into the granny under some
load. Currently we soft pedal and it shifts down first time - every
time. Of course with a tandem the added rider coordination takes a
little longer than on a single and the loss of momentum is more
severe. Usually a little planning solves the problem and we can take
the correct approach, but every once in a while it would bail us out
of trouble if we could just pedal through the shift.

Both Sheldon's and Peter White's web sites mention that after market
chain wheels do not shift quite as well as Shimano's originals. How
do they shift better?

I dunno, I'm not seeing how the chainrings could make much
difference for the downshift, upshift yes, downshift ???

Ask David Millar, 2003 Tour de France prologue. He complained that his
team was too cheap to fit un-ramped chainrings on his single-ring
prologue bike, and the ramped rings made it easier for the chain to come
unshipped, which likely cost him the win (he was second by 0.08 seconds).

Mark J.

Booker C. Bense bbense+rec.bicycles.tech.Jun. said:

In article <[email hidden]>,

2. Figure out whether your front derailler is meant for a 42 or
39t middle ring. Get the one that matches.

I neglected to mention that I have 2006 Ultegra shifter and FD. Works
fairly well with FSA 42 middle, may work better with standard 39 but I
have never used one.

In article <[email hidden]>,

Wayne said:

Booker C. Bense bbense+rec.bicycles.tech.Jun. said:

In article <[email hidden]>,

2. Figure out whether your front derailler is meant for a 42 or
39t middle ring. Get the one that matches.

I neglected to mention that I have 2006 Ultegra shifter and FD. Works
fairly well with FSA 42 middle, may work better with standard 39 but I
have never used one.

I am reasonably sure that a 2006 Ultegra Triple front is meant to
work with a 39T middle cog. It's likely that you have your
derailler higher than is optimal since you need to have the
clearance to get over the middle chainwheel. If you don't want to
swap chainrings, switching to a 105 triple might help your
shifting problems.

Check out Sheldon Brown's page on derailler adjustment and see if
your's is significantly above the 52T ring.

http://www.sheldonbrown.com/derailer-adjustment.html#front

New shimano deraillers come with a handy transparent sticker on
them to check this easily.

_ Booker C. Bense

Booker C. Bense bbense+rec.bicycles.tech.Jun. said:

In article <[email hidden]>,

Wayne said:

Booker C. Bense bbense+rec.bicycles.tech.Jun. said:

In article <[email hidden]>,

Quoted message said:

Quoted message said:

2. Figure out whether your front derailler is meant for a 42 or
39t middle ring. Get the one that matches.

Quoted message said:

I neglected to mention that I have 2006 Ultegra shifter and FD. Works
fairly well with FSA 42 middle, may work better with standard 39 but I
have never used one.

I am reasonably sure that a 2006 Ultegra Triple front is meant to
work with a 39T middle cog. It's likely that you have your
derailler higher than is optimal since you need to have the
clearance to get over the middle chainwheel. If you don't want to
swap chainrings, switching to a 105 triple might help your
shifting problems.

Check out Sheldon Brown's page on derailler adjustment and see if
your's is significantly above the 52T ring.

http://www.sheldonbrown.com/derailer-adjustment.html#front

New shimano deraillers come with a handy transparent sticker on
them to check this easily.

_ Booker C. Bense

I do have the FD higher than normal because I have 30/42/54 rings on
the crank and realize the larger gap between the big and middle ring
means it is tougher to shift from middle to granny. The FD just
clears the middle 42 when I am in the big ring. I am considering the
standard Ultegra 30/39/52 setup to match the rings with the FD.

My question is what are the chances that it will down shift under load
into the granny?

In article <[email hidden]>,

Wayne said:

I do have the FD higher than normal because I have 30/42/54 rings on
the crank and realize the larger gap between the big and middle ring
means it is tougher to shift from middle to granny. The FD just
clears the middle 42 when I am in the big ring. I am considering the
standard Ultegra 30/39/52 setup to match the rings with the FD.

My question is what are the chances that it will down shift under load
into the granny?

The short answer is "better than now", the long answer is that if
you use "exactly as designed" Shimano components they are
certainly meant to be downshifted under load. My limited
experience with the "standard" setups is that they do this
pretty well.

My problem with that is that I don't particularly care for Shimano's choice of
gears and I'm a hopeless tinkerer when it comes to bikes. In
order to get the gears I want, I'm willing to put up with a more
finicky shifting setup.

On my bike with the larger gap from 39 to 26t I have to be a bit careful
downshifting, but I can usually do it under load as long as I
do it before getting to big sprocket on the middle chainwheel.

_ Booker C. Bense

Quoted message said:

My wife and I ride a Comotion Speedster with FSA 30/42/54 crank and
Shimano triple FD and shifters. The system shifts well, but of course
I want it to do something extra, down shift into the granny under some
load.

Front derailers never shift well under load, because the front
derailer has to work with the part of the chain that is transmitting
power. The rear derailer gets to use the bottom, slack run of chain,
so rear derailers often shift quite well under load...sometimes too
well, because shifting under load is very stressful to the chain.

Quoted message said:

Currently we soft pedal and it shifts down first time - every
time.

Yes, this is how all experienced cyclists do it.

It's particularly challenging on a tandem, because both riders have to
soft pedal, or else one of the riders has to actively resist the other
a bit.

Quoted message said:

Of course with a tandem the added rider coordination takes a
little longer than on a single and the loss of momentum is more
severe. Usually a little planning solves the problem and we can take
the correct approach, but every once in a while it would bail us out
of trouble if we could just pedal through the shift.

Anticipating downshifts when climbing is an important skill, keep at
it!

Quoted message said:

Both Sheldon's and Peter White's web sites mention that after market
chain wheels do not shift quite as well as Shimano's originals. How
do they shift better?

Up. The pins and ramps help there.

For downshifting, there's no benefit.

Sheldon "Technique Matters" Brown
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