Derailleur Tab Height

[veryredbike]

I know I saw this on the frambuilder's collective forum, but I can't get to that now and am having trouble finding it elsewhere. I remember there being a specific height to drill the little peg-hole for Sachs front derailleur tabs so that they'll work for the most derailleurs. I could try to reverse engineer it, but figure that asking would be wiser.
Little help?
Also, does that peg go on the centerline?

Thanks!

[e-RICHIE]

Here - go mental atmo.
It's 121mm - 122mm above the shelf of the shell, and on the center-line.
I never use a fixture for this.

20 july atmo - - a set on Flickr

[veryredbike]

Awesome, exactly what I needed!

[druptight]

I emailed these photos to myself a few months back when I bumped into them elsewhere and have used them once already. I'm sure it won't be the last time.

[blasdelf]

The whole truth and nothing but:

Braze-on-derailure-postition-road-web.jpg

Required-seat-tube-dimentions-for-front-derailure-web.jpg

Shimano is great at this shit

[veryredbike]

I have a follow up question: do you guys care if the tab is placed across the butt transition? Is the stress on this small enough that it doesn't matter, or should I trim things to try to put it 100% on the thin section? (Doesn't look like I can get it all on the thick section)

[e-RICHIE]

I have a follow up question: do you guys care if the tab is placed across the butt transition? Is the stress on this small enough that it doesn't matter, or should I trim things to try to put it 100% on the thin section? (Doesn't look like I can get it all on the thick section)

I don't care. It's a risk (for lack of another word) I have no issue assuming atmo.

[veryredbike]

Roger!

[NBC]

is the measurement for the UOS tab the same ?

what is the distance from the peg to the center of the slot ?

thanks

NBC

[e-RICHIE]

is the measurement for the UOS tab the same ?

what is the distance from the peg to the center of the slot ?

thanks

NBC

It's the same - 121mm measured the same way for both pieces, assuming it's a normal road rings combo atmo.

[NBC]

thanks :)

regards the tab, i see you don't use them on your cyclocross bikes, would love your insight into this

thanks

NBC

[e-RICHIE]

thanks :)

regards the tab, i see you don't use them on your cyclocross bikes, would love your insight into this

thanks

NBC

It's been explained many times already. Try a search first. Thanks atmo.

[Will Neide]

thanks :)

regards the tab, i see you don't use them on your cyclocross bikes, would love your insight into this

thanks

NBC

I don't know about e-Richie, but I don't put them on because so many folks like to go 1x up front on CX bikes. Using a clamp is less "ugly" to me than having an unsused FD tab. All my own opinion of course.

I addition, CX folks like to run all kinds of funky/odd set-ups from MTB drivetrain to road drivetrain. Road bikes are pretty straightforward.

[hmbatrail]

It's the same - 121mm measured the same way for both pieces, assuming it's a normal road rings combo atmo.

At the risk of stating the obvious for those that are asking, this assumes a 40mm diameter BB shell. If you were planning on BB30 or some such setup your number would be +/- 117mm. Also, for frames that plan on compact rings I set the center of the FD tab at 125mm above the BB shell, so I drill the hole at +/-118mm. For cross frames, unless the customer specifically tells me to not, I usually add one of Richard's tabs.

Failing those examples, ditto what Richard said for me.

[Dallas Tex]

I don't know about e-Richie, but I don't put them on because so many folks like to go 1x up front on CX bikes. Using a clamp is less "ugly" to me than having an unsused FD tab. All my own opinion of course.

I addition, CX folks like to run all kinds of funky/odd set-ups from MTB drivetrain to road drivetrain. Road bikes are pretty straightforward.

I used to use them, and still do on request. I don't like to use them because it seems to limit future options without offering any worthwhile upside. IMHO nothing looks worse than a FD mounted all the way south in the tab's travel slot.

[NBC]

i placed the hole 115mm above the shell in the end (40mm OD) to give 142mm to the centre of the mount

going to use dura ace 7800 and never going to need anything bigger than 53, seemed to make sense for me

NBC

[e-RICHIE]

i placed the hole 115mm above the shell in the end (40mm OD) to give 142mm to the centre of the mount

going to use dura ace 7800 and never going to need anything bigger than 53, seemed to make sense for me

NBC

???
I use 121mm - 122mm for a 53 outer.
How did you calculate for a hole 6mm lower atmo?

[NBC]

shimano framebuilder info book, like posted above,

142mm to the centre of the mount, just measured where the pin was below the centreline and went from there
says it works with 48-53 outer, which is good for me

NBC

[e-RICHIE]

shimano framebuilder info book, like posted above,

142mm to the centre of the mount, just measured where the pin was below the centreline and went from there
says it works with 48-53 outer, which is good for me

NBC

Mine measure 148mm when done. So, good luck there.

[Mtblucas]

[QUOTE=e-RICHIE;497479]Here - go mental atmo.
It's 121mm - 122mm above the shelf of the shell, and on the center-line.
I never use a fixture for this.




Perhaps this is a rather dumb question, but does that hole you drill into the tube correspond to the center (vertically) of the tab? In other words, is the center of the tab 121-122mm above the BB? Never have brazed a tab on before and just want to be sure. Thanks!