My wife's old Diamondback MTB (circa 1995) is now serving commuter duty on pavement. It's great, except that she's dissatisfied with the gearing since the 8-speed Deore LX cassette is very widely spaced (for offroading). It's probably a 12-32 with big jumps between each gear.

Can we substitute a new Shimano or IRD 8-speed road cassette, perhaps a 12-23? I imagine we'd need to remove a couple links from the chain. But is the cog spacing compatible between road and mountain? Would the LX rapidfire index shifters still work? Any snafus matching up the new cassette with the old LX rear Der'? Thanks for any advice...

Cog spacing is compatible on all Shimano 8sp cassettes, except D/A. The shifters will work. I agree you probably will have to remove a couple of links. Not sure what kind of snafus you're expecting, but once the chain length is dialed-in, I can't see any problem, other than that the shifting on the rear might be a teeny bit less "crisp" than with a road-specific derailleur.

...the shifting on the rear might be a teeny bit less "crisp" than with a road-specific derailleur.

Hmmm... Since I have your ear... We also have a 'retired' Ultegra double road kit circa 1999. I wonder if we can put the short cage Ultegra derailleurs and the 53/39 double crank on that MTB in order to improve its drivetrain (still assuming the narrow range 8-sp cassette)? We'd keep the rapidfire shifters on flat handlebars. Perhaps that would be a bit goofy looking, but it's all in the name of tigher shifting on pavement.

Assuming that works, I can just imagine how many iterations of gain ratio I'll be looking at on Sheldon's website tonight...

I've never seen a road crank installation on an MTB that was a happy affair--given the wider spread of the chainstays, the bottom bracket spindle has to be freakishly long, and there goes the chainline! You'd be better off getting the largest "cheap" aftermarket chainrings that'll fit the MTB cranks you have; if you have a 110mm BCD, you can scare up a 48 or 50 pretty easily. It's hard to say outright that the Ultegra mech will or won't work. The issue here is chain wrap, not maximum cog size. I once bought a used 'cross bike the previous owner had kitted out with a triple (52/40/32) and a 12-25, running a 600 r. der, and it actually worked fine. My suggestion? Try running the narrow-range cassette with the LX derailleur first--there's every chance that you won't need to do anything else, and if you do find you want to use the Ultegra, it's no big deal to swap it after testing the LX's suitability.

Edit: OOPS! I just had enough caffeine for the mention of "1999 Ultegra" to slip through. The one-size-fits-all Octalink BB will not only make it undesirable, but most likely impossible to use the Ultegra--I can just picture that 53T gouging a nice slot in the driveside chainstay....