GRX FD-RX400 Grrrrr!

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MartinC
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GRX FD-RX400 Grrrrr!

Postby MartinC » 27 Jul 2020, 10:35pm

I'm trying to install one of these. I've followed the instructions to the letter but it won't move nearly enough to change onto the big chainring.

I can move the cage by hand far enough but the cable connected to the shifter won't. I can't even see how it's supposed to work - the link plate just seems to be there to waste about 5mm of cable movement.

FC-RX600 (46-30, BB86), RD-RX400, FD-RX400, ST-RS405, all compatible by the chart. Chainline is right (46.5mm). Shifter has right number of clicks and moves cable (checked by tensioning the cable by hand and operating shifter). Cable routing is internal, the front cable is bare beneath the BB.

Clearly I'm doing something wrong but I haven't got a clue what. The Tiagra transmission I'm replacing used technology I recognised (it's cage plate has an almost identical cage to the GRX one but can't cope with the 46.5mm chainline. Is this all part of Shimano's mission to optimise and complicate everything to the point that it's not worth having? Please don't mention the support bolt or my retrogrouch tendency will get worse.

Please. Does anyone know how to install these? Techdocs doesn't help and google doesn't offer anything useful.

Jdsk
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Joined: 5 Mar 2019, 5:42pm

Re: GRX FD-RX400 Grrrrr!

Postby Jdsk » 27 Jul 2020, 10:44pm

MartinC wrote:Techdocs doesn't help... .

That's the Shimano user and dealer manuals?
https://bike.shimano.com/en-EU/product/component/grx-10-speed/FD-RX400.html

Jonathan

gregoryoftours
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Joined: 22 May 2011, 7:14pm

Re: GRX FD-RX400 Grrrrr!

Postby gregoryoftours » 27 Jul 2020, 10:54pm

Please post a photo of the cable routing from the BB shell and up to where it's clamped.

Brucey
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Re: GRX FD-RX400 Grrrrr!

Postby Brucey » 27 Jul 2020, 11:11pm

this is the manual for FD-RX400

https://si.shimano.com/pdfs/dm/DM-GAFD001-00-ENG.pdf

it would be better if you didn't need a 26-page guide to help you set one up and of course more steps = more ways you can go wrong.....?

FWIW point 2) on page 16 is a place where you can easily go awry.

cheers
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~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~

MartinC
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Location: Bredon

Re: GRX FD-RX400 Grrrrr!

Postby MartinC » 27 Jul 2020, 11:12pm

Hi, thanks. Yes I've been looking at the dealer manual.

Gregory, will post a pic tomorrow. You may be onto something here - I may not be getting enough tension on the cable 'cos there's a bendy guide involved. If that's it I'll be surprised at how much difference it makes!

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Redvee
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Re: GRX FD-RX400 Grrrrr!

Postby Redvee » 28 Jul 2020, 12:58am

You're not alone having problems with the new style Shimano front mechs, when I first installed it on my old frame I had to have a second attempt to get it working properly.

I watched this Youtube video several times to understand how to install the front mech and I still got it 'wrong' when I built up my Tripster AT frame with R70/70 groupset.

https://www.youtube.com/watch?v=ZdF8O-2UbZE




Although this video is for GRX810 front mech the principal is the same for R7000/R8000/R9000 front mechs.

scottg
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Location: Highland Heights Kentucky,, USA

Re: GRX FD-RX400 Grrrrr!

Postby scottg » 28 Jul 2020, 1:48pm

Set the inner limit using a chain, big cog, small ring.
The Shimano manual method, had the inner cage rubbing on the chain.
Extra low bb threw the Shimano method off.
Which requires another round of adjust cable tension, undo annoying
rotating cable bolt, reset cable tension.

Once you figure out the tension screw it shifts very well,
and easy to check & adjust cable tension after the first few rides.

The Porsche 911 of front derailers, a poor idea (indexed front mech),
redeemed by lots of extra engineering. :)
+++++++++++++++++++++++++++++++++++++
Why not the best, buy Cyclo-Benelux.

MartinC
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Joined: 10 May 2007, 6:31pm
Location: Bredon

Re: GRX FD-RX400 Grrrrr!

Postby MartinC » 28 Jul 2020, 2:40pm

Just been to the garage to take photos. Much better frame of mind than last night. Couldn't help testing the mech again by moving the link plate manually and again it would only move the cage by about 5mm. Thus I couldn't see how the mech could possibly work - so I twiddled the High adjustment screw. Eureka! It needs to be nearly all the way in for the mech to move. Counter intuitive - screw in to allow the cage further out and of course you need to start with it overshifting. Mystery solved. I don't recall seeing this anywhere in Mr S's manuals or in the many videos. Every day is a school day.

