Help diagnosing chainring wear

Was it a used bike? That chain ring looks pretty worn. Stretched, worn chains usually cause this. I’d say your chain is probably stretched pretty hard which tore the chain ring teeth down. You probably want to get a new chain right away, however a new chain on a worn chain ring has a tendency to jump the teeth making riding impossible. If that’s the case after you get a new chain, you’ll need to replace the worn chain ring(s). Because the worn chain wears into the worn chain ring, this won’t happen with your current set up.

The best way to prevent this in the future is to periodically check your chain for wear. There are numerous ways you can do it from mechanic’s tools to garage hacks. This will prolong both the life of your chain ring and cassette cogs. In my early days I learned that lesson the hard way.

I’m not sure if a derailleur could damage the chain. When I had front derailleurs the chain seemed to always be rubbing the side of the derailleur, but again I don’t know if that contributes to wear. I’ve been told shifting on climbs or when you’re hammering down on the cranks is not the best, but I can’t say for sure that that will take the piss out of your rings/cogs. It’s also entirely possible both your chain and chain ring are fine, just keep an eye on the chain stretching.

As a professional mechanic for 40+ years, I would offer a  couple of things to check:

1) It looks more like this wear is from the chain being cross-chained than actual “load” wear on the teeth.  So – as far as user-related things to check – do you ride in that larger ring often with the rear being in the larger two or three gears?  That makes the chain have to angle onto the front ring as it engages at the top, under load this will wear the outside faces of the teeth as you pedal.  If this is something that you do (common these days on 2x drivetrains), when you approach a hill that you think you will need a lower gear to get up, shift to the smaller front ring BEFORE you get to the start of the effort, and run the chain in the middle of the range in the back or larger cog as you need.   This will keep the chain running “straighter” and also slightly reduce the tension it is under as it comes off the teeth, reducing wear.  (Be aware though, that the smaller ring may also wear a bit faster as it has less teeth, so they engage the chain more frequently…)

2) Your chain appears to be clean – that is good.  Have you been lubricating your chain with a high-quality chain-specific lubricant?  That will also help it “slide” onto the drivetrain teeth as you ride.  Get a good, ‘dry lube’ style of lube (I have been a big proponent of the Boeshield T-9 lube), Rock’nRoll, Prolink, Purple Extreme and others work well too.  Don’t over-lube the chain – I wipe mine off after each ride with a rag, and then rub my fingers on the chain after – if I get any sign of lube coming off on my fingers, I probably have enough lube for another ride.  If the chain made noise while riding, or feels dry after wiping the dirt off, I lube AFTER I am done riding and let the bike sit – a quick wipe-off before I head out again (takes 30 seconds) helps make sure that no new dirt adheres to the chain.  (Over-lubing the chain, or doing it right before you ride tends to attract dust and dirt and you will get some fast wear and a shitty-looking drivetrain!)

Get a chain-checker.  Use it every few weeks/half-dozen rides and as soon as the chain checker “fails” on the first check level, replace it.  You can usually get a few chains over a cassette and rings before they will need to be replaced.  I use good quality but not flashy high-end chains.  I consider them wear items that need to be replaced regularly.  I buy high quality cassettes and chainrings, as a well-maintained and regularly replaced chain will make them last a long time.  One other thing – if the above recommendations are already being done, have a qualified mechanic check the bicycle’s chain-line.  Sometimes, the parts spec’d on a less-expensive bike (not sure what you have…) may not be optimum for the geometry of the frame and the chain will never really run at the best angle.   This might be able to be changed with a part swap or two – see if the dealer will help you out with a discount on the parts, or even a warranty if this is the case.  It’s rarer that this happens these days, but still not unheard of.

Enjoy your bike!

Budget bike is a completely acceptable way to start.  If you like it enough to stay with it, save up for a nicer bike next year (if you need to save…)  If you go Full-suspension, my personal rec is to not bother unless you are willing to spend $2K or more.  Giant and a few others make bikes in the $1500 range, but the difference in quality and performance for another $500 – $1k is huge.  Keep the old bike for muddy days or a loaner/back-up.  Nice to have a bike handy if you have a friend that wants to ride while visiting from out of town, etc…

I find it hard to believe it is the components, I have a 2015 Giant Stance, (budget FS $1300) came 3×9 and I have just changed my chain for the first time this month. And I had over two years and at least 500 miles on it.  To measure your chain wear all you need is a ruler. A full link, three pins, should be one inch. I usually measure 12 links, and if it is more than 12 and 1/16 inches you should replace it, more than 12 and 1/8 inches it probably needs cassette and chain ring also.  I just upgraded to a Wippermann connex chain. they are suppose to last longer, and have a great quick release master link.

If it is the talon 3, 3×8 shifting and you run mostly in the center front, it should not have worn that fast. If it is the talon 2 with 2×9 and you leave it in one ring and use all the back gears, especially if you use 2 on the left and use 1 and 2 on the right a lot it would wear faster. If it is less than a year old the shop should check it for free.

From 22t on the small ring to 36t on the big ring is a fair sized jump. So do you actually use low range 1st gear, or high range 9th gear on your 2×9?   If not, it might be better to go 1x.  I had a 3×9 and found I almost always used the center ring, a 30t.. So I removed the front derailer, switched to a 32t oval narrow-wide chain ring. Later decided I wanted a lower 1st, so added a Wolftooth link to lower my derailleur and put on a wide ratio 11-40 9 speed cassette. The only thing you would have to watch going 1x is getting the right size spacers for the chain ring so it lines up with the 5th (center) gear on the rear cassette.