tractopelle

Hello there,

I currently don't have the parts in my possession, so all of this is still purely theoretical for me. Despite my efforts, I couldn't find the specific combination I have in mind on Sheldon Brown's dedicated page. However, I believe it's more likely that the combination I'm envisioning doesn't work rather than Sheldon never considering it.

I have a fondness for brifters, especially because I ride "tall" bikes (around 64cm center to center), but I've encountered difficulties when it comes to using them on "older" bikes. In particular, I have an old frame from the 70s that only accommodates 126mm rear wheels, and for the time being, I don't wish to modify it.

Let's say I were to come across a Dura Ace 7400 wheelset with a 7-speed freewheel (not the later 8-speed cassette). I'm curious if there's any combination of rear mech with a 7400 or 7700 brifter (with potential alternate routing) that could make it work.

Thank you for your assistance.

maddog34

here ya go... looks like DA 7 sp rear ders. are only compatible with other DA index shifters... so yes, a DA 7 sp. brifter will work with the DA rear der of the 7400 vintage... other brifters need not be attempted, although someone might know of a homespun "work-around".... luckily, i went with DA indexers on my ALAN with all 7400 DA.... 1.9 ratio for DA, compared to 1.7 pull Ratio for all other 6 to 9 sp. Shimano groups....

https://bike.bikegremlin.com/1278/bi...mpatibility/#1

datlas 

Surely you can track down and use a Dura-Ace 7402 drivetrain but honestly you will be happier if you spread your rear triangle by 2mm on each side and get a 21st century drivetrain like Ultegra 6800 or even 105 5700.

If you are dead set on vintage that’s viable but you will get more support in C&V.

KCT1986

Dura ace brifter started at 8 speed. 7 was down tube. It still used the 1.9/1 cable pull ratio.

Kontact 

8 speed Shimano can shift 7 speed decently. Adjust from the middle of the cogs.

7400 RDs will shift 8 speed spacing with a 7400 8 speed shifter, or will shift 8 speed spacing with a 7700 9 speed shifter - due to the difference in their pull ratios. Shimano advertised this fact as a brifter replacement on otherwise 7400 bikes.

Any Shimano spaced 9 speed shifter will work as well.

icemilkcoffee 

Are you hung up on Dura Ace brifters? Why not just use 7 speed brifters like the RSX ST-A410, or Sora ST3300, or Tourney ST-A070, or Microshift R7?

Kontact 

You caught the part about the different pull ratios?

(Which can be addressed by moving the cable to the outside of the fixing bolt.)

maddog34

as Kontact mentioned above... this is from my reply above: "1.9 ratio for 7400 DA, compared to 1.7 pull Ratio for all other 6 to 9 sp. Shimano groups....

https://bike.bikegremlin.com/1278/bi...mpatibility/#1

tractopelle

Thank you all for your valuable feedback and information, it's greatly appreciated.

No, I'm not fixated on using Dura Ace brifters. In fact, I don't even own one at the moment.

I must admit, I lack confidence in attempting to spread the frame on my own. Despite the frame having minimal value, it fits me perfectly, and I would feel ashamed if I were to inadvertently damage it in the process.

I will continue my research and may return with additional questions, if you're willing to assist further.

Once again, thank you for your help and support.

wheelreason

8 speed D-Ace shifters will work with uniglide 7 speed freewheel, you just need to block out the last shift with the limit screw. Cheaper older 8 speed shifters will work but not perfectly. Alternate cable routing will make other options viable as well.

tractopelle

Good to know, thank you.

Now, I'll have a conversation with my banker/significant other/younameit to assess whether I can afford to assemble a mixed 7400 group.

tractopelle

I found a Dura-Ace rear hub that is 126mm wide but that can take 7s cassette.
Is that for real, or did the vendor make a mistake?
Thanks.

KCT1986

DA did have a 7 speed @ 126.5mm OLD. It used uniglide style sprockets, with a threaded smallest sprocket of a smaller diameter than most uniglide. Be sure that you are able to get/afford a suitable cassette or at least the threaded lockring.

Same hub was used for 6 speed DA, but had an axle spacer setup that was slightly different.

HillRider

Fitting a 130mm hub (8+speed) into 126mm dropouts is neither difficult or damaging. If you don't "cold set" the frame the wheel will be a bit of a struggle to install but not at all bad. Easier than trying to cobble up a 7-speed brifter arrangement.

BTW, during the 7 to 8+ speed transition period in the early 90's several frame makers, Trek for one, spaced some of their frames 128mm and sold the complete bikes with both 7-speed and 8-speed groups at different price points. Later, Surly did the same thing, spacing their frames at 132mm to take both 130mm road hubs and 135mm MTB hubs. Both approaches worked well.

maddog34

Take a look at Shimano Exage and 600 hubs.. they work great and hold up to the tests of time and mild neglect ! I see many of them in my shop.. rarely is one not salvageable...

same for the 600, RSX and STX derailleurs...rock solid and very nice operation too... 600 Arabesque stuff is collectible.. and the 600 Tri-color groups are still very popular!

and i fully agree with the 7400 DA recommendations.. i have that group on my ALAN.. nice stuff. And my Trek runs a 126mm DA rear hub...6 speed.

also.. Resetting the rear axle to 126 and re-dishing the wheel is not as difficult as people fear...

Andrew R Stewart 

I have one of these in my basement waiting for other decisions concerning a friend's bike rebuild. The freehub has had a spline ground off to allow a current HG cassette to fit and will use the old threaded last cog as the lock ring, 7 speed, 126...mm. My question is whether the 7401 rear der will index well with the current 1.2/1.1 cables, as it was designed around the 1.5ish diameter of the early 1980s. This was the only version that was not speced for the 1.2mm cables that quickly followed. So few talk about this aspect. Andy

KCT1986

If you're thinking about the thinner cables having less pull as it wraps around the 'spool' of shifter, interesting question!! Guess that may have a little effect, but a lot of things were different back then:

The SIS housing was different, early versions were some type of wound casing (like current brake) that had a fixed low friction lining, compared to brake housing that sometimes had loose lining.
Don't remember if the DA supplied cables were the old style braided (AKA double wound) or twisted. Can't remember which was supposedly better.
Downtube shifters also had shorter cable runs & housing at the RD was much shorter.

For DA brifters, Shimano speced 1.2mm cables.

During that same time period, Suntour (who had some issues with their Accushift system) recommended 1.2mm cables, and did not endorse braided cables. They also recommended high quality wound housing with fixed lining and did not endorse 'linear' style housing. Suntour had a service bulletin for shops to follow to troubleshoot Accushift problems and resolve problems.

Andrew R Stewart 

When Shimano first came out with their SIS They stated 17 aspects of the drivetrain that had to be "on spec" for their indexing to work as designed. It was likely in this forum that I have mentioned this long ago then trying to remember the complete 17 details). But as you say this was many generations of their systems ago and how we even talk about this stuff has changed some, let alone what we are talking about. Andy

rccardr 

Having had a lot of experience with the entire 740X range, I can say with complete confidence that modern cables work as well, if not better with these components, than the OEM spec cables.

tractopelle

Thanks a lot for your feedback, folks, I do appreciate it.