Going from triple to double

http://groups.google.com/group/rec.bicycles.tech/browse_frm/thread/9bfbd31fd5509bd5/a5cbf434faf8022c?q=triple+to+double&rnum=1#a5cbf434faf8022c

I think this thread covers the points best.

Quoted message said:

The usual question, based on my search of the list, is from riders who
want to triplize their double cranksets.

However, I was wondering if there is any reason not to get the Dura-Ace
triple (7703) and remove the granny, use the 109.5 BB, and ride it as a
double.

I have monetary and technical reasons for doing this, so what I'm
asking is: Will it work?

You might be exposing the very worst "feature" of the 7703 drivetrain- a
very poorly-designed middle (now small for you) chainring that was notorious
for dropping the chain to the inside, as you're just riding along... no
shifting required. Mitigating this somewhat is the fact that you'll have a
more-favorable chainline, but if you're talking about the 9-speed DuraAce
triple components, that middle (39t) chainring is possibly a really bad
option for an inside chainring.

The reason for it dropping the chain is that Shimano cut down and altered
the tooth profile, to make it easier to shift off the 39 and onto the 30.
That's a difficult shift (due to the differential in height between the 39 &
53t chainrings), and Shimano hadn't figured out the optimal front derailleur
or tooth profile on the 7703 series. The 10-speed triple works dramatically
better, both on Ultegra and DuraAce.

--Mike Jacoubowsky
Chain Reaction Bicycles
www.ChainReaction.com
Redwood City & Los Altos, CA USA

"Bob Cooper" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

The usual question, based on my search of the list, is from riders who
want to triplize their double cranksets.

However, I was wondering if there is any reason not to get the Dura-Ace
triple (7703) and remove the granny, use the 109.5 BB, and ride it as a
double.

I have monetary and technical reasons for doing this, so what I'm
asking is: Will it work?

Bob "Cold in Western New York" Cooper

If the ghost shifting with the 39t becomes a problem, just replace that
ring with one from a double.

Quoted message said:

If the ghost shifting with the 39t becomes a problem, just replace that
ring with one from a double.

Right, but at what cost? If he wants a DuraAce 39t chainring, those things
are quite expensive. That would possibly kill most (perhaps all) of the
savings he's trying to accomplish. My guess is that he found a killer deal
somewhere on a DuraAce triple, and is trying to make it work as a double and
still come out ahead.

--Mike-- Chain Reaction Bicycles
www.ChainReactionBicycles.com

Mike Jacoubowsky said:

Quoted message said:

The usual question, based on my search of the list, is from riders who
want to triplize their double cranksets.

However, I was wondering if there is any reason not to get the Dura-Ace
triple (7703) and remove the granny, use the 109.5 BB, and ride it as a
double.

I have monetary and technical reasons for doing this, so what I'm
asking is: Will it work?

You might be exposing the very worst "feature" of the 7703 drivetrain- a
very poorly-designed middle (now small for you) chainring that was notorious
for dropping the chain to the inside, as you're just riding along... no
shifting required. Mitigating this somewhat is the fact that you'll have a
more-favorable chainline, but if you're talking about the 9-speed DuraAce
triple components, that middle (39t) chainring is possibly a really bad
option for an inside chainring.

Sorry Mike, don't agree. I do agree that the 7703 is a POS, but when
it's a triple, it doesn't shift to the 30t w/o any shifter input, I
would just remove the 30t, get the 109.5, and adjust the front
der(either double or triple) and go ride.

Quoted message said:

The reason for it dropping the chain is that Shimano cut down and altered
the tooth profile, to make it easier to shift off the 39 and onto the 30.
That's a difficult shift (due to the differential in height between the 39 &
53t chainrings), and Shimano hadn't figured out the optimal front derailleur
or tooth profile on the 7703 series. The 10-speed triple works dramatically
better, both on Ultegra and DuraAce.

--Mike Jacoubowsky
Chain Reaction Bicycles
www.ChainReaction.com
Redwood City & Los Altos, CA USA

"Bob Cooper" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

The usual question, based on my search of the list, is from riders who
want to triplize their double cranksets.

However, I was wondering if there is any reason not to get the Dura-Ace
triple (7703) and remove the granny, use the 109.5 BB, and ride it as a
double.

