Long to Short cage mech?

[Pickle]

I am 85% certain than when my rear mech goes, I want to change to short cage (I think they look great!).

So....

Would it simply be a case of removing a handful of chain links, or is there more to it?

And, as I have never used short cage before, do they run smoothly with 24 speed?

Ta

 

[hamster]

Ok, the important point is the mech's capacity - how much chain it can wrap. This is the total difference in chain teeth (so for a 11-28 cassette and 22-32-44 front it's 28-11+44-22 = 17+22 = 39)

From what I've tried a med cage just wraps an 11-28 with a 22-32-42. The Shimano site gives all this stuff in its tech data. Usually they err on the safe side.

On the road I run a 12-23 rear with 30-39-48 with a Chorus short cage mech - just.

Whatever you do, make sure that the chain is long enough to do the big-big combo. If the mech can't quite handle it and it all goes a bit flappy in small-small that is liveable.

Running chains too short for big-big usually drags the mech into the cassette, and then it's a case of what breaks first...chain, mech, dropout, wheel or even seatstay. It's not pretty. Often it is also accompanied by a hospital visit.

 

[sastusbulbas]

You also have to watch chain length with full sus bikes.

Commencal for instance, the Meta 5.5.3 and its like.

These require a lot of chain if running a triple set up, but are supplied with the wrong rear mech for the job, and have too much chain slack with middle and granny ring use.

Poor design or spec? You decide, but it does show magazine and manufacturer ignorance, I mentioned this when it was first released, and each successive year the same problem.

Some very incompetent shops and mechanics suggest shortening the chain, but by removing two links the chain tightens so much under compression that the bike cannot reach full travel, with over 1cm of stroke left on the shock.

The bike requires a long cage rear mech, or should be run with a bash guard and shorter chain, or no granny ring.

If you are running triple then medium to long depending on cassette choice is the better option for most MTB hardtails. Function over fashion for me every time.

 

[hamster]

Good point, sorry, as a hardtail diehard I didn't even consider that.

I guess that a really big hit could rip the mech off the hanger or tear the mech to pieces, if the chain doesn't go first... :shock:

 

[Err]

Remove two front chainrings and you'll be fine!

 

[scant]

just run the chain slightly long so that its slack in small/small & it'll be fine.
chain growth on FS is an excepted norm & no biggie!

 

[Jones]

I've run short cage rear mechs for years without problems you've just got to remember not to use silly gears

You shouldn't be going anywhere near big/big anyway :shock:

 

[Andy R]

I've run short cage rear mechs for years without problems you've just got to remember not to use silly gears

You shouldn't be going anywhere near big/big anyway :shock:

I agree entirely - why would you ever feel the need to do so ?

 

[Wold Ranger]

Mechs

Apart from my "attack anything" modern bike, which is running 44/32/22 and 12/34 where I run a Dura ace triple mech (vastly superior to any MTB mechs inc XO) I only run short cages on all my bikes and have done for 20 plus years. Much less slap and more precise shifting. You may lose certain ratio's but you would never run a big ring onto the top two or three sprogs would you anyway? All set ups overlap. Another way around is to run 2 up front x whatever out back, I run 36 or 38 big ring with a 26 to 30 lesser and a bash ring this can allow a larger rear sprocket set then too, and saves a trip into A. & E. when you stuff your big ring between your calf muscle and fibia as I once did! Be careful on over shortening your chain though as the increased tension can snap it! Ideally the mech Jockey wheels want to be in line and vertical when on the middle ring and largest back sprog.

 

[hamster]

I've run short cage rear mechs for years without problems you've just got to remember not to use silly gears

You shouldn't be going anywhere near big/big anyway :shock:

I agree, but there are moments when you grab a gear and are trying to avoid some numpty in a pimped BMW who is simultaneously trying to overtake you and turn left.

I'm not saying that deliberately using big-big is a great idea, but it's not exactly bright to have a gear that initiates 'drivetrain self-destruct' when selected.

Far better to have a little slack.