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Brifter compatibility with 6 speed Dura-Ace 7400

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Brifter compatibility with 6 speed Dura-Ace 7400

Old 05-25-19, 03:01 PM
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thunderfoot
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Brifter compatibility with 6 speed Dura-Ace 7400

I have a '72 Peugeot PX10 with full Dura-Ace 7400 (6 speed). My dad built the bike in the early 80's when I was a kid. A few years ago, he passed it down to me... and besides a minor tune-up, new tires, seat and bar tape, I ride the bike exactly as he built it way back when. I've loved this bike since I was 6 years old and riding it now, in my 40's just like my dad did, makes me truly happy.

I'd like to upgrade to aero levers and get new bars to improve the ergonomics and overall look.... simple enough, however in my quest for this more modern/ ergo set up, I started thinking about upgrading the SIS downtube shifters to brifters and killing two birds... or so I thought. I've searched the forum and internet for brifter compatibility with Dura-Ace 7400 6 speed but it doesn't seem very feasible OR maybe I'm just not understanding what I'm reading(?).

Ideally, I would like to change as little of the current set up as possible, for cost as well as sentimental reasons, but I'm open all suggestions even if they include rebuilding the rear wheel with a different hub/ gearing that would make this switch easier.


Thanks in advance


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Old 05-25-19, 03:11 PM
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a Gevenalle Brifter with 2 friction shift levers..

shift cable comes out the top


I personally use bar end friction shifters on my 6 speed s
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Old 05-25-19, 03:47 PM
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If brifters are not an absolute, you can get a rear wheel with 8,9 speed hub and the DT shifters, in friction mode, will work through the gears no problem. If the levers are 6 speed index only, it will not work. You can get a doublewall wheel with 8/9hub for under $75, a single wall for $50 or so.

91 Ochsner using 9 speed wheel/cassette with DT shift levers.
I did this with a rebuilt early 90s steel bike. I also cold set the rear spacing to 130 mm so the wheel would fit in the drop outs properly. I have yet to reset the drop outs but will do soon. Both not hard to do. Video by rjthebikeguy.
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Old 05-25-19, 03:56 PM
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Is your rear 6 speed a cassette or a freewheel?

Depending on your answer we can give you more focused suggestions about what to upgrade next in order to keep the parts playing well together.
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Old 05-25-19, 05:40 PM
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Originally Posted by thunderfoot View Post
I've loved this bike since I was 6 years old and riding it now, in my 40's just like my dad did, makes me truly happy.

I'd like to upgrade to aero levers and get new bars to improve the ergonomics and overall look.... simple enough, however in my quest for this more modern/ ergo set up, I started thinking about upgrading the SIS downtube shifters to brifters and killing two birds...

Ideally, I would like to change as little of the current set up as possible, for cost as well as sentimental reasons, but I'm open all suggestions even if they include rebuilding the rear wheel with a different hub/ gearing that would make this switch easier.


Thanks in advance


...if you are open to suggestions, mine would be to not do this project. It's dubious that it would be an upgrade, and from a C+V point of view, putting ergo bars and brifters on that bicycle will be one of those adventures you look back on in about ten years and ask yourself, "Why did I do that ?"
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Old 05-25-19, 05:46 PM
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..FWIW, I just took some perfectly functional Record 8 speed brifters off a Bob Jackson Super Tourer that someone before me assumed was an upgrade. It was PIA always reaching forward every time I wanted to shift gears. I replaced them with some very plain looking Sora 8 speed indexed downtube shifters, rebuilt the wheels with new, better rims and a Shimano compatible freehub, and I'm a lot happier when I ride it now.

I just find it a lot easier to drop one hand to the downtube and be able to shift either lever, or both at once with one hand.
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Old 05-25-19, 06:12 PM
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The short answer is that there in no Brifter/STI made that has the same cable pull as 6 speed 7400.
You could get 7403 STI units and mate them with a later 7402 RD and a matching 7403 wheelset but then you'd be at 8 speed.

