GRX front derailleur issue (mechanical)

[Mr.Gib]

I am starting to doubt that this FD is a good design. I am using the 48-31 GRX crankset and a Shimano ultegra 11-34 cassette. I can just barely get the cage to clear the chain in the small/big (31/34) combo. To get this clearance means heavy FD cage rubbing at the small end of the cassette (the 11 and 12 cog). On the big ring it is a similar story, perhaps a bit worse. Setting the FD to give clearance for the 48/11 combo pretty much means light rubbing at the other end of the cassette in the big/big (48/34) combo. It is as if the cage simply isn’t wide enough to accommodate cross chaining. Setting the FD cage up parallel to the chainrings as per Shimano instructions makes things worse. The best performance seems to be with the tail end of the cage set inboard a bit.

I would not have thought much of this, as shifting is very good and I have had zero chain drops under pretty rough conditions, but my wife’s gravel rig, which is full on Frankenstein, with first generation Sram Red 10 speed shifters, a praxis 48/32 crankset, Sram Red 22 FD, Shimano 10 speed 11-34 cassette, Sram Force 22 wifli RD, and Sram 10 speed chain, gets every gear combo with zero rubbing, zero chain drops, and is dead silent. Just a substantially better performing drive train in all respects.

I'd like to think I am doing something wrong but I have struck out in my diagnosis. Ideas?

[TurboKoo]

Do you have 4 positions ie trims on both chain rings?

[bigrace]

Sorry to jump in on this but there wasn't a reply.

Ive had my revolt for a year now with grx 810 and can never get 4 positions on the front mech no matter how hard I try. I'm not a bike mechanic but I can follow instructions (shimano) and I just can't get it right

Sent from my SM-G991B using Tapatalk

[de lars cuevas]

@Mr.Gib

Hi,

there's nothing wrong with the design. Just don't cross chain. The user manual explicitly states you shouldn't. https://si.shimano.com/#/en/iUM/5NL0A/n ... _USE-TITLE

Cheers, Lars

[Tabe]

Like TurboK said first identification that all is good is that all 4 trims work.

I have mech GRX 810 in my Revolt too with same rings and casette, work very well with right lenght chain and also with tad too short chain. I've set my fd bit tight so that inner plate rubs just a bit when powerclimbing standing when 31/34. This to prevent chain drop, I know kinda useless but but..

Many installation manuals and how-to's over the internet, but found this when lately changed new u8000 fd to my roadie and sorta felt it's good and kinda foolproof...so I suggest this:

https://cycling-obsession.com/installat ... erailleur/