Originally Posted by carlharsch
With a triple, the difference between a 9 and 10 speed would be 3 speeds, which you probably won't even notice. More important is the hub on your rear wheel and whether it supports the cassette on the rear. The rear hub/cassette gear teeth, in conjunction with the gear teeth on your crankset, have a lot to do with determining the lowest/highest gear you'll obtain.
What is your current gearing situation with your bike? And, what is your end goal for the change?
The 4603 is the newer version of the Tiagra, designed to be coupled with the 10 speed cassette. From first look, they appear to be the same, but I don't know if they are interchangeable with older hubs or not.
I'm currently in the process of swapping from 8 to 9 speeds, but the question arose due to the cost difference in the two tiagra triple cranksets.
i find the 4503 is $15 more than the 4603 despite being older.
so i was wondering if the '9/10' speed on the crankset mattered at all.
the reason for the crankset swap in lieu of just retaining my current 48/38/28 MTB triple, is to give me a slightly higher top speed, and to drop some serious weight with the square taper and heavy ass crankset
I'll be retaining a MTB rear derailleur and cassette, so I'll be able to run a 9 speed 11-34t cassette, with a 50/39/30 road triple (if I can find a 28 chainring to fit the bcd, i'd run 50/39/28 as my intended derailleur setup would support it).
my current rear hub (and future shifters) support 9 speeds.