ZachWuth

If I were to adjust the rear derailleur so that it doesn't shift into the 2 highest gears, would anything bad result? Thanks.

JohnDThompson 

No. You just have two fewer gears available.

HillRider

You will have slack cable if you forget and shift into those locked-out cogs. No harm but you will have to down shift a couple of empty clicks to get to a larger cog when you want one.

Retro Grouch 

Maybe. It really depends on why you are doing this. If you're trying to make a 7-speed shifter work with a 9-speed cassette, it isn't going to index properly.

ZachWuth

I have 3x9 friction shifting. I just don't want to have to worry about shifting into those two gears at all. And I don't want to take it apart and take them out, so I figured if I limited the rear derailleur it would give me the 3x7 that I want.

Nerull

Couldn't you just not use them? This seems bizarre.

ZachWuth

I have a hard time judging where I am in the cogset with bar-end shifters, so to prevent constantly looking down to see where the chain is, I figure I could limit the derailleur.

Thanks for all the replies, I appreciate it

HillRider

Even so, the lockout will not prevent you from moving the shift lever to the unavailable gears.

Bill Kapaun

Your legs tell you if you are in a suitable gear. You don't need to look!

FastJake

No, it won't cause any issues. But as HillRider said the shifter will still have two "dead clicks" in it which might be annoying.

I would suggest getting a different cassette that is more useful to you, since those two gears apparently are not.

Nerull

If you're really set on ignoring two perfectly good gears, the trick is to set the limits to lock out the gears you don't want, then set your cable tension so that the highest position on the shifter is the highest non-locked out gear. The low RD limit will keep the shifter from moving into it's last two positions. It's very important that your low limit be set properly, and that it stays set, because the shifter will try to put the RD into the spokes if you do try to shift into those "gears".

Leaving dead clicks/excessive slack in the cables could allow your housings to come out their guides.

FBinNY 

You're over thinking this. If your system is set up properly, no harm will come from riding in any combination so there's nothing to worry about. Don't look or worry about it, when your feet ask for a lower gear downshift, if they say they can handle a higher gear upshift. When you feel you're near the end of the cassettes range in either direction, shift the front, and select the right gear in back.

Yes, every once in a while you'll find yourself bumping the end of the cassette's range when you should have shifted the front, but the extremes of the lever travel are fairly easy to recognize so after a short while that will become instinct.

While no harm will come from locking out the two higher gears, it means you won't have the use of them when they might be what you need with the middle chainring.

The bike is there to serve you and not the other way around, ride it and enjoy it, and don't sweat details.

ZachWuth

So if I understand correctly, if i were to adjust it according to your advice, there would be no dead clicks or excessive slack?

Nerull

No. What you are doing, in this case, is moving the indexing over two gears. The highest gear on the shifter is actually your 3rd highest gear. The 2nd is the 4th, and so on. The last two indexes on the shifter are off the end of the cassette. Since there is no higher position on the shifter than your setup allows, there is no cable slack. Even if you backed the limits out, it would not shift into those gears (But it would shift into the wheel).

ZachWuth

I see. Thanks for clarifying.

I suppose I'll gain more experience with the bike before deciding what action I may take.
Thanks for the advice everyone, greatly needed/appreciated!

FBinNY 

The validity of this advice depends on the RD geometry. Most RD pantographs do not have linear response to cable movement. The amount the RD moves for any given cable input changes as the geometry of the parallelogram changes through the working range. Levers compensate with slightly different click spacing. The difference is tiny, but when using the lever at the wrong end of it's range can add up causing poor shifting at either end of the range.

Also, while not ever having a slack cable may be desirable, the risk of over stressing a cable when accidentally shift to a ghost position at the low end is more of a problem. It can shorten cable life, and lead to cable failure, which isn't a crisis, but tends to happen at inopportune times.

The OP should either leave things alone, or leave the two ghost positions at the slack (high) end of the range. If his cable guides are open and the wire tends to slip, that can easily be fixed with a piece of electrical tape over the slot.

FBinNY 

Not true, the low gear limit would prevent that in any case. (if correctly set). It's the low limit's job to protect the wheel, and that's independent of the cable and lever.

Nerull

"Even if you backed the limits out, it would not shift into those gears (But it would shift into the wheel)."

dsbrantjr

"Also, while not ever having a slack cable may be desirable, the risk of over stressing a cable when accidentally shift to a ghost position at the low end is more of a problem. It can shorten cable life, and lead to cable failure, which isn't a crisis, but tends to happen at inopportune times."

My concern when you accidentally try to shift into one of the "ghost" positions would be jamming the ratchet in the shifter due to the overly-taut cable, leaving you unable to upshift and possibly damaging the shift mechanism trying to get it unjammed.

FBinNY 

Yes, I misread the "the backed the limits out phrase" thinking you were still referring the the high gear limits the OP wanted to change.

reddog3

No disrespect intended, or trying to over-simplify this, but how 'bout learning to ride. Once you get it your biking experience will be so much better.