the medium cage....

[wheels]

I was told that you can run 2x9 with a short cage and you run 1x9 with a short one and you run full 27 speed with a long one so what the heck do you use the medium size cage for?????

[BrewMaster]

It's not neccessarily a function of how many rings you run, but how much chain slack you need the rear DR to pick up.

Read the second post in this thread for all the info you need.

[Chewyeti]

Originally Posted by BrewMaster

but how much chain slack you need the rear DR to pick up.

Read the second post in this thread for all the info you need.

which is a function of how many front rings you run

3 rings, 9 speeds, long cage. (has to take up slack from BIG BIG to Small Small Combinations)

2 rings, 9 speeds, medium cage. You just lost the BIG BIG combo, so now you only have to take up the gap from Middle BIG to small small combinations)

1x9 Short cage, you only have to take up slack between 9 cogs in the rear.

[BrewMaster]

Originally Posted by Chewyeti

which is a function of how many front rings you run

3 rings, 9 speeds, long cage. (has to take up slack from BIG BIG to Small Small Combinations)

2 rings, 9 speeds, medium cage. You just lost the BIG BIG combo, so now you only have to take up the gap from Middle BIG to small small combinations)

1x9 Short cage, you only have to take up slack between 9 cogs in the rear.

In general yes, but the SIZE of the rings and cassette are really the difference makers. If you run a road cassette or non-standard sized rings, then the standards you call out do not necessarily apply. It's better to understand the reasoning than just go a with a rule of thumb IMO.

[freekengo]

Originally Posted by Chewyeti

which is a function of how many front rings you run

3 rings, 9 speeds, long cage. (has to take up slack from BIG BIG to Small Small Combinations)

2 rings, 9 speeds, medium cage. You just lost the BIG BIG combo, so now you only have to take up the gap from Middle BIG to small small combinations)

1x9 Short cage, you only have to take up slack between 9 cogs in the rear.

Why would you ever run BIG/BIG or SMALL/SMALL? talk about having extreme chain line issues. No wonder people break chains all of the time.

By the way, I run a med cage with a 3x9. works fine for me! Love the speedy and snappy shifting!

[Chewyeti]

Originally Posted by BrewMaster

In general yes, but the SIZE of the rings and cassette are really the difference makers. If you run a road cassette or non-standard sized rings, then the standards you call out do not necessarily apply. It's better to understand the reasoning than just go a with a rule of thumb IMO.

True...
The circumference of the rings (or the mathematical difference between 1gr and 9gr on your cassette that dictate it....
so yeah... rule of thumb works too... but i agree.

Originally Posted by freekengo

Why would you ever run BIG/BIG or SMALL/SMALL? talk about having extreme chain line issues. No wonder people break chains all of the time.

By the way, I run a med cage with a 3x9. works fine for me! Love the speedy and snappy shifting!

You are nucking futz tho

BUT... why have gears you cannot use?

[freekengo]

Originally Posted by Chewyeti

You are nucking futz tho

BUT... why have gears you cannot use?

Thanks chewy. the 27 speed systems have many "overlapping" gear ratios. I also like to get some longevity out of my components. I figured I'm never going to use small/small or big/big combos so I went with the mid cage. Made for crisper shifting also(less delay). my 2 yens.

[Rockinthecasbah]

On a big travel bike, where the wheelbases stretches/shrinks a short cage may not work.
Additionally each cage has a different shifting feel, softer to firm engagement ride a long cage bike and a short cage and you will notice the difference

[DirtymikeTDB]

Rule of thumb, 1 up front, short, 2 medium, 3 long

Proper, is to make sure your derailer will take up the slack off sexcess chain when needed figured in link listed above.

Also something nothed in this thread to take into consideration, Certain bikes themselves cannot use a short cage due to chain growth/shrinkage For example My Brothers bike, Faith 3, when running a 32 tooth granny, it needs to have a medium cage min, The back end grows just enough to need that little extra bit of chain.


One last thing that has not been mentioned yet. Maximum range of the derailer. I am able to run a Short cage, by the numbers that is, but Sram short cage dont work with a 32 tooth cassette!!!! So I run a Medium, it works well for my setup. Well long story short, check your max cassette size for the derailer you want to run as well as everything else!!!