Originally posted by doctorfrau
I definitely need a triple ring set, but will 24 speeds be enough, or should I cough up the cash for 27?

Does it really help? Are those other three on the "extremes", or are they stuck somewhere in the middle of the range where I won't notice the difference?
It depends on how many teeth each of the cassette gears have. Not all 8-speeds have the same gears. Not all 9-speeds are the same. Assuming that both bikes you are comparing have the same chain rings (probably 52/42/30) then you have to compare how many teeth each of the gears on the 8-speed or 9-speed cassette have.

If the 8-speed gears range from 12 to 26 and the 9-speed is 12 to 28, your lowest gear (easiest to pedal) will be slightly lower on the 9-speed (8-speed low gear 30:26. 9-speed low gear 30:28). It all depends on the number of teeth. But they do make 8-speeds that are 11 to 34. That would have a REALLY low low gear.

As far as "old technology" goes, I agree with pedalfaster in principle, but there is one more thing to consider. The 9-speed may need more fine adjustments. There is less space between the gears, so the derailleur needs index more precisely, or you may have some trouble shifting. On the high end components (Dura-Ace or Campy Record) the derailleurs are very accurate. But on lower end parts, the 8-speed might be less problems than the 9-speed. If you don't go with the higher end parts, your 9-speed bike may spend more time in the shop for adjustments. (Just my opinion... not fact). I hope this helps.