Dura ace 7700
Dura ace 7700
Hi, I'm running a dura ace 7700 triple group on my bike, I am thinking of changing to a 7700 double chainset. Will I need to change the bottom bracket?
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rareposter
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- Joined: 27 Aug 2014, 2:40pm
Re: Dura ace 7700
7700 is double only - triple is 7703.
We need a lot more info as to what you've actually got on the bike - shifters, chainset and both mechs.
There's a strong possibility that you'll need a new L/H shifter too. Front mechs, especially of that era, are marginally more open to being used across double or triple but DA did have some specific compatibility factors at various points in its incarnations.
The 7703 triple is a weird one anyway, it was a bit of an afterthought from Shimano and they basically made a special 39T ring with mounting points for an inner chainring (rather than the usual system of having inner bolts). It required special middle and inner rings and then a longer BB to space it out.
We need a lot more info as to what you've actually got on the bike - shifters, chainset and both mechs.
There's a strong possibility that you'll need a new L/H shifter too. Front mechs, especially of that era, are marginally more open to being used across double or triple but DA did have some specific compatibility factors at various points in its incarnations.
The 7703 triple is a weird one anyway, it was a bit of an afterthought from Shimano and they basically made a special 39T ring with mounting points for an inner chainring (rather than the usual system of having inner bolts). It required special middle and inner rings and then a longer BB to space it out.
Re: Dura ace 7700
Thanks for replying, I guess it's a 7703 setup I have then. Triple left shifter ,triple front mech, triple chainset. I want to replace just the chainset with a double if possible. I'm guessing if I have a longer bb on my set up it won't work. All is good at present but the chainline never looks good to me. Maybe I have the wrong length bb fitted now.
Re: Dura ace 7700
Note 1 on the compatibility chart below confirms that the axle lengths are different:
It also confirms that the STI lever and front mech are also different so you might be opening a whole can of worms with your proposal. As for whether the current BB is correct - do you think the chainline is too large or too small?
IMV 7700 was the most beautiful groupset Shimano have ever made, and the triple version is like hen’s teeth so if you are set on a double setup and your 7703 is in good condition you would get a good price for it. I paid some crazy money for a ‘long cage’ rear mech last year as it was in like new condition. I have no regrets on it either.
IMV 7700 was the most beautiful groupset Shimano have ever made, and the triple version is like hen’s teeth so if you are set on a double setup and your 7703 is in good condition you would get a good price for it. I paid some crazy money for a ‘long cage’ rear mech last year as it was in like new condition. I have no regrets on it either.
Re: Dura ace 7700
The bb looks too long, maybe needs setting up. Its a new bike to me and I do prefer a double. It is in very good condition though so maybe take it all off and fit campagnolo which I prefer.
Re: Dura ace 7700
I struggle to think how the chainline could be too big with an Octalink triple chainset and BB. Perhaps an extra spacer has been added to the drive side for some reason. There were 2 versions of the Octalink splines but I’m not familiar with the other one.
There isn’t really a ‘setup’ - the BB screws directly into the frame and the chainset bolts onto the splined BB spindle.
Whatever the issue, it does sound like if you can afford a new groupset, a Campy double one is the way to go for you.
Whatever the issue, it does sound like if you can afford a new groupset, a Campy double one is the way to go for you.
Re: Dura ace 7700
Can I ask why it is you wish to dispense with a triple?
I don’t need super low gears on my road bike but appreciate the small gear steps a triple can offer. I run an Ultegra set up with 30-39-52 and 12-25 cassette.
I don’t need super low gears on my road bike but appreciate the small gear steps a triple can offer. I run an Ultegra set up with 30-39-52 and 12-25 cassette.
The older I get the more I’m inclined to act my shoe size, not my age.
Re: Dura ace 7700
Nothing against triples at all, if I can get this set up better I'll keep it. Been having a look today and maybe front mech isn't parallel to the rings.
Re: Dura ace 7700
Front mech set up can be tricky if it is clamp-on. Re-tightening the clamp after adjusting the angle can result in the angle going wrong again as the front face of the clamp ‘bites’ more and drags the main body round.
The older I get the more I’m inclined to act my shoe size, not my age.
Re: Dura ace 7700
Its a braze on but it needs turning slightly and dropping a little.
Re: Dura ace 7700
From memory, the Octalink BB for the 7703 triple is 118mm and the BB for the 7700 double 109.5mm. So if you run it as a double on the BB for the triple, the chainline will be out by several millimetres. The Octalink double BBs for Ultegra 6500 and 105 5500 are the same length as the Dura-Ace 7700, so you could use one of those as a cheaper alternative if you want to run your existing crankset as a double. You need to make sure the BB is Octalink V1 and not Octalink V2.