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GS or SGS?
NB: Originally posted elsewhere on the Global Riders Network and appears via syndication.
Hey Guys,
A few months ago I replaced my rear XT derailleur with a new M770 XT SGS (long cage). When comparing the two it looks like the cage on my new one is longer than my old one.
Looking at the Shimano site I can see that SGS is actually super long cage.
Since getting the new derailleur I have broken two hangers – one because a stick wound its way up through the lower jockey wheel. This lends me to think I need the shorter GS (medium cage) derailleur.
I run a 11-32 cassette and 3 rings up front.
What do you think?
EDIT: I think I worked out my total capacity is 43T, which means I need a long cage but I'm still confused as to why my old one had a shorter cage.
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Here is a link that explains what length is required.
http://blogs.phred.org/blogs/alex_wetmore/archiv...
I reckon I could get away with the GS according to that.
Can someone elaborate on that?
If you are running triple rings up front you need a long cage.
The meduim/short cage can work with a single or twin ring setup depending on the difference between the number of teeth. Sounds like you had the wrong derailleur originally.
If you have broken 2 hangars, either it has been through damage, or your chain is/was too short. If the latter, you can check by shifting the chain to the biggest cog at the back, the big ring at the front, and confirm you have 2-3 links 'extra' slack. Any more and it's a waste, (you'll be losing tension), any less and you're likely to snap hangars when in this gear combination and the suspension compresses.
Most suspension designs have a chain growth (centre to centre lengthening) of around 15mm at full travel, meaning you need 30mm of slack (hence the 2-3 links spare).
Hope that helps some more!
Whisperer
then run a medium cage, besides the big cog is only really useful for ripping into your leg or ankle anyhow.
This was where I found and convinced my other half of the need for two bikes, my normal ride (red hill and manly dam, even something like ourimbah) I found I was never using the big cog, but the more epic rides that include a little bit of road and some flat fire trail I need the big cog..
So the real answer to your problem is to remove the big cog and long cage derailleur, replace with 2x9 setup ( or 1x9 ) with a medium cage, then get another bike to go with your spare big cog and derailleur
I need the big dog....I use it a lot at the Dam. I used to have just the middle/small combo with a bash guard but then I found that during races and as my fitness increased I needed the use of the big ring more. It's the granny I never use. Ideally I should probably have a suitable 2x9 set up...
Whisperer - I've broken hangers, not due to the chain but once was because I slammed my bike on a rock and the other time a spindly stick wound its way up through the jockey wheel and into the spokes.
then it looks like (if you don't change your riding style) you need to keep the long cage and a whole bunch of spare hangers.
or
1> use it as an excuse to get another bike for your races. ( assuming your doing most damage during training/fun rides )
2> what gears did you used to run in your 2x9 setup before? perhaps you could go for a 36T or 38T (hard to find, will it work?) middle ring with a larger granny in a 2x9 setup, and change to medium cage ( I think its 33T capacity and should work with 24/38 ring combo )
That would be ideal. The Minister for War and Finance doesn't agree though!
When I had 2x9 before it was the standard 22,32 combo. I agree though, I should get a bigger granny + a bigger middle for a sweet 2x9....Or SRAM XX?
Just want to focus on the derailleur now at the moment though as that’s what needs replacing (it’s still slightly bent after the last incident). Really I think I just had some bad luck with the hangers as the two incidents happened right after each other (within a month) and within 10m on the same section of track.