Cyclocross and Gravelbiking (Recreational) This has to be the most physically intense sport ever invented. It's high speed bicycle racing on a short off road course or riding the off pavement rides on gravel like :The Dirty Kanza". We also have a dedicated Racing forum for the Cyclocross Hard Core Racers.

Shimano GRX gravel group

Old 05-07-19, 05:11 PM
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31 is prime, it only "lines up" once per rotation. Bet you a Happy Meal that 48-32 would line up better...
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Old 05-07-19, 05:29 PM
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Originally Posted by Darth Lefty View Post
31 is prime, it only "lines up" once per rotation. Bet you a Happy Meal that 48-32 would line up better...
Not sure I follow, the shift ramps don't have to line up with any teeth at all
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Old 05-07-19, 06:49 PM
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Can someone explain to me how this compares with my Ultegra 2X drivetrain with 48-32 chainrings, Ultegra RX rear derailleur? Any advantages running GRX 2x over my existing Ultegra? BTW I have a Giant Revolt gravel bike.
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Old 05-07-19, 07:25 PM
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Originally Posted by Noctilux.95 View Post
Can someone explain to me how this compares with my Ultegra 2X drivetrain with 48-32 chainrings
The new stuff has 48-31t chainrings.
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Old 05-07-19, 07:30 PM
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Originally Posted by tyrion View Post
The new stuff has 48-31t chainrings.
Based on price and weight, the components seem to be 105 level.
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Old 05-07-19, 07:35 PM
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Originally Posted by Noctilux.95 View Post
Based on price and weight, the components seem to be 105 level.
As I understand it, there are multiple levels, currently ranging from Ultegra DI2 level to Tiagra level.
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Old 05-07-19, 07:43 PM
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So....honest question do we pronounce this "gurcks"? Is it pronounced as individual letters?
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Old 05-07-19, 08:00 PM
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Originally Posted by Marcus_Ti View Post
So....honest question do we pronounce this "gurcks"? Is it pronounced as individual letters?
How do you pronounce XTR?

OTOH, how do you pronounce SRAM?
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Old 05-07-19, 08:22 PM
  #34  
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Originally Posted by wgscott View Post
How do you pronounce XTR?

OTOH, how do you pronounce SRAM?
Shram of course
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Old 05-07-19, 08:26 PM
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Originally Posted by wgscott View Post
How do you pronounce XTR?

OTOH, how do you pronounce SRAM?
“Sachs”
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Old 05-07-19, 08:31 PM
  #36  
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Originally Posted by Noctilux.95 View Post
Can someone explain to me how this compares with my Ultegra 2X drivetrain with 48-32 chainrings, Ultegra RX rear derailleur? Any advantages running GRX 2x over my existing Ultegra? BTW I have a Giant Revolt gravel bike.
If your bike currently has issues with tire clearance near the FD it could be useful, the chainline is 2.5mm wider
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Old 05-07-19, 08:36 PM
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Originally Posted by redlude97 View Post
Apparently the shift ramps line up better with a 31T
Originally Posted by redlude97 View Post
Not sure I follow, the shift ramps don't have to line up with any teeth at all
Sometimes I just don’t understand you humans
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Old 05-07-19, 09:34 PM
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Originally Posted by Noctilux.95 View Post
Based on price and weight, the components seem to be 105 level.
GRX has several tiers.

Ultegra Di2 is RX815
Ultegra Mechanical is RX810
105 is RX600
Tiagra 10 speed is RX400

My question is whether RX815 components will play well with 8050 components from an electronic perspective.



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Old 05-07-19, 09:47 PM
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Originally Posted by Darth Lefty View Post
31 is prime, it only "lines up" once per rotation. Bet you a Happy Meal that 48-32 would line up better...
Originally Posted by Darth Lefty View Post
Sometimes I just don’t understand you humans
Was this supposed be some kind of bad joke?
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Old 05-07-19, 10:31 PM
  #40  
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My old gravel bike I scraped the FSA for a CX 50 crank aka Shimano with Dura Ace BB, night and day difference the rest of the bike was already Ultegra 10 speed. I’m a Shimano fan and I have SRAM bikes I just know how to service Shimano components.
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Old 05-07-19, 10:40 PM
  #41  
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Geez y’all made me get out my Shimano fishing reels. Oh no Shimano has the best long distance surf casting reel mankind has ever had. My Ultegra 50-34 was revolutionary now that is so yesterday Same old gears just different ratios.
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Old 05-07-19, 10:42 PM
  #42  
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Originally Posted by Darth Lefty View Post
31 is prime, it only "lines up" once per rotation. Bet you a Happy Meal that 48-32 would line up better...
"Lines up" in the context of shift gates doesn't necessarily mean that the tooth alignment is repetitious.

