Rear Derailleur

[Brendon On Dad Brown]

So here's a question: Has anyone changed the roller arms on a short cage jockey to a long cage and has it worked. Reason is i have heard that short cage jockeys can take 11/32 cassette with 34/50 crankset. I was bit sceptical as a short cage Ultegra /Dura ace can go up to 28.  Then i saw a video where it is working perfectly fine. 1)What would the longevity be of the Jockey?

2)would an extender to the jockey not be a better option?

[David Marshall]

1 hour ago, Brendon On Dad Brown said:

So here's a question: Has anyone changed the roller arms on a short cage jockey to a long cage and has it worked. Reason is i have heard that short cage jockeys can take 11/32 cassette with 34/50 crankset. I was bit sceptical as a short cage Ultegra /Dura ace can go up to 28.  Then i saw a video where it is working perfectly fine. 1)What would the longevity be of the Jockey?

2)would an extender to the jockey not be a better option?

Be careful of what you see and hear.  Different series and speeds of derailleur have different capacities. For example Ultegra 11 speed 6800GS can handle a 32/11 cassette while the 8000GS can accommodate a 34/11.

There are hacks to get around the max capacity but in my experience there is always some compromise.

[Brendon On Dad Brown]

HI, Yes hence me asking as the older DuraAce / Ultegra 10sp would allow up to 28 cog, so when i saw a 11/32 and it was shifting I was How is this possible, even without the Jockey extender to assist travel.

[bleedToWin]

6 minutes ago, David Marshall said:

... while the 8000GS can accommodate a 34/11.

And folks would see this somewhere and then promptly slap a 11-34t on a R8000-SS 🙈

[bleedToWin]

OP, what exactly are you trying to do on what generation derailleur with what cage length? Also, what's a roller arm?

[droo]

It depends. If the RD you have has a long cage version, you should just be able to swap the cage out if you can find the long cage version for that specific RD.

A hanger extender is a recipe for terrible shifting.

[bleedToWin]

3 minutes ago, droo said:

If the RD you have has a long cage version, you should just be able to swap the cage out

Very rarely is it only the cage design that is different. Most often the long cage version has a different derailleur body design too.

[Brendon On Dad Brown]

42 minutes ago, bleedToWin said:

OP, what exactly are you trying to do on what generation derailleur with what cage length? Also, what's a roller arm?

Hi.Im not sure what model Ultegra derailleur it is , but what i do know there was a 11/28 cassette on, now there's a 11/32 WITH 50/34 crankset upfront.

[DieselnDust]

56 minutes ago, David Marshall said:

Be careful of what you see and hear.  Different series and speeds of derailleur have different capacities. For example Ultegra 11 speed 6800GS can handle a 32/11 cassette while the 8000GS can accommodate a 34/11.

There are hacks to get around the max capacity but in my experience there is always some compromise.

Spot on, GS does not equal GS on every derailleur model. It just denotes the shorter cage version. 

For increased capacity ones could consider a SGS derailleur cage option but tread carefully as they are not all compatible with all derailleur models

[DieselnDust]

57 minutes ago, Brendon On Dad Brown said:

HI, Yes hence me asking as the older DuraAce / Ultegra 10sp would allow up to 28 cog, so when i saw a 11/32 and it was shifting I was How is this possible, even without the Jockey extender to assist travel.

its possible due to the 34 small ring. With a 36 the largest sprocket would be a 30 and with a 39 inner chain ring that would drop to a 28 tooth sprocket

[Brendon On Dad Brown]

Okay then possibly i understood the explanation incorrectly. Thanks all

[bleedToWin]

42 minutes ago, DieselnDust said:

its possible due to the 34 small ring. With a 36 the largest sprocket would be a 30 and with a 39 inner chain ring that would drop to a 28 tooth sprocket

Why would this matter? This only affects chain length really.

This generation derailleur did not support larger than 27t officially, probably mostly because those cassettes didn't exist back than. The only 27t cassette was a 12-27t, and if you wanted the 11t you had to take the 11-23t. The SS vs GS allowed for a larger jump in the chainrings. I'm guessing the guide pulley is actually capable of handling larger than 27t so with aftermarket options folks figured out it can clear a 32t without issue. Note that total capacity is 29 on the SS, so with an 11-32t you can only have 8 tooth difference up front (which you won't find anywhere). With GS the capacity is 37, so 34/50 or 36/52 or 39/53 should all work.

[DieselnDust]

formula for derailleur capacity is (Bigring-smallring) + (bigsprocket - small sprocket)

DeCap= (BR-SR) + (bs - ss)

 

if we consider ss a constant then size of the small ring v the big sprocket becomes the driving factors

Ys chain length is an influencer too

on the same bike with a given chain, if you reduce the size of the small ring you can increase the size of the big sprocket to remain within the capacity of the derailleur.

 

Am I a little clearer than a one liner + caveat now?

[bleedToWin]

14 minutes ago, DieselnDust said:

formula for derailleur capacity is (Bigring-smallring) + (bigsprocket - small sprocket)

DeCap= (BR-SR) + (bs - ss)

 

if we consider ss a constant then size of the small ring v the big sprocket becomes the driving factors

Ys chain length is an influencer too

on the same bike with a given chain, if you reduce the size of the small ring you can increase the size of the big sprocket to remain within the capacity of the derailleur.

 

Am I a little clearer than a one liner + caveat now?

It's not recommended (sometimes not even possible) to go down to to such a small small ring without also reducing the big ring size, so I took BR-SR as mostly constant.

[bleedToWin]

2 hours ago, DieselnDust said:

With a 36 the largest sprocket would be a 30 and with a 39 inner chain ring that would drop to a 28 tooth sprocket

 

19 minutes ago, DieselnDust said:

DeCap= (BR-SR) + (bs - ss)

And also, your math aint mathing

First post said larger SR would reduce DeCap 😉

Edited September 26 by bleedToWin

[DieselnDust]

2 hours ago, DieselnDust said:

its possible due to the 34 small ring. With a 36 the largest sprocket would be a 30 and with a 39 inner chain ring that would drop to a 28 tooth sprocket

 

5 minutes ago, bleedToWin said:

 

And also, your math aint mathing

First post said larger SR would reduce DeCap 😉

now you're putting words in my mouth....

Where did I say larger small ring reduces decap? I said it would start to limit the big sprocket size. What I didn't clarify was "for the same chain length".

Even then it doesn't necessarily have to limit the cassette used, just the available sprockets that can safely be used without changing the chain length