Shimano GRX 48-31T, 46-30T - RX810, RX600, RX400

Especially for light weight issues concerning cyclocross / touring bikes & parts.

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fourfa
Posts: 11
Joined: Mon Sep 26, 2011 3:04 am

by fourfa

tomh79 wrote:
Mon May 13, 2019 10:18 am
fourfa wrote:
Mon May 13, 2019 6:55 am
I've been riding this very happily with DA 9120 shifters, DA 9100 FD, Ultegra RX800 RD, FSA SL-K 46/30 crank (630g). 11-36 on my 650B x 47 gravel wheels, 11-32 on my 700C x 28 road wheels. Shifting is great. No experience with GRX yet, but I imagine it has to be the same or better?
How do you like that FSA crank? Also thinking about buying it...Easton wouuld be best I suppose but so expensive. 48/30 combo with 11-36 would be awesome. Wondering if it would work - since Shimano will release a 31/48 - if they could make it work with the new FD...they probably would have released a 30/48...
Love it. Not cheap of course, but the occasional 20% coupon at the full-retail sites reduces the sting a little, and honestly it's decent value for the weight. Two things to think about: most MTBers riding carbon cranks off-road want some sort of hard plastic boot on the crank ends, and I haven't found one that fits. How much that matters to you, depends on how hard you shred. I'm primarily a roadie with some fire roads, so I'm ok with it. Second, it comes with some plastic film to protect the arms and this is rather short-lived. I had to peel one off, about to do the other, and replace with something tougher, stickier, and with more coverage.

(If you're tempted to play with the rings like I am, I'll just note it's cheaper to buy the 48/32 crank and replace the 32 with a 30, than to buy the 46/30 crank and replace the 46 with a 48. Just sayin)

tomh79
Posts: 86
Joined: Thu Dec 27, 2018 9:50 pm

by tomh79

Thanks a lot! In the German review I posted the only flaw they found was "variing chainring stiffness" - probably meaning there are stiffer chainrings or the rings aren’t equally stiff?! did you notice anything?
Easton (670g total) would set me back about 620 EUR with BB, FSA (727g total) about 335 EUR and Rotor Vegast (716g total) about 370 EUR.

Actually, did you play around with 30/48? got it working?
Last edited by tomh79 on Mon May 13, 2019 9:57 pm, edited 1 time in total.

by Weenie


fourfa
Posts: 11
Joined: Mon Sep 26, 2011 3:04 am

by fourfa

I weighed my SLK crankset with 46/30, with spindle, no pedals no BB, at 630g. Not sure where 727g comes from?

I'm not sure what varying chainring stiffness could refer to. The flat spline-mount construction can't be as laterally stiff as the thick oversized Shimano chainsets, but FWIW I can't tell any difference with the FSA on my stiff carbon gravel bike vs the Ultegra 6800 crankset on my flexy titanium roadbike.

Haven't gotten the 48T ring in yet to play with, but I can report back when I do.

tomh79
Posts: 86
Joined: Thu Dec 27, 2018 9:50 pm

by tomh79

fourfa wrote:
Mon May 13, 2019 7:33 pm
I weighed my SLK crankset with 46/30, with spindle, no pedals no BB, at 630g. Not sure where 727g comes from?

Sorry, the weights above are incl BB (90g BSA FSA).
fourfa wrote:
Mon May 13, 2019 7:33 pm
Haven't gotten the 48T ring in yet to play with, but I can report back when I do.

That would be great!

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onemanpeloton
Posts: 240
Joined: Wed Jul 12, 2017 11:30 am
Location: Edinburgh, UK

by onemanpeloton

Can anyone advise how well the RX812 (the 1x version) rear mech would work with an 11-32 cassette?

I'd like to use a 42t cassette when gravel riding and a 32t cassette when racing cyclocross. Will the mech handle this change as long as I have the correct chain length for each set up?
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ooo
Posts: 756
Joined: Sat May 21, 2016 12:59 pm

by ooo

RX812 looks like XT rear mech. I have both XT di2 rear mech and ultegra di2 rear mech, and for 1x 11-32 I prefer to use ultegra

Di2 1x setup weight is ok (with ST-R8070 shifters),
but for mechanical shifting shimano will be heavier comparing to sram cx1,
left "1x" lever is actually 2x lever with pads removed (saving just 50-60 grams) >230g (vs 119g sram cx1 left lever)
ST-R9120-R + ST-R9170-L + RD-RX812 - this 1x combo may have have better weight, not sure how comfortable it is

Image Image
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ChiZ01
Posts: 195
Joined: Wed Jan 01, 2014 6:20 pm

by ChiZ01

that lever is for dropper post

MichaelB
Posts: 570
Joined: Tue Apr 22, 2008 4:31 am

by MichaelB

It's a pity the GRX Levers weren't available sooner, so ended up going for R7020 levers to replace the munted RS505's on my Slate.

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Noctiluxx
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Joined: Tue Feb 07, 2017 7:17 pm
Location: Southern California

by Noctiluxx

I'm interested in the RX 810 2X (48-31) crankset to replace the current Ultegra 8000 on my 2019 Giant Revolt gravel bike. I assume it should be no issue?
2018 Bianchi Oltre XR4, (Celeste Matt)
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2019 Giant TCR Advanced SL (Chameleon Blue)
2019 Giant Revolt Advanced 0

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TonyM
Posts: 3022
Joined: Thu Jan 22, 2015 4:11 pm

by TonyM

Noctiluxx wrote:I'm interested in the RX 810 2X (48-31) crankset to replace the current Ultegra 8000 on my 2019 Giant Revolt gravel bike. I assume it should be no issue?
You will need the GRX front derailleur also (Shimano moved the chainline a bit)

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