Long, medium, and short Derailleurs, What's the differences?

PB Forum :: Mechanics' Lounge
Long, medium, and short Derailleurs, What's the differences?
Previous Page |
Author Message
Posted: Feb 14, 2011 at 19:48 Quote
I'm building a dirt jumper and was wondering what the differences are between long, medium and short caged rear derailleurs other than the obvious? This is my first time piecing a mtb. together from scratch and have usually just swapped parts or purchased completes and I see on E-Bay they are all different cage lengths. Which length is best for a dirt jumper?

I'm assuming short is the best so it won't slap against the frame when jumping but some additional info would be greatly appreciated.

Thanks

Posted: Feb 14, 2011 at 20:09 Quote
Long cage are best on triple ring set ups,medium for dual and single ring setups,and short for road block cassettes,using a short cage on a triple set up will result in the mech getting ripped of due to chain growth.

To stop the chain slapping your chainstay either go,ss/use a tube around your chain stay and/or ensure your chain is the right length,how ever on a full sus you need extra links as the chain will get stretched out more due to the suspensions compression which in turn changes the chain stay length.

Posted: Feb 14, 2011 at 20:24 Quote
marquis wrote:
Long cage are best on triple ring set ups,medium for dual and single ring setups,and short for road block cassettes,using a short cage on a triple set up will result in the mech getting ripped of due to chain growth.

To stop the chain slapping your chainstay either go,ss/use a tube around your chain stay and/or ensure your chain is the right length,how ever on a full sus you need extra links as the chain will get stretched out more due to the suspensions compression which in turn changes the chain stay length.

Ok, well this helps. On my 18 speed Chameleon I must have a Medium LX then and it does slap but I use a Lizard Skin to dampen the noise and stop any damage. Is what I'm doing what you mean wrapping something around the chainstay? I'm going to run a 34 or 36 tooth chainring up front with bashguard and chain tensioner. So I guess I would a Meduim caged rear derailleur then?

What do you mean by road and block cassettes? Thanks for your help by the way its greatly appreciated.

Posted: Feb 14, 2011 at 20:25 Quote
when you mentioned ss I assume you mean stainless steel?

Posted: Feb 14, 2011 at 20:47 Quote
He means single speed, which i also would agree with, for a dj bike its better in almost every way

Posted: Feb 14, 2011 at 20:49 Quote
oh ok, gotcha thanks man. so a short cage it is then.

Posted: Feb 15, 2011 at 4:00 Quote
xtremevert wrote:
marquis wrote:
Long cage are best on triple ring set ups,medium for dual and single ring setups,and short for road block cassettes,using a short cage on a triple set up will result in the mech getting ripped of due to chain growth.

To stop the chain slapping your chainstay either go,ss/use a tube around your chain stay and/or ensure your chain is the right length,how ever on a full sus you need extra links as the chain will get stretched out more due to the suspensions compression which in turn changes the chain stay length.

Ok, well this helps. On my 18 speed Chameleon I must have a Medium LX then and it does slap but I use a Lizard Skin to dampen the noise and stop any damage. Is what I'm doing what you mean wrapping something around the chainstay? I'm going to run a 34 or 36 tooth chainring up front with bashguard and chain tensioner. So I guess I would a Meduim caged rear derailleur then?

What do you mean by road and block cassettes? Thanks for your help by the way its greatly appreciated.

Yes lizard skin.Salute

Posted: Feb 15, 2011 at 4:02 Quote
Road block is a road ratio cassette used on road bikes and dh,11 to 23 is the usual ratio for them.


Mtb block is 32 to 11 ratio and to big to run a short cage as the ratio on the largest cog is just too high.


Posted: Feb 15, 2011 at 7:11 Quote
marquis wrote:
Road block is a road ratio cassette used on road bikes and dh,11 to 23 is the usual ratio for them.


Mtb block is 32 to 11 ratio and to big to run a short cage as the ratio on the largest cog is just too high.

Not true, the distance from the hanger to the top pulley is the same from short to long cage. Meaning they can both in theory run a mountain block in back. (I've done it, I've put it on customers bike a million times) the difference in the cages is the distance from pulley to pulley. It has to do with how much slack in can take up from shifting from ring to ring, it takes up the slack going from small to big. Front's are for tripples, mids are for doubles, and shorts are for singles. Although if you don't cross chain mids work fine on triples and shorts are cool on doubles.

Road derailers are actually shorter from hanger to the top pulley so that's why they can't shift into the bigger cogs of a mtn block

Posted: Feb 15, 2011 at 8:10 Quote
oh my, so it's ok to go with a short caged MTB derailleur then? It's all good? I can actually use a long, medium or short but you say a short is best right? Or a medium work fine too? let me know because I would like to buy a good used one this week.

Posted: Feb 15, 2011 at 8:33 Quote
just go for the middle length one. best choice. you can run a short cage if you run a road cassette. i personally don't recommend the short cage on the normal 11-32/34 cogs. on a normal cog set, the short cage tends to be over tensioned when you go down on the gears (down - larger cog, smaller ratio). you might get shifting issues, or even get the derailleur caught up in the cogs on a hard impact (happened to me, so i run a medium length cage on a single chain ring and 11-32 cogs).

Posted: Feb 15, 2011 at 8:58 Quote
kixx wrote:
just go for the middle length one. best choice. you can run a short cage if you run a road cassette. i personally don't recommend the short cage on the normal 11-32/34 cogs. on a normal cog set, the short cage tends to be over tensioned when you go down on the gears (down - larger cog, smaller ratio). you might get shifting issues, or even get the derailleur caught up in the cogs on a hard impact (happened to me, so i run a medium length cage on a single chain ring and 11-32 cogs).

Good point. Ok, that comment made up my mind. I'll stick with a medium cage then. Thanks man.

Posted: Feb 15, 2011 at 10:15 Quote
themontajew wrote:
marquis wrote:
Road block is a road ratio cassette used on road bikes and dh,11 to 23 is the usual ratio for them.


Mtb block is 32 to 11 ratio and to big to run a short cage as the ratio on the largest cog is just too high.

Not true, the distance from the hanger to the top pulley is the same from short to long cage. Meaning they can both in theory run a mountain block in back. (I've done it, I've put it on customers bike a million times) the difference in the cages is the distance from pulley to pulley. It has to do with how much slack in can take up from shifting from ring to ring, it takes up the slack going from small to big. Front's are for tripples, mids are for doubles, and shorts are for singles. Although if you don't cross chain mids work fine on triples and shorts are cool on doubles.

Road derailers are actually shorter from hanger to the top pulley so that's why they can't shift into the bigger cogs of a mtn block

Not disagreeing just going of what shimano said.

Posted: Feb 15, 2011 at 12:27 Quote
so either one is fine then???? uugh... Facepalm

Previous Page |

 
Your subscriptions
no posts

Copyright © 2000 - 2014. Pinkbike.com. All rights reserved.
dv88 0.017246
Mobile Version of Website