The compact chainring front mech issues thread

[super slim]

I am a Shimano man from childbirth, and I think I made the right choice back then, as Shimano derailleurs SEEM to be MUCH easier to adjust on the outer, but I use a chain guide on the small triple, and shifting to the granny with NO load can be disastrous.

 

[cpml123]

Chain guard may help but I have not used that specific model.

I have Sram Force FD; 50-34 and yes, the problem I have encountered is the chain jumping off the outside of the big ring. I have mostly worked out that problem though not completely. The trick seems to be to play quite a bit with the outer limit screw. Do the basic Sram Yaw derailleur set up (that can be a little tricky but there are plenty of good YouTube videos - particularly the Art's Cyclery video). When you are done with that you will likely find that the chain can jump off the big ring, especially if you shift quickly or with inadequate pedal pressure. The last step is to work the outer limit screw in and out no more than 1/8 turn, maybe even less, at a time. You want it to set where on shift, you almost can't get the brifter to click as required. 1/8 - 1/16 of a turn too little/much and the chain jumps. that much too far in the other direction and the shift won't catch. Even with that I have to be careful on my shifts to the large ring. The shifting trick seems to be moderate (but not too much) force on the pedal as you shift until the chain slips into the chainring teeth, then continue the shift until it clicks in place. If you shift to quickly, the chain slides right by the teeth on the slight overshift that is designed into the Sram derailleur.

Now that I have this all worked out I only occasionally drop the chain . . . usually when I'm waiving and smiling at some pretty young woman or a TV camera! Karma has no sense of humor!

Another thought... rather than putting on a chain ring guard, what if I replace the 50t ring with a 52t ring 110bcd? Is it as simple as unbolt the 5 screws and replacing the big ring? This way I will end up with 52/34.

 

[paco1961]

Another thought... rather than putting on a chain ring guard, what if I replace the 50t ring with a 52t ring 110bcd? Is it as simple as unbolt the 5 screws and replacing the big ring? This way I will end up with 52/34.

Be careful w 52:34. Many FD designs list 16 tooth jump as the maximum. Of course many mechs operate outside mfg recs but I've not tried it. But as long as the chainrings have same bcd it is a simple change.

 

[paco1961]

I am a Shimano man from childbirth, and I think I made the right choice back then, as Shimano derailleurs SEEM to be MUCH easier to adjust on the outer, but I use a chain guide on the small triple, and shifting to the granny with NO load can be disastrous.

Longtime Shimano guy also but the Sram Yaw FDs (Force 22 in my S40 case) give full 22 gear combos w no chain rub. The cage pivots rather than sliding in and out parallel to the frame. The trade off is finickier set up. Moving from DF to CB I wanted all the gear flexibility I could get!

 

[Seth Cooper]

I have Sram Force FD; 50-34 and yes, the problem I have encountered is the chain jumping off the outside of the big ring. I have mostly worked out that problem though not completely. The trick seems to be to play quite a bit with the outer limit screw.

I have SRAM etap FD on my vendetta with the SRAM red 50/34. I was having some chain jumping until I got the outer limit screw set right, but now I have it seems to shift great.

 

[Seth Cooper]

I just got a longer chainstay with the new longer FD slot. unfortunately it is still a little higher than SRAM would like. The slot for the screw is long enough, but the etap module hits the top of the bracket, so the extra slot is somewhat wasted. One pic shows the amount of lowering that still is required for the ideal position, the 2nd shows the etap FD resting on the top of the bracket. This problem I think is fixable with a dremel tool and a cut-off wheel, only part of the bracket is overlapped by the FD, and that can be nipped off I think and still leave enough structure around the slot intact. Tagging the man himself...@Robert Holler

 

[cpml123]

After tolerating dropping chain for a year, I finally gave up. My problem was chain dropping when shifting from 34 to 50 on my S40. It was adjusted many times by various folks. I knew replacing 50t with 52t has been successful for people, but I didn't want to take apart the nice new Cobb crankset.

