ChrispySD

Hi folks!

I'm bored during CoVid and trying to get my Fuji Roubaix RC road bike working after many years of non-use.

When I first tried to shift, nothing worked. After hours of YouTube videos, I used a can of WD40 to clean the gunk and now the rear gears shift fine. However, when I try to shift the front, I get a loud "clunk" from front derailleur when shifting from large cog to small.

I have watched a lot of derailleur videos, but found nothing about the clunking sound. Front cage height is good off the large cog (about 2.5 mm at smallest point) and seems to be aligned with chain. Can anyone tell me what I should look for, or what could be the most likely culprit in the clunking noise? Again, works fine going from small front cog to large. Only clunks when going from large to small.

My components are...

• Component Group Shimano Ultegra
• Brakeset Tektro RX40 brakes, Shimano Ultegra STI Dual Control levers
• Shift Levers Shimano Ultegra STI Dual Control
• Front Derailleur Shimano Ultegra, bottom-pull/clamp-on 31.8mm
• Rear Derailleur Shimano Ultegra
• Crankset Truvativ Rouleur GXP, 39/53 teeth

I plan on getting Boeshield T9 to lube everything up again once this is done.

Thanks in advance for your guidance!
Chris

dsbrantjr

The derailleur cage returns inwards under fairly strong spring pressure; if the clunk is the derailleur hitting its stop that may be normal behavior. If it shifts OK otherwise I would tend to think it was fine.

shelbyfv

Try loosening the FD limit screw for the big ring. If it is too tight and the FD is impeded from easily making full movement there will be tension in the system causing an abrupt drop when shifting to the small ring.

ChrispySD

Thanks! Other than the clunk it shifts normally. To be more specific, it's a two part noise...light clunk when I start to move left shifter from large cog to small, but no chain movement. Then as I press the left shifter hard, I get the secondary loud clunk, and the chain transfers smoothly to the small ring.

I'll check the limit, thx!

canklecat

That may be normal behavior, depending on the shifter. Usually a left/front derailleur indexed shifter in an integrated brake/shifter setup will have two clicks per shift, which offers a little wiggle room for trimming the FD to minimize chain rub.

And with some chainring combos, like a 52/39 or 50/34, there's a big jump between chainrings so it can be tricky to finesse the shifts.

Sometimes a minor tweak to cable tension via the barrel adjuster can help. If the cable has stretched you may want to loosen the cable clamp at the front derailleur, take up the slack and check the shifting again.

And, depending on the FD and frame, sometimes a minor adjustment to the angle of the front derailleur can help. That may not be possible or easy with some direct mount FDs.

KJK

This "clunk" is perfectly normal. It will never be as smooth and slick as shifting the rear derailleur because the chain rings are larger and the jump between gears is greater as well.

WizardOfBoz

It sounds like one of several things. It could be a normal sound, but you shouldn't have to push the shifter hard to shift.

One problem might relate to adjustment. You could try loosening the cable a little to see if its too tight.

Another problem might be a sticky FD. You might disconnect the cable (with the chain in the small chainring) and see if you can easily move the FD chain guide in and out with your hand. If its stiff, or sticky, you might try some oil or spray grease, or even taking the thing off and cleaning in mineral spirits and then letting it dry and adding some oil to pivot points In extremis, you could replace a sticky FD.

Don't think its the low limit screw because it "clunks" when it does shift, indicating that the shift is accompanied by movement and that the limit screw isn't limitint till after the clunk problem.

If could be that your high limit is too slack (not screwed in enough) AND your cable is setup to hit that limit screw (that is, too tight).