coopr

I'm planning a change to my already-customized 2001 Specialized S-Works M4 cross bike and I'm trying to finalize my shopping list. I've done a lot of research online, and I'm most of the way confident that my changes will work - once I pick one of the correct RD options.

The drivetrain is mostly stock - Shimano Ultegra, with 2x cranks (large ring 50t), 9-speed cassette (12-27t), and Ultegra RD-6500 rear derailleur (short cage).

This bike came originally with drop bars, which I had converted to flat bars by using Shimano SL-R660 flat bar shifters.

This setup has been working great for years, but... well, I'm getting older, and the hills around my house aren't getting any less steep. Plus, my kids are nearly old enough to kick my butt on climbs, and I want to put that off a few more years

So, I need a lower low gear, and for that I need to make some changes - which I'm trying to minimize. I'm hoping I can change just the cassette, the rear derailleur, and the chain - sound good so far?

• I'll change the rear cassette to a 9-speed 11-34t - probably Shimano XTR CS-M970 - right?
• I'll change to a longer chain, just normal Shimano 9-speed chain - right?
• I'll change the rear derailleur to... this is where I'm a little stuck - can I use brand new Shimano Ultegra RD-R8000-GS (medium cage), or is that an 11-speed-specific derailleur and I need 9-speed? Shimano 105 long cage? Which specific model numbers are compatible (and where might I find such a list)? And, is there such a thing as a "9-speed derailleur"?

Canker

A 9 speed shimano mountain bike RD will work.

Davet

The RD8000 rear der is not compatible with your shifters. A 9-speed Shimano MTB rear derailleur works perfectly and is very common on touring bike and old farts like you and me who need better gearing.

shelbyfv

Yes. 9 speed mtb derailleur for your 34T cog. Neither the 105 nor the 11 speed RD will work. 9 speed from Deore on up will work for you. Same for your cassette. 9 speed XTR stuff is getting hard to find and would be inconsistent with the rest of your components. Would work but why do it?

Bill Kapaun

You don't even have to use Deore quality, although I'm not going to fault YOUR choice.
My 8 speed Altus still shifted fine when I upgraded to 9 speed. I do use "road" (12/13-23/25) cassettes though which "might" help?

shelbyfv

I wouldn't disagree. I can't keep up with all the names so just went with what I knew

Davet

To the OP: Any Shimano or SRAM 9-speed cassettes are compatible with your components.

velojym

My JtS came with 105, but kinda narrow in back for my riding, so I swapped it out for XT in back, and have had it on for nearly 20 years now. Works great!

coopr

OK, thanks for your quick replies - I sure wish I could find a nice summary of which Shimano derailleurs have which features!

I think my rear derailleur options (I'm tending towards top-of-the-line, excluding lower-end models) are as follows:

• Shimano Deore XT RD-M750-SGS
• Shimano Deore XT RD-M760-SGS
• Shimano Deore XT RD-M771 or RD-M772
• Shimano Deore XTR RD-M952
• Shimano Deore XTR RD-M970
• Shimano Deore XTR RD-M972

(I know some of those are Rapid Rise / low-normal)

I'm found mixed messages on whether any of the following are compatible - some things I read say "Yes!" others say "No!":

• Shimano 105 RD-5701-GS or RD-5700-GS 10-Speed Rear Derailleur

shelbyfv

The two 105s will not work with your proposed 34T cog. I'm surprised any source says they will. You may have to take what you can find with the vintage derailleurs but I'm not fond of Rapid Rise or Shadow for this type of conversion. Good luck, you should be pleased with the result.

cpach

Definitely do a MTB der for this configuration, XT is fine, just say no to rapid rise unless you really know you love it, because it shifts worse and is less reliable.

Davet

No To any RD-5700 or RD-5701 derailleur to run with a 34t cog. There are kludge work arounds but the results aren’t good.

Any Shimano 9-speed rear derailleur will work and do what you want it to do.

The rd 772 and rd 972 are Shadow derailleurs and while they will work fine they don’t have a cable adjuster on them so the bike must have a rear derailleur cable adjuster somewhere else in the system.

The derailleurs that have the ‘SGS’ designation are designed for more the chain take up for triples but they will work.

The ‘rapid rise, low normal’ will work but boy will their “backwards” shifting will make you nuts.

coopr

I purchased and installed a 9-speed 11-34t Shimano XTR CS-M970 cassette - then I reinstalled my rear wheel and experimented with my current Ultegra RD-6500 rear derailleur (short cage) - I expected it to have trouble with the largest cogs, but was surprised to find it seems to work well!

I'd already bought an XTR long cage rear derailleur, but now I'm wondering if I really need it - do I? If my previous derailleur is working (even though the fine folks in this thread, and in some other places I've found, suggest it is not compatible) then what will I gain by changing derailleur?

70sSanO

Okay, here is some food for thought. There are two parts to the story. The chain wrap and the derailleur hanger.

If you are running a 6500 2x, with a 50t the worst case if 12t difference, not a typical 20t spread with a triple. So you might be able to use a RD-6501 and it might work. A lot depends on the chain length and what things look like in the big-big, that is the real determining factor. I've heard people say certain things work when they shouldn't.

The other part is the derailleur hanger. The further down the attach point is from the drop out the larger the cog that can be run. The Wolf Tooth Road Link is built on this premise. If you have a generous derailleur hanger, then you can run your Ultegra RD with a 34t.

John

Davet

Your derailleur may be compatible....to a point. There’s going to be a couple, at least, gear combos that the derailleur can’t handle. Most likely the big/big combo. Yeah, you’ll say that you will never cross-chain like that but frequently you can forget in the ‘heat of battle’ and maybe ruin something.

You have the correct derailleur in hand, the XTR, why not use it and ride happy?

fietsbob

Clicks in the shift lever, your RD has no 'speeds', per se,* just age ,, so 9 speed is not the latest stuff..

* cable pulls it moves inward..




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