Ultegra RX Rear Derailleur Review

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pamountainbiker
Posts: 67
Joined: Mon Jan 12, 2009 3:49 am

by pamountainbiker

Wanted to post about my experience with the new Ultegra RX rear Derailleur. I installed it on my gravel bike, an Ibis Hakka MX. The rear cassette is an XTR 11-40 unit. The derailleur isn't rated to that cassette size but it works perfectly well, the b screw is only screwed in about 2/3 of the way. The shifting is precise, accurate and works as you'd expect it to on a smaller road based cassette. This is particularly important because I'm running it 1X.

Regarding the clutch action, Shimano says that the tension is (slightly) less than on an MTB unit. While I'm sure this is true, it doesn't "feel" true when comparing to my mountain bike clutched derailleurs. They feel equally strong. When the clutch is off, the unit works like a regular road derailleur. Even when the clutch is off there's a fair amount of tension in the spring. I havn't ridden on exceptionally rough roads or trails but on regular gravel whatever that is, the derailleur is pretty stout. For example bunny hopping doesn't make the chain slap, even with the clutch off, however, the Hakka MX has a dropped driveside chainstay. Your mileage may vary in this regard.

With the clutch on, the bike over gravel and bunny hopping or impacts is a lot quieter. Not because it's necessarily keeping the chain from slapping but because it's eliminating erroneous chain movement. In the workstand there is definitely a little more driveline friction when the clutch is on particularly in larger cogs. However, on the road it's not noticeable at all really. On that note, on the road, I almost never use anything but the smallest 5 cogs of the XTR cassette (42T up front), and in those cogs the added drag of the clutch is less and generally the chainline is better. Shift effort in the stand feels slightly higher; out on the road, it's impercetible. In fact, you can shift (mechanical) to a larger cog with one finger, at least I can. It feels no different to me. Shift precision remains the same.

I basically leave the clutch on all the time, even on the road. Here's why, in my experience, even when running a lightweight XTR cassette, there is still enough inertia that when cranking really hard and then coasting the chain slackens significantly. So much so that if the Hakka MX did not have a dropped stay it would easily hit the stay every time. This never happens with road style cassettes or 2X. But for me, running 1X with a big cassette, it happens. When the clutch is on, it totally and completely eliminates this inertia induced movement. So, even on the road I run it with the clutch on.

I bought it retail for $115, it weighs 242 grams on my scale and in my viewpoint is well worth the security.

by Weenie


kafreeman
Posts: 57
Joined: Thu Jul 23, 2015 8:46 pm

by kafreeman

How are wheel changes?

I've got the regular 8000 on my Crockett and it's a PITA to pull back the derailleur and line the rotor up. Seems to bind up when trying to drop the wheel in.

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emotive
Posts: 72
Joined: Tue Nov 01, 2016 10:40 am
Location: Melbourne, Australia

by emotive

thanks for the detailed review. I'm sold.

pamountainbiker
Posts: 67
Joined: Mon Jan 12, 2009 3:49 am

by pamountainbiker

kafreeman wrote:
Sun Jul 15, 2018 4:35 am
How are wheel changes?

I've got the regular 8000 on my Crockett and it's a PITA to pull back the derailleur and line the rotor up. Seems to bind up when trying to drop the wheel in.

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Great question, this is my only complaint. Wheel changes are difficult more so in my opinion than a regular 8000 series unit because the geo around the b knuckle looks like its slightly different. The knuckle sits farther forward toward the front of the bike and the tension of the unit pulls the wheel toward the front. Thus when removing the thru axle the derailleur basically jams the wheel forward. Using a big cassette also doesn’t help. It’s annoying for sure so much so that when I first took the wheel out it jammed the rotor against the inside of the stay marring the paint (off topic the Hakka has nice looking but fragile paint). Putting the wheel back in is a big pain. Lining up
The thru axle, rotor and chain is difficult so much so that you’ll most likely have to rest the bike upside down if in the field or else the inside stay will get completely marred (or the caliper will) by the rotor when struggling to get the chain on the cogs and the axle into the thru axle slots. There is no way you could do this in a race scenario at least I couldn’t. Also the clutch must be off to do any wheel change. This is really my only complaint. Frame geo might make it easier on other bikes as well.

TheKaiser
Posts: 525
Joined: Thu Sep 05, 2013 3:29 pm

by TheKaiser

pamountainbiker wrote:
Sun Jul 15, 2018 2:27 am
Regarding the clutch action, Shimano says that the tension is (slightly) less than on an MTB unit. While I'm sure this is true, it doesn't "feel" true when comparing to my mountain bike clutched derailleurs. They feel equally strong.
I wonder if that could be due to wear on the MTB derailleur's clutch. They do wear over time, I have a SRAM one now that doesn't seem to do much at all. The Shimano MTB ones are adjustable though, which is nice. Not sure about the road clutches though.
pamountainbiker wrote:
Sun Jul 15, 2018 2:27 am
When the clutch is off, the unit works like a regular road derailleur. Even when the clutch is off there's a fair amount of tension in the spring.
That is an interesting observation. I wonder if they changed the spring stiffness vs. regular R8000 when they designed the clutch model.

kafreeman
Posts: 57
Joined: Thu Jul 23, 2015 8:46 pm

by kafreeman

R8000 is far stiffer than 6800.

I'm almost tempted to go back to a 6800. I've got 3 wheelsets for this bike by accident.

