SRAM AXS Front derailleur microadjust

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samarskyrider
Posts: 170
Joined: Wed Sep 17, 2008 5:14 pm
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by samarskyrider

Hello everyone,

I'm running Rival AXS FD and at many occasions it throws chain outboard when going from small to big ring. Set aside that I have custom setup with Praxis Works 52/36 rings (claimed to be AXS compatible), but people have similar issues with original SRAM 2х 12spd rings

I've been going through changelog of FD firmware and noticed a micro adjust feature introduced to RED/FORCE front derailleurs, but not for Rival. Makes me wonder how that micro adjust works on FD and if it's of any help?

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by Weenie


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TobinHatesYou
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Joined: Mon Jul 24, 2017 12:02 pm

by TobinHatesYou

Only think I can think of is some shared settings such as the FD overshift feature. It is more dramatic when the RD is shifted onto the larger cogs. It is virtually non-existent when in the smallest cogs. There is no actual individual Micro Adjust feature for the FD.

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wheelsONfire
Posts: 6283
Joined: Mon Jul 07, 2014 8:15 am
Location: NorthEU

by wheelsONfire

No idea how AXS is compared to gen 1 Etap (2*11), but from what i have heard, it's slightly easier setup!?
What chainline does your setup have?
I can shift from (11-26 and 11-28) through the whole cassette using any chainring with zero drops) using both big and small chainring.
According to Sram, the middle cog on the cassette is where issues is most likely to happen (overshift).

Part from above, i have a question.
If we assume you have set the FD in the correct height, so that the upper tab inside the FD cage is set, so it's not to high. The tab inside the cage helps preventing chain from bouncing to high, because chain will hit that tab instead of traveling more up when shifting from small to big.
Though, if the FD is to low, chain will scrape on the tab and that is ofcourse going to be a problem when going from small to big.

If you go to inner chainring and adjust FD more inboards and then shift up to big chainring and adjust the FD more inboards.
What happens then?
This alters the whole FD to be in a more inboard position.
Another step could be to remove the crankset and add one or two plastic micro spacers on the axle.
This would move the whole chain line 0.5mm for each plastic spacer/ shim.
Ofcourse the whole crank is moving along.

I believe you can get the shifting to work, it's just very picky.
When you shift from small to big, don't pedal static. Just a small stop in spinning when you actually shift, so the chain catches on the cog or cogs of the big chainring.

Don't give up!
Bikes:

Ax Lightness Vial EVO Race (2019.01.03)
Open *UP* (2016.04.14)
Paduano Racing Fidia (kind of shelved)


Ex bike; Vial EVO D, Vial EVO Ultra, Scott Foil, Paduano ti bike.

samarskyrider
Posts: 170
Joined: Wed Sep 17, 2008 5:14 pm
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by samarskyrider

wheelsONfire wrote:
Thu Dec 08, 2022 9:00 am
Part from above, i have a question.
If we assume you have set the FD in the correct height, so that the upper tab inside the FD cage is set, so it's not to high. The tab inside the cage helps preventing chain from bouncing to high, because chain will hit that tab instead of traveling more up when shifting from small to big.
Though, if the FD is to low, chain will scrape on the tab and that is ofcourse going to be a problem when going from small to big.

If you go to inner chainring and adjust FD more inboards and then shift up to big chainring and adjust the FD more inboards.
What happens then?
This alters the whole FD to be in a more inboard position.
Another step could be to remove the crankset and add one or two plastic micro spacers on the axle.
This would move the whole chain line 0.5mm for each plastic spacer/ shim.
Ofcourse the whole crank is moving along.

I believe you can get the shifting to work, it's just very picky.
When you shift from small to big, don't pedal static. Just a small stop in spinning when you actually shift, so the chain catches on the cog or cogs of the big chainring.

