52/36 and 11-30: short or medium cage?

[AW84]

R8000 medium or short cage for this gear setup? And can the same RD support a jump up to 53/39 on the front if so desired?

[K4m1k4z3]

Short is what came stock with 52/36 & 11-30 on my TCR. Works flawlessly. Should work the same if not better with 53/39 since that lowers the total capacity compared to 52/36 (14 teeth difference vs 16 teeth on the chainrings).

[spdntrxi]

you can do it with short...

[TomHelly]

Short. Unless you plan to use an 11-34 sporadically in the future.

I'm running that combination with an even 'shorter' cage 9070 and yet it works in big/big and small/small.

[posaunemeister]

Agreed with all. I have the same setup on one of my bikes and it works just fine. Also agreed that 53/39 wouldn't be a problem either.

[RussellS]

Shimano's specifications for the derailleurs is 35 capacity for the short, 39 capacity for the medium. 52-36=16. 30-11=19 16+19=35 So in theory the short should work. With zero margin for anything extra. Suppose you wanted to go to the mountains and wanted lower gearing. You're not a professinal who can climb mountains in a 39x23. So you either put on a 11-32 cassette or put on a 34 inner ring. Now your capacity is at 37, over the official maximum for the short cage. Maybe or maybe not a problem. But lets say you want to go crazy and go 11-32 cassette AND 34 inner ring. Now you are at 39 capacity. More chance it is now a problem with the short cage. And you insist on keeping the 52 outer instead of changing it to 50 outer because you want to zoom down the mountain at 100 kph in the 52x11. And changing outer rings is really expensive. I have long cage and short cage derailleurs on bikes. Never noticed any difference in shifting between them. Makes more sense to go with the medium length cage to give yourself all opportunities in the future.

[kytyree]

Yep, short should work but as mentioned above I went with the long recently. Even though 11-30 is more than enough where I live I can see me adding an 11-34 once in awhile if I'm going to be in the mountains. I think it shifts great.