Bicycle Mechanics - SRAM Rival FD limit other than high limit screw?

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Again
06-15-12, 03:29 PM
I installed a new Rival group on a CF frame and can't get the FD to move out far enough to clear the big ring, although the limit screw is not touching at all. I can't see anything it hits, so what is the cause of that?
It is mounted on braze-on, and I can't see anything I can do to bring the guide out far enough to clear the big ring.


JTGraphics
06-15-12, 04:00 PM
With cable off can you move the cage using your fingers so the FD cage is past the large ring? and check height 1mm from cage to top of large ring.
Check limit screws again also just incase your moving the wrong one.
Turn in all barrel adjuster also before you hook up cables later.
If you can place the chain on large ring set the limit screw so you have about 1mm from chain to inside outer cage.
I'll use the limit screw on the FD to get the chain onto the small ring turn in the low screw some using the screw I turn it till the chain drops to small ring.

Make sure shifter is clicked all the way down hook up cable remove slack secure cable clamp, shift lever up to big ring if it does not move turn barrel adjuster till it does fine shift back down and check fine tune with barrel adjuster as needed.

HillRider
06-15-12, 04:01 PM
I would guess the cable isn't adjusted properly. As JT noted, disconnect the cable and see if the derailleur will move far enough just by hand.


JTGraphics
06-15-12, 04:03 PM
I actually have the filling you did not have the lever all the way down when you hooked up your cable so you are just running out of pull

vettracer
06-15-12, 04:37 PM
Shifter was probably in the trim position when you installed the cable.

Disconnect the cable from the FD and pull on it while shifting to get the ratchet all the way to the inner ring position.

Re-attach the cable to the FD, adjust cable tension and you should be good.

Again
06-15-12, 05:07 PM
Cable disconnected, high gear limit screw out all the way, can not move guide with fingers to clear the big ring. I can not see what it hits, but it does make a distinct metallic sound.

JTGraphics
06-15-12, 05:23 PM
Could you provide some pictures or even a short video of this? sounds strange its most likely something very simple.

HillRider
06-15-12, 05:27 PM
Is the front derailleur's inner cage plate hitting the middle chainring and not allowing the cage to move further? If the derailleur is mounted too low or has a deep inner cage plate and the chainrings don't have a large enough tooth difference that can happen.

JTGraphics
06-15-12, 05:33 PM
I'm kind of thinking FD cage is to low also.

Again
06-15-12, 06:26 PM
Cable not connected:

http://www.bikeforums.net/asset.php?fid=224777&uid=236260&d=1339805182

Sorry, bad pic!

Again
06-15-12, 06:34 PM
256255

Again
06-15-12, 06:37 PM
I can barely move the outer guard far enough out to line up with the big wheel, which is not out enough to clear the chain from rubbing.

JTGraphics
06-15-12, 07:55 PM
I have a few things to ask but going to start from the beginning since I have no idea what you have also changed with this FD.
Did you also change anything else crank?
At this point I cannot assume all parts are installed correct something just isn’t right here.
Can you give some details on what and how much you disassembled so we can go thru the entire setup this shouldn’t be hard LOL.

Again
06-15-12, 08:17 PM
I have a few things to ask but going to start from the beginning since I have no idea what you have also changed with this FD.
Did you also change anything else crank?
At this point I cannot assume all parts are installed correct something just isn’t right here.
Can you give some details on what and how much you disassembled so we can go thru the entire setup this shouldn’t be hard LOL.I installed all original SRAM Rival parts that came with the gruppo (http://www.ebay.com/itm/Newest-SRAM-Rival-Group-Set-Complete-Factory-Kit-w-cables-housing-GXP-BB-/110893547332?_trksid=p4340.m185&_trkparms=algo%3DSIC.NPJS%26its%3DI%252BC%26itu%3DUA%26otn%3D5%26pmod%3D120893942429%26ps%3D63%26clk id%3D9165163620316272070#ht_2339wt_905
I chose the braze-on FD, the 50/34 crank, and a mid cage RD for the 11/32 cassette. It was a new install, so I did everything from scratch.

JTGraphics
06-15-12, 09:15 PM
A quick measurment not the correct way but will give a good idea of the chain line for me measure from the edge of your seat post to the large chain ring. Should be right around 1.25"

Again
06-15-12, 09:39 PM
A quick measurment not the correct way but will give a good idea of the chain line for me measure from the edge of your seat post to the large chain ring. Should be right around 1.25"Mine measures closer to 1.5"!

kevbo
06-16-12, 06:22 AM
MTB crankset + road FD?

