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Discussion Starter · #1 ·
Here is my current drivetrain:

XO Shifters and rear derailleur
3rd Gen XTR crankset, front Derailleur, and 11-34 cassette with Shimano 7701 9 sp chain.

Can anyone speak with experience regarding this combination as compared to using an identical drivetrain EXCEPT to change the rear cassette to a SRAM PG 990 11-34 and the chain to a SRAM PC991.

I haven't been astounded with the shifting in my current setup, and I really expected to be.

Perhaps the SRAM components would interface better?

Thanks for any and all intelligent comments.
 

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Discussion Starter · #3 ·
Yes, I've tweaked. Tried 2 different high end cablesets, and I am hopeful for the new XTR models I just installed...

Anyone with any experience with XO vs XTR as I mentioned above?
 

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bang
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Bernard3rd said:
Yes, I've tweaked. Tried 2 different high end cablesets, and I am hopeful for the new XTR models I just installed...
what does that have to do with tweaking? unless there is excess friction in the cable / housing, there is no need to change it out. is the cassette, crankset and chain in the same condition (i.e., all new)? i new chain and chainrings with a worn cassette could cuase issues, etc.

barnett's chapter on rear derailers
sram derailer manual

how is the current drivetrain shifting? what don't you like about it? what did you have befor and how did that shift?
 

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I say this often, but have you checked the straightness of your derailleur hanger? Hangers that are slightly out of whack can be a source of slightly off shifting. Every shop should have the tool to check this and it shouldn't take more than 15 minutes.

*Edit*
To actually answer your question, instead of being a pontificating jerk, I don't think there would be much difference. Every company always states that you need everything to be the same to achieve maximum performance, but in my opinion your setup should be fine.
 

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Discussion Starter · #6 ·
Thanks for the suggestion of straightening the Der hanger., and yes that is something that I did replace.

Some more background to my situation. Got a new Blur LT about last September... The shifting was finicky from the start. I didn't expect this from XO der/shifter combo with the touted 1:1 ratio, I expected it to be very reliable, but the shifting would go out of whack relatively easily. Then it would be clicking and skipping, and the trail I ride on has alot of G outs that require you to dump a number of gears to get up the other side... If the gear skips and catches, you can blow apart a chain - which had never happened to me in 20 yrs of mt biking, but did happen on my very first ride with this bike/setup. Additionally, I noticed a hesitance to shift up the cogset to an easier gear when the rear suspension was articulating/compressing (at one point on my ride there is a steep hill and you need to get speed up and then dump about 3 gears to make it cleanly, but the point where I would dump the gears has a good sized bump/rocky ledge, and it seems that the rear didn't want to shift if I tried to dump the gears while pedaling over/up this approx 8" ledge... I never had this problem on My 1998 GT STS with full XT grouppo... I was surprised, because I expected the overall drivetrain performance to surpass the GT STS/XT setup and it didn't even perform as well. Then in Moab in October the rear derailleur somehow got sucked into the spokes just partway down Porcupine rim trail... The thing was completely upsidedown, but neither the der hanger or the derailleur snapped, so luckily, I was able to gingerly bend the thing back and got it setup to singlespeed on home, but it was a pain in the butt. I had the fancy cables that have the individual links and inner liner (Aztec I think)...

So I just now coughed up the dough to buy the new XO rear Der and put it back together (Yes I got a new Der hanger from Santa Cruz), and now I am using XTR cables and housings, so I hope that this alleviates the problem(s). I have yet to take the bike out for the first real trail ride, but that will be this weekend.

Bottom line is that I bought top of the line stuff and expected it to perform as such. To this point it hasn't, but I wondered if the problem is that the cassette and chain may be fighting the Der/shifter combo...

I really just don't want to eat another XO rear derailleur at over $200.00 bucks and was wondering if anyone here had any insight...
 

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I used to own a first generation Blur and G-outs were the thing that caused random gear issues. You likely notice the pedal kickback on G-outs. I found that it would often come out of those with the chain popping up a gear or two on the cassette and it would take a pedal revolution to get it back onto the gear the derailleur was in. I was running an XTR Rapid-Rise rear derailleur, I switched to an XT normal rise and that helped some but did not eliminate it.

It seemed that as the top of the chain shortened under full compression and kicked the pedal back, the tension would get suddenly slack on the bottom of the chain and jump a gear or two down the cassette, as the suspension returned in height, the gear would chatter as the chain was dragged back up into the bigger cogs. It definitely wasn't responsive to down shifting in that condition.

I tinkered with the B-tension screw and chain length but never completely solved it. (well I did eventually, I bought a Rocky Mountain ETSX to get rid of the G-out pedal kickback :D )

As to your original question, I mix Shimano and SRAM cassettes and chains and have never noticed any issues with performance between the higher end units in either product line.
 

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this probobly doesn't really answer your question as i have no experience with newer xtr stuff. but.... i'm running an x.9 der and shifter, a pg 990 11-34 cassette and a pc 991 chain and its the best shifter setup i've ever used. even when rediciulously muddy.

my other experience is 8sp xtr stuff, and i find this new sram kit to be a serious step upwards.

well anyways, ya know that red spider is just a great piece of bike bling, so i say go for it!
 

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I think rockyuphill shacked it. Your shifting issues have got to be outside of the realm of that particular SRAM vs Shimano parts interface. I've got a full SRAM drivetrain, but I can't believe (nor would I expect) that a comparable Shimano cassette and chain would make any significant or even noticeable change in overall shifting performance. The issue is with something else, methinks. I wish you godspeed hunting it down!

But, yeah, like euroford says, I do like my PG990 bling :D

Cheers, Chris
 

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Discussion Starter · #14 ·
I guess that I should have inserted an "and" between my statements above so that it would read: Yes I've tweaked AND tried 2 different cablesets. the reason that I chose to ditch the original Aztec set is that the inner liner which is a thin plastic piece was eventually somehow sucked down onto the little thingy on the XO derailleur that allows the cable to run a 180 degree bend... As such the cable seemed to be binding a bit in the inner cable liner at the 180 degree bend at the rear derailleur, so I decided to ditch them for the XTR set... However, I think that a strong case could be made that the switching of cables and housings could actually fall under the category of "Tweaking" even though I intended it to be a separate category entirely...

I really appreciated the info from Rocky uphill... this is helpful info. I hope the Blur LT doesn't have some sort of fatal flaw in the way the rear articulates in such situations that prevents me from totally loving it... It is really great in alot of areas.
 
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