Many thanks for all your input and help. Even having to explain something to a knowledgeable and helpful audience puts you in the right frame of mind to solve a problem.

I liked to Porsche analogy - but I mustn't dwell on it or ranting will result.

Brucey
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Re: GRX FD-RX400 Grrrrr!

Postby Brucey » 28 Jul 2020, 3:09pm

MartinC wrote:…. - so I twiddled the High adjustment screw. Eureka! It needs to be nearly all the way in for the mech to move. Counter intuitive - screw in to allow the cage further out and of course you need to start with it overshifting. Mystery solved. I don't recall seeing this anywhere in Mr S's manuals or in the many videos....


fig 3 on p21 gives A and B directions, and CW movement is A which is to allow the cage further out. So it is there, just not obvious.

Glad it is all sorted out though!

cheers
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simonineaston
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Location: Live & work in Briz'l

Re: GRX FD-RX400 Grrrrr!

Postby simonineaston » 28 Jul 2020, 3:12pm

I had to have a second attempt to get it working properly.
Just 2, Brucey? That could be construed as kicking the fellow, while he's down! :wink:
ttfn, Simon in Easton
(currently enjoying a Moulton TSR & a nano Brompton...)

MartinC
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Re: GRX FD-RX400 Grrrrr!

Postby MartinC » 28 Jul 2020, 4:29pm

Brucey wrote:fig 3 on p21 gives A and B directions, and CW movement is A which is to allow the cage further out. So it is there, just not obvious.


Yes. If all else fails, read the documentation! I would claim that the instructions would be better if the said to wind A in while they were telling you to wind B in to align the outer plate.

Anyway I expect those tiny Allen screws will never be seen again after they've been doused in Belgian toothpaste and those extra pivots are gunged up - it is a gravel groupset after all!

fredN4
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Re: GRX FD-RX400 Grrrrr!

Postby fredN4 » 29 Jul 2020, 9:35am

bit late in the day but I have found plenty of vidoes on utube that explain how to set the stop screws. Arts Cyclery for one. Glad you sorted it.

Brucey
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Re: GRX FD-RX400 Grrrrr!

Postby Brucey » 29 Jul 2020, 12:44pm

MartinC wrote:...Anyway I expect those tiny Allen screws will never be seen again after they've been doused in Belgian toothpaste and those extra pivots are gunged up - it is a gravel groupset after all!


that is a very fair comment; I have to say that my eyebrows were raised when I saw that they had used this infernally complicated design on a 'gravel bike' groupset; I think for it to have the slightest chance of working/lasting well it ought to be hosed off and sprayed with water displacing lube after every ride.

Arguably it is just another nail the coffin of 'practical lightweight bike'; the headstone would make note of it's descent from workhorse to show pony. I've owned and enjoyed my fair share of show ponies but it is getting to the point where it is difficult to build a really practical machine using current lightweight parts.

cheers
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~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~

scottg
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Re: GRX FD-RX400 Grrrrr!

Postby scottg » 29 Jul 2020, 3:11pm

The bike shop told me that GRX = Geriatric Road Xtension.

Damm decent of Shimano to make a group for old codgers.
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Why not the best, buy Cyclo-Benelux.

MartinC
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Re: GRX FD-RX400 Grrrrr!

Postby MartinC » 30 Jul 2020, 12:18pm

scottg wrote:The bike shop told me that GRX = Geriatric Road Xtension.

Damm decent of Shimano to make a group for old codgers.


That's pretty much nail on the head! It's exactly why I was changing my Trek ALR4 to it from a Tiagra 50-34 11-34 set up. At the weekend my son was laughing at me for the 30-36 bottom gear I was aspiring too. I had to point out that he rode around on an 11 speed 50-34 compact with an 11-28 cassette but when I was his age and up to my forties I rode everywhere on a 7 speed 52-42 with a 13-23 freewheel so I was old and he was lazy!

Comparing different technologies directly will be interesting. I built my current touring bike a couple of years back - Spa steel frame, 7 speed triple,46-36-24 chainset, 13-34 cassette, DT shifters, V brakes. I upgraded my steel, 26" wheel, V brake IGH bike recently with a Rohloff hub (bottom gear is now 1.5 metres). So the Aluminium gravel bike with Hydro brakes, 10 speed, enclosed cables, STI's means I've covered all the old codger options. I'm pretty certain I know which will be the cheapest to maintain.