Switching to a Medium Rear Derailleur Cage

Hey Folks,

I am planning on doing more climbing this summer and I am interested in putting a 34T cassette on my road bike. My bike has Shimano 105 and the rear derailleur currently has a short cage but I’ve read that in order to use a 34T cassette, i’ll need a medium derailleur cage.

So I am wondering if anyone knows if it is possible to just upgrade the derailleur cage itself, or if I am going to have to upgrade the entire rear derailleur?

If the current setup doesn’t work, just change the whole thing. RDs are pretty cheap, and if you start to pull it apart there’s a fair chance of ending up with little parts all over the floor. Life is short.

1 Like

Yeah, you could do it…but it is easier and likely close to the same cost to just get a whole new RD.

With 32 you can probably go with limiter screws , not sure about 34 (apparently it works with short cage). But if the change will be permanent not occasional change - then go with rear deraileur…they are probably one of the cheapest part of your bike :wink:

Problem Solved… $25 for the Road Link!

Using this on my Campagnolo Record Short Derailleur running a 32 on the back without issue.

They (Wolf) even state I could run a 36 back there… and measuring… yip… I could!


Under 50 bucks for a new 105-level RD from Competitive Cyclist.

From the RoadLink description: “RoadLink repositions your derailleur to provide clearance for larger cassette cogs but it does not increase derailleur capacity. It is critical to find and understand your derailleur’s capacity before attempting to expand its gear range.”

If you know what this means, and saving $30 makes a difference, go for it. But if it’s mumbo jumbo to you, get the new RD.

1 Like

Also check your chain length. You might need to add some links.


Absolutely possible, I went the opposite direction to you, went from a ‘climbing set up’ and swapped my stock GS cage to a set of OSPW.

However I’m fairly certain that if you want to swap to a stock Shimano cage (SS or GS), then it doesn’t come as a complete unit. You have to buy the components separately - inner plate, outer plate and maybe another set of pulley wheels (unless you take the wheels off your existing SS cage).

As others have mentioned, you should probably weigh up the cost of going down this route vs just buying a new 105 rear mech.

Unless you’re running di2 :money_with_wings:

1 Like

Definitely new rear derailleur, you will compromise your shifting otherwise :frowning:

There’s a reasonable chance that your current derailleur will work with the 34T even though Shimano says it won’t. Give it a go before you go buying new parts. It worked for me on the cross frame I just built up. You might need to adjust your b-tension screw.

Thanks everyone for the great advice. I think I am going to go the new RD route because I am going to be running this setup for awhile.

Now I get to go down the compatibility rabbit hole. I have the Shimano 105 5800 groupset, but Shimano 105 7000 has to be compatible right. :crazy_face:


1 Like

Sure is, I did exactly what you are planning and put the long cage 105 R7000 with the rest of my 5800 groupset so I could run the 11-34 cassette, it works smoothly.

With all that gear range I do find my chain flaps more, creating noise, especially noticeable on rougher roads. Because of this I actually wish I’d spent a little bit more and got the RX800 mech with the clutch. But the 105 still works great. And you might need a new chain for extra length too, so it does all start to add up.

1 Like

Thanks @Dylan_van_Green! This saved me having to go through the compatibility charts!

I have a SRAM 36 cassette on a 105 Der with a RoadLink, it works fine.

1 Like

Long cage or short cage?

A longer rear derailleur doesn’t just have a longer cage. The geometry of the parallelogram also differs, so that it tracks closer to the steeper angle of a larger cassette.

1 Like