For example, consider the fact that a chain has narrow inner links and wide outer links, and that there are "two ways" of aligning the chain on a chainring.
Suppose that all of the pins on the big ring are positioned to "catch" a wide outer link upon a specific tooth alignment between the two chainrings. This might work perfectly every time if the chain is in one of its two possible alignments, but the pins would always miss badly if the chain is in the other alignment.
Chainring manufacturers need to design around stuff like this. And, there are different approaches to designing shift gates. Some manufacturers make 48-32 combos that seem to shift fairly well, but it wouldn't surprise me if Shimano's approach attained better shifting with a different small ring. And when it comes to front shifting, they seem to know what they're doing.
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Old 05-07-19, 10:48 PM
  #43  
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Get on that bike ride 100 miles a week for one year then come back and talk about gear ratios someone quoted that phrase so I don’t want to steal it but it is a great quote. Makes a lot of sense.
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Old 05-08-19, 06:48 AM
  #44  
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Originally Posted by Noctilux.95 View Post
Can someone explain to me how this compares with my Ultegra 2X drivetrain with 48-32 chainrings, Ultegra RX rear derailleur? Any advantages running GRX 2x over my existing Ultegra? BTW I have a Giant Revolt gravel bike.
Wont be that much different, the hoods have a different shape to them which is suposed to give you a more secure grip on the rough stuff and the front mech is a bit wider to acomodate wider tires.
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Old 05-08-19, 06:52 AM
  #45  
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Originally Posted by Darth Lefty View Post
That does appear to be the intent. You can see they're quite a bit different. They're also notable for having a clutch like a MTB derailleur.

The 11-42 is the XT M8000 version which means we'll have 11-42 cassettes around for at least another generation. Whew! Was worried they'd be Eagle'd away. But also means a road hub will need a spacer, since the MTB stuff never went away from the 8-9-10 speed freehub width.

RD-RX810 Search in Compatibility






I still am not sure if I can use the RX-812 rear mech with a 2x setup and an 11-42 cassete. That would be the ideal setup, same 42-30 low gear I have on my XC bike with a bigger gear for road riding. Things can get real steep around here and is not smooth at all. And we're having to ride on tarmac longer and longer to reach the off road stuff its a drag on a mountain bike.
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Old 05-08-19, 07:27 AM
  #46  
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Originally Posted by MAGAIVER View Post
I still am not sure if I can use the RX-812 rear mech with a 2x setup and an 11-42 cassete. That would be the ideal setup, same 42-30 low gear I have on my XC bike with a bigger gear for road riding. Things can get real steep around here and is not smooth at all. And we're having to ride on tarmac longer and longer to reach the off road stuff its a drag on a mountain bike.
If it helps, I run an 11-42 XT cassette with an RX805 GS derailleur.

The B screw is turned around and a 1.85 mm spacer used behind the cassette to fit road hubs. Front rings are 46/30. An entire 116 link chain is used.

No wolftooth is used. It shifts fine.


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Old 05-08-19, 08:09 AM
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If you don't like the 800 series 31 tooth ring then get the 600 series with a 30 tooth ring and run it with the rest of the 800 series components.

You gain a few grams and have to piece everything together. Those who feel like one tooth is going to make the difference are probably willing to do so.


Dave: We hope to see more gearing options in the future. We’ll watch to see how the first generation plays out. We’re already hearing that a 38T option for 1x would be good to produce. The 1x group, in particular, plays well in cyclocross and 38T chainrings are a popular choice there. Additionally, I’d like to see the 46/30 chainrings later on in the 800 series.

Read More...

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Old 05-08-19, 08:13 AM
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Q&A with Shimano Engineers about this groupset.

https://gravelcyclist.com/bicycle-te...-grx-groupset/

It is a good read and the engineers seemed to have been bitten by the gravel bug themselves. Their answer's are actually quite reasonable, not just marketing crud.


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Old 05-08-19, 09:14 AM
  #49  
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If the 2x10 RX400 derailleurs are actually compatible with 10 speed road shifters, and not Tiagra's 10 speed cable pull, I'm really stoked. I could finally use my 10-speed barcons, indexed, with a clutch mech. My current crankset is fine, but I'd for sure get a matching RX600-10.

Edit: too good to be true. According to this Bicycling article, the 10 speed stuff is compatible with Tiagra 4700. Big bummer!
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Old 05-08-19, 10:30 AM
  #50  
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I'm pretty surprised this hasn't come up yet. Shimano is sadly notorious for "introducing" components that don't see the market for 12+ months. What's the over/under on how many months it will take these components to actually come to market? I know what the article says . . . Shimano always says that. (Shimano doesn't have road 1x YET. It's not real until it's no longer a "pre-order.")

My guess (sadly) is that some cable-actuated components arrive in stores in November/December and most of the components will be in stores by February/March. The components I want most? I'm thinking May, 2020, if then.

(SOMEBODY tell the bike and component companies -- You lose an awful lot of potential product momentum when your product "introductions" happen a full year or more before customers can buy the product. STOP IT!!)

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