goraman

Ok,as you move up the long line of derailleurs what do you get for your money is the Acera junk when compaired to the XT?
Is it alloy vs. plastic ?
Better springs?
What are we paying for as we move up as Shimano always just says "Smoother shifting".
Is there a point where cogs stay steel or do they become alloyed ALU?
Dose the top end have a carbon fiber body.
Is the Altus carved from stone?
All kidding aside what do you get with each model up the line?
Bragging rights?

Hiro11

https://www.youtube.com/watch?v=GYY3bIseIAU

fietsbob

Robot stamped sheet metal, rivet pins thru holes and paint, fully assembled by machines .

Vs forged and polished aluminum carbon and titanium parts with pivot pins thru Bushings.
but still wont be assembled by watchmakers.


But if you knock off the RD against a rock neither will survive.

goraman

So the at what point do things get reasonably good?

fietsbob

all are Quite adequate , function as designed ..


spend as much as You wish. Black painted Deore is on my bike with Shimano derailleurs

I got it 10+ years ago.. from one of those mail Order places ..

andr0id

Same as with the road groups, stick to the top 3.

goraman

I have had good luck with Acera,the Autus sucks.
I am getting an XT front and leaving the Acera in back.

goraman

The problem is its a 7 speed.
So much of the top end stuff won't jive with 3/3 2nd chain.

fietsbob

look for NOS parts from the 80s on that auction site .. Im using stuff I got back then, still .

I dont do single track , just use the Long cage stuff for the touring gear range.

JonathanGennick 

The answer varies from year to year, and Shimano themselves make it amazingly unclear sometimes. You almost have to pick two models and study the specs, and sometimes the information is clearer on vendor websites than on Shimano's own site.

Reduced weight is often in play as you go up the line. The current Deore RD-M615 model is listed at 338 grams, whereas the next level up SLX RD-M675 is listed at 311 grams. These weights are from Shimano.com, which also lists an SLX RD-M670 (no clutch mechanism) at 281 grams.

Different features come and go. The M615 and M675 are Shadow+ design with direct cable routing, a design that doesn't protrude out as much from the bike, and a clutch mechanism to reduce chain slap agains the driveside chainstay. The Alivio M430 appears to require the old-style cable loop at the back of the bike, has no clutch mechanism, and does not implement the Shadow design.

It's not always easy to tease out these details. Probably I've just spent 20 minutes on the above. There's no weight given on Shimano's site for their Alivio model. I've got twelve tabs open on three different sites to help me compare just the three models I've looked at.

FWIW, I just kind of have a component level that I aim for that is friendly to my pocketbook. Also FWIW, I don't like components to be wildly different from each other. I wouldn't buy an SLX derailleur for a bike with Tourney-level shifters on it. I like too keep the component level somewhat balanced across an entire bike.

What bike do you have? Are you replacing your rear derailleur? What level are the other drivetrain components?

Abu Mahendra

Road, you want Ultegra and 105, unless you really need the weight savings, bragging rights and want to pay for Dura Ace.

Mountain, you want XT or SLX, unless you really need the weight, bragging rights and want pay for XTR.

Retro Grouch 

How thinly can you slice the baloney?

I don't even know how many mountain groups Shimano markets anymore. What I do know is that the cheesiest, Tourney, works just fine with a reasonable tune up. Anytime that you are out and about, check out the rear derailleurs on the bikes that you see. Tourney derailleurs are probably on the majority of derailleur equipped bicycles in the United States. If your objective is the lowest price for a functional derailleur, Tourney is it. It even comes with your choice of mounting systems.

As you move up the food chain I have no doubt that Shimano derailleurs get lighter in weight, more precise operating and definitely better looking. All that you have to do is to figure out where your appreciation of those things matches your price gag point. For me on mountain bike stuff it's Deore or LX, mostly for style points. YMMV.

goraman

Ok, I just had a Shimano XT M780 T- swing upper derailleur installed and it rubs the new derailleur like hell on the big outside sprocket.
The chain is 3/32.
I think tipple chain rings suck.
Is the chain to damed wide?

badger1

You answered your own question in your post #8 above. The XT front 780 was designed for a triple (785 for 2x10), but 3x10 -- so, 'modern' chainring spacing and chain width.

If you are using a 3x7 drivetrain > much older generation. Possible incompatibility (chain width and possible chainring spacing) is hardly a surprise, is it. You might be able to adjust it out to some extent by playing with the limit screws.

Otherwise: either bring your drive train (or bike) up to date, or go ebaying for NOS stuff that will play nicely with what you have.

goraman

My bike is only 2 years old, I am probably going to move to a FSA Gossamer cross crank 46/36 double.
This should put things right.

The derailleur will have one less chain ring to deal with.

goraman

Can't do that cogs are 1/8.

JonathanGennick 

What bike do you have goraman? Have you had a shop look at that front derailleur? Maybe the rub can be adjusted away. It sounds to me like you would benefit from some in-person help at a good bike shop.

goraman

I got the XT and had it installed at Preference bicycle, my chain is 3/32 and it has a 7 speed hub.
It is a Target Schwinn trail way.
I replaced the Altus because it was clunky, but it didn't rub.
By the way my Target bike weighed in at 24.04 lbs. today.
I removed the head badge, bell and head light, water bottle and tool kit.

Darth Lefty 

A thorough answer requires a thorough reading of the specifications, which is pretty boring and time consuming. As a summary,

XTR and Dura Ace have extra racy light weight parts (titanium, CF) and some mechanical features (pulley bearings for instance) to take out as much weight and inefficiency as reasonably possible
XT/Ultegra has all the same mechanical features but with mostly aluminum and stainless parts
SLX/105 has a few plated steel parts and bushings in the pulleys
Deore/Tiagra is all metal, more steel, some paint where there was plating
Alivio/Sora starts adding plastic pieces and some of the hardware is not plated...
And so on down to Tourney where all the parts are painted steel or plastic, there's no aluminum, and only a few nuts and bolts are plated.

There's probably a steady drop in quality as you go down too. You can tell holding a race derailleur that it's a precision instrument while a Tourney looks and feels like something from the toy car aisle.

Retro Grouch 

Thanks, Lefty, I appreciate the amount of effort it must have taken to provide your factual answer. I've often wondered about those details but not enough to really dig into the details the way that you have. I still think, however, that it's important to remember that even the relatively crude Tourney still works.

JonathanGennick 

Is the plastic pants-guard still in place? Is that what is rubbing against the derailleur?

OldsCOOL

I have a vintage pre-Diore read derailleur sitting on my bench next to a Suntour 13-34 6sp freewheel. Back in the day, this is what you used. Rugged, dependable and quality were some of the words to describe them.

Altus works. It is a working class RD that performed like the early Diore. I have one on my '02 Trek 820. It works near flawlessly and stands up to my winter slush and snow rides.

Retro Grouch 

You need a VGT to go with that 13-34 freewheel. One of the nice things about a VGT is you could use it to pound in tent stakes at night, put it back on your bike and it would work flawlessly the next day. And it was designed so that you didn't even have to break the chain when you took it off of your bike to pound the stakes.

OldsCOOL

goraman

Thank you everyone, The XT was wrong for my set up, to narrow.
I had them reinstall the Altus and a new cable adjust everything and it's better than ever!
I think the new cable was key.