FD adjustment tips (Simplex SLJ 'triple')?
 

First caveat- I know that running my setup the way I am is a little outside the bounds of what the components were originally designed to do and probably somewhat pushing limits. Second caveat is that for the most part it’s all working pretty well, & while the issue I’m having is a PITA, I can live with it if I have to.

So… 14-28 7sp freewheel, tripled Stronglight 93 crank with 30-42-45 rings, Simplex SLJ GT RD, SLJ FD. Occasionally when shifting from the middle ring to the big I’ll lose the chain to the outside. If I go any tighter on the big ring limit screw I get rubbing when in big ring/smallest sprocket. Also, going from the small ring to the middle is a little less-than-nice seeming, taking a bit of finesse and pretty regularlyI end up overshifting to the big ring, and have to drop back down from there.

I’ve tried lowering the FD some with the bike in the stand, but when I do that the chain completely jams (at an angle) between the cage and the rings I’m shifting from & to.

Anyway, any tips on what I might try to get better performance with the FD?

Thx



Oh, and a picture….

https://cimg4.ibsrv.net/gimg/bikefor...4d106d78ac.jpg

I’m not an expert but I would say it’s weird, there should be a fine tuned position enabling the shifting without rubbing. Does it rub on the inside or outside of the inner cage? Did you check shifters tightening to make sure the cable doesn’t get looser after shifting? Also I’ve never installed a FD so high above the big ring, on the contrary I was always very close, but also never had a 45 as bigger ring. Last check, is the chain ok? 7s?

Two recommendations: 1) Mount it lower. I aim for the outside of the cage to be about an eighth of an inch above the large ring. When you lower it, you'll probably have to adjust cable tension 2) Check the orientation of the cage. The plates have to be parallel to the chain. To adjust, loosen the derailleur clamp and rotate it until things are lined up.

The other thing that could affect shifting is the step between the two outer rings being too small. Sometimes inner part of the cage will hit the middle ring when shifting up. This could explain the jamming you see when the FD is lowered.

Rubs on the outside of the outer cage when on the big ring if I have the limit set to keep it from dropping- but it's only when on the smallest, or maybe the two smallest cogs.

Chain is a 7sp.

I always re-adjust the cable tension whenever I move it, and the cages are parallel to the chain/rings.... But I'm wondering if maybe when I tried it lower I didn't go low enough and ended up in a weird spot where the chain would jam up. Hard to exactly describe how it jams- the chain is half-way up on to the big ring but jamming against the inner cage of the mech. I'm 90% sure it isn't the cage hitting the middle ring. But I'll have to get it on the stand and mess around some more.

Yeah, I know the small difference between the rings could be the source of all the problems- but I've got such a nice spread of ratios going with it that just works really well (for me)!

He can't go much lower without the tail of the derailleur cage snagging on the rear derailleur cable:

https://cimg4.ibsrv.net/gimg/bikefor...4d106d78ac.jpg

Doh, you're right- I forgot that THAT's why I couldn't go lower before. Though maybe I can get the RD cable lower by swapping out the Delrin guide with a metal one I've got from another 'project'... But it probably won't buy me much more lowering room.

Another option would be to route the rear derailleur cable under the bottom bracket. There are plastic cable guides you can attach to the bottom bracket for this. Most use a bolt to hold it in place, but I suspect a decent adhesive would do the job if you're not up to drilling and tapping a hole for the bolt.

If you need/prefer to keep the cable routing as it is, you could modify the front derailleur by shortening the cage. Once again, you'd have to drill some holes and possibly tap some threads.

Wow, didn't see that at all. Good catch.

Appears that you have it set up as a half-step plus granny. I'm a big fan of half-step gearing, but that's a throw-back to the time when 7+ rears were not available.