Sadly, Shimano never made 6 speed STI units and 7400 cable pull is incompatible with other Shimano SIS systems.
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Old 05-25-19, 06:34 PM
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IIRC at the time 7400 was current the only 6 speed indexed system was the Shimano Positron, but it wasn't referenced as being "indexed". Andy
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Old 05-25-19, 06:56 PM
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The good news is you can still get some aero brake levers and call it done.
Or get the first generation Dura Ace brifters (8 speed), matching derailleurs, and a compatible wheelset and use the same crankset. Save the original stuff and ride , ride , ride.
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Old 05-25-19, 09:54 PM
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  • Per the attached (hope the attachment work, new to this), there are a couple of option that would work. Use the URL to see full site.
  • Assuming that you have a 6 speed Shimano freewheel the 7 speed shifter option should work with the 7400 series RD. Unfortunately, the only 7 speed road brifter I know of is the original RSX from the mid '90.
Attached Files
File Type: pdf
Spacing.pdf (118.6 KB, 17 views)
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Old 05-25-19, 10:20 PM
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Trust me: you do want brifters; all of my vintage bikes have been retrofitted with these for convenience and safety. I suffered with downtube shifters for 25 years - never again.

As correctly identified by KCT1986, Shimano 7-speed shifters will index a 6-speed cogset with a 7400 rear derailleur. I suggest a Microshift 7-speed unit, which can be had for less than $100 on AliExpress or Fleabay. Of course, you'll need cable housing terminators, to cover the downtube shifter bosses. And please strip off all of your old cables and housing and replace with new. Plus a new 6/7/8 speed chain.

'Vintage' brifters, such as RSX? Good luck with these... I volunteer at a big-city Co-op, and we see many sets of these pass through our doors. Unless they were packed in a time capsule, there is only a snowballs' chance that a set of 25-year old Shimano brifters are functional or recoverable.
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Old 05-25-19, 10:48 PM
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Shimano does make 7-speed brifters (albeit for entry-level groups): https://www.amazon.com/Shimano-Tourn.../dp/B00961NHA4

The math seems to work when I use @KCT1986's chart -- thanks for that.
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Old 05-26-19, 12:34 AM
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Originally Posted by fietsbob View Post
a Gevenalle Brifter with 2 friction shift levers..

shift cable comes out the top


I personally use bar end friction shifters on my 6 speed s
Nifty alternative to bar end shifters. That should solve the problem for pre-index shifting 6 speeds.
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Old 05-26-19, 05:30 AM
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Gevenalle shifters get my vote.
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Old 05-26-19, 07:24 AM
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Originally Posted by thunderfoot View Post
I have a '72 Peugeot PX10 with full Dura-Ace 7400 (6 speed). My dad built the bike in the early 80's when I was a kid. A few years ago, he passed it down to me... and besides a minor tune-up, new tires, seat and bar tape, I ride the bike exactly as he built it way back when. I've loved this bike since I was 6 years old and riding it now, in my 40's just like my dad did, makes me truly happy.


I'd like to upgrade to aero levers and get new bars to improve the ergonomics and overall look.... simple enough, however in my quest for this more modern/ ergo set up, I started thinking about upgrading the SIS downtube shifters to brifters and killing two birds... or so I thought. I've searched the forum and internet for brifter compatibility with Dura-Ace 7400 6 speed but it doesn't seem very feasible OR maybe I'm just not understanding what I'm reading(?).


Ideally, I would like to change as little of the current set up as possible, for cost as well as sentimental reasons, but I'm open all suggestions even if they include rebuilding the rear wheel with a different hub/ gearing that would make this switch easier.



Thanks in advance




Classic vs. Brifters...


Have you ridden much with brifters? If not, I suggest you try them a few times, and see what you think... I have a LeMonde with Shimano Ultegra. It is a great riding bike. It is, and yet I ride it less than the others (probably sell it, actually) . "Suffering with downtube shifters for 25 years"? Yikes... If I felt that way, I'd get brifters too. I don't though. Just saying try them out. Then if you want brifters, and someone here has a solution you like, go ahead. It's your bike. I understand the money thing- Swapping out rear wheel, bars, derailleurs, shifters, cables, bar tape,,, Probably be less expensive, certainly less headache to find a good used bike from the '00s than to completely rework your bike. BTW, I think your bike looks great.
Cheers


