Does my crank care whether I'm using 7 sp or 9 sp?
 

I know, there are millions of variations of the which components care what speed your set up is. I still don't get this one, though. Here's the deal--I bought a used bike, it's running 7sp casette with a triple. It's just about time to get a new wheelset, and I'm thinking it makes sense to build on new 9 sp hubs in case I want to upgrade the whole drivetrain. I know I can use a spacer to run my 7 sp cassette on my hub until I upgrade.

Here's my question--when I upgrade to 9 sp, I know I need to change casette, chain and RD. Do I need to chain my crank or chainrings?

Also, I'm using barcons. I'm not sure what speed they are. How can I tell what speed they are. They're Shimano "light duty" bar ends.

Thank in advance. I know these "what speed" questions get tedious.

No to crank and chainrings, and no to RD probably either. If you're using barcons and don't know what speed they are for, count how many clicks there are. If it doesn't match up you can always use them in friction mode.

I agree that you don't need to change your chainrings and I also doubt that you'll have any rear derailer issues.

if you can find a Shimano part number on the barcons then you can just google them to find out the number of speeds.

If you're counting the number of clicks to determine the number of speeds then remember that you get one more speed than the number of clicks. (Somebody please correct me if I'm wrong about this. I've thought too hard about it while typing, and I'm starting to doubt myself.)

You're correct, 8 clicks for a 9 speed. The position for the smallest cog is with the cable all of the way out, that's not a click.

Al

Uh, if the bike is currently set up 7-speed, then wouldn't the barcons be 7-speed? (If they're indexed.)

You never know.

True. The OP didn't actually say anything about the barcons.

Sounds like they might be friction-only barcons, and the OP is concerned that they might not shift over a nine-speed cassette.........If that's the case, then no worries, they'll shift nine-speed with a friction setup just fine. And if you want indexed nine-speed barcons, those are available, too, not terribly expensive. If the current barcons are indeed indexed for a seven-speed, then no, they won't work with a nine speed cassette in index mode, it'll have to be friction only.

And there's always the rear drop-out spacing question. 7 speed were normally on 126mm spacing, 9 speed requires 130mm.

Possibly, but not necessarily. For a while, frames were built with 130mm, but some groups offered 7-sp only, so there are quite a few 130mm 7-sp bikes out there.