sram axs etap FD skew when tightened

Discuss light weight issues concerning road bikes & parts.

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Boxxy
Posts: 11
Joined: Fri Apr 27, 2018 3:37 am

by Boxxy

I am building up an etap bike and when I tighten my FD it won't stay parallel to the chain ring.. it goes waaay off because the sram rival interface is squared but the hanger is rounded, like all other braze on hangers i've ever seen? Am I losing my mind?

by Weenie


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TobinHatesYou
Posts: 9058
Joined: Mon Jul 24, 2017 12:02 pm

by TobinHatesYou

Boxxy wrote:
Fri Dec 03, 2021 2:28 am
I am building up an etap bike and when I tighten my FD it won't stay parallel to the chain ring.. it goes waaay off because the sram rival interface is squared but the hanger is rounded, like all other braze on hangers i've ever seen? Am I losing my mind?

Use the appropriate wedge.

the jackel
Posts: 95
Joined: Wed Aug 22, 2007 7:44 pm
Location: London

by the jackel

I have had this issue with sram mechanical and a 2007 Cervelo frame. I just ended up compensating for it when I set it up.

I'd definitely second the idea of trying the wedge. I'm not 100% convinced it will work as I tried something similar with mine and it would slowly return to the position it wanted to.
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DaveS
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Joined: Fri Mar 24, 2006 1:26 pm

by DaveS

This is not something new. Position the FD so it moves into the desired position after tightening. This is not what a wedge is used for. I've set up AXS FDs many times and never use a wedge.

I measure the gap between the FD cage where the screw holding the tail end together is located, so I get the proper angle after tightening. My FDs usually only move by 1-2mm.

This is the most common cause of chain drops and adjustment problems. The installer fails to recheck the marks on the cage to be sure that they are still parallel to the big ring.

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

by TobinHatesYou

DaveS wrote:
Fri Dec 03, 2021 3:10 pm
This is not something new. Position the FD so it moves into the desired position after tightening. This is not what a wedge is used for. I've set up AXS FDs many times and never use a wedge.

Using the wedge allows you to set the desired angle beforehand and then you can apply a constant force while tightening so that it doesn’t kick out when fully tightened.

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wheelsONfire
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Location: NorthEU

by wheelsONfire

Boxxy wrote:
Fri Dec 03, 2021 2:28 am
I am building up an etap bike and when I tighten my FD it won't stay parallel to the chain ring.. it goes waaay off because the sram rival interface is squared but the hanger is rounded, like all other braze on hangers i've ever seen? Am I losing my mind?
I don't know what comes along with AXS FD, but there are 3 wedges with first gen Etap.
Set the FD and use the best suited wedge. You can ofcourse skip using the wedge(s), but it's along to hinder the FD from moving when you shift.
First set the FD, when that is done you mount the wedge, to keep FD fixed!
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DaveS
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Joined: Fri Mar 24, 2006 1:26 pm

by DaveS

The FD could kick out or in. The wedge won't keep the FD from kicking out at the tail end. The wedge is supposed to help with wimpy FD mounts that are prone to flexing during a shift. It's not hard to get one setup without the wedge. The FD mounts on my Colnago and Cinelli frames don't need it.

Boxxy
Posts: 11
Joined: Fri Apr 27, 2018 3:37 am

by Boxxy

DaveS wrote:
Fri Dec 03, 2021 7:12 pm
The FD could kick out or in. The wedge won't keep the FD from kicking out at the tail end. The wedge is supposed to help with wimpy FD mounts that are prone to flexing during a shift. It's not hard to get one setup without the wedge. The FD mounts on my Colnago and Cinelli frames don't need it.
yeah i've tried with all the wedges and it's definitely not an issue with that, it's kicking out the tail end part of the FD cage into the chain ring. I might just go 1x tbh as I have discovered the rival fd doesn't work with 52t rings :lol: never expected a chainring to be hidden behind a paywall but hey here we are!! have to buy red to be able to use larger rings :D

DaveS
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Joined: Fri Mar 24, 2006 1:26 pm

by DaveS

Last I read, the FD that could handle a chain ring larger than 50 was only sold with the matching crank.

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

by TobinHatesYou

Boxxy wrote:
Fri Dec 03, 2021 9:58 pm
DaveS wrote:
Fri Dec 03, 2021 7:12 pm
The FD could kick out or in. The wedge won't keep the FD from kicking out at the tail end. The wedge is supposed to help with wimpy FD mounts that are prone to flexing during a shift. It's not hard to get one setup without the wedge. The FD mounts on my Colnago and Cinelli frames don't need it.
yeah i've tried with all the wedges and it's definitely not an issue with that, it's kicking out the tail end part of the FD cage into the chain ring. I might just go 1x tbh as I have discovered the rival fd doesn't work with 52t rings :lol: never expected a chainring to be hidden behind a paywall but hey here we are!! have to buy red to be able to use larger rings :D

My point with using the wedge was to pre-stress the FD by using the wedge as a brace while you tighten the bolt. The FD won’t yaw out of the desired position if you’re firmly holding it in place.

bobones
Posts: 341
Joined: Mon Aug 12, 2013 11:19 am

by bobones

The Rival FD definitely works with a 52 ring. Got that exact setup in my garage right now.

DaveS
Posts: 3560
Joined: Fri Mar 24, 2006 1:26 pm

by DaveS

bobones wrote:
Sat Dec 04, 2021 12:38 am
The Rival FD definitely works with a 52 ring. Got that exact setup in my garage right now.
That only proves that it works on your bike, not all bikes. The FD made for larger rings has two sets of mounting holes.

bobones
Posts: 341
Joined: Mon Aug 12, 2013 11:19 am

by bobones

DaveS wrote:
Sat Dec 04, 2021 3:06 pm
bobones wrote:
Sat Dec 04, 2021 12:38 am
The Rival FD definitely works with a 52 ring. Got that exact setup in my garage right now.
That only proves that it works on your bike, not all bikes.
No, it disproves the statement made earlier that "The Rival FD does not work with 52 tooth rings".

There is nothing unusual about this bike: it's a size 54 Scott CR1. There's actually quite a bit of room for it to go higher on the braze on mount, perhaps not enough for big TT rings, but easily enough for a 52.

I'll post some photos later showing the height of the braze on tab in relation to the chainrings, and you can judge for yourself.
[Edit: photos added]

Showing size of crank
Image

Showing running height
Image

Showing maximum height
Image

Ruler resting on chainring between teeth and parallel to braze on
Image

DaveS
Posts: 3560
Joined: Fri Mar 24, 2006 1:26 pm

by DaveS

The pictures only prove that the FD mount on that frame allows the FD to be raised higher than some brands. It's not like there's a standard that all frames are made to. The sram FDs must also allow a 46T small ring.

Not every frame will allow that height.

bobones
Posts: 341
Joined: Mon Aug 12, 2013 11:19 am

by bobones

Of course I cannot speak for every frame; however, I have provided a counter example which categorically proves that the statement "the Rival FD doesn't work with 52 tooth rings" is false. Given the images above, I would suspect it would work for a large number of frames, and the photo with the ruler may help someone determine if it is likely to work on their particular frame.

by Weenie


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