FBinNY
06-16-12, 07:21 AM
Quick questions.

What is the seat tube diameter?
What is your crankset centerline distance?

FDs are engineered with a range of possible travel (discounting the limit screws which can only reduce it)

Over the years, outboard bearings have pushed crank centerlines out a bit, but larger seat tube diameters have also pushed the FD out so designers didn't have to modify FDs to compensate. But if you have the unfortunate combination of a 1-1/8" seat tube diameter with a slightly outboard crank, your FD may not reach.

This is the reason that Campagnolo stopped making clamp on derailleurs in 1-1/8". Doing so would require that they redesign for more travel, something they didn't want to bother with.

The fix for inadequate outward travel is to move the cranks inward. If that isn't possible, Then a larger clamp and shim is the next alternative. Folks with braze-on FDs that don't reach have a tougher job. The FD and braze-on can be modified with some skillful filing, but it's lots of work, and before trying this, I'd look for a different FD with a bit more outward travel range.

JTGraphics
06-16-12, 07:34 AM
He thinks he found the trouble.

Again
06-16-12, 09:15 AM
Quick questions.

What is the seat tube diameter?
What is your crankset centerline distance?
seat tube diameter at braze-on is 1.18"
center of tube to center of crank is 2".

Again
06-16-12, 09:22 AM
He thinks he found the trouble.But he ain't sure what to do about it. There is a rubber seal on the crank, and I am afraid to remove that:
http://www.bikeforums.net/attachment.php?attachmentid=256322&d=1339860068&thumb=1&stc=1

FBinNY
06-16-12, 10:12 AM
I can't tell from the photo if that can be removed or thinned, but if not there's possibly another way.

If your braze on adapter is screwed or pop-riveted to the frame, you might be able to replace it with one that mounts the FD more outboard. There are a few makers of these adapters and they're not all identical, so some careful searching may find one that'll solve the problem. Or a decent mechanic should be able to make you a small shim to put under the adapter to push it out a bit.

Last option is to look at the FD itself. Take it off the bike and find the parts that actually touch limiting the outbound range. If there's enough meat, you can carefully file or Dremel a bit away to buy yourself an extra few millimeters of travel.

Again
06-16-12, 01:59 PM
Last option is to look at the FD itself. Take it off the bike and find the parts that actually touch limiting the outbound range. If there's enough meat, you can carefully file or Dremel a bit away to buy yourself an extra few millimeters of travel.That was my primary option, and it seems to have brought results. I took off the FD and looked for the spot that limits movement. Found that it was one end of the spring hitting the guide, and used my Dremel to trim it down a bit. That provided plenty of extra movement for the guides to promise the needed range.I will only need to redo the chain and the cable now and should be back in business.
Thanks very much for your help!

FBinNY
06-16-12, 02:36 PM
That was my primary option, and it seems to have brought results. I took off the FD and looked for the spot that limits movement. Found that it was one end of the spring hitting the guide, and used my Dremel to trim it down a bit. That provided plenty of extra movement for the guides to promise the needed range.I will only need to redo the chain and the cable now and should be back in business.
Thanks very much for your help!

Next time I might list it as a first option. I used to do that, but I'd get roundly flamed for the sacrilege of telling people to modify stuff.

JTGraphics
06-16-12, 02:40 PM
I don't think those rubber seals should be on the crank, those may be to protect the crank for shipping were the bearings press onto the crank, I have never seen any seals like those on a crank.

Again
06-16-12, 02:59 PM
Next time I might list it as a first option. I used to do that, but I'd get roundly flamed for the sacrilege of telling people to modify stuff.Well, we wouldn't need to modify (afro-engineer?) anything if the designers would give it more thought. That spring end limitation is totally unnecessary, and the Sram people could substantially increase the FD range and spare users a lot of frustration!

Again
06-16-12, 03:00 PM
I don't think those rubber seals should be on the crank, those may be to protect the crank for shipping were the bearings press onto the crank, I have never seen any seals like those on a crank.That seal looks too good and solid just to serve as a shipping protection!

Again
06-16-12, 10:31 PM
All is put together again, the FD has all the reach it needs, and all settings work fine.
I want to thank all contributors for their ideas and efforts to help me out of this dilemma!
Have a good ride! :thumb:

JTGraphics
06-16-12, 10:51 PM
:thumb: