AeroGut

I suspect the problem here is with your shim, not the derailleur. Plenty of people (myself included) run these with shims without any problems. Mine is on a 28.6 steel frame.

With respect to specs, Shimano does publish (quite conservative) specs on its website (https://bike.shimano.com/en-EU/produ...D-R3030-B.html).
For this DR, it says that the max spacing between low and high chainring is 20 teeth, and that max large chainring is 50T. The intended middle to large spacing is 11 T (39-50). If you are using the stock Sora 8spd triple crank, your chainrings are 30-42-52, so you are technically out of spec by 2 teeth on the large chainring, and your middle to large spacing is too small by a tooth (10 vs 11T). That's why you have to place the derailleur a little bit higher to clear the middle.
Most Shimano specs are conservative enough that you can exceed them slightly with no trouble. I haven't tried to run a 52T with this derailleur, but I have used a 26 small ring, which exceeds the spacing spec by 4 teeth, with no problem.

BianchiBravaUS

"Symptoms suggest that your cable is attached in a way that is reducing the leverage so you have to put too much force on it."

AeroGut, can you explain this a bit more? I am just seeing a simple downward pulling cable that is attached to a pinch bolt that must be squeezed behind a nub to keep it in place.
The cable routing is as it was when purchased.

Also.. you have enlightened me on how these devices are spec'd out. Teeth count instead of other measurements.

my mind changes like the weather on this problem. Today I am feeling the power of three's.
2 teeth larger tall gear, 1 tooth under mid to large, and a weakened mount due to the struggling clamp on with the shim.
Combine this with a newbie trying to set up without the original temp shim to hold in place and ..
Issues abound.
I have just purchased another front DR and it has the complete set up with new shims so..
I try again from scratch.
Thanks

oldbobcat

Maybe the problem is that you're using leftist "soros gears." Try a swap to Koch Brothers.

Just kidding. With a proper shim and sufficient torque on the clamp bolt and using the proper shim, I have never had the problem of a front derailleur sliding out of position because of cable-pull. That would be over 50 years of working on my own bikes and 12 years of getting paid to do it on other people's bikes. I just don't know now. Take it to a shop. Or if you're in Boulder County, PM me.

AeroGut

If the cable passes on the outside of the pinch bolt (meaning the side farther from the frame), the effective lever arm is shortened quite a bit, which means that you have to apply more force to get it to move, and it won't move the correct distance, so you'll never get it to shift well. The proper routing is on the side of the bolt closer to the frame. If that's how you've got it set up now, you're good to go.
Also, if you haven't managed to find the Shimano set up instructions, here's a link:https://si.shimano.com/en/pdfs/dm/RB...001-01-ENG.pdf
Note that it's combined instructions for four different derailleurs, so make sure you skip to the pages that are indicated as R3030, not the R3000/2000 steps.

BianchiBravaUS

DOOOn't Get me Started!!! that was a good one. I won't even correct my mistake!


The fun part is that after the original front DR failed - I took it to the shop cause I did not want to be the one to break the chain. They used a ridiculous piece of material as a spacer for my 28.6 frame. That was about the time I quit riding.

Fast forward to a couple of weeks ago I ask them to fix what they did. They did using a chrome clamp spacer even though I saw them thumbing through a drawer that had real shimano clamps.

That lasted for 2 rides before it slipped into the cogs - again. I think they were having the same struggles as I am having now and that is why they tried the metal version.

Could be simply the wrong DR for the gearset I have.

This is why I decided to learn what I needed to get it done right..

Once I get the chain breaker kit I ordered I will start fresh with a new Sora front DR and see if I can make it work.

If not the options are still to go to a MicroShift 3x8 front DR if I can confirm it to be compatible with my 52 tooth front gearset or start a rebuild from the BB up.

Thanks!

oldbobcat

If it were my decision, I wouldn't hesitate to use a Microshift R8, in spite of it's being spec'ed for a 50t maximum on the big ring. The only dimension that affects this is the inner arc radius of the outer plate. Comparing the R8 to the regular and compact versions of the R10, it looks like it's easily sufficiently flat for your 52t, and even if it's a little off (1 percent?), it's no big deal to mount the unit a millimeter higher so everything clears. And if it's any consolation, Shimano has been using the same cages for 105, Ultegra, and Dura-Ace, for 50-53t for over a decade. For a triple, the arc radius of the inner plate is far more important.

oldbobcat

And if the R8 still raises doubt, here's a Claris unit right now. https://www.ebay.com/itm/40310077771...Cclp%3A2563228

Also says 50t maximum. Sora 3x9 says 50t max, too. If your feet are still cold, here's a quick and easy fix for that: file off a millimeter of material from the front corner of the outer plate.