Change of cage on derailleur

Discuss light weight issues concerning road bikes & parts.
darkblue08
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by darkblue08

Im planning my next bike. Im aiming for a light, quality bike which will let me climb 20+ % ascents. I known I want SRAM gear system. I was thinking about SRAM Red (black edition), but would like a medium cage instead of a short cage, because I want the option of a 11-32 cassette. Does anybody know if you can swap cage between a Rival with medium cage and Red rear derailleur? Maybe even swap it every time I swap between mountain and flat setup by changing it along with chainrings, cassette and chain.

Or doesn anybody have a better idea? :idea:

by Weenie


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saroadie
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by saroadie

From your OP, it is unclear if you are planning compact or standard chainrings.
If you had not considered compact, 34x28 is a pretty close gear to a 39X32.
Sram manufacture 11-28 cassettes so this may be an alternative to investigate if you had not already considered compact chainrings.
I'm not preaching compact, just offering a possible alternative to messing about swapping derailleur parts and cassettes.
"Bite off more than you can chew, then chew like hell." Peter Brock.

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prendrefeu
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by prendrefeu

darkblue08 wrote:Does anybody know if you can swap cage between a Rival with medium cage and Red rear derailleur? Maybe even swap it every time I swap between mountain and flat setup by changing it along with chainrings, cassette and chain.


The maximum cog size for both Red and Rival (and Force) is 28.
SRAM Apex allows for a larger rear cog, it has a larger rear cage by default. As it is perfectly compatible with the rest of the SRAM system, why not just use that? It was good enough for Clentador in the Giro, it will be good enough for you.

You have a few options:
-Replace cage with an APEX cage.
-Replace cage with custom longer cage (Fiberlyte)
-Replace standard upper 11t pulley wheel to 10t, but I'm not sure how much larger this will allow you to go to. Certainly at least 30. Some other folks here may note the more precise answer for this method.
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TCx
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by TCx

Alternative - swap to shimano and get a ki2 set up.
Can you ever have to many bikes?

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madcow
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by madcow

We've built several climbing bikes with a compact 34/50 and an 11-32 in the back using Sram. Use any Sram road shifter and combine it with the Sram XX rear derailleur and XX cassette. http://cdn.fairwheelbikes.com/cycling-b ... rlee_1.jpg

darkblue08
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by darkblue08

saroadie: Im already on compact. But I found that is not enough for +12% climbs for me.

prendrefeu: Its correct that all the Road derailleurs with short cage support a max of 28 teeth, but Rival and Apex is made in a medium version that supports 32 teeth. That why I got the idea of replacing the cage on a Red. It doesnt looks so good with an expensive bike that says Rival or Apex on the rear derailleure

I thought about DI2 but the Dura-Ace is very expensive and Ultegra is heavy. And they both add the element of a batteri that can go flat. If I had the money, I would have a bike for the flat/sprint with DI2 and one with SRAM Red for the mountain. Is so many things in live, i have to make compromise.

madcow: Nice bike! I dont need to go to mountain bike gear groups unless I want the 11-36 cassette.

Chris_W
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by Chris_W

I thought it was the geometry of the RD that determined max cog size. The cage length only determines chain wrap capacity. To use a cassette with a 32-tooth cog, I would think using the Rival or Apex derailleur would be the only options, swapping the cage on another model would not change the max cog size for that model.

I'd be happy to be corrected on this if someone knows better.

aaric
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Joined: Thu Jun 09, 2011 4:10 pm

by aaric

darkblue08 wrote:saroadie: Im already on compact. But I found that is not enough for +12% climbs for me.

prendrefeu: Its correct that all the Road derailleurs with short cage support a max of 28 teeth, but Rival and Apex is made in a medium version that supports 32 teeth. That why I got the idea of replacing the cage on a Red. It doesnt looks so good with an expensive bike that says Rival or Apex on the rear derailleure


The difference in weight here is ~40grams between red and rival. I'd bet a very significant portion of that is going to be due to the carbon cage on the red, which you'd be throwing away. Rumor has it the shifting is pretty similar. IMO, you'd probably do better to tune the Rival with lighter pulleys, and possibly machine the cage a bit to save weight.

Really seems like there's no point to it.

Grasschopper
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Location: Central PA

by Grasschopper

I guess I'm digging up an old thread here but I have the same interest. It isn't so much about the weight as it is about the asthetics of the rival rd with Red everything else.

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Valbrona
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by Valbrona

darkblue08 wrote:Im aiming for a light, quality bike which will let me climb 20+ % ascents. ... because I want the option of a 11-32 cassette.

Or doesn anybody have a better idea? :idea:


Yes ... use a triple. A sprocket set with a 32 as the largest is going to be heavy. I use a compact triple: 11-23 at the back, and 26/34/42 at the front. And 30 gears is much more logical than 20.

nickbooky
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by nickbooky

Chris_W wrote:I thought it was the geometry of the RD that determined max cog size. The cage length only determines chain wrap capacity. To use a cassette with a 32-tooth cog, I would think using the Rival or Apex derailleur would be the only options, swapping the cage on another model would not change the max cog size for that model.

