AMoney

A month ago, I replaced the chain and cassette on my road bike. I thought about replacing the chainrings but didn't because I replaced them last year and thought I could get more use out of them. I've been having some shifting issues since. After going to the LBS, they told me that the inner chainring was beginning to wear out. I attached pictures of my chainrings. Should I replace just the little chainring, or the big one as well? I know that ideally I would've replaced everything at the same time. Would it still be possible to keep the relatively new chain and cassette if I change one or both chainrings? I measured the chain and it isn't worn out.

trailangel

It's brand new

Berg417448

That small chain ring doesn't look worn at all.

Bill Kapaun

What shifting issues do you have?

VicBC_Biker

This ^^^^^^

ThermionicScott 

Both chainrings look great to me. Maybe your FD needs an adjustment?

SapInMyBlood

What shifting issues have you had exactly?

Those chainrings look brand spanking new, your bike shop is on some good ****

Litespud

if anything, it looks like your big ring is in trouble. I can see some "shark fin" asymmetry in the teeth. Your small ring looks OK

AMoney

The biggest issue I had is that it was difficult to shift into the big ring. Occasionally, the chain dropped from the big chainring to the crank. It also seemed liked at times that even when I wasn't shifting the chain wanted to drop from the big chainring to the little chainring though it hasn't done so (yet).

The bike shop did adjust the front derailleur, but they said that they couldn't get the trim perfect. I'm hopeful that my bike will be working better after my visit to the shop, but if not I might have a different bike shop take a look at it.

On a side note, my big chainring is 46t, which is smaller than most road chainrings. Is having a road front derailleur instead of a cx derailleur part of the issue? If so, that would seem strange to me because I haven't been having issues until recently despite having the setup for a year.

AMoney

The LBS may have said that it was the inner side of my big chainring that was worn; the wording may have led me to believe that he said that the inner chainring was worn out. Based on the picture, do you think that the wear on my big chainring is the cause of the shifting problems?

m21bmr

One thing I see on your setup is that your chainrings have been changed from the original Shimano rings. It could be the spacing between the two rings is slightly different than the originals were, which is causing some of the issues. You mention that your large ring is 46T. Lowering the front derailleur may also help somewhat assuming your original chainrings were 50 or 52 tooth rings.

It sounds like the shifting issues may have only been occurring after the rear cassette & chain replacement. It could be that the pins on the inside of the large cog aren't catching the new chain very well.
I don't have tons of experience with adjusting derailleurs, but I recently swapped out my crankset from a Bontrager (SRAM) 52/39/30 triple to a Shimano Ultegra 5600 52/39/30 triple. I couldn't get the original set up to shift to the largest ring reliably at all. It would often just grind the chain against the large ring when trying to lift to the large ring, then if I adjusted to allow more outward travel from the derailleur, the chain would regularly come off the large ring. I tried all sorts of adjustments for weeks without satisfactory results. Once I installed the used Shimano crankset, and shifting is now basically flawless after the initial setup. The Bontrager chainrings on my original crankset didn't look very worn, but in my case the shifting performance of the Shimano chainrings has been lightyears better.

AMoney

Do you think that the new chainrings work better because they were or a different brand? Or do you think it was because that they weren't worn out? When you installed the Shimano crankset, was it used or new?

Litespud

I don't think so - I would expect some noise or clatter as the new chain engaged with what I think is a worn chainring (that alone would be enough to make me replace the chainring). I suppose the teeth could ultimately become so worn and "hooked" that you'd start to experience chain suck, where the chain wouldn't disengage at the bottom of the chainring, but you're nowhere near that, and that's not the problem you're reporting.

BTW a 46T big ring should be well within the capabilities of your standard FD - it is can push the chain off the small ring (36?), it can push the chain off a 46. Just make sure that your FD cage is close (~2 mm) to the top of the teeth when on the big ring - hard to tell from the pics, but it looks a little high to me.

It's also possible that the after-market rings are spaced sufficiently differently from the original Shimanos that it's throwing off the front shifting. However, I'm assuming that the shifting was OK until you replaced the chain and cassette, so slightly off chainring spacing. Do you still have the original rings? Could you reinstall them, measure the ring spacing and compare it with that of the new rings?

m21bmr

My guess is that the Shimano chain rings have a better designed ramp / pin setup that results in the improved shifting performance. The Shimano crankset I installed was used.

zandoval 

Evidently you are replacing the chain rings because they look a little worn. If so then do all the components. Really it looks like its a front derailuer problem and a slightly worn ring.

AMoney

I no longer have the original chainring, but it was a 50t Shimano 105 5700 chainring. My current chainring is a 46t FSA Pro Road chainring. Also, my small chainring is 34t.

Are you suggesting that I replace the front derailleur be replaced as well? If so, would a cyclocross front derailleur work better with a 46t chainring than a road front derailleur?