[EDIT: zeroth, that's not a triple SLJ, it's a double, and your big is only 45-ish with a tripleizer, so it is no wonder you are having cage/ring/cable clearance issues]

First, yes that front mech is too high above the teeth, but even when it's correct there is a tweak he can try if it still overshifts - bend the cage.
Make the bends at the very front "nose", such that the cage is narrower.
As the chain rides up the inner plate its final position will be more precisely controlled.
You only need a little bit:


https://cimg0.ibsrv.net/gimg/bikefor...df838a2fd0.jpg

Before continuing - a warning. The alloy used in these mechs is fragile.
The version shown (like that of the OP) can crack at the hinge, and at the cable-eye.
The hinge cracks are linked to metric/imperial tube and clamp mis-matching.
The cable-eye crack is due to poor design. the cable groove is too close to the bolt threads and the section is too small:


https://cimg0.ibsrv.net/gimg/bikefor...9e83422759.jpg

However, he still needs to get that cable lower.
Rather than modifying the mech or the frame, I'd look for a way to run the cable itself lower - there is room.
Runnning the cable under will need a chainstay stop under as well, if he doesn't have a clamp-on one now that can be flipped.
He's got the version of the front mech that pretty much requires a length of housing, so the front end of that will need a stop anyway.

Slide the guide down, the Simplex guide bits that might interfere with the bb shell can be easily filed to fit, they're plastic.
Or find one that has a lower exit like the Huret:


https://cimg8.ibsrv.net/gimg/bikefor...0db5fc444f.jpg
https://cimg0.ibsrv.net/gimg/bikefor...d1f511c8ed.jpg

And further, in regard to the chain jamming when he tried a mounting it lower, likely it wasn't lower enough as "enough" would mean the cage would certainly be hitting the rear mech cable.
The lower edge of the inner cage plate can cause a jam if it is at a certain (slightly too high) level.
The top inner edge of the chin rides up that cage plate edge and if the 3-D alignment is *just* wrong one of the chainring teeth will catch the diagonally opposite edge of the same chain link.

Also- just for giggles- how's your chainline?

Yeah, that's exactly what was happening when I tried to lower it... I'm going to see if swapping out the delrin guide for a metal one might get the RD cable a little lower and get me a little more lower with the FD...
Early AM 30mi ride today I managed to not drop the chain off once by making shifts from the middle to the big ring much slower....

Chainline is good, at least by eye...

A photo from above, showing the chainline in relation to the angles of the two plates, might help others diagnose.

A quick follow-up..... Between house-renovation projects and nice riding weather, tinkering got put on pause, but a thunderstormy afternoon gave me a little time in the 'shop' (ahem....... dank basement.....). Forgot I had another SLJ FD off a $10 Craigslist 'project' that has the slight bend to the cage. Decided to give that FD a try (for all intents & purposes it appears to be exactly the same as the SLJ FD I've been using), and swap out the Delrin cable guide for the metal one off the above $10 'find'. Routed the short length of housing for the FD under the BB this time- a wee bit 'awkward' as it comes out of the metal cable guide, but it allows the guide to be positioned absolutely as low as possible- so low that when the RD cable comes out of it, it might be rubbing the top of the BB. But if it is, it's just barely. But it lets me get the FD down a little bit more than it was before. Even though the 'new' FD looks identical to the one I was using, it just barely has enough travel to make the big ring with the limit screw pretty much all the way out. But it does get there. Anyway, on the stand and on a quick and soggy run up and down my (long) driveway, it seems to be working well. I've had to tighten up the Retrofrictions some to achieve enough hold to keep the FD far enough out when I'm on the big ring/small cog and not have it rub, but I think this'll work. Looks to be a wet week ahead, so not sure when I'll be able to get in a real-world test. If all seems good, I'll probably try bending the cage on the original FD and put that back on for the bit more range on the big ring it seems to have.
Once again, thx for all the tips.

Addendum for future reference after a humid pre-breakfast 25mi ride this AM. Shifting is pretty darn good now- no losing the chain, going from the granny to the middle is improved, back and forth from middle to large is very nice. Wee bit of sometimes rubbing in big ring/small cog, but I rarely spend much time in that gear so I can live with it. Shifter is tighter to keep the RD from slipping and trimmed properly on the big ring, but not too stiff, and I can get used to that. Of course I changed several things, so can't 'scientifically' say what has really made the difference. Forgot to mention above that I also put a fresh chain on yesterday. I'm 95% sure that the one that came off isn't significantly worn, but the fresh one I put on is different than those I've been using. Most of my chains are KMC Z8.1- I use hot wax and rotate through several, but I picked up a KMC X8 chain on sale a while back so decided to try it this time. I'm really not sure what the differences are between the two models of chain, but changing to the X8 could be part of the improved shifting.