I'd be happy to be corrected on this if someone knows better.



firstly hi im very new here, so i hope i dont step on anyones toes with my post but just my 2cents worth if your interested.

yeah from what I understand this is correct. The only reason that you would go a longer cage is if you decide to run a triple crank. As there is a greater difference between the smallest and largest chainring, as compared to a double crank (compact or standard). Hence the need for the longer cage to be able to cope with chain tension.
It is the derailleur body itself that determines the distance from the largest cog on the back to the top of the "guide" jockey wheel. So thats why swapping the cage, unfortunately won't fix your problem.

If you want to run sram and be able to have a 32 cog on the back you will need to use something like the apex. But as you want something a little more high end I would go the xx derailleur. Just like fairwheel have done. Even David Miller used one in the Giro Mountains.
[url]http://www.theroaddiaries.com/2011/05/25/david-millars-xx-equipped-cervelo-s3-giro-2011-2/
[/url]
yeh i know he ran a 36t but there is no reason why you couldn't run a 32t cog

Grasschopper
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Location: Central PA

by Grasschopper

nickbooky wrote:
Chris_W wrote:I thought it was the geometry of the RD that determined max cog size. The cage length only determines chain wrap capacity. To use a cassette with a 32-tooth cog, I would think using the Rival or Apex derailleur would be the only options, swapping the cage on another model would not change the max cog size for that model.

I'd be happy to be corrected on this if someone knows better.



firstly hi im very new here, so i hope i dont step on anyones toes with my post but just my 2cents worth if your interested.

yeah from what I understand this is correct. The only reason that you would go a longer cage is if you decide to run a triple crank. As there is a greater difference between the smallest and largest chainring, as compared to a double crank (compact or standard). Hence the need for the longer cage to be able to cope with chain tension.
It is the derailleur body itself that determines the distance from the largest cog on the back to the top of the "guide" jockey wheel. So thats why swapping the cage, unfortunately won't fix your problem.

If you want to run sram and be able to have a 32 cog on the back you will need to use something like the apex. But as you want something a little more high end I would go the xx derailleur. Just like fairwheel have done. Even David Miller used one in the Giro Mountains.
[url]http://www.theroaddiaries.com/2011/05/25/david-millars-xx-equipped-cervelo-s3-giro-2011-2/
[/url]
yeh i know he ran a 36t but there is no reason why you couldn't run a 32t cog


Ok but why does Campagnolo say their short cage RDs are only good up to 26t and you have to run the medium cage for the 29t cassettes (this was in the 10s). I have swapped cages on Record RDs with no issue and it would be great if you could put the Medium cage on a Red RD.

My understanding is that the longer cage is used to take up more chain which is needed when you have larger cogs in the back or if you are running a triple in the front.

nickbooky
Posts: 2
Joined: Wed Nov 23, 2011 4:50 am

by nickbooky

it is probably due to the position of campag's b tension screw. which acts directly on to the cage itself. where as sram and shimano both have their b tension screw located at the back of the derailleur, pushing the entire derailleur body away from the cassette, compared to campag which is only the cage.

and besides your wanting to use a "small" ratio mountain bike cassette on your road bike with the 32 rather than a "big" road cassette of a 28 or so.

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js
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by js

Nickbooky - welcome to the forum and thank you for these posts, which are well written and accurate in their information.

I've seen this set-up a few times on our Randonnees, if you want to run up to a 32t cog, you can use SRAM Apex or Rival mid-cage (in fact, SRAM even sell a climbers upgrade kit now - cassette, chain & mid-cage Rival RD). If you want to get up to a 36t cog, you'll need any one of the SRAM 10spd MTB derailleurs (X.7, X.9, X.0 or XX).

The 9spd versions of SRAM's MTB derailleurs are not compatible with 10spd shifting (road or otherwise) due to different cable-pull ratios.

by Weenie


xrs2
Posts: 228
Joined: Mon Nov 07, 2011 5:46 am

by xrs2

darkblue08 wrote:Im planning my next bike. Im aiming for a light, quality bike which will let me climb 20+ % ascents. I known I want SRAM gear system. I was thinking about SRAM Red (black edition), but would like a medium cage instead of a short cage, because I want the option of a 11-32 cassette. Does anybody know if you can swap cage between a Rival with medium cage and Red rear derailleur? Maybe even swap it every time I swap between mountain and flat setup by changing it along with chainrings, cassette and chain.

Or doesn anybody have a better idea? :idea:


I am currently having a bike built for me for the same purpose. Lots of very steep climbs, often on dirt/gravel, poor condition roads.

My solution was a THM mountain bike crankset (44/30 rings), standard 11 (or 12? can't remember right now) to 27 cassette. That way I'm not going beyond the capacity of the derailleur. The 44 ring is fine for my purposes...my rides are usually ultra long distance, so I try to conserve energy by coasting down hills. Thus an extremely high gear (eg, 53-11 or even 50-11) isn't really necessary.

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