8 to 9 spd

[james6]

If I have a 9spd Tiagra rear derailer w/ Sora shifters can I swap out the 8 speed stock cassete for a 9spd? Would I need different shifters? Or really just not a notable difference for the $35???

[curby]

assuming the shifters are 8sp a 9sp cassette is not gonna work with them. 9sp cassette cogs are spaced 4.34mm on center, 8sp are 4.8mm so the first couple cogs 'might' work but then the others will not align at all

until you get to the 9th position of a 8sp shifter and then it would shift very close to on top of the 10th cog of a 9sp cogset... hehe (just kidding around)

4.8 mm x 9 = 43.2mm
4.34mm x 10 = 43.4mm

all's'miles

curby

[Peter@vecchios]

If I have a 9spd Tiagra rear derailer w/ Sora shifters can I swap out the 8 speed stock cassete for a 9spd? Would I need different shifters? Or really just not a notable difference for the $35???

Chain distance moved per shift is determined by the shifter, not the rear derailleur.
9s cassette, 9s shifters.

[longfemur]

Don't bother. There is very little difference in real riding... certainly no meaningful difference. I would upgrade something else or buy some other accessory.

[artemidorus]

You'd need new shifters, new chain and new cassette. Wait until you break a shifter.