shimano grx

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

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rides4beer
Posts: 143
Joined: Wed Nov 28, 2018 5:27 am
Location: SC

by rides4beer

bm0p700f wrote:
Sat Jun 15, 2019 11:21 pm
In answer to an earlier question I will be swapping my grx rd rx812 to replace a 105 rd5800gs when the cassette wears out.

Currently i have a 42t single ring with a 12-34t cassette but will swap to an 11-42t which will help with the hills. This is on a road bike. For gravel I have an mtb.
Thanks, that's exactly the swap I'm looking to do, rx812 w/ 11-42 cassette. I did fine this past weekend with the 34, but if the terrain had been a lil steeper or looser, some extra gear would have been good. This is on a gravel bike with 48/32 up front.

emotive
Posts: 155
Joined: Tue Nov 01, 2016 10:40 am
Location: Melbourne, Australia

by emotive

tomh79 wrote:Maybe a stupid beginner question: but how does this wider chainline affect the cassette? Compared to the 43.5mm I have now, the chainrings of the crank will be 2.5mm more to the right/outside looking down from above? Which would mean, more crosschaining in the lower gear cogs?
Yes that’s right.

I’ve switched from Absolute Black 32/48 oval with a -1.5 chainline to Easton 32/47 with a 145 (+1.5mm) chainline and I can’t say I notice the crosschaining, and I spend plenty of time climbing in the 34T cog.

by Weenie


Finx
Posts: 67
Joined: Wed Jun 15, 2016 1:14 am

by Finx

The chainline changes because they moved the front derailleur out 2.5mm for better tire clearance to the derailleur. You have to use the GRX FD and Crankset together. None of the other components matter. you can mix and match all you want within the Shimano 11 speed family (and within the limits of the individual components).

raisinberry777
Posts: 196
Joined: Wed Jul 30, 2014 1:09 am

by raisinberry777

rides4beer wrote:
Mon Jun 17, 2019 8:24 pm
Thanks, that's exactly the swap I'm looking to do, rx812 w/ 11-42 cassette. I did fine this past weekend with the 34, but if the terrain had been a lil steeper or looser, some extra gear would have been good. This is on a gravel bike with 48/32 up front.
The RX812 is for 1x drivetrains only. The RX810 is for 2x drivetrains and has a maximum cassette range of 11-34 (but will fit more, easily 11-36 and in some cases may fit 11-40).

rides4beer
Posts: 143
Joined: Wed Nov 28, 2018 5:27 am
Location: SC

by rides4beer

raisinberry777 wrote:
Thu Jun 20, 2019 7:05 am
The RX812 is for 1x drivetrains only. The RX810 is for 2x drivetrains and has a maximum cassette range of 11-34 (but will fit more, easily 11-36 and in some cases may fit 11-40).
Thanks, didn't realize that. It's still clutched, which is good, and if I can squeeze a little more gear, that would be nice.

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TonyM
Posts: 3112
Joined: Thu Jan 22, 2015 4:11 pm

by TonyM

raisinberry777 wrote:
rides4beer wrote:
Mon Jun 17, 2019 8:24 pm
Thanks, that's exactly the swap I'm looking to do, rx812 w/ 11-42 cassette. I did fine this past weekend with the 34, but if the terrain had been a lil steeper or looser, some extra gear would have been good. This is on a gravel bike with 48/32 up front.
The RX812 is for 1x drivetrains only. The RX810 is for 2x drivetrains and has a maximum cassette range of 11-34 (but will fit more, easily 11-36 and in some cases may fit 11-40).
Is then the RX812 for up to 46T?

EDIT: Just checked and the RX812 is ok for up to 42T
https://bike.shimano.com/en-US/product/ ... RX812.html

CarlosFerreiro
Posts: 336
Joined: Thu Jan 08, 2009 1:41 pm
Location: Shetland, Scotland

by CarlosFerreiro


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