11-34 cassette on a short mech?

pete1336

I'm off cycling abroad in May with the nearest and dearest. She rides a Liv Langma with an ultegra r8000 groupset. She currently has a 11-30 casette with the shorter Shimano rear mech.
This guy on YouTube https://youtu.be/mltI7fkfP5I
demonstrates you can run a 11-34 on the shorter mech...it appears to work ok.
My question is about my options in case this doesn't work for me and I do need a longer mech. Do I need to buy a whole new rear mech or can you just buy the longer cage between jockey wheels? If I can't just buy a longer jockey wheel cage and have to buy the whole longer rear derailleur...would a wolftooth roadlink be a more affordable work around?
Thanks in advance

trevor.hall12

Shimano recommend a 32 max and as with all other previous versions you can go minimally 1 up from what they recommend .
Put this on a Liv Langma not too long ago and it works perfect

Mad_Malx

As above, You’re prob ok. Prob need to wind in the b screw.

Longer cage alone may not help. The cage length takes up the extra chain, but the ramp angle on short cage derailleurs is shallower so doesn’t always clear the big cog (but you may get away with it). Wolf tooth helps this by moving the derailleur further away.

pete1336

Thanks for your replies but I'm quite keen to know whether you can keep the upper part of the rear mech and jockey wheels and just buy from somewhere a longer cage between the jockey wheels?

Mad_Malx

Buy & fit the 11-34, wind in the b screw, and see if it works. Prob need a few more links on the chain, but there then might be too much chain to take up.
Whether it works or not depends (in part) on the geometry of your specific bike.

As I said above, the ramp angle may be a problem. If the derailleur does clear the big cog, then using an oversize jockey wheel might be a better solution than putting a long cage on a short body.
I’d say a long cage 105 is a better economy fix than messing around with the cage.

lesfirth

.
The only way to see if your short cage can handle a 34t sprocket is to try it. It is a bit frame/hanger dependant.
The difference between a short cage and a GS rear mech is not simply the cage, the body of the mech is different. Shimano only make short and GS rear mechs, no such thing as a long cage.
Exceeding the chain wrap capability of you rear mech is not a problem unless you use small sprockets and small chain ring, and if you inadvertently do you simply have a droopy chain. No disaster
.A used ( or new) GS rear mach. is not megabucks. A wolftooth thing is not cheap and in my experience do not work very well.
Unless you ( like me ) enjoy messing about with bike bits, just do as earlier posts advise and get a GS rear mech.
Messing about with your own bike is OK but not recommended with you other halves bike.

N0bodyOfTheGoat

I bit the bullet and bought a 7000 GS rear mech when I fitted an 11-34 a few years ago, which replaced a 5800 GS mech that was ~3 years old at the time. Just to simply know it officially worked.

The switch from an 11-32 was a transformation for my riding, despite just a 2T increase in range. The loss of 1T jumps at the high end didn't bother me at all because I rarely give it beans on the flat and downhill, but having more sprockets in the 16-34 range was great for the climbing gear options.

banditvic

Fitted a 11-34 to a mates Giant Propel r800 short mech, fitted and works perfectly.

navrig2

pete1336 said:

Thanks for your replies but I'm quite keen to know whether you can keep the upper part of the rear mech and jockey wheels and just buy from somewhere a longer cage between the jockey wheels?

I don't think you can just buy the cage, you need to buy a whole new rear derailleur.

N0bodyOfTheGoat

Don't know if it's cheapest place, but https://www.merlincycles.com/shimano-105-rd-r7000-rear-derailleur-11-speed-117065.html is £45 and https://www.merlincycles.com/shimano-ultegra-rd-r8000-rear-derailleur-11-speed-102880.html is £70 in their Shimano sale before Topcashback and using some loyalty points discount on a £75+ basket.

MidlandsGrimpeur2

Even though I don't run anything smaller than a 28 cog, I run a long cage on all my bikes now. It may just be in my head, but it does feel like it allows for smoother shifting across the smaller gears.

Plus, when I do need a bigger cassette the option is there for me.