What derailleur to use?

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Posted: Jun 20, 2021 at 21:52 Quote
Just wondering what the differences are between the shimano derailleurs slx xt and xtr?

Posted: Jun 20, 2021 at 22:12 Quote
eddyendo wrote:
Just wondering what the differences are between the shimano derailleurs slx xt and xtr?
Get a deore RD and a XT shifter, done.

Posted: Jun 21, 2021 at 2:32 Quote
mtbtrekracer wrote:
eddyendo wrote:
Just wondering what the differences are between the shimano derailleurs slx xt and xtr?
Get a deore RD and a XT shifter, done.

So much this..
What most newer riders does not realise is how much the actual shifter matters. Thats why you see rider built rigs running XTR shifters and SLX deraillurs for instance.
Whereas the bullsh't marketing departments default to usual upgraded deraillur, although in all fairness I've seen some brands doing it right.

Posted: Jun 21, 2021 at 2:50 Quote
Without looking at it in too much detail (I'm not up to date on shimano specs), and assuming they are all similar cage length, with clutches and no Di2, then they are very similar designs, but you get slightly better and lighter materials on the higher up, eg XTR might have a titanium fixing bolt, a carbon cage plate, and sealed (possibly ceramic) bearings on the lightweight jockey wheels. Whereas SLX might be steel and alloy with unsealed steel bearings. Even lower spec you might see resin parts.

Is it worth spending more for top of the range? For your average rider probably not, hence the responses above, but the 10g weight savings, good bearings and having the most expensive parts really get some people going.

Posted: Jun 21, 2021 at 17:37 Quote
No one fully answered your question so here's the important bits: XT and XTR shifters have two clicks down, SLX one. Get the XT unless you want bling + even more less weight (XTR) or 1g more weight + no multishift (SLX)

SLX, XT, and XTR derailleurs are almost identical except for materials, clutch, and jockeys. XT and XTR have an easily adjustable clutch, SLX is more fiddly to adjust (remove the cover). XT and XTR have bearing jockeys, SLX bushing. The derailleur weight differences are a lot more if that matters to you. The XTR is 25% lighter than the SLX. I would get the XT if you're going to be pedaling the bike a lot or the SLX if mostly pointed down, or again if you want the bling and ultimate weight reduction, XTR.

Posted: Jun 22, 2021 at 9:34 Quote
XTR shifter shift much more crisp and have lighter actuation than even XT imo, they also have a rubberised grip. Imo for the little extra the XTR shifter is worth it. In terms of derailleurs there is f all difference aside from weight, looks and price, the performance benefit there is negligible.

Posted: Jun 22, 2021 at 10:28 Quote
There's a huge difference in efficiency between bushing and bearing jockeys. Ceramicspeed studied this and found over a watt of losses IIRC, which doesn't sound significant but the effect is cumulative. Pedalers or riders who do big days should consider deferring to XT or XTR for that reason alone.

Posted: Jun 22, 2021 at 11:37 Quote
HaggeredShins wrote:
There's a huge difference in efficiency between bushing and bearing jockeys. Ceramicspeed studied this and found over a watt of losses IIRC, which doesn't sound significant but the effect is cumulative. Pedalers or riders who do big days should consider deferring to XT or XTR for that reason alone.
Xt use bearings in both jockey wheels, xtr use bearing on the tension and a teflon/some bluish plastic bush on the guide pulley 10&11 spd that is, have not check 12 spd yet but I guess it's the same.
1 watt?! After some dust settles on the chain you are done, let alone the whole drivetrain getting dirty. Lab test are fun, marketing bs, ceramic speed use bigger jockey wheels, longer chain more drag etc, marginal "gains" even bigger marketing bs.
Also bearings have more drag than bushes. No 1 is seal drag and no2 grease, bushes use no seals and can work on minimal amount of grease or lack thereof, bearings on the other hand develop less play in the same amount of miles but risking total failure if contaminated which is highly probable on an mtb me thinks

Posted: Jun 22, 2021 at 12:25 Quote
Whoa dude lmao. First off, bearings do not have more drag than bushings (follow the breadcrumbs here). Second, we're not talking some $1000 unobtanium pulleys, its a controlled test. Third, your reasoning isn't accounting for compounding--lab tests are great because they isolate variables. Dirt and contamination are a compounding factor regardless of what kind of bearings or bushings are involved, in this specific case or other.

If your view is as narrow as the derailleur being the sum of a bicycle then sure, 1 watt is meaningless. As it turns out you're in a sport where incremental improvements are made across the sum of a system, which matters to people who have specific goals.

OP asked for the differences, not opinions about the differences. As the facts present, its pretty easy to make a call about what's important to each individual rider here, whatever their goals are.

Posted: Jun 22, 2021 at 13:15 Quote
Bearings do have more drag than bushes, actually a 30mm bb bearing with both seals and packed with grease has 7w loss compared to one without seals. Dirt, contamination, temp etc are defining factors of how a component performs in the intended environment, of what use is a dragless bearing if it can't keep the dirt out of the bearing resulting in premature failure, A well sealed bearing has significant drag and is affected by many factors, 1w isn't huge loss of efficiency in the total but rather insignificant value that can't be isolated, it's less than marginal, add all factors that contribute to drag on a drivetrain it's even more insignificant that you trying to make it, and exactly compounting values is the reason you can't call it a gain, it's a system and that's how it should be measured. If you can test and verify that every single bearing in production can be within less than 1w variable then you have to do the same for every link in a chain etc. Specific Lab tests are great for marketing bs. Get out and ride 10 simillar setups in the dirt and do the test again and see the results, then only under real working conditions you'll get an idea what matters or not, like it or not systems tend to wander much off the scale of lab tests.
But a simple test, fit two jockey wheels on a cage one bushed jockey wheel and one with bearing, spin them and see which one spins easier and for a tad longer.

