I've been on a mission to find a NOS Shimano XTR RD-M95x series RD for my Trek FX. My triple front 48/36/26 and cassette 12/27 give me a total capacity of 37 teeth. I'm only able to find, within a reasonable price, a GS model that is rated as 34 teeth of total capacity. As long as I'm not doing any extreme cross-chaining should I be OK with a GS model? I can find SGS models in NOS but the price seems to double.

Thanks,
TMT

The der's wrap capacity is about how much chain will get taken up, not whether the der guide pully will give cog clearance. The minimum chain length is about being able to not have the der ripped off the hanger when in the big/big ring/cog combo. So if you have a long enough chain and not a rear der that can completely wrap that chain, given the ring/cog numbers, then the chain will droop when in the small ring and "some" of the smaller cogs. The question then becomes will you ride in these ring/cog combos that have chain droop? (And I would NOT suggest asking the other side of the equation- will you use the large ring and larger cog combos if you should set the chain length to not be long enough).

So will you be able to limit your ring/cog combos while riding? Many can, a few don't seem to even pay attention to this shifting/effort relationship at all. Which are you? Andy (who has done this exact chain droop choice before with no issues)

As long as you have your chain sized big enough to shift into the 48/27 combination without stressing the rear derailleur you will do no harm, but you may end up with a slack chain in the 26 chainring and the smaller rear cogs, which you shouldn't be using anyway.
I have had good luck with Microshift products, maybe one of their products may be priced more to your liking. https://www.microshift.com/en/produc...ar-derailleur/

Thank you for the insights. Avoiding any serious cross-chaining is not a problem. I can't even think of a situation where I would be tempted to even approach those extremes (big/big small/small). I am conscious and hyper-aware of what is going on with regard to gearing while on a ride. Probably to a fault.

As vain as this might sound... this is more about aesthetics and group-set continuity than price (although price is still the determining final factor)

As aware as you are you should definitely avoid a chain which is too short to shift into the biggest combination; a slack chain will not hurt anything but a too-short one will do instant damage to your derailleur and possibly your frame. Even if you do not forget, someone else (borrower, repair person) may not know about the chain being too short.

This is just my opinion... I have never been a fan of the XTR-95x series rear derailleurs. I have found, more than once, that the b-spring seems to be weak and has a difficult time supporting even the recommended max cog. Granted, mine were not new, but over time the spring seemed to lose tension.

I’m not trying to dash your hopes and dreams, and maybe I just bad luck. Hopefully others can chime in and dispel my feelings.

John

Is the longer cage available as a replacement part for the RD you have?

Barry

as noted make sure you can use big big.....that combination has a way of sneaking up on you and then making for a sudden stop. I did this once, knowing big big did not work and wanting to ride, just knowing I would not do big/big..... wrong and I got lucky it was at slow speed and no harm to me or the bike

An "ounce of prevention"... I think I'll just wait until a reasonably priced SGS model becomes available.

Thanks to all, some great input and food for thought,
TMT