Sora for Shimano 105

[krysarn]

Hello, I bought entry level roadbike with Shimano Sora on it. Derailleur is Shimano Sora RD-R3000 9 speed with Shimano CS-HG200, 11-34T cassette.
I ride bike more and more and would love to add some more gears. Is it possible to buy just the shimano 105 derailleur with new cassette and swicth it. And stil be able to use Sora shifters and original sora Front derailleur? Or do I need to buy the whole new system that means probably to just buy a new bike. I really like my current bike so just the upgrade would be better for me. Can you please advice. Thank you. Christopher

 

[Ajax Bay]

You'd need to swap your RH 9sp Sora STI for an 11sp one (you have 8 clicks now: you need 10 (obv)).
The rear wheel freehub is likely to be 8-10sp: an 11sp cassette will not fit on. But you can replace the freehub (for an 11sp one). Or there are some 11sp cassettes which would fit (see other threads).
Otherwise should work: the 11sp chain will work on the current chainset, though there is a risk the narrower chain can get stuck between the 2 rings.
There are N+1 treatments for upgraditis.

 

[Jameshow]

You'd need to swap your RH 9sp Sora STI for an 11sp one (you have 8 clicks now: you need 10 (obv)).
The rear wheel freehub is likely to be 8-10sp: an 11sp cassette will not fit on. But you can replace the freehub (for an 11sp one). Or there are some 11sp cassettes which would fit (see other threads).
Otherwise should work: the 11sp chain will work on the current chainset, though there is a risk the narrower chain can get stuck between the 2 rings.

Except that a 11spd sti will not work with a Sora rear mech the pull ratio is different. You'll need a 11spd 105 rd too. Your looking at £100 sti, £50 rd, £35 cassette £15 chain.
Not to mention the freehub issue Ajax refers too above.

You could go to 10spd by changing to tiagra 4600 pretty easily.

 

[Ajax Bay]

Is it possible to buy just the shimano 105 derailleur with new cassette and swicth it

a 11spd sti will not work with a Sora rear mech the pull ratio is different. You'll need a 11spd 105 rd too.

The OP recognises the need to procure a 105 11sp RD (see OP).

 

[boydj]

I doubt that the upgrade you suggest would make very much real-life difference to your cycling, especially for the money and effort to make the changes. If you don't have a gear you can comfortably cruise in or you want a higher gear to let you go a bit faster, then swap out the cassette for something a bit more suitable.

Enjoy your cycling and save up your money for a better bike - there are some great 2nd hand buys on e-bay that would give you a better quality frame and higher level components.