Compact cranks and big cassette on DA 7700

[Brad Simeral]

'O wise ones of SF2G. I am pretty certain that someone on this list has already answered this for themselves; please share.

I'd like to change the gearing on my road bike, which has a full Dura Ace 7700 groupo circa 2001 (tiny hubs and all). I am currently running with a 11-27 rear cassette and 39-53 front chainrings. I'd love to change this to a compact crank gear set with a 34 front and at least a 28 rear though preferably 32. 

What's the easiest and/or best way to do this? I'd like to keep as much of the old groupo as possible, but not sure if brake levers will be compatible, etc.  

If the recommendation is to just swap everything out (which I fear it is), at which point did Ultegra cross over to being as good as / better than the 7700? 

Thanks,

-brad

[steve armijo]

you'll swap out cranks/bb(most likely but that's good, stupid 7700 octalink goo).

then you'll need to lower your front derailleur.

you'll also probably remove some links from your chain.

i expect that's all that's needed.

-s

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[Peter Colijn]

I believe you will need a different derailleur (or at least a bigger cage) to accomodate a 32t in the back. 28t may be fine. I am by no means an expert in this stuff though. Fortunately there are a bunch of 9sp-fetishists on the list :)

On Thu, Aug 18, 2016 at 4:45 PM, Brad Simeral <bsim...@gmail.com> wrote:

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[steve armijo]

hmm, this is a good point.  i totally fail at reading comprehension and neglected the bike butt portion of the question.

according to http://sheldonbrown.com/gloss_ca-g.html#capacity you can probably go all the way to 30 with no issues.  for 32 you might try it out and if it doesn't clear the cassette then you may need to as Peter suggests find a 9 speed shimano MTB derailleur

-s

[Yuanyu Chen]

50/34+11-28 short cage def works fine with the current gen, but if the DA7700 cage is substantially shorter than the current gen shimano RDs then you might have problems.

11-32 might even be okay. If you want to risk it, just get the cassette (or, more cheaply, borrow one from a friend?), then screw in the b-screw probably all the way. If that's still hitting, try a longer b-screw. If that doesn't work then it's either 11-28 or buy a 'medium' cage RD.

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[Viet-Trung Luu]

According to Shimano's manual, the RD-7700 SS has a rated capacity of 26t (though they rate capacity extremely conservatively). They also specify the largest allowable cog at 26t (obviously also very conservatively).

Capacity needed is (biggest chainring - small chainring) + (biggest cog - smallest cog). So it's unlikely to work with the short cage.

(I can't find the manual for the 7700 long cage (GS).)

On Thu, Aug 18, 2016 at 5:02 PM, Yuanyu Chen <yuany...@gmail.com> wrote:

50/34+11-28 short cage def works fine with the current gen, but if the DA7700 cage is substantially shorter than the current gen shimano RDs then you might have problems.

11-32 might even be okay. If you want to risk it, just get the cassette (or, more cheaply, borrow one from a friend?), then screw in the b-screw probably all the way. If that's still hitting, try a longer b-screw. If that doesn't work then it's either 11-28 or buy a 'medium' cage RD.

On Thu, Aug 18, 2016 at 4:50 PM Peter Colijn <caff...@colijn.ca> wrote:

I believe you will need a different derailleur (or at least a bigger cage) to accomodate a 32t in the back. 28t may be fine. I am by no means an expert in this stuff though. Fortunately there are a bunch of 9sp-fetishists on the list :)

On Thu, Aug 18, 2016 at 4:45 PM, Brad Simeral <bsim...@gmail.com> wrote:

'O wise ones of SF2G. I am pretty certain that someone on this list has already answered this for themselves; please share.

I'd like to change the gearing on my road bike, which has a full Dura Ace 7700 groupo circa 2001 (tiny hubs and all). I am currently running with a 11-27 rear cassette and 39-53 front chainrings. I'd love to change this to a compact crank gear set with a 34 front and at least a 28 rear though preferably 32. 

What's the easiest and/or best way to do this? I'd like to keep as much of the old groupo as possible, but not sure if brake levers will be compatible, etc.  

If the recommendation is to just swap everything out (which I fear it is), at which point did Ultegra cross over to being as good as / better than the 7700? 

Thanks,

-brad

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[Jason Thorpe]

This is doable.

You can stick with your 9sp levers.  And if you limit yourself to a 28T in the back, you can probably stick with your DA7700 derailleur; it’ll work OK with some frames, but you’ll have to turn the B adjust all the way in, most likely.  I have a 28T on one of bikes that has a DA7700 rear derailleur.

The crank — well, if you want a compact, you’re going to have to replace that.  And your BB, because you’re not going to find a compact crank that fits that BB spindle.  But you will be able to use the DA7700 front derailleur with compact rings without any problems.

It might be a challenge to find a 9sp cassette with a 28T large cog, but you might find that with your 11-27 just moving to a 34T small ring is enough.

Thanks,

-brad

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-- thorpej

[Peter Chang]

Le jeudi 18 août 2016 17:02:27 UTC-7, steve a écrit :

according to http://sheldonbrown.com/gloss_ca-g.html#capacity you can probably go all the way to 30 with no issues.

yep, i ran my geared mtb (when it actually rolled) w/ a 30t and 7700 short cage derailler. it's actually an 8sp cassette / spacer / 30t cog, which was actually a thing for people w/ spare parts laying around.

the front was a 36 (single ring) though so there was some wiggle room for the rated max tooth thing.

but if you go compact / mountain in the front you can get a ~straight block in back!

\p

[Brad Simeral]

Thanks all! 

So no luck for individual 34T chainrings that fit? If I change out the crank, I'm going to start looking a bit frankenstein with the gunmetal grey new stuff vs my beautiful old polished look. 

Any knowledge as to whether I can custom swap the cogs on a DA7700 cassette? 

-brad 

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-- thorpej

[Jason Thorpe]

> On Aug 18, 2016, at 5:48 PM, Brad Simeral <bsim...@gmail.com> wrote:
>
> Thanks all!
>
> So no luck for individual 34T chainrings that fit? If I change out the crank, I'm going to start looking a bit frankenstein with the gunmetal grey new stuff vs my beautiful old polished look.

The problem is that the smallest chainring that will fit on a 130BCD crank is 38T.

> Any knowledge as to whether I can custom swap the cogs on a DA7700 cassette?

Not sure about the DA7700 cassette, but Shimano used fixed cassette spiders for the largest 3 or so cogs on the 6500, at least, so no swapping just the large one. It’s be tricky anyway because of the HyperGlide ramps.

-- thorpej

[Peter Chang]

Le jeudi 18 août 2016 17:48:09 UTC-7, Brad Simeral a écrit :

So no luck for individual 34T chainrings that fit?

too small for 130bcd.

 

Any knowledge as to whether I can custom swap the cogs on a DA7700 cassette? 

the top N cogs come as a single unit. if you have the spacer you can put a cog behind these and drop a cog from the loose set. thinking about it, that's how i actually did my conversion.

\p 

[djconnel]

Then there's this:

https://twitter.com/boxdogbikes/status/766431234511831040