ArgoMan

Hi all! In another thread I described how I installed a Wolf's Tooth 1x chainring. I now want to switch out my 9-speed Sora rear derailleur to a 105 11-speed. I have a 34 tooth cassette I'll be using, so I just need a new rear mech and likely a new chain. One poster advised that I get a long cage derailleur. I ride basically nothing but flat roads. So, for my needs - and I'll be using a 50T 1x with an 11-34t rear - should I be using a medium or long cage (of short)? And why?
Thanks!!

Maelochs

I believe the matching derailleur would be a GS 7000 for the latest 105 and GS 5800 for the generation before .... I believe for road stuff Shimano offers "short" and "medium" only .... but the 5800 or 7000 GS should handle 34 teeth without any issues (I have a GS 5800 and a GS 6800 which handle 11-32 cassettes with lots of room.) I'd bet (if it were my bike) that it could handle 36 teeth, but I wouldn't tell you try that because I haven't though I have others have.

JohnDThompson 

There's no downside to using a longer-than-strictly-necessary derailleur cage beyond a couple grams additional mass. So if you have to guess, I recommend guessing on the longer side of your choices.

Camilo

Make sure that regardless of the long vs medium cage that they can handle the 34t sprocket. Often (usually) that spec won't be different between the long and short cages. But... 34t is pretty much within what usually works.

You can easily find the actual specs for both maximum sprocket size and chain wrap if you know the model number of the RD, just look it up.

SoSmellyAir

Wrong, at least with respect to OP's inquiry re: 11-speed Shimano 105 drive trains:.RD-_____-SS is short cage; and RD-_____-GS is medium cage. The first generation 105-5800GS can officially handle a 32T max cog, but everyone reports that it handles a 34T max cog just fine. The second generation 105-R7000-GS can officially handle a 34T max cog.

delbiker1 

Personally, I would definitely go with the GS, med length cage. As stated above, no downside. Keep the option of going to a larger max cog. I presently have a 7000 GS matched with a 7000 crank set that I switched to 46-36 rings. I have used from 11-28 to 11-36 cassettes, just changing chain length. I have an 11-40 cassette that I may try out of curiosity,

Jughed

I run a 34 with the medium cage 11-speed 105... no issues at all. I also run a 30 and change nothing when swapping over - chain length works for both situations.

Iride01 

If you ride flat roads, I don't think you'll ever have a need for a 34t rear sprocket. A 50 front with 34 rear combo is a 1.47 ratio. Do you find you need that ratio on your current bike very often enough to make it worthwhile having? If however you are carrying or pulling a load, then I'd understand better why you might feel you need that low a gearing to help you get going from a stop.

I think you previously said you have a 52/36 2x with 9 speed. With it in the 36 front and 24 rear it was close enough to the same ratio at 1.50. 1.44 if you were in the 25 rear.

Consider if you used those gear combos or lower often enough to make the extra cost of what you are doing with the wolf tooth worth it. However if you've already bought it, then that's moot now. But actually on a 105 GS in the current RD-R7000-GS, the max low sprocket is 34t. So you don't even need a wolf tooth.

ArgoMan

Thanks Iride. I have a 50T front 1x chainring with a 9-speed cassette presently. I'll have to check the cassette to see how many teeth the large ring has. I see your point as to the 34t sprocket. I actually never use it. In fact, I never even use the next largest sprocket. I seem to always stay within a range of 3-4 sprockets located in the middle to smaller. The bike in question that I'm building out is my "second" bike that I ride only occasionally when I want to feel extra speedy. For that purpose, is it better that I choose a cassette with smaller rings than one that leads up to a 34T? Thanks again!

Trav1s

I've used the 5800GS and 7000GS with the 11-34 cassette with FSA and Shimano 105 50/34 cranks without problems.