slisher

Hi All,

Complete amatuer here hoping you can help!

I've recently swapped my Shimano 10sp (11/25) cassette with a HG500 (11/34) to try and help on the climbs.

After swapping the cassette I now understand that I also need to change my rear derailleur (currently a Tiagra 4600 short cage).

However, I'm struggling to find one that is compatible with the HG500 cassette and Shimano STI 4600 shifters I have.

Does such a thing exist or do I need to look at changing more of the setup?

Thanks for any help.

BTinNYC 

Welcome to BF!
I checked the compat chart linked below and was surprised that the 5701-GS 105 RD I recommend has a listed max of 32 tooth rear cog. I am running that rear derailleur with 34 tooth cassette. YMMV

Compatibility chart

shelbyfv

A 9 speed Deore would be another choice.

Crankycrank

First, try the new cassette with your current derailleur as they sometimes have a little fudge room. Here is a chart that will show some compatible derailleurs if you want to switch. (4600 SS cage listed on row 185) Bicycle Cassettes & Drivetrains - Google Sheets You need a derailleur with a pull ratio of 1.7 to be compatible with your shifters and look at top of the page for the pull ratio column and find derailleurs that can also handle at least a 34t cog. Speeds listed are not important as 8,9, and 10 will all work.

grumpus

You might be able to extend your current derailleur with a hanger extender (search wolf-tooth road-link then find a cheap Chinese substitute if you prefer). Or you may need a longer derailleur for overall capacity.