Worn chainrings
 

In the 6 months that I have owned my Cannondale CAADx, I have put 1600 miles on it. After looking at the 50 and 39 rings, many of the teeth show significant wear. Some are to the point where they are chipped off half way. When I shift from my chainrings, I do not do so under a heavy load or anything. That occurs sometimes with my rear cogs, and none of those teeth are cracked/chipped. I wrote an email complaining to Cannondale about what was happening, and they wanted me to take it to the LBS where I bought it from and let them handle it with FSA. To me, Cannondale is missing the point. They should be standing behind parts that they are putting on bikes when they send them to the LBS for sale. I also complained about the brakes pads that went to bare metal after 1000 miles. I have a road bike with 6200 miles and none of the teeth on the 50/34 show any wear whatsoever. The 39 ring is the worst, so I am going to replace it. Are chainrings just standard? Will a Shimano 105 one fit? I sure as heck do not want to replace it with a crappy FSA one.

I doubt that your chainrings are worn anywhere near to the point of needing replacement. I ride road chainrings until they're razor sharp, and would serve as fancy Ninja rings. That takes 25-50,000 road miles, and even then they work.

Mtn biking is a bit different because it's a harsh environment and it's easier to wear out rings, but it's usually the inners because thet see the heavy work of hard hill climbing. Even here, it's well near impossible for you to worn out your rings.

I suspect that the chipped and badly worn teeth you're seeing were that way when new. a few teeth are cut down and sculpted to create shifting gates which make it easier for the chain to switch to and from the neighboring smaller ring. (inners, don't have gates because the chain is lifted or dropped on them from the top.

If you're still concerned about the ring's wear, here's an easy test.

use a screwdriver tip to gently lift the chain away from the ring at the front (1/2 way around the wrap). A new chain on a new sprocket will barely lift away. With wear the chains pitch increases, and the sprocket gets smaller, so slack is created. If you can pull the chain away to see 1/4" of daylight under the chain there's serious wear, (but even that will rin OK). Note that the chain wear and the sprocket wear are both contributing to the slace so the way to isolate sprocket wear is to do so this tease with a length of new chain.

As a practical matter don't even worry, no matter how worn the sprockets are, they're fine until they're worn to the point that the chain slip under high load, like when your standing on the pedals. (you'll know). Until then ignore the sprocket condition unless you're planning a long tour, in which case you might want to do some preventative medicine.

From experience FSA rings do wear far quicker than Shimano, but were still talking about a 10000-15000 mile lifetime rather than 25000.

Would be suspect that the wear you are seeing is the normal ramping as described by FBinNY and was there the day your purchased the bike; it's probably just a little more highlighted now with a little wear and dirt after the first 1600miles you have done.

For Cannondale asking you to take it back to the bike shop you got it from, do you expect them to personally send a representative to your home? If you take it to the dealer they will deal with any warranty process / service as needed, do you need to know the details of the inner workings of this? The Dealer should be your first point of contact for any service, you shouldn't need to contact a manufacture unless the dealer can't sort the issue out.

For your brake pads, you used them, they are consumables; depending on the conditions you are riding in, they may last a single ride, or many years.

Many people complain about worn or broken chainring teeth when it's just the way some of the teeth are shaped to promote easier shifting. So it's not unreasonable for Cannondale to want you to have the bike looked at by your LBS. That should be the first step in getting any issue resolved. FWIW, the large chainring on my Cannondale also wore out after less than 90,000 miles.

I at no time asked Cannondale to provide replacement or the rings or pads. I was just telling me how crappy the parts were from their vendors and nothing else.

You bought the bike. Are you really sure the chainrings are wearing prematurely?

Go into any bike shop and look at the chainrings on brand-new mountain or road bikes: they all look the same as your rings. And don't feel bad. Lots of people jump to the same conclusion that you did.

So worn teeth on a NEW bike? I assure you that the chainrings were in perfect condition when I bought the bike new. I do a lot of climbing as I live on the top of a 500 foot plateau which I am riding up and down all the time. I also do ride up mountain passes on logging roads, so maybe I am asking too much from the lower level parts? Shifting is still adequate on the front rings, so I guess I will wear them down to nubs...which will probably be in a few thousand miles at the rate I am going...

I have several other bikes at home with many more thousands of miles on them and the teeth on them are not worn down like this.

Service flow chart always goes thru the dealer first.
if not the one you bought it thru
then another C 'dale dealer nearer to where you live..


( some people see the shorter teeth and skip tooth ramps and gates,
to make them shift early as worn, when the teeth were really designed that way)

Let's think about this -- if the tips of the teeth are wearing or chipping off, you should be able to feel that while riding, since the chain will be sliding over the top of them. Is that happening?

Methinks your other bikes with "many thousands" of miles are old enough not to have shifting aids built into the rings. Pics would always help.

I will take it up with the dealer then.

I will post pictures when I have time. It is not even wear. It is a case of good teeth, then a few chipped ones etc. This is the only bike that I have where this is occuring.

Please let us know what the dealer tells you.

I think most of us can venture a pretty good guess. If you tried to make book on this, you'd have to offer long odds to get anyone to cover the bet.

Just being subtle:beer:

What you're describing really does sound like tooth shaping designed to aid shifting. I found a pic on Sheldon's page HERE -- look at the teeth on the bottom ring, particularly the one(s) just to the right of the pin.

(The shaping on my own Campy chainring is pretty pronounced. I feared some teeth were worn or broken when I first saw it, too.)

Okay, let me be more blunt -- does the chain ever skip on the chainrings? Unless you're doing BMX tricks, that's the only way you could be wearing the teeth down...

Like Joe_5700 I was more than a little worried when I saw that 6 or so teeth on my middle, 42 teeth Shimano RX100 chain ring were worn/broken down to about half the height of the other teeth. And, even though the bike is 20 years old, it has less than a 1000 miles on it. So I was, to say the least, concerned.

But, I found reading this thread reassured me -- but not enough to overcome my natural born, doomsday paranoia.

So, today when I visited my LBS I asked. And I got the same answer: "They were designed and made that way to facilitate shifting" (And, it was clear that that was about the one millionth time he had answered that question!)

... Darn! Now I have to go find something else to worry about!

Does it look something like this?http://bikeforums.net/attachment.php...hmentid=259505

I'm with everyone else here thinking its just ramped teeth for shifting ease and that the oP just wasn't aware of it when he bought the bike. I know what to look for in regards to worn teeth and i have acquired a few nice sets of cranksets due to someone not knowing that the teeth were supposed to be almost in half in certain parts of the chainring.

I also go though this nearly weekly with people who bring in their bike and say "look, the teeth are really worn" and then show them now there is a pattern to the teeth, such as with some Shimano, you have 2 lower teeth, then a middle taller tooth, then 2 more lower teeth, then 180 degrees away, the pattern repeats.

One tech even said "Hey Bo, check out the ripping teeth on that chain ring" and I had to explain to him that those teeth were made that way for shiffting ease.

It is how the chain ring was designed.

[QUOTE=onespeedbiker;14434126]Does it look something like this?

Yep, that's what my 20 year old Shimano RX100 looks like.

They should be forced to put a warning on these things like they do on cigarettes:
"WARNING: These chainrings can make newbies a little crazy"

Which is even better evidence that the "chipped" teeth were made that way intentionally to improve shifting. FSA cranks aren't the best available but they are functional and adequate. You would have to ride in hub deep sand all the time to wear them out in 1600 miles.

Yes! Many of the teeth look like 1 o'clock and 3 o'clock.