Hey sram...

Discuss light weight issues concerning road bikes & parts.
glepore
Posts: 1160
Joined: Thu Mar 28, 2013 4:42 pm
Location: Virginia USA

by glepore

Why would you save basically no weight by using easily stripped ti (4mm) grub screws one of which is LEFT thread on your etap derailleurs. Known issue. Oh, so you can charge $40 retail for the screw kit that is out of stock everywhere? On a $400 derailleur ? Sheesh.
Cysco Ti custom Campy SR mechanical (6.9);Cannondale SS Evo Di2 7970 (5.79); Willier Cento Uno Air Di2 9070 (7.0); C40 Mk2 DA 7800 ; Anvil Custom steel Etap;1996 Colnago Technos Record

by Weenie


Chris3g
Posts: 38
Joined: Sun Aug 20, 2017 2:51 pm

by Chris3g

Yeah it’s annoying, I’ve kind of been casually looking for a front derailleur low limit screw for a while now, sram won’t send one and I can’t bring myself to pay $40 for 1 screw.

glepore
Posts: 1160
Joined: Thu Mar 28, 2013 4:42 pm
Location: Virginia USA

by glepore

The low is easy, more or less as its at least right hand thread. A left thread grub screw is unicorn.
Cysco Ti custom Campy SR mechanical (6.9);Cannondale SS Evo Di2 7970 (5.79); Willier Cento Uno Air Di2 9070 (7.0); C40 Mk2 DA 7800 ; Anvil Custom steel Etap;1996 Colnago Technos Record

NiFTY
Posts: 1221
Joined: Sat May 26, 2012 11:26 pm

by NiFTY

The bigger issue is the titanium axle on the inner plate versus steel retention screw. Axle gets eaten and cage pops off (sometimes into rear spokes - bye bye lightweights)
Evo 4.9kg SL3 6.64kg Slice RS 8.89kg viewtopic.php?f=10&t=110579" onclick="window.open(this.href);return false;" onclick="window.open(this.href);return false;

MyM3Coupe
Posts: 164
Joined: Thu Nov 24, 2016 10:32 pm

by MyM3Coupe

NiFTY wrote:
Mon Feb 12, 2018 3:29 am
The bigger issue is the titanium axle on the inner plate versus steel retention screw. Axle gets eaten and cage pops off (sometimes into rear spokes - bye bye lightweights)
Got to love SCAM quality. Lol.

jih
Posts: 166
Joined: Fri Jan 29, 2016 12:54 pm

by jih

How are these easily stripped? If you're putting a lot of torque into a limit screw you're doing it wrong. It's not supposed to actually be tightened while it is resting on anything - it's a screw hanging in space.

The left/right threading is to maintain the clockwise-restricts-more, anticlockwise-restricts-less that everyone is used to in mech design.

glepore
Posts: 1160
Joined: Thu Mar 28, 2013 4:42 pm
Location: Virginia USA

by glepore

Probably a combination of a slightly worn allen, the fact that it doesn't actually "limit" the cage like a traditional screw but actually moves it outboard to its setpoint and the fact that the end of travel isn't really clear. Some of it is user error, sure, but for those of us that don't see these regularly (I've got shop experience but not with etap) it's easy. And there is no appreciable weight savings here, just bragging rights. Its this difference probably between .2g and .15.
Cysco Ti custom Campy SR mechanical (6.9);Cannondale SS Evo Di2 7970 (5.79); Willier Cento Uno Air Di2 9070 (7.0); C40 Mk2 DA 7800 ; Anvil Custom steel Etap;1996 Colnago Technos Record

Kurets
Posts: 154
Joined: Thu Feb 25, 2016 9:55 pm

by Kurets

Stripped is not synonymous with rounded off hex socket. Rounded of hex sockets happen when you use wrenches with sloppy tolerance compared to the socket. While the choice of a left hand thread is debatable, managing to round of the socket is poor choice of tools and heavy handedness, if it feels sloppy the tool won't work.

TheKaiser
Posts: 541
Joined: Thu Sep 05, 2013 3:29 pm

by TheKaiser

Man, I thought SRAM was known for their awesome warranty and small parts dept, so even though their stuff failed more than Shimano or Campagnolo they at least took care of getting you replacements. This sounds like a real change of pace, which is especially crappy on their premier group.

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wheelbuilder
Posts: 531
Joined: Wed Feb 08, 2017 2:10 am

by wheelbuilder

I'm trying to figure out how it was rounded out to begin with? Was it being manipulated over and over, with a poor quality or wrong sized Hex? These don't take any force at all to manipulate, and I am struggling to understand what exactly happened? ...........details?

commendatore
Posts: 194
Joined: Mon Dec 30, 2013 1:51 am

by commendatore

TheKaiser wrote:
Mon Feb 12, 2018 6:24 pm
Man, I thought SRAM was known for their awesome warranty and small parts dept, so even though their stuff failed more than Shimano or Campagnolo they at least took care of getting you replacements. This sounds like a real change of pace, which is especially crappy on their premier group.
If it is actually stripped... maybe. But if the head is rounded out, thats more user error.

The etap FD setup is a bit more fiddly, so I do have SOME sympathy.

jih
Posts: 166
Joined: Fri Jan 29, 2016 12:54 pm

by jih

wheelbuilder wrote:
Mon Feb 12, 2018 6:52 pm
I'm trying to figure out how it was rounded out to begin with? Was it being manipulated over and over, with a poor quality or wrong sized Hex? These don't take any force at all to manipulate, and I am struggling to understand what exactly happened? ...........details?
Exactly. I haven't measured but I've turned these and I'd say they take roughly 1nm to turn. I'm pretty sure I don't have a torque wrench that can measure that low.

How do you round off a head, even a 2.5mm ti hex socket, while applying so little torque?

darnellrm
Posts: 230
Joined: Thu Sep 10, 2009 1:06 pm
Location: NC, USA

by darnellrm

jih wrote:
Tue Feb 13, 2018 11:30 am
wheelbuilder wrote:
Mon Feb 12, 2018 6:52 pm
How do you round off a head, even a 2.5mm ti hex socket, while applying so little torque?
You try to adjust the screw when it is already against the stop and/or use a worn wrench.

Shrike
Posts: 1391
Joined: Fri Jun 03, 2016 5:08 pm

by Shrike

Softer material will wear out faster, appropriate fitting hex or not, and SRAM's FD does need a lot of adjustment. I had a hell of a time getting mine right. In the end I had to compromise, even guys in the best local LBS couldn't get it set up without compromise ie. Some rub in some ratios. Not even talking about extremes here.

Main problem I have with my eTap FD is that after half a dozen rides, it seems to need a touch up.

glepore
Posts: 1160
Joined: Thu Mar 28, 2013 4:42 pm
Location: Virginia USA

by glepore

Yeah, its finicky, and mine hasn't been on the road yet. The setup, with the lines and such, doesn't account for parallax and old eyes. I have it spot on sorta, but if it needs adjustment later, and it sounds like it will, I'm screwed.

And yes, its probably my fault. But it wouldn't have happened without ti grubs that serve no purpose being ti. Off to SRAM support to supplicate.
Cysco Ti custom Campy SR mechanical (6.9);Cannondale SS Evo Di2 7970 (5.79); Willier Cento Uno Air Di2 9070 (7.0); C40 Mk2 DA 7800 ; Anvil Custom steel Etap;1996 Colnago Technos Record

by Weenie


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