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Old 05-26-19, 11:01 AM
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I've reworked a few vintage bikes over the past couple years and have added brifters to most of them (for various reasons). Basically, I went to brifters because of age and experience (both young and old) and perceived safety. On my main rider (1980 Pro Miyata), I converted to a full Dura-Ace 8-speed brifter setup for which I had to spread the rear dropouts to accomodate the 8-speed hub. It works perfectly, and I would not hesitate to do it again. On my grandson's '89 Miyata 312, I added a 7-speed freewheel and an early Sora 7-speed brifter - also works very well. On my son's '88 Schwinn Circuit, I have a mish-mash of parts, but the shifting is done with RSX brifters and a 105 rear derailleur. That setup shifts just fine, but the RSX units need more attention and maintenance in terms of lubrication. I think a bike as nice as your PX10 begs to be ridden and it deserves a nice setup. I'd recommend you bite the bullet and do a nice, vintage Dura-Ace 8-speed setup. It might be a bit more expensive, but it will really increase your riding enjoyment. Have fun with the bike!
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Old 05-26-19, 06:12 PM
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...I don't get the "safety/perceived safety " with brifters thing ? How do you guys get a drink from your water bottle ? Do you stop every time you pull it out of the cage ? Serious question. How is reaching for a DT shifter any harder than retrieving a water bottle on the fly ?

In fairness, I do have some bar mounted bottle cages, but only on bikes that originally came without DT bottle cage braze- ons.
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Old 05-27-19, 07:40 PM
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First off, I just want to say thanks for ALL of the responses and especially the kind words about the bike.


In response to a few of the posts above:


It is a 6 speed freewheel, not a cassette.


I've seen the chart that KCT1986 posted, but I don't really understand how to read it. I mean, in my case am I basically just using that chart to identify the length of cable pull?


Also, I did some digging on the Microshift 7 speed brifters. The price is right, although I did come across a guy that had tried using them with a 7402 RD and it didn't sound like it worked very well. He ended up having to switch to a Microshift derailleur and even then it seemed as though he was kind of just making due.


Dave Mayer, have you experienced any issues with them?


If the Microshifts worked perfectly with my RD, I would be down to go this route, however if I need to get into switching derailleurs, I would rather invest in a proper upgrade (more gears, cold setting the frame, new RD, etc). It kind of sounds like I may be headed in this direction.....
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Old 05-27-19, 09:27 PM
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Originally Posted by thunderfoot View Post
I've seen the chart that KCT1986 posted, but I don't really understand how to read it. I mean, in my case am I basically just using that chart to identify the length of cable pull?
I had to stare at it a bit myself. Along the left side, you have the cable pull for various Shimano/Campy shifters. And along the top, you have shift ratios for various Shimano (including DA), Campy, and SRAM rear derailleurs. When you multiply the two numbers by each other, you get the RD's lateral movement per shift, which needs to match the cog spacing (pitch). For the drivetrains on my bikes, Shimano 7-speed shifter (2.9mm cable pull) times the derailleur's shift ratio (1.7) equals the cog spacing (5.0mm). Well, close enough (4.93). A lot of this data is user-gathered.

So for Shimano 6-speed, the bogey value for pitch is 5.5mm. If your rear derailleur's shift ratio is 1.9, then you need a shifter that pulls about 2.9mm of cable per shift. Hence why a couple of us figure that a regular 7-speed shifter might do the job.
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Old 05-28-19, 01:37 AM
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The info in the PDF is just a brief part of the explanation. Use the URL on the top of the screen capture to read all of the info. The web site isn't mine, just something I found while doing research on mixing drivetrain parts.

