Index shifting questions
 

So I am new to Index shifting, I have never owned a bike that uses itnor have I worked with installing index shifters.. I mean I get the concept and everything. But friction has always worked for me.

Anyway I am building a road bike and I have 7speeds (13-28) in the back and 2 (34-48) up front. I know my chain capacity (29 btw)and everything else and so on.


I am looking at shimano ultegra short cage RD and ultegra FD for my bike but I want to use downtube shifters.

And for my shifters I found a 7sp shimano sante, or my other option would just to go with a dura ace shifter.

I found some a couple places selling some Dura Ace downtube shifters but they are rated for 9 or 10 speed. I found a couple used ones and some NOS that are rated for 7speeds.

Do I have to go with shifters that are rated for 7sp or can I use a 10sp one, and modify it in some way**********

I am far from an expert, but I do believe it is best to use a 7 speed index shifter with a 7 speed rear derailleur. Sometimes there are ways to make a 7 speed shifter work with a 6 speed derailleur, etc. I am not aware that you can take a 9 or 10 speed shifter and utilize it with a 7 speed rear derailleur. In other words, the number of clicks in the shifter must equal the number of indents and clicks in the rear derailleur.

I figured this, though in the past I have used friction RD that are rated for 10sp on a 5 or 6 speed bike. And they worked fine, I think my chain came off my gears maybe twice this summer.

Anyway if I use a 7sp shifter I would think that it would utilize only 7 clicks on a 10 speed RD since the cable can only pull so far.

the number of "stops" in the shifter must correspond to the number of gears on your rear wheel (except in a few cases of "they happen to line up if we finnagle it this way").
You need 7-speed Shimano shifters, and if you've got them, then great.

Now, Shimano rear derailers produced since the advent of indexed shifting all have the same ratio (of how far they travel per amount of cable pulled by the shifter) and are thus in theory compatible with each other. (This excludes pre-9-speed Dura-Ace, which had its own unique cable-pull ratio)
What differs now is that the tolerances of derailers have gotten tighter as number-of-gears has increased. So a 9-speed-era rear derailer will shift fine (and very snappily) on a 7-speed system, but a 7-speed-era rear derailer will probably shift sluggishly on a 9-speed system.

[QUOTE=jacksbike;10122467, the number of clicks in the shifter must equal the number of indents and clicks in the rear derailleur.[/QUOTE]

I don't mean to sound like a smart a$$ but actually a 7-speed indexed shifter will click 6 times because the first position is simply all of the cable out.

Your shifter needs to match the number of gears in your cassette. A 9 or 10 speed shifter pulls a different amount of cable than a 7 speed and won't line up your rear derailleur. You could try it, but would most likely find that it feels like the chain is always needing to finish a shift-like it's stuck between gears.

The rear derailleur doesn't matter. It moves whatever amount the shifter tells it to.

So basically any indexed shimano shifter will work, exluding dura ace.

I think i will go with the Sante shifter then. Thanks!

modern derailuers don't have clicks, they move, within the limits of the hi/low stops, to what ever position that the shifter pulls them to. if you
have a 7 speed cassette, you must use a 7 speed shfter, if you want index shifting!!

Just take good care of those Sante parts, as they are starting to have some collectable value.

No, you've got it backwards. Since you have a 7 speed cassette (or freewheel) you need 7 speed shifters. Any derailer will work.

haha oh duh....