tellyho

I write in desperation. I have been trying to fine-tune my RSX triple FD for a year. I can get it to where I get chain rub during extreme cross-chain (large-large, small-small), which I expect. However, when tuned thusly I still loose the next two cogs on the rear cassette as well (7 spd.). Meaning, my chain rubs on the smallest three cogs on the cassette when in my granny ring. I feel like this is unreasonable.

Things I have tried:

Cable tension
Limit screws
Derailleur height
Derailleur line-up with chainring

I guess what I need to know is: a. should it be possible to set this up so that I only get chainrub when cross-chaining (or not at all), and b. do you have suggestions as to how I do this? TIps? Tricks?

Or do I get a new FD?

Ingleside

Somestimes you'll still get chain rub in some combinations other than just when you are in the extremes.
Honestly, i consider the granny and the hardest rear gears cross chainging. you could proabbly get a similar ratio in the middle ring and some of the lower gears.
Assuming your FD cage is straight make sure the outer cage is aligned with the outer chainring looking form the top down and that the cage is aobut 3 to 4 mm above the teeth on the outer chainring. The other thing to make sure is dialed is the lower limit screw on the FD. Usually you can dial it in so that the inner cage is within about 1 to 2 mm from the chan when the FD is in the granny and the RD is in the easiest gear. Just make sure that the chain will still shift down from the middle to the granny and you should be set.
Once you have thoes two things set up leave the FD in the granny and shift the RD to the gear that are giving you trouble in the back. if you still get rubbing theres proabbly nothing you can do without performing some type of special bend that will allow you to run the combo you want to.

Sheldon Brown

Most RSX front derailers were designed for 46-36-26 chainwheels. Are those the sizes you're using?

See also: https://sheldonbrown.com/derailer-adjustment

Sheldon "Our Essex" Brown

Retro Grouch 

So do you ever use the smallest three cogs when riding in your granny ring?

RussB

Even if your derailers are adjusted perfectly you will still get chain rub in the most extreme cross chaining configurations. I have a triple in the front and 10 gears in the back. I used https://www.parktool.com/repair/ to setup my derailers. The also have a good section on breaks too. But when riding I don't cross chain to that extreme very often I usually run the granny gear when approching steep or very long hills. and the large chainring when approching nice downhill runs. I use the middle chainring most of the time. But check out the parktool website. After I used the setup (in order) from that site. I went for a test ride and only made a couple quarter turn adjustments and it was perfect. Don't forget, If you have a triple in the front, your front derailer probably has what is called "trim". When you shift you may feel what seems to be 4 shifting positions with only 3 gears. By using this "half shift" or "trim" on the middle chainring you won't have any chainrub when running the middle gear.

tellyho

Russ - no trim on RSX, sadly. They're base-level STI.

Sheldon - your site is, of course, invaluable. I am running the RSX gruppo, so the crank and rings should be the numbers you quoted. I haven't checked. Prior owner would not have been the person to change that up.

Retro Grouch - your point is a good one, and the answer is mostly "no". However, I feel like I should be able to use them. I am entitled to functioning gears!

Ingleside - thanks for the number reminders on FD clearance. I will check all of those.

Thanks all for the suggestions. The general impression I am getting is a mild and gently-put "suck it up". So suck I shall.

HillRider

I'm a bit late to this thread but there is one possible thing you should check.

Shimano front derailleurs have a little tab that sticks out on the inboard side of the cable fixing bolt at about the 8:00 or 9:00 position seen from the rear of the bike. The cable should be routed over and above this tab. It should NOT be routed between the tab and the fixing bolt. Routing the cable correctly makes a big difference.

tellyho

Good point. I'm pretty sure it's routed correctly, but if it isn't, I'll kiss you.

Al1943

I believe RSX triple chainring sets came in two different sizes. I think that is why Sheldon asked the question. If you don't know the size of the chainrings look for a stamped number on the rings or count the teeth. The derailleur needs to match the chainring sizes within a reasonable tolerance.
The RSX triples that I'm familliar with had great shifting performance, at least as good as Ultegra.

Al

Portis

The more prudent thing is to just not run those combinations. I ride triples all the time and can't ever remember running in the granny and the 3 outer rings. What would be the point? Isn't the point of a triple to give you an extra chainwheel?

oilman_15106

+100 on this.

tellyho

Oh, I could definitely not run those combos, and am a very conscious shifter in general. But then I would be thinking "I can't use those combos, and probably never would, but dammit, I SHOULD be able to."

I like knowing that if my FD shift cable broke in the middle of a long ride while I was in the small chainring, I'd be able to use all of my cogs. And yes, I know it's ridiculous.

Al1943

It would be normal to have chainrub on the most extreme cross-combinations, but yes, you should be able to use all others, whether it's advisable or not.