Don't give up!
Frankly speaking, I gave up on the idea that it's possible to adjust FD to the point where it shifts perfectly. I had eTap 1st gen. on Tarmac SL6 and literally had zero issues on the front, it just worked and never shifted outboard or inboard.

Now I have Specialized Crux '18 with clamp-on FD adaptor (which is not good by itself) and 110BCD 5-arm QUARQ with Praxis Road Buzz 12spd rings, Ultegra 11-30T cassette and XT 12spd chain. The combo is kind of weird, but in the middle of pandemic I had zero options except this. If I did the setup according to instructions, it either rubbed on 52-23 (and up) when cross-chained or on 52-14 (and down) if I make adjustments to FD screws when cross-chained. So there is no scenario when it does not rub both on 52-30 and 52-11 (in my case) or not shifts outboard (when it make overshift to go from big to small ring). I've setteled for the middle ground and adjusted screws when on big ring so there is no rub on 52-23 (and up), since I rarely use gears like 52-14,13,12,11.

In any case, front shifting experience is far-far from being perfect. Maybe it's due to the fact that I run clamp-on adaptor and it's hard to make tiny height adjustments, plus you have to make YAW after that. My hope was that micro adjust on FD could solve the problem, but I don't know for sure

Later on I've managed to source Force 10-33 cassette (use it on gravel wheelset), it shifts slightly better even with XT chain (haven't tried Force chain yet)

JaeOne3345
Posts: 142
Joined: Wed Apr 21, 2010 5:27 am

by JaeOne3345

I am running a frankenstein build as well on an old rim brake bike. It runs great. No front chain drops with the chain anywhere across the cassette.

-Rival FD with a SRAM 34.9 clamp adapter (I find it very good quality and even has a built in brace which means you don't need a wedge)
-Rival RD
-8100 Ultegra 12s 11-30 casette, XT chain, and 52/36 8100 chainrings
-Rotor 43.5 Axle + ALDHU arms + Sigeyi power. (Shimano chainline)

I had no issues setting the FD up. I used the plastic tool they include. I first eyeballed it, and used the high limit screw to bring the cage alignment marks over the chainrings. Then, loosened the clamp, installed the tool, and tightened the clamp up making sure nothing moved. Followed this by making the high/low adjustments. I am not exaggerating when I say it took me no longer than 10 mins to get the FD set up.

-Is your dub crank preload ring adjusted correct? I helped a friend at crit practice fix his AXS front issues just by noticing his preload wasn't set properly, allowing the crank to move side to side.

-Could be your clamp. What kind is it?

-Could be the chainrings. Nothing shifts as butter as Shimano chainrings in my experience.

-Could be the chainline. If I was you, since you are running a Shimano cassette which sits more inboard than a SRAM cassette, you may possibly need to pay more respect to the chain line since the margin for error is less forgiving with these hybrid set ups. The 5 bolt Quarq is based on a 45mm chainline.

Since you are dealing with rubbing no matter what you do at the extremes, I would look into the chainline. I don't have any issues with the yaw/rubbing at extremes. My frame has 410mm length chainstays if that helps.

by Weenie


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samarskyrider
Posts: 170
Joined: Wed Sep 17, 2008 5:14 pm
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by samarskyrider

JaeOne3345

I'm running a generic 31.8mm clamp adaptor from Aliexpress (bought it long time ago for some reason and it was laying around since then)
Image

- My CruX frame is PF30, so I'm running BB30 110bcd 5-arm quarq crankset, there is a standard spacer on the driveside and preload adjustment ring on the opposite (see pics). Chainstays are 425mm

Image

Image



- With regards to chainrings, I had no other options except for Praxis Works Buzz 52/36 which are claimed 12spd compatible for 110mm BCD 5-arm spider. Running 12spd chain for a while on those rings made me realize that it's marketing BS and older SRAM 52/36 11spd rings could have worked just fine. I would also agree that Shimano rings shift so much better, but since I have Quarq PM, it's a no match :-)

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