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2021 Revolt Advanced 2 experiencing serious chain rub in multiple gears and each ring on the FD.
Multiple trips to multiple shoppes and seems that it cannot be fully mitigated, according to the 'experts.' It is not completely incompatible to the point of non-function but it is,at best, not really an acceptable situation. The chain line seems off by several mm and even with limit screws fully tweaked there is rub on top 2 or 3 three cogs and smallest 2 or 3, regardless of FD position. Forget about cross chaining, NOT EVEN POSSIBLE.
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Have seen multiple threads in multiple forums from others having same experience and now they seem to be going down a memory hole. F'rinstance: https://old.reddit.com/r/gravelcycling/comments/nffmaa/grx_rx810_front_derailleur_compatible_with_praxis/
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Is Giant aware of the issue? They sure seem to be and are doing nothing about it except perhaps playing some games on social media sites.
Both shoppes I went into seemed non-plused about the whole thing and acted as if I was being a bit of a wank to suggest the chain should not be rubbing on the front derailleur. They seemed more inclined to handle me rather than the issue, a behavior which might seem to have some motives behind it. And now I see posts on the issue that were up for a while over a few months have now gone missing, deleted, or sent to defunct pages.
Anyone have any info on this issue? Any possible solutions or working hacks to make this work the way a drive train on a $2600 bike should?
abcspjbjd wrote:The GRX front derailleur has a 2.5 mm further reach than any other Shimano series derailleur, specifically designed to work with GRX cranks. Unless they spaced the crankset on the drive side out that far, it's going rub.
Thanks for some info.
The way in which it currently runs seems to require even further derailleur reach than 2.5mm. Adding spacers to this current situation would serve to make matters worse as the rub is on the interior/frame side.
But this and your info combined does make me think it is possible that they did add too many (or too large) spacers and that is causing the crank to sit further than the derailleur limits.
It's back in a 3rd shop that has at least agreed to take a deeper dive than the first two, which merely played with adjustments and told me it was as good as it gets.
^ That does appear to be a viable path.
Ty.
GOT PARTS ?
:-)
The GRX chainrings are shifted outboard 2.5mm relative to the Shimano road groups(room for wider chainstays/bigger tires), and the GRX front derailleur was designed to match. If the Alba has the “road” chainline a 105 or Ultegra FD might be the solution.
On any recent Shimano FD, make sure that the trim positions are set correctly. There are two positions for each chainring. Those are easy to get wrong.
The most recent solution is that I have pulled off the 2x and gone to a GRX 1x crank and change cassette to 11-42.
If the 31/48 GRX ever comes in I may swap out again but at this point I say the Alba 32/48 is definitely NOT optimal fit on this geometry.
justride17 wrote:
The unfortunate thing is, not many manufactures make T47 BB's yet. So, the shop put in a new Praxis/Shimano BB for free. Hoping this one lasts a little longer than 2 months.
https://wheelsmfg.com/bottom-brackets/t47/t47-angular-contact-bb-for-24mm-shimano-cranks-black.html
mtbnut87 wrote:
Wheels Mfg. is the answer you seek. Put one of these in my wife's Bombtrack and it is SWEET.Thank you!
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