Posted: Jun 22, 2021 at 13:17 Quote
DCA says "derailleur baaaad..!!!"....

...sorry, I just couldn't help that Wink

(showing myself out the door)

Posted: Jun 22, 2021 at 13:54 Quote
adespotoskyli wrote:
Bearings do have more drag than bushes, actually a 30mm bb bearing with both seals and packed with grease has 7w loss compared to one without seals. Dirt, contamination, temp etc are defining factors of how a component performs in the intended environment, of what use is a dragless bearing if it can't keep the dirt out of the bearing resulting in premature failure, A well sealed bearing has significant drag and is affected by many factors, 1w isn't huge loss of efficiency in the total but rather insignificant value that can't be isolated, it's less than marginal, add all factors that contribute to drag on a drivetrain it's even more insignificant that you trying to make it, and exactly compounting values is the reason you can't call it a gain, it's a system and that's how it should be measured. If you can test and verify that every single bearing in production can be within less than 1w variable then you have to do the same for every link in a chain etc. Specific Lab tests are great for marketing bs. Get out and ride 10 simillar setups in the dirt and do the test again and see the results, then only under real working conditions you'll get an idea what matters or not, like it or not systems tend to wander much off the scale of lab tests.
But a simple test, fit two jockey wheels on a cage one bushed jockey wheel and one with bearing, spin them and see which one spins easier and for a tad longer.

Apologies if the last post came off strong but this is unequivocally false. We aren't talking about hydrostatic journal bearings or even high quality PTFE stuff, we're talking about a cheap ass bolt in sleeve assembly that barely qualifies as a plain bearing. The 'bushing' jockey will spin longer and more freely unloaded because the tolerances are garbage to the point where you can usually rock them side to side on the fastener--obviously in that case the ball bearing has more static and kinetic friction to overcome, that's a no brainer.

Loaded, ball bearings involved in bicycles have magnitudes less static and kinetic friction within their applications, full stop. It's what the CS test linked above is demonstrating and its why we don't make our hubs, bb's, and headsets with PTFE bushings, but we do favor them in high load applications (eyelets). That type of assembly is used in derailleur pulleys because its cheap, not because its the best solution.

I'm no meche but I'm going to take CS's word on this one.

Posted: Jun 22, 2021 at 14:03 Quote
HaggeredShins wrote:
adespotoskyli wrote:
Bearings do have more drag than bushes, actually a 30mm bb bearing with both seals and packed with grease has 7w loss compared to one without seals. Dirt, contamination, temp etc are defining factors of how a component performs in the intended environment, of what use is a dragless bearing if it can't keep the dirt out of the bearing resulting in premature failure, A well sealed bearing has significant drag and is affected by many factors, 1w isn't huge loss of efficiency in the total but rather insignificant value that can't be isolated, it's less than marginal, add all factors that contribute to drag on a drivetrain it's even more insignificant that you trying to make it, and exactly compounting values is the reason you can't call it a gain, it's a system and that's how it should be measured. If you can test and verify that every single bearing in production can be within less than 1w variable then you have to do the same for every link in a chain etc. Specific Lab tests are great for marketing bs. Get out and ride 10 simillar setups in the dirt and do the test again and see the results, then only under real working conditions you'll get an idea what matters or not, like it or not systems tend to wander much off the scale of lab tests.
But a simple test, fit two jockey wheels on a cage one bushed jockey wheel and one with bearing, spin them and see which one spins easier and for a tad longer.

Apologies if the last post came off strong but this is unequivocally false. We aren't talking about hydrostatic journal bearings or even high quality PTFE stuff, we're talking about a cheap ass bolt in sleeve assembly that barely qualifies as a plain bearing. The 'bushing' jockey will spin longer and more freely unloaded because the tolerances are garbage to the point where you can usually rock them side to side on the fastener--obviously in that case the ball bearing has more static and kinetic friction to overcome, that's a no brainer.

Loaded, ball bearings involved in bicycles have magnitudes less static and kinetic friction within their applications, full stop. It's what the CS test linked above is demonstrating and its why we don't make our hubs, bb's, and headsets with PTFE bushings, but we do favor them in high load applications (eyelets). That type of assembly is used in derailleur pulleys because its cheap, not because its the best solution.

I'm no meche but I'm going to take CS's word on this one.

uh, sir, please delete and just answer the Question without thinking like you know what your talking about.
also Pinkbike are doing a 10 part series on "how to bike" suggest you tune in.

Posted: Jun 22, 2021 at 14:07 Quote
mtbtrekracer wrote:
uh, sir, please delete and just answer the Question without thinking like you know what your talking about.
also Pinkbike are doing a 10 part series on "how to bike" suggest you tune in.

Sick burn bro. Maybe you'll add something to this thread in your third post.

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