Figure this one out? Front Der not shifting on rollers?

I recently changed chainrings on my compact FSA SLK crankset. The Campy compact front derailleur (braze on) on this 2005 Giant TCR advanced frame has always been touchy for adjustment. It took a lot of work to get it adjusted to shift into the big ring smoothly and consistently without rubbing the crank but it has worked well for years and it seemed to be working fine after the chainring switch, on the work stand (no load), trainer (under load) and on the road (although I haven't ridden it much on the road since switching rings). But I was on the Kreitler rollers (with Headwind fan so also under load) while watching a world cup game and it would not shift into the big ring? I remounted the front der with a variety of subtle adjustments as much as I can do without rubbing the crank arm but no luck. The front cage is about as close as I can get to the teeth of the big ring. I have a another bike I ride more and could use on the rollers but this issue bugs the hell out of me. I've even played a bit with chain tension and the Campy A screw adjustment on the rear derailleur after revisiting Sheldon Brown's treatise on derailleur adjustment. I can adjust the front limit screw to go more outboard and get the crank rub and get it to shift and then trim it back but this isn't a very satisfactory solution. Any ideas?

I have to say I don't like the braze on mount on this bike. It seems a bit flexy even with the mount screws torqured properly from carbon flex in the seat tube. The new chain rings I put on do seem stiffer than the old ones..

On Friday, June 27, 2014 6:39:36 AM UTC-7, CKendall wrote:
I recently changed chainrings on my compact FSA SLK crankset. The Campy compact front derailleur (braze on) on this 2005 Giant TCR advanced frame has always been touchy for adjustment. It took a lot of work to get it adjusted to shift into the big ring smoothly and consistently without rubbing the crank but it has worked well for years and it seemed to be working fine after the chainring switch, on the work stand (no load), trainer (under load) and on the road (although I haven't ridden it much on the road since switching rings). But I was on the Kreitler rollers (with Headwind fan so also under load) while watching a world cup game and it would not shift into the big ring? I remounted the front der with a variety of subtle adjustments as much as I can do without rubbing the crank arm but no luck. The front cage is about as close as I can get to the teeth of the big ring. I have a another bike I ride more and could use on the rollers but this issue bugs the hell out of me. I've even played a bit with chain tension and the Campy A screw adjustment on the rear derailleur after revisiting Sheldon Brown's treatise on derailleur adjustment. I can adjust the front limit screw to go more outboard and get the crank rub and get it to shift and then trim it back but this isn't a very satisfactory solution. Any ideas?



I have to say I don't like the braze on mount on this bike. It seems a bit flexy even with the mount screws torqured properly from carbon flex in the seat tube. The new chain rings I put on do seem stiffer than the old ones.

Same kind of chainring, just new?

Der plates need a little bending with the pliers?

Re-mount the ring?

(You did put a new chain on, right?)

On Friday, June 27, 2014 6:39:36 AM UTC-7, CKendall wrote:
I recently changed chainrings on my compact FSA SLK crankset. The Campy compact front derailleur (braze on) on this 2005 Giant TCR advanced frame has always been touchy for adjustment. It took a lot of work to get it adjusted to shift into the big ring smoothly and consistently without rubbing the crank but it has worked well for years and it seemed to be working fine after the chainring switch, on the work stand (no load), trainer (under load) and on the road (although I haven't ridden it much on the road since switching rings). But I was on the Kreitler rollers (with Headwind fan so also under load) while watching a world cup game and it would not shift into the big ring? I remounted the front der with a variety of subtle adjustments as much as I can do without rubbing the crank arm but no luck. The front cage is about as close as I can get to the teeth of the big ring. I have a another bike I ride more and could use on the rollers but this issue bugs the hell out of me. I've even played a bit with chain tension and the Campy A screw adjustment on the rear derailleur after revisiting Sheldon Brown's treatise on derailleur adjustment. I can adjust the front limit screw to go more outboard and get the crank rub and get it to shift and then trim it back but this isn't a very satisfactory solution. Any ideas?



I have to say I don't like the braze on mount on this bike. It seems a bit flexy even with the mount screws torqured properly from carbon flex in the seat tube. The new chain rings I put on do seem stiffer than the old ones.

Being on rollers should have no effect on the operation of your FD. Neither should your rear derailleur, unless you're cross-chaining.

One explanation is that you mis-set the pre-load on the crank when it was re-installed (if removed)or that the washers or spacers are missing or mis-located. Check the crank to see if it slides or rocks side to side. If it is sliding to the chain ring side, the FD might not have enough travel to get the chain on the big ring. Make sure you have spacers (if there are any)in the correct locations so the big ring is not too far from the FD.

It could be that the big ring was mis-installed, but that's pretty hard to do, and you would have noticed it on the stand or while riding on the road. You should check anyway.

More mundane problems with the FD including slipping down on the mount, cable slipping and for some models of Shimano, the pivolt bolts come loose. They have cap-bolts and can be tightened easily. I don't use Campy, but I think their pivots are fixed. Check your pivots. It would show up as a lot of slop in the movement of the changer cage.

Also, it sounds like you may have the FD too close to the big ring. Andrew can correct my math here, but for most brands, you're looking at 2mm or so of clearance from outer cage plate to the top of the big ring, with the outer cage plate being in line with the ring.

Another possible problem is that you're just not pulling enough cable, but that should not be related to your rollers. If you are getting a lot of flex in your BB while on the rollers, that may cause ghost shifting or hard shifts, but I wouldn't think that it would prevent you from getting in to the big ring. Check your levers and all the cable routing to see if the cable is hanging up.

-- Jay Beattie.

On 6/27/2014 8:39 AM, CKendall wrote:
I recently changed chainrings on my compact FSA SLK crankset. The Campy compact front derailleur (braze on) on this 2005 Giant TCR advanced frame has always been touchy for adjustment. It took a lot of work to get it adjusted to shift into the big ring smoothly and consistently without rubbing the crank but it has worked well for years and it seemed to be working fine after the chainring switch, on the work stand (no load), trainer (under load) and on the road (although I haven't ridden it much on the road since switching rings). But I was on the Kreitler rollers (with Headwind fan so also under load) while watching a world cup game and it would not shift into the big ring? I remounted the front der with a variety of subtle adjustments as much as I can do without rubbing the crank arm but no luck. The front cage is about as close as I can get to the teeth of the big ring. I have a another bike I ride more and could use on the rollers but this issue bugs the hell out of me. I'
ve even played a bit with chain tension and the Campy A screw adjustment on the rear derailleur after revisiting Sheldon Brown's treatise on derailleur adjustment. I can adjust the front limit screw to go more outboard and get the crank rub and get it to shift and then trim it back but this isn't a very satisfactory solution. Any ideas?

I have to say I don't like the braze on mount on this bike. It seems a bit flexy even with the mount screws torqured properly from carbon flex in the seat tube. The new chain rings I put on do seem stiffer than the old ones.


Yeah, braze fronts. Meh.
See if the changer itself is worn. Does the cage rock in and
out with your fingers more than other nearby front changers?
If it shifted before and nothing else has changed, the
pivots are worn.

--
Andrew Muzi
www.yellowjersey.org/
Open every day since 1 April, 1971