L
Hi all,
I currently have a 9 Speed Dura Ace drivetrain with a 12-23 cassette
and a 53-39 chainring. I have just purchased a 12-27 Ultegra 9 speed
cassette because a 12-23 isn't going to do me any favours on hills
(though I managed to do the ride up from the Bobbin Head marina along
Bobbin Head Road in Sydney on a 12-23). I have also purchased a Dura
Ace CN-7701 chain to go with the new cassette.
I have done a bit of research on chain sizing and installation using
the Park Tools and Sheldon Brown websites and the Shimano service
instructions, but I would like some advice from a.b'ers. I realise
there are a lot of different variables here, so I'll try to give as
much info as possible.
So, the questions are ...
i) Since my current cassette is a 12-23 and I want to put a 12-27
cassette in, I assume my existing chain will not be long enough to
handle the larger cog with 27 teeth. The previous owner of the bike
knows more about bikes than I do so I assume the chain length has been
optimised for a 12-23. OK, no problems so far, I will just calculate
the required length based on the equation given on the Park Tools
website.
However, since I might want to swap between cassettes on a regular
basis (the 12-23 will be used for crits, the 12-27 will be used for
hills and training), won't this mean I will have to regularly have to
swap chains by breaking them and reconnecting them using the special
Shimano reinforced connecting pins? This sounds like a real pain to do
(and I will have to keep a large enough supply of special connecting
pins). Is there a "halfway point" for the chainlength so that it can
accomodate both a 12-23 and 12-27 cassette? I realise this might mean I
have to be careful not to use the small-small and big-big gear
combinations.
ii) The service instruction sheet for the DA-7700 rear derailleur
states that the largest sprocket size it can accomodate is 26. A bit of
Googling reveals that Shimano tends to understate the maximum
accomodated sprocket size. Has any one here used a 7700 rear
derailleur with a 12-27 cassette?
iii) Is there anything else I might need to do once I install the new
cassette and chain, e.g. derailleur adjustments?
Thanks in advance. Once I get the cassette and chain installed, it will
be time to look at wheels ...
I currently have a 9 Speed Dura Ace drivetrain with a 12-23 cassette
and a 53-39 chainring. I have just purchased a 12-27 Ultegra 9 speed
cassette because a 12-23 isn't going to do me any favours on hills
(though I managed to do the ride up from the Bobbin Head marina along
Bobbin Head Road in Sydney on a 12-23). I have also purchased a Dura
Ace CN-7701 chain to go with the new cassette.
I have done a bit of research on chain sizing and installation using
the Park Tools and Sheldon Brown websites and the Shimano service
instructions, but I would like some advice from a.b'ers. I realise
there are a lot of different variables here, so I'll try to give as
much info as possible.
So, the questions are ...
i) Since my current cassette is a 12-23 and I want to put a 12-27
cassette in, I assume my existing chain will not be long enough to
handle the larger cog with 27 teeth. The previous owner of the bike
knows more about bikes than I do so I assume the chain length has been
optimised for a 12-23. OK, no problems so far, I will just calculate
the required length based on the equation given on the Park Tools
website.
However, since I might want to swap between cassettes on a regular
basis (the 12-23 will be used for crits, the 12-27 will be used for
hills and training), won't this mean I will have to regularly have to
swap chains by breaking them and reconnecting them using the special
Shimano reinforced connecting pins? This sounds like a real pain to do
(and I will have to keep a large enough supply of special connecting
pins). Is there a "halfway point" for the chainlength so that it can
accomodate both a 12-23 and 12-27 cassette? I realise this might mean I
have to be careful not to use the small-small and big-big gear
combinations.
ii) The service instruction sheet for the DA-7700 rear derailleur
states that the largest sprocket size it can accomodate is 26. A bit of
Googling reveals that Shimano tends to understate the maximum
accomodated sprocket size. Has any one here used a 7700 rear
derailleur with a 12-27 cassette?
iii) Is there anything else I might need to do once I install the new
cassette and chain, e.g. derailleur adjustments?
Thanks in advance. Once I get the cassette and chain installed, it will
be time to look at wheels ...