I have monetary and technical reasons for doing this, so what I'm
asking is: Will it work?

Bob "Cold in Western New York" Cooper

sunderland said:

If the ghost shifting with the 39t becomes a problem, just replace that
ring with one from a double.

Agree-an Ultegra 39t is cheap, cheap and othes are even less. ANY 39t
will work on this crank.

But as I stated, the 39t will work fine. Add a $10 jump stop if it
shucks the chain when going to the 39t...and bob's yer uncle'...

Quoted message said:

Quoted message said:

You might be exposing the very worst "feature" of the 7703 drivetrain- a
very poorly-designed middle (now small for you) chainring that was
notorious
for dropping the chain to the inside, as you're just riding along... no
shifting required. Mitigating this somewhat is the fact that you'll have
a
more-favorable chainline, but if you're talking about the 9-speed DuraAce
triple components, that middle (39t) chainring is possibly a really bad
option for an inside chainring.

Sorry Mike, don't agree. I do agree that the 7703 is a POS, but when
it's a triple, it doesn't shift to the 30t w/o any shifter input, I
would just remove the 30t, get the 109.5, and adjust the front
der(either double or triple) and go ride.

Been there, tried that, doesn't usually work on the bikes we see. Puts the
30t chainring too close (actually touches, usually) the chainstay. My guess
is that a steel frame with smaller-diameter chainstays (or larger
indentations) might let you do this... you your guess is that you see a lot
more steel frames at the high end than I do. And your guess would be right!

On the other hand, my guess is also that we've probably got more experience
with 7703s than perhaps any other shop around, which might have had
something to do with the visit from two Shimano engineers a while back after
we let our views about the worthiness of the product be known. In our shop,
a customer pretty much has to beg to be sold a double crankset... then they
have to sign a release... (just kidding!).

--Mike-- Chain Reaction Bicycles
www.ChainReactionBicycles.com

"Qui si parla Campagnolo" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Mike Jacoubowsky said:

Quoted message said:

The usual question, based on my search of the list, is from riders who
want to triplize their double cranksets.

However, I was wondering if there is any reason not to get the Dura-Ace
triple (7703) and remove the granny, use the 109.5 BB, and ride it as a
double.

I have monetary and technical reasons for doing this, so what I'm
asking is: Will it work?

You might be exposing the very worst "feature" of the 7703 drivetrain- a
very poorly-designed middle (now small for you) chainring that was
notorious
for dropping the chain to the inside, as you're just riding along... no
shifting required. Mitigating this somewhat is the fact that you'll have
a
more-favorable chainline, but if you're talking about the 9-speed DuraAce
triple components, that middle (39t) chainring is possibly a really bad
option for an inside chainring.

Sorry Mike, don't agree. I do agree that the 7703 is a POS, but when
it's a triple, it doesn't shift to the 30t w/o any shifter input, I
would just remove the 30t, get the 109.5, and adjust the front
der(either double or triple) and go ride.

Quoted message said:

The reason for it dropping the chain is that Shimano cut down and altered
the tooth profile, to make it easier to shift off the 39 and onto the 30.
That's a difficult shift (due to the differential in height between the
39 &
53t chainrings), and Shimano hadn't figured out the optimal front
derailleur
or tooth profile on the 7703 series. The 10-speed triple works
dramatically
better, both on Ultegra and DuraAce.

--Mike Jacoubowsky
Chain Reaction Bicycles
www.ChainReaction.com
Redwood City & Los Altos, CA USA

"Bob Cooper" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

The usual question, based on my search of the list, is from riders who
want to triplize their double cranksets.

However, I was wondering if there is any reason not to get the Dura-Ace
triple (7703) and remove the granny, use the 109.5 BB, and ride it as a
double.

I have monetary and technical reasons for doing this, so what I'm
asking is: Will it work?

Bob "Cold in Western New York" Cooper

Mike Jacoubowsky said:

Quoted message said:

Quoted message said:

You might be exposing the very worst "feature" of the 7703 drivetrain- a
very poorly-designed middle (now small for you) chainring that was
notorious
for dropping the chain to the inside, as you're just riding along... no
shifting required. Mitigating this somewhat is the fact that you'll have
a
more-favorable chainline, but if you're talking about the 9-speed DuraAce
triple components, that middle (39t) chainring is possibly a really bad
option for an inside chainring.

