Peyote

I gave my LBS an XT rear mech and chain to fit today and I was told that I had bought the wrong size. They fitted it anyway and said that it should be fine but try to avoid Big - Big gearing.

My set up is 22/32/44 with 11-32

I have rode it around town and it is shifting fine and very responsive, it does look stretched to max when using certain gears. Is there any advantage using a medium cage over the correct long cage ? More importantly, will any part of my drive-train wear quicker due to incorrect cage size ? I have read on other forums that some people are using the same setup but out of choice and mention no problems but fail to mention the dis-advantage. I'm curious because my entire drive train is brand new; I do not want to damage/wear it out.

DCB0

The only disadvantage of a shorter cage derailleur over a longer cage one is that the derailleur cannot take up as much chain slack, and so the gear spread (called the 'capacity' of the derailleur) you use is limited. If you have a derialleur with insufficient capacity for your particular gear setup, either the chain will go slack when you use the small chainring and small cogs, or you will run out of chain when you try to use the larger chainring and larger cogs. If the derailleur is not able to go into the big-big combo, but you inadvertently shift into it, you can damage your derialleur, chain, or even your frame.

Peyote

Ah ok, I have looked at the chain while changing gears and I can not see a slacking chain and it does shift to all gears including big - big and small - small; the rear mech is almost horizontal when in high gears (?) .. or is it low ?? Anyway, It seems to shift fine in all gears with some noise/rub in big - big, which the mechanic advised not to shift into.

Peyote

Any other experience/knowledge of this ? Should I be worried and just buy and intstall a XT long cage

Monster Pete

If you set the chain length correctly (usually with the big-big +1" method) the derailleur will work and shouldn't damage anything. The only problem will be with the chain going slack in the small-small gears. If you tend to use those gears, it's best to use the correct length derailleur.

Peyote

Ok thanks. I never cycle in small small or big big so frrom what has been said here and from what I have read from google searches, if the chain was set up in big big combo + 1-2 links, which I think it was because it shifts fine to big big combo; then I should not have any problems. I was more concerned with an increased rate of wear but no one mentions this here or other places.

I think I will stick with it plus a lesson learned.

Thank you all !

Road Fan

Seems to me you might have a problem with needing to add a chain link or two. That should loosen up the cage. The possible downside is a loose chain on small/small.

However, your gearing has a spread of 43 teeth, which is fairly high capacity. It might be your medium cage is actually overtaxed.

If you put your gears in the small small position, look at where the chain comes close to the jockey wheel (closest to the cassette). If it clears the chain by 1.5 cm or less, you shouldn't add any more links, and your derailleur is barely able to handle what you have. If it clears by a few cm, you can add one link at a time to see if you can loosen up the derailleur at the big-big extreme without making the chain drag on the jockey wheel.

I could imagine prolonged tight running causing wear to the jockey and idler wheels, eventually.

Capecodder

If I were you, I would lengthen the chain so that It can go into the BIG-BIG combo but slack out in the small-small combo till you can replace the RD with a Long cage. You will not be paying attention one time and accidentally shift BIG-BIG and ruin your RD or worse. Bottom line, get the correct RD!

shelbyfv

Clearly if you can shift to the big/big you are ok if not optimal. Shift to the small/small and see if there is still tension on the chain. Visualize what adding another link would do. If it looks like your RD could handle another link or more, your chain may have been sized short. It's possible your LBS may be playing a little game with you since you brought in a component you purchased elsewhere.

rogerstg

I wouldn't worry about it if it works correctly. The big/big and small/small theoretically create cross chaining issues. As long as you can shift into those gears without a catastrophe, you should be fine.