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wheelsONfire
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by wheelsONfire

Got the 6870 GS on my UP. I drilled a new hole for the tension spring, removed the B-srew and removed the Wolf tooth Road link.
Got the chain much closer to the PG-1170 cassette (11-36) with no issues.
But i still guess the clutch operated RX would be more safe talking chainslap and remaining in place.
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LiquidCooled
Posts: 54
Joined: Mon Oct 02, 2017 5:46 am

by LiquidCooled


kafreeman wrote:R8000 is far stiffer than 6800.

I'm almost tempted to go back to a 6800.

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I'm curious why you're tempted. I was thinking of going the other way (6870 to 8050), so any info/opinions are welcome. Is it just that the stiffness of the 8000 increases shifting effort, or is it something else?
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ooo
Posts: 570
Joined: Sat May 21, 2016 12:59 pm

by ooo

what is distance between guide pulley and 11t cassette cog (with 11-40T cassette settings)
'

pamountainbiker
Posts: 67
Joined: Mon Jan 12, 2009 3:49 am

by pamountainbiker

ooo wrote:
Mon Jul 16, 2018 5:13 pm
what is distance between guide pulley and 11t cassette cog (with 11-40T cassette settings)
The distance is about 30mm. That's on my bike (Ibis Hakka MX). Other bikes will have slightly different distances based on hanger geometry, of course.

kafreeman
Posts: 57
Joined: Thu Jul 23, 2015 8:46 pm

by kafreeman


LiquidCooled wrote:
I'm curious why you're tempted. I was thinking of going the other way (6870 to 8050), so any info/opinions are welcome. Is it just that the stiffness of the 8000 increases shifting effort, or is it something else?
Wheel changes are a pain. Otherwise it's fine. Need to reindex as I'm getting some chain jumping on the lower gears when I drop down for bigger grades. Never noticed in Texas.

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bikeguy0
Posts: 17
Joined: Mon Feb 18, 2013 6:01 am

by bikeguy0

pamountainbiker wrote:
Sun Jul 15, 2018 2:27 am
Wanted to post about my experience with the new Ultegra RX rear Derailleur. I installed it on my gravel bike, an Ibis Hakka MX. The rear cassette is an XTR 11-40 unit. The derailleur isn't rated to that cassette size but it works perfectly well, the b screw is only screwed in about 2/3 of the way. The shifting is precise, accurate and works as you'd expect it to on a smaller road based cassette. This is particularly important because I'm running it 1X.

Regarding the clutch action, Shimano says that the tension is (slightly) less than on an MTB unit. While I'm sure this is true, it doesn't "feel" true when comparing to my mountain bike clutched derailleurs. They feel equally strong. When the clutch is off, the unit works like a regular road derailleur. Even when the clutch is off there's a fair amount of tension in the spring. I havn't ridden on exceptionally rough roads or trails but on regular gravel whatever that is, the derailleur is pretty stout. For example bunny hopping doesn't make the chain slap, even with the clutch off, however, the Hakka MX has a dropped driveside chainstay. Your mileage may vary in this regard.

With the clutch on, the bike over gravel and bunny hopping or impacts is a lot quieter. Not because it's necessarily keeping the chain from slapping but because it's eliminating erroneous chain movement. In the workstand there is definitely a little more driveline friction when the clutch is on particularly in larger cogs. However, on the road it's not noticeable at all really. On that note, on the road, I almost never use anything but the smallest 5 cogs of the XTR cassette (42T up front), and in those cogs the added drag of the clutch is less and generally the chainline is better. Shift effort in the stand feels slightly higher; out on the road, it's impercetible. In fact, you can shift (mechanical) to a larger cog with one finger, at least I can. It feels no different to me. Shift precision remains the same.

I basically leave the clutch on all the time, even on the road. Here's why, in my experience, even when running a lightweight XTR cassette, there is still enough inertia that when cranking really hard and then coasting the chain slackens significantly. So much so that if the Hakka MX did not have a dropped stay it would easily hit the stay every time. This never happens with road style cassettes or 2X. But for me, running 1X with a big cassette, it happens. When the clutch is on, it totally and completely eliminates this inertia induced movement. So, even on the road I run it with the clutch on.

I bought it retail for $115, it weighs 242 grams on my scale and in my viewpoint is well worth the security.
**updated to the Roadlink DM recommendation.

Look at the Wolftooth Roadlink DM: https://www.wolftoothcomponents.com/col ... oadlink-dm
Designed to give you better chain tracking of a larger cassette. That is why someone asked above about your distance from the 11T cog when the b-screw is adjusted for the 40 in the back. What happens is the jockey wheel is pushed back away from the cassette so it can clear the 40 but then as you move down the cassette it can be too far away from the smaller cogs making the shifting sluggish.

I've run the Goatlink 11 on my XTR Di2 RD that I use with a SRAM 10-42T cassette for a 1X gravel setup and it makes the RD track the cassette better. $27.95 on their site.
Last edited by bikeguy0 on Tue Aug 21, 2018 6:58 pm, edited 1 time in total.

markdjr
Posts: 40
Joined: Sun Sep 17, 2017 10:21 pm

by markdjr

The Goatlink 10 will work, the newer Roadlink DM is the recommended product. I tried both and found the Roadlink to function a little better for my set of variables.

Milese
Posts: 109
Joined: Wed Mar 17, 2010 12:04 am

by Milese

I'm sure there is a quick answer, but i heard that the 10speed mtb shadow mechs work with 11 speed road shifters.

True or false? (Ie is there a cheaper alternative to get a clutched mech on my 11s shimano cx bike?

ooo
Posts: 570
Joined: Sat May 21, 2016 12:59 pm

by ooo

false
'

by Weenie


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