Also, I'm debating whether or not to just get new chainrings or a crankset as well. A new crankset wouldn't cost that much more than getting the chainrings. I've had my current cranks for over six years. If I'm not currently having problems with the crankset, should I replace it as a preventative measure? Or do cranks last for a very long time?

woodcraft

Don't replace anything (except possibly the LBS)- nothing is worn out.

Shifting won't be quite optimized with mismatched rings, but should still be fine.

The FD may want to be lowered closer to the big ring- hard to see in the pic. Get a better mechanic to adjust it, or watch some youtube and do it yourself.

70sSanO

Right now I don’t have a bike in our garage that is running the original spec’d outer chainring. In my experience there is no consistent rule on FD distance above the chainring.

Some FD’s can run close to the standard couple mms and same need a substantially larger gap, 10mm. FWIW that set was a 50t to a 46t, but it was a triple.

The shop setting up the FD has to take into consideration the inner cage and the best place to shift from the inner ring to the outer. When running a smaller outer chainring than spec’d that seems to be the driving factor.

There can also be an issue where the inner FD cage will inferfere if the FD is too low. But that shouldn’t be an issue with a 34t.

John

Bill Kapaun

The fact yo went to a 46T from 50T means the FDER is going to have to sit noticeably higher than normal above the big ring.
You can't lower it to match the 46T because it'll interfere against the small ring.
You may simply be having an issue because of the mismatch.
Note the gawdawful gap when I replaced the 44T with a 36T. Shifting to the big requires "help".
Any lower and it hangs against the middle ring on the downshift.

Phil_gretz

Why in the world would you use other than Shimano rings? Shimano's are established standards for terrific shifting...

Also, your bike shop doesn't know what it's doing. The FD needs adjustment based on the symptoms that you've described.

AMoney

I think I got the FSA brand for the big chainring because the 46t chainring is becoming increasingly less common. The small chainring is Shimano 105. That being said, next time I'll get Shimano for my big ring. I prefer Shimano over other brands but didn't have any problems until recently.

masi61

I concur with what has been said about trying a cyclocross FD. The 46 tooth big ring isn't playing well with your 105 road double FD. The big chainring does look a bit worn. I thought I heard that FSA chainrings are made from a softer series of alumimum but I might be wrong. Shimano makes a cyclocross specific front derailleur as does IRD which is supposed to match the arc of the smaller "big" chainring.

Also, I'm not sure if you have the documentation for your front derailleur or not but sometimes it pays to do your set up step by step from the very beginning. The orange "set up block" that is packaged with Shimano front derailleurs in the box really does help on triples (not sure if it is as critical with doubles) since it changes the initial cable tightening to a position midway between the chainrings. Then (with the high and low stops set - to prevent throwing the chain to the inside or the outside) you can use the adjuster barrel to fine tune how many rear cogs you can shift through before you have to deploy the "trim" click.

Have you considered returning to the original 105 50 tooth chainring? This set up might just work best.

AMoney

The original front derailleur was 105. When it broke, I got a lightly used (but heavily discounted) Dura Ace front derailleur from my LBS at the time (a different one than now; I moved). That being said, I don't have the documentation. I don't want to go back to a 50 tooth chainring unless it is absolutely necessary. I personally don't like the big jump of a compact. I'm also able to spend more time in the big ring with the 46 tooth chainring. I would rather get a cyclocross front derailleur than go back to the 50t chainring. That being said, I know that even many cyclocross bikes with a 46/36 crankset (including one I previously owned) had the same derailleurs that road bikes have.

Thanks for letting me know about the difference between FSA and Shimano chainrings. I think that the first thing I would do is try to a Shimano 46 tooth chainring. I didn't know this until recently, but there is a Tiagra 4600 46t chainring that is designed to be paired with a 34t chainring. I also plan on having a different LBS looking at the front derailleur.

70sSanO

Don’t go to a 50t if you like the 46t. Despite reports to the contrary you can run a 46-36 without problems. It might be a tad slower shift, due to needing to soft pedal, but unless you are getting paid to ride, it is moot.

To back this up a little bit, has the shifting ever been good with the 46t and the DA FD? Or is this 46t a recent change?

I don’t know which DA FD you have, but generally the DA line doesn’t offer the greatest range since it is designed for racing. I’ve run a 7703 (triple) with a 46t and it was okay, but not ideal. But never had issues of throwing a chain or not wanting to shift.

John

AMoney

I'm running a 46/34, not a 46/36. I've had the DA derailleur for a few years. I've had the 46 tooth chainring for one year. I know that 46 tooth chainrings are generally designed to be paired with a 36 tooth chainring. However, my 46/34 setup with the DA derailleur worked well up until recently. Also, in my experience, the minor mismatch was offset by having a 12t difference between the chainrings instead of a 16t difference.