Cablestein

I bought a brand new Shimano XT crankset about 8 months ago.

I've put about 5000 km's on the large 44t chainring (never used the other rings all this time).

The teeth are starting to look like shark fins... are they worn out?

If I replace the chainring, is there a better aftermarket brand to use that's more durable?

How often do daily commuter riders replace their chainring?

JohnDThompson 

If they're looking like shark fins, it's time to replace the ring. If you want durability, install a steel ring rather than aluminum.

HillRider

Depending on where you ride, 5000 km (~3100 miles) should never wear out any decent chainring and Shimano's XT is more than decent. If you ride in sand and very abrasive, wet conditions all the time, maybe they can actually be worn but otherwise it's not likely. I've got Shimano road cranks with 30,000+ miles and the chainrings are still in decent shape and their MTB cranks are the same quality.

Are you sure you aren't looking at the shaped and gated teeth that are purposely made to improve shifting? They are shorter than the others and can look worn but are intentionally made that way.

Cablestein

Half my riding has been in snow/slush/rain conditions (Toronto), there has been lots of grit.

I'm looking at the overall condition of all the teeth, they are all beginning to have a shark fin shape, and the tips are very sharp and pointy. I'm aware of the varying teeth sizes, I'm looking beyond that fact.

HillRider

OK, I believe you. The forum gets a lot of questions about "worn chainrings" from new riders who don't understand what they are looking at so I wanted to ask.

I'd use the current ring until the chain begins to skip. No point in changing it until you have to. Also, if the chainring is that bad, I'm sure both the chain and cassette are even worse so plan to change everything.

As to better chainrings, I don't know of any Al rings any better than Shimano's. Steel rings may last better but I don't know if you can get