I finally had it 2 weeks ago. I went to REI and ordered a FSA Super Road 52t ring, thinking that I could always return it if it doesn't work. I got it in 3 days, replaced it, and just took the bike out today. I am happy to report that it actually works! Although it's not buttery smooth like my DF Ultegra, it shifts up with no dropped chain! I tried it with varying cog in the back, and they all worked. It clunks but it works fine. Yeah! So now the front is 52x34 instead of 50x34.

Couple bonuses..
1. I think the FSA ring looks nicer than the Cobb ring.
2. REI's price, to my surprise, was great. It was $50, cheaper than ebay, and that's before I applied the 20% member discount! Just FYI, I also ordered 2 Schwalbe g- one All-around 700x38 from REI, and they came in at $40 each. Ebay price is around $70 each. REI is awesome.

Here is the picture.

 

[benphyr]

Might I suggest chain waxing to you fine gentlemen? Your chainrings will look even better with less gook on them.

 

[cpml123]

Might I suggest chain waxing to you fine gentlemen? Your chainrings will look even better with less gook on them.

It is waxed. I guess I need to clean the wax residue from the rings.

 

[3WHELZ]

I had a 52/34t Cobb set-up that I rode last year. I found it was too much of a jump between chainrings for my liking. I swapped out the small ring for an FSA 36t ring. I was surprised how much of a difference it made when it came to shifting between chainrings, much smoother.

 

[cpml123]

I had a 52/34t Cobb set-up that I rode last year. I found it was too much of a jump between chainrings for my liking. I swapped out the small ring for an FSA 36t ring. I was surprised how much of a difference it made when it came to shifting between chainrings, much smoother.

Isn't it annoying that we should have just bought the 52/36 to begin with? Now we have spent more money and have extra chainrings sitting around doing nothing. I hope Cruzbike is fixing the FD stalk thing in the next version.

 

[3WHELZ]

I agree that would have been simpler from the start. As you have discovered, a 52t is the smallest large chainring that you can use and still satisfy Shimano /Sram's recommended tolerances.

I am interested to hear whether you experience the same challenges shifting between a 52 and a 34.

 

[paco1961]

Remember that almost all major manufacturers of FD mechs recommend a max spread of 16 teeth. No surprise some of you are having trouble w larger jumps. The new Shimano gravel groupset bumps that max jump to 17.

 

[cpml123]

I agree that would have been simpler from the start. As you have discovered, a 52t is the smallest large chainring that you can use and still satisfy Shimano /Sram's recommended tolerances.

I am interested to hear whether you experience the same challenges shifting between a 52 and a 34.

52 to 34 is great. No problem there. 34 to 52 about 50% time shifts sharp. The other 50% time the chain drags a little before engaging the big ring. This is still way better than dropping chain though. I think I am good for now. My expectation has been set very low due to chain drop previously.

 

[DocS]

Out of curiosity, have any of you swapped out the front for a Patterson Transmission or the like?

They currently offer a 28, 32 and 36 tooth chain ring...

Blessings,
DocS

 

[jond]

Another thought... rather than putting on a chain ring guard, what if I replace the 50t ring with a 52t ring 110bcd? Is it as simple as unbolt the 5 screws and replacing the big ring? This way I will end up with 52/34.

I ran Shimano Ultegra 6800 52-34 and couldn’t tell difference to 36 small.

 

[jond]

Remember that almost all major manufacturers of FD mechs recommend a max spread of 16 teeth. No surprise some of you are having trouble w larger jumps. The new Shimano gravel groupset bumps that max jump to 17.

They also love to sell chainsets. Chainrings small are pretty cheap.

 

[Karl42]

This is a real challenge and more and more people are asking for smaller rings - but with" stock" parts (The hanger is a stock part right out of the road bike catalog) you cannot have it both ways. The newer FD mount on the next run of stays (a ways out and I still need to get through the current ones so please don't flood the email) is in the works. We had to have a custom hanger made that is longer than anything else out there, as we couldn't just move the current one down a shorter stalk as then people who run QXL's or bigger rings would be out of space.

Hi @Robert Holler,
Does the new V20c have the new long FD mount? Do you think it will work with a large chainring smaller than 50t ?