Sorry Mike, don't agree. I do agree that the 7703 is a POS, but when
it's a triple, it doesn't shift to the 30t w/o any shifter input, I
would just remove the 30t, get the 109.5, and adjust the front
der(either double or triple) and go ride.

Been there, tried that, doesn't usually work on the bikes we see. Puts the
30t chainring too close (actually touches, usually) the chainstay. My guess
is that a steel frame with smaller-diameter chainstays (or larger
indentations) might let you do this... you your guess is that you see a lot
more steel frames at the high end than I do. And your guess would be right!

On the other hand, my guess is also that we've probably got more experience
with 7703s than perhaps any other shop around, which might have had
something to do with the visit from two Shimano engineers a while back after
we let our views about the worthiness of the product be known. In our shop,
a customer pretty much has to beg to be sold a double crankset... then they
have to sign a release... (just kidding!).

Too bad these guys and shimano don't listen. 7803 'may' work better but
the bolt onto the middle ring thing found on 7803 is just plain dumb,
but very shimano. making something unique...unique from shimano,
imagine that!!

Did ya ask why the aluminum compact costs so dern much? How about how
they waved fairy dust onto their double front der to 'handle' a 50/34
combo(don't these guys try this stuff?)

Maybe ask them about why we have had to warranty 5 7800 levers?

any why they don't stock spokes for their 7700 wheels, or......never
mind, they will never visit me.

Quoted message said:

Maybe ask them about why we have had to warranty 5 7800 levers?

I thought that there were no 10s shifter issues, at least when you said that
a couple of months ago...

--
Phil, Squid-in-Training

Quoted message said:

I thought that there were no 10s shifter issues, at least when you said
that a couple of months ago...

So far, the only 10s lever issues we've seen have been with the electronics
(the FlightDeck interface). And that's REALLY annoying, because it doesn't
show up until after you've set it all up. We need to come up with a way of
testing them ahead of time.

To their credit, I don't think Shimano's refused a warranty claim for us,
and they've been pretty quick on taking care of things. On the other hand,
we don't send them things that have been obviously abused... and it *is* a
pain when you have to replace a lever on a new bike.

--Mike Jacoubowsky
Chain Reaction Bicycles
www.ChainReaction.com
Redwood City & Los Altos, CA USA

"Phil, Squid-in-Training" <[email hidden]> wrote in
message news:Ncfrf.9247$NS.631@dukeread04...

Quoted message said:

Quoted message said:

Maybe ask them about why we have had to warranty 5 7800 levers?

I thought that there were no 10s shifter issues, at least when you said
that a couple of months ago...

--
Phil, Squid-in-Training

Phil said:

Quoted message said:

Maybe ask them about why we have had to warranty 5 7800 levers?

I thought that there were no 10s shifter issues, at least when you said that
a couple of months ago...

--
Phil, Squid-in-Training

We warrantied our first more than a few months ago. Since we have sent
in 5...3 rights and 2 lefts, exibiting the same 'big lever travels with
small, no shift' problems as 9s.

This compared to dozens of 9s levers....

Mike Jacoubowsky said:

Quoted message said:

I thought that there were no 10s shifter issues, at least when you said
that a couple of months ago...

So far, the only 10s lever issues we've seen have been with the electronics
(the FlightDeck interface). And that's REALLY annoying, because it doesn't
show up until after you've set it all up. We need to come up with a way of
testing them ahead of time.

To their credit, I don't think Shimano's refused a warranty claim for us,
and they've been pretty quick on taking care of things.

I haven't seen a warranty refused since I was in another shop almost a
decade ago.
Their warranty is fast...either a good thing...or a bad thing.

On the other hand,

Quoted message said:

we don't send them things that have been obviously abused... and it *is* a
pain when you have to replace a lever on a new bike.

--Mike Jacoubowsky
Chain Reaction Bicycles
www.ChainReaction.com
Redwood City & Los Altos, CA USA

"Phil, Squid-in-Training" <[email hidden]> wrote in
message news:Ncfrf.9247$NS.631@dukeread04...

Quoted message said:

Quoted message said:

Maybe ask them about why we have had to warranty 5 7800 levers?

I thought that there were no 10s shifter issues, at least when you said
that a couple of months ago...

--
Phil, Squid-in-Training