theopowers

So where does one get parts to space a hub? I don't even know what to type in online to search. I got ahold of an older Cannondale touring frame that should be spaced at 126, but it's actually a little over 128, and I suspect that clamping down on the hub is causing some shifting problems with the rear derailleur.

I have overhauled hubs before, but I've never needed to make any changes. Can I just throw any old washers on from the hardware store, or can I get lightweight bike specific stuff easily for DIY?

well biked

I doubt that's what's causing your shifting problems. With 128mm dropout spacing, I'd guess your frame is from the very late '80's or early '90's. That was fairly common during that time period so that either 126mm or 130mm hubs could be easily used. Any derailleur misalignment caused by that small a distance wouldn't amount to enough to cause problems, assuming the derailleur hanger's properly aligned to begin with-

theopowers

Cool, that's a useful tidbit. The "shifting problem" is actually that the chain won't go to the smallest cog, limit screw be damned. I can get it to drop with just a little pressure from my hand, so I was hoping that that little one millimeter of angle might allow that extra little movement it seems to need.

vpiuva

A LBS that's been in business awhile should have a large assortment of spacers in their parts bin they will sell you cheap. If you do buy something at the hardware store make sure it is stainless as their regular fasteners, including the galvanized stuff, will rust.

DannoXYZ 

That's a sure sign of cable-friction. The spring isn't strong enough to overcome the friction and pull through the cable that last little bit. Make sure the BB cable-guide is clean, a little oil on the cable helps. Also drip some oil into the RD pivots. Also the loop between the chainstay & RD should be even with no kinks. The cable should go through the cable-stop and housing-ends in a straight line.

Bill Kapaun

Is the cable still a bit "snug"?
Loosen it up a bit more and see if it shifts.
You could try any old washer that fits, if it works, get a stainless one??? plastic???

theopowers

I should have said "limit screw and cable tension be damned". I have the problem with no cable installed.

well biked

You might just try a different derailleur. Is it the original derailleur that was on the bike?

theopowers

It is original, and my first instinct was that the derailleur was just done. But I don't know anything about SunTour derailleurs and compatibility, and I don't see anything on the net that is as useful as Sheldon's pages on Shimano.

well biked

Are you using friction or indexed shifters?

theopowers

Friction.

well biked

If it turns out that a different derailleur will solve the problem, there's no compatibility issues to worry about between brands of derailleurs or shifters; your friction shifters will work regardless-