COMBINING COMPONENTS

yes, provided both are compatible, specially if they belong to the same drivetrain family (7 or 8 or 9 or 10 gears)
check that out first,

the shift levers are the most expensive part of the whole system, so afterwards you could continue upgrading your bike one bit at a time,

It won't work. Since 105 is 10 speed, and Sora is 8/9 You'd have to get a new Rear Derailleur, Cassette, Chain, Shifters, and most likely a Front Derailleur. Your absolute minimum cost for all the components new will be about $450-500 if you're extremely lucky or buy used.

Quoted post said:

Originally Posted by ohwut [IMG]/img/forum/go_quote.gif[/IMG]

It won't work. Since 105 is 10 speed, and Sora is 8/9 You'd have to get a new Rear Derailleur, Cassette, Chain, Shifters, and most likely a Front Derailleur. Your absolute minimum cost for all the components new will be about $450-500 if you're extremely lucky or buy used.

This is true.

Campagnolo 9-speed shifters will index perfectly with your 8-speed Shimano Sora--and you won't have to replace anything else.
http://www.ctc.org.uk/DesktopDefault.aspx?TabID=3946

Hi. Thank you all for your answers. 2009 105 shimano does have 9 speed. Will it work?

Quoted post said:

Originally Posted by afcolector [IMG]/img/forum/go_quote.gif[/IMG]

Hi. Thank you all for your answers. 2009 105 shimano does have 9 speed. Will it work?

If your current Sora setup is 9-speed, then you probably can convert it to 10-speed with 105 (5600 series) levers, cassette, and chain. Possible issues will be running the chain through your current 9-speed chain rings and shifting the 10-speed chain with the Sora front derailleur, which is optimized for 9-speed.

5700 stirs the pot some more because the front shifter, front derailleur, and chainrings have been optimized to work with the new asymmetric chain. I'd avoid 5700 unless you're open to the possibility of upgrading everything except the rear derailleur.

Consider waiting 'til spring when Shimano introduces its new 10-speed Tiagra.