Agentbolt

So the 2009 Stock Surly LHT complete comes with the RD-M761 SGS rear derailler. Which looks like this.



However the rear derailleur that came on my stock LHT looks like this:



Which looks like a 770 or 771.

So a couple of questions:

#1. Since when are there even different subsets of XT rear derailleurs? Isn't Shimano's product hierarchy confusing enough as is? Is there any difference between the models as long as they're all XTs?

#2. Could someone else with a completely stock 2009 LHT look at theirs and see if they've got my RD, or the one that's supposed to come with the bike per Surly's page?

Obviously this doesn't really matter in the grand scheme of things, I'm just curious what the difference is between the two, and if there's something weird with my Surly specifically.

sstorkel

Yes, there are differences.

XT, like most Shimano groups, includes both short cage and long cage rear derailleurs. If I recall correctly, these are indicated by the GS and SGS designations.

In addition XT now offers a "Shadow" configuration, that keeps the rear derailleur tucked close to the bike frame so that it's less likely to be damaged in a crash.

Finally, there are differences in the "relaxed position" of the derailleur. Most rear derailleurs return to the highest gear (= smallest cog) if there's no tension on the derailleur cable. This is called "top normal" by Shimano. There's a new option which causes the derailleur to position itself near the lowest gear (= largest cog) when there is no tension on the derailleur cable. Shimano calls this "low normal" but it may also be referred to as "rapid rise". Allegedly, rapid rise requires less effort to shift into easier gears as opposed to top normal which requires less effort to shift into more difficult gears. Rapid rise is popular among mountain bikers, who often need to switch to an easy gear quickly so that they can climb a steep slope or clear an obstacle. Road racers like top normal rear derailleurs, because it makes it easier to switch to a higher gear so they can counter a sprint or attack.

So, the XT rear derailleur configs are:

M772: Top Normal, Shadow
M771: Top Normal
M770: Low Normal/Rapid Rise

Agentbolt

Sweet, okay, so it's way more complicated than I thought. Probably doesn't make much difference to an clueless tourer like me. It's definitely not a Shadow model, those are the ones that hide under the chainstay if I recall, to avoid getting damaged from a fall. (Edit: Duh. You also just said that in the post above mine)

So where does the M761 fit into that list, and why doesn't my bike have one if it's what's supposed to come on the stock Surly? I guess in a certain understatedly stupid way, I'm curious if the 770/771 I've apparently got on there is better or worse than the 761 I'm supposed to have. Obviously I'd never know the difference unless someone told me, but I'm curious.

nubcake

what storkel said is all true but as to the actual differences between the first pic and the second is that the second is the newer version of the same style xt. I am not sure where they upgraded it for the new year but one thing they are doing now is getting rid of barrel adjusters on the derailer itself. You are just expected to rely on the barrel adjuster at the shifter. Never have had an issue with it before but I am not super fond of the idea

zoro

Does not make a significant difference since the bike will be on the road or gravel roads most of the time. It makes a difference when it's used for MTB since the strenght factor varies from model to model.

Also, shorter cage derailleurs tend to shift crisper than long cage (although the difference was more significant a couple years ago, now it seems to be marginal)

sstorkel

As nubcake suggests: the 761 has been discontinued and is no longer being produced by Shimano. It's been replaced by the 771. Obviously, Shimano believes the 771 is better than the 761. Whether that's actually true or not, I have no idea...

tacomee

For touring, the new style Shimano MTB rear derailers are not as good as the last generation, but it really doesn't matter on the Surly LHT. Surly specs their bikes with whatever parts then can get cheap.

Agentbolt

Yeah, we all know Shimano takes the occasional step backwards with new models. Anyways, thanks for clarifying everything, folks. Surly should change their site to indicate the current model.

rodar y rodar

Haha! Plenty confusing for me, but I doubt it will EVER be sufficiently confusing to satisfy any of the component manufacturers!

What`s this about eliminating the cable adjustment from the RDs? I hope that idea doesn`t take off across the board since a lot of shifters don`t have adjusters. I know there are inline adjusters available, but it seems a shame to mess up the easy simplicity just to save a dime. Oh yeah- Shimano. It`s probably "for our own good" since we`re too stupid to know we`re better off without adjuster screws

Bacciagalupe

I'm confused as well -- how are you supposed to adjust the indexing on this thing if you have bar-end shifters?

juggleaddict

They actually make secondary adjusters that fit anywhere on the shifter cable. They come on the windsor tourist I believe. Not sure where to buy them though, that's a really dumb idea shimano u.u really dumb.

juggleaddict

yea, here's a link to a review of it, there's a good pic of these. Again, I don't know where to pick them up, but they'd be a good alternative, not sure if they'd let water get to the cable

https://cycling.peltonweb.com/2009/05...ndsor-tourist/

Bacciagalupe

OK, I'm seeing barrel adjusters on the downtube shifter bosses (I assume that's the correct name). I think they did it for the weight savings. No worries.

I guess you'd be a little bummed out if you had downtube shifters, though.

sstorkel

You can put these barrel adjusters virtually anywhere there's a cable stop. You can also use inline adjusters anywhere. There are lots of different variations available. Of course, everything works easier if the adjuster is just built into the derailleur, brake caliper, etc.

surfjimc

I think removing the barrel adjuster was a big pain in the ass. It makes it much easier to fine tune the STI shifting when it is right there at the rear derailuer, rather than having to reach or to keep moving back and forth to get the derailuer in just the right place. My adjusting barrel is on the down tube shifter boss. I don't like it nearly as much. I guess Shimano figures it was redundant and saves a little weight, and you can adjust on the fly with the barrel adjuster on the handle bars. It is definitely creates little compatibility problems when adapting to non Shimano groupo bikes.