Regarding the comment of problems with the Microshift & RD-7402, I wonder if they were trying to use a 7 sp shifter & RD-7402 with a 7 sp spaced cogset.
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Old 05-28-19, 07:08 AM
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Originally Posted by 3alarmer View Post
...I don't get the "safety/perceived safety " with brifters thing ?
Open spaces I use DT shifting. It is proven that reaction times slow with age. As our town grew I added brake/shifters on my town bikes and bikes I travel with for time in downtowns like Portland, OR. I want both hands on the bars in traffic. It is a frequency thing, I grab a bottle much less frequently than shifting and most often at cities frequent stop lights or signs.
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Old 05-28-19, 07:59 AM
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Originally Posted by ThermionicScott View Post
I had to stare at it a bit myself. Along the left side, you have the cable pull for various Shimano/Campy shifters. And along the top, you have shift ratios for various Shimano (including DA), Campy, and SRAM rear derailleurs. When you multiply the two numbers by each other, you get the RD's lateral movement per shift, which needs to match the cog spacing (pitch). For the drivetrains on my bikes, Shimano 7-speed shifter (2.9mm cable pull) times the derailleur's shift ratio (1.7) equals the cog spacing (5.0mm). Well, close enough (4.93). A lot of this data is user-gathered.

So for Shimano 6-speed, the bogey value for pitch is 5.5mm. If your rear derailleur's shift ratio is 1.9, then you need a shifter that pulls about 2.9mm of cable per shift. Hence why a couple of us figure that a regular 7-speed shifter might do the job.
Thanks for breaking it down, this makes perfect sense now.

Originally Posted by KCT1986 View Post
The info in the PDF is just a brief part of the explanation. Use the URL on the top of the screen capture to read all of the info. The web site isn't mine, just something I found while doing research on mixing drivetrain parts.

Regarding the comment of problems with the Microshift & RD-7402, I wonder if they were trying to use a 7 sp shifter & RD-7402 with a 7 sp spaced cogset.
I guess I missed where you said to check out the URL for more info... I read through it and it definitely helps. Thanks... again

The guy with the Microshift and 7402 RD WAS USING A 7 speed cog set... oddly enough he originally had a 6 speed but I donít think he ever tried to run it, he upgraded the cog set at the same time he put the brifters on.

I havenít seen what the cable pull is on the Microshift units.... it just says they are totally compatible with Shimano... that doesnít instill confidence in me, lol
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Old 05-28-19, 05:33 PM
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Originally Posted by thunderfoot View Post

I haven’t seen what the cable pull is on the Microshift units.... it just says they are totally compatible with Shimano... that doesn’t instill confidence in me, lol
...AFAIK, the Shimano cog spacing is all the same Within a specific number of rear cogs....even with the early DA stuff. Where DA was distinct from the other Shimano stuff was in the DA pull ratios in the shifters and rear derailleur. So If something says it's compatible with Shimano, and you have a Shimano cogset on your rear freehub, the combination should work.

It gets more confusing if you try it with a freewheel. Early Dura Ace worked very, very well. It was just designed intentionally to not work mixed with the other Shimano component lines, like 600.
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Old 05-28-19, 06:35 PM
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Originally Posted by 3alarmer View Post
...
It gets more confusing if you try it with a freewheel. Early Dura Ace worked very, very well. It was just designed intentionally to not work mixed with the other Shimano component lines, like 600.
Two things: first, Shimano 600 SIS came after Dura-Ace 7400. 600 was designed to not work with Dura-Ace, not the other way around. I don't know the reason for the change, which was probably due to the longer cable travel of 600 SIS being more resistant to indexing 'issues'. Such as dirt, bad cable housing and various mis-adjustments. Or it may have been due to Suntour's Accushift system being released after Dura-Ace 7400, and Suntour copied the same cable pull ratio. By then changing the pull ratio of every SIS system subsequent to Dura-Ace, Shimano sure pulled the rug from underneath Suntour! Shimano did the same thing a few years later with Gripshift, and Shimano's new light spring derailleurs.

But the main point here is that Shimano 6-speed cassettes and freewheels all have the same cog spacing. They are all cross-compatible, regardless whether they are Dura-Ace, 600 or Tourney.

Same as with 7-speed systems. Shimano is all cross-compatible.
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Old 05-28-19, 09:07 PM
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Hey Dave,

You mentioned early Accushift, do you know if anyone has accurately measured the shifter pull/derailleur actuation ration for these. I have an early set, Sprint 7000 series, I believe (1987?) and am curious if these are like the Shimano 7400? 600? or totally different? Trying to figure out of these work with any Shimano brifters. Since the RD doesn't have Centeron, trying to figure out how close to optimum alignment it would be.

Thanks for any info available.
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