Rear Derailleur Question

DCBassman

Going up hills, very slowly...
Going from 8 to 9 speed...
Does a 9-speed mech travel any different distance to an 8? The cassettes are the same overall size, no?
Just wondering if I need change to a specific 9er if all else is changed, ie cassette and shifters...
 
You should be able to use the existing mech. As long as the largest cog is not massively larger than what you have on the old cassette. You will obviously need a new shifter.

I recently bought a new chain and there were chains for 6/7/8 speed cassettes then different chains for 9 speed cassettes. I'm just stating what I came across, I'm not in a position to say whether you need a new chain but in sure someone else has the knowledge.
 
OP
DCBassman

DCBassman

Going up hills, very slowly...
Good question.
Unhelpful answer.
More helpful answer: yes. See here...
https://www.artscyclery.com/science...ce-behind-the-magic-drivetrain-compatibility/
Ok, thank you for that.
To rephrase, @Yellow Saddle , I wish to continue using the RD-M410 I have, instead of buying an RD-M430 (which I just missed on the classifieds, dammit...).
So far as I can tell from the supplied link, all should be well. New cassette and new shifters, obviously, and they are all inbound.
If nothing else, I will try it and see! The new RD is not *that* pricey, but money doesn't grow on trees either, so if I can make it work properly, fine and dandy.
Thank you for your answers!
EDIT: I should also clarify my reasons: I'm going to fit a 12-36 cassette in place of an 11-34. The extra gear is not the issue but the larger sprocket. May well need an extender or a long B screw, of course.
 
Last edited:
Location
Loch side.
Ok, thank you for that.
To rephrase, @Yellow Saddle , I wish to continue using the RD-M410 I have, instead of buying an RD-M430 (which I just missed on the classifieds, dammit...).
So far as I can tell from the supplied link, all should be well. New cassette and new shifters, obviously, and they are all inbound.
If nothing else, I will try it and see! The new RD is not *that* pricey, but money doesn't grow on trees either, so if I can make it work properly, fine and dandy.
Thank you for your answers!
EDIT: I should also clarify my reasons: I'm going to fit a 12-36 cassette in place of an 11-34. The extra gear is not the issue but the larger sprocket. May well need an extender or a long B screw, of course.
Your question is still not clear but let me try.

Derailers travel in two directions.

Lets treat up and down first. This has to do with sprocket size. Some can't handle sprockets above size X, others can. Look up if the derailer you have/want to use, can handle a sprocket up to the size you now want to fit. Remember that derailers have specific capacities. Capacity is a function of both front and back sprocket differences. That's been explained here plenty of times. Search how that works and then look up what the capacity and maxim sprocket size is whatever RD it is you want to use.

Now for left and right. Generally, all derailers can move far enough left and right to handle any number of sprockets on a cassette/freewheel. However, That doesn't mean that it is compatible when indexing. For instance. Shimano and Campag RDs are not compatible in spite of the fact that they can both move far enough right and left. Indexing as to do with how much it moves left or right with each click of the shifter. Even that is strange. For instance, on Shimano 10-speed road and 10-speed MTB shifters, the amount of throw (cable pulled per click) varies even though the distance the derailer moves is the same between the groups.

That's enough info for you to figure out if what you want to do, will work for you. You can work it out for there, no matter how you phrase your question.
 
OP
DCBassman

DCBassman

Going up hills, very slowly...
Your question is still not clear but let me try.

Derailers travel in two directions.

Lets treat up and down first. This has to do with sprocket size. Some can't handle sprockets above size X, others can. Look up if the derailer you have/want to use, can handle a sprocket up to the size you now want to fit. Remember that derailers have specific capacities. Capacity is a function of both front and back sprocket differences. That's been explained here plenty of times. Search how that works and then look up what the capacity and maxim sprocket size is whatever RD it is you want to use.

Now for left and right. Generally, all derailers can move far enough left and right to handle any number of sprockets on a cassette/freewheel. However, That doesn't mean that it is compatible when indexing. For instance. Shimano and Campag RDs are not compatible in spite of the fact that they can both move far enough right and left. Indexing as to do with how much it moves left or right with each click of the shifter. Even that is strange. For instance, on Shimano 10-speed road and 10-speed MTB shifters, the amount of throw (cable pulled per click) varies even though the distance the derailer moves is the same between the groups.

That's enough info for you to figure out if what you want to do, will work for you. You can work it out for there, no matter how you phrase your question.
Answer is still yes, so far as I can see, thank you.
Will be on the limit, certainly. But probably ok.
Certainly worth a shot!
 

smutchin

Cat 6 Racer
Location
The Red Enclave
Not really. If the pull ratios are different the rear mech won’t be compatible. It’s not a hard concept, what don’t you get?
The question the OP asked was "is there a difference... etc" to which you answered "you need to check if there's a difference..."

The link I provided includes detailed information on the cable pull, shift ratios and cog pitch of Shimano, SRAM and Campag systems. HTH
 
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