jamesteoh8177

Need some advise on this issue and answers found online seem to make me even more confused...
My chainwheel is on 53/39T and I have options of pairing it with:
1. 12/27T cassette
2. 12/25T cassetteI have a both short Cage and medium cage RD.

Questions:
1. Should I use short cage RD?
2. If short cage is the best option, does it mean medium cage is not usable with either cassettes? and vice-versa?
3. What could possibly happen, if medium cage is used? I mean like the possibilities of slipping OR chain drop OR anything that would lead to malfunction during shifting OR failed function?
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Andrew R Stewart 

I nearly always suggest a rear der with more capacity then what the gear ranges requires. Something "wrong" IMO about using a system at it's max all the time. I don't think your 40K time will suffer with either der choice but those who feel as I do will use the medium cage. Andy

dsbrantjr

There is a miniscule possibility that the medium cage derailleur will slow the shifting slightly but in the vast majority of cases this is nonexistent or imperceptible.

davidad

Either will work well. The longer cage will allow for a larger cog.

jamesteoh8177

What type cage are u having on ur RD and whats's drive setup?

jamesteoh8177

That's what I read from the internet. Have u tried using medium cage on such drive setup similar to mine?

jamesteoh8177

Have u tried them or u are running on this setup on ur bike?

davidad

On my road I have a triple with a medium cage der. and have used a 30t cog. I have indexed down tube shifters.

cxwrench

Please explain this. The shift happens at the upper pulley, how does cage length have any affect on this? If you are thinking it's the greater mass of the longer cage plates that's pretty much ridiculous.
For the OP, I'd run the SS just because you don't seem to have any plans to use a larger cassette. If you do decide to do that just swap the derailleurs.

blamester

If you where going to buy one I would say get the medium.
but you have both so try both. Either one will work but you might like the look of one over the other. Or you may notice a difference in shifting of one over the other. I don't know if one will help the front shift better or not. It might.
But be carefull with chain length. Measure to the longer cage one first. One chain length might work for both
Check the limit screws before you ride them
Cable will stay the same.


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Litespud

I went with a med cage RD years ago because I wanted the capacity for a 13-29 cassette I occasionally used for climbing, even though my normal cassette (12-23) is within the capacity of a short-cage RD. Never noticed any difference between the med-cage RD and the the short-cage that preceded it.

jamesteoh8177

I think the medium cage looks better, since you have mentioned that functionality wise both are the same.
Just gotta be sure on the chain length first...
​​​​​​ thanks...

jamesteoh8177

Well noted, thanks...

70sSanO

If you “already” have both rear derailleurs, use the short cage now. If you don’t have either, buy a medium cage. This is also assuming that both are the same quality level.

John

Andrew R Stewart 

Don't take my personal set ups (a few bikes...) as the path for you. But you did ask. I run triples on my frequently used bikes. I mix brands and have Shiftmates on some of the bikes. All run a long (NOT medium) cage der.

I ride in the Finger Lakes region of NYS and have low gears around 18 to 22 inches (24 or 26 in front and 32 or 34 in back with either 622 or 559 tires). I am nearly 65 and never had much power but love the hills and like to spin (I look forward to a cassette with a 12 or 13T hi cog and no single tooth jumps). Andy

jamesteoh8177

I have both RDs but not the same quality. DA7700 is medium cage RD and a Shimano 600 Tricolor is short cage RD.

jamesteoh8177

Not to take your setups as direct guide but it's good to know that medium cage RD or long cage RD works on 27T or even 25T on low gears.
Thanks...

Andrew R Stewart 

Shimano does not make much claim for forward system compatibility. IIRC the tricolor is a 9 speed unit from many years ago and might not play as nice with current cog counts. I looked back on the thread and don't see how many rear cogs you are running. Andy

jamesteoh8177

I am running a 9-speeder with 2 options of cassettes (12-25T and 12-37T)

79pmooney

I'd toss on the short cage. Run a chain over the big ring and and 27 tooth cog, through the derailleur and and back to itself at and opposite link so the chain is a link or two longer than the derailleur pulled tight. (Don't shorten or connect the chain. Just match the narrow to the wide link.) Mark that link. Now move the chain to the small ring and cog. Match it to that marked link. Is the chain slack within reason? If not, go to the medium cage derailleur. If you think you will ever go to a larger cog, go medium.

If you go to too tight a big-big combo, you are making that nice derailleur older every time you use that combo. And there is risk of bad things happening. (Damaging the derailleur or the dropout or the wheel or the frame or yourself or any combination of the above.) A bit of slack in the small-small is rarely an issue and it is a combination most of us don't use a lot. I much prefer derailleurs that don't care at all if I go big-big.

79pmooney

12-37 or 12-27? You said 12-27 in your first post. Big difference. (And yeah, we've all made embarrassing typos. )

jamesteoh8177

Well... As age is catching up, I will definitely need bigger cogs. It will be a literally an uphill battle to paddle up hill with small cogs.

jamesteoh8177

Hahaha...
U got me there. Guilty as charged.
Apologies to u for my typo error. It should be 27T.

Yes, it is a huge difference 27T and 37T.

canklecat

FWIW, I've use a Shimano 600 Tricolor (early Ultegra, for 8-speed) with 7 and 8 speed setups on a couple of bikes. Currently I have one of my 600 Tricolor RDs on a 2011 or so Diamondback Podium frame with 53/39 Ultegra crankset, and 11-28 cassette. No problems. However I feel subjectively more drivetrain drag than I do using a medium or long cage RD with the same and similar setups. If I had a lighter weight long cage RD I'd use that instead and save the short cage RDs for cassettes/freewheels that max out at 25 or 26 T cogs.

70sSanO

Here my take... the 7700 GS is a fabulous rear derailleur. The max cog capacity is 27/29, but I have read people running a 30t cog.

The Shimano 600 is a very nice derailleur, but if you use it and then need to get a cassette with a 32t you could potentially lose the opportunity to use the 7700.

I’m a sucker for Dura Ace and would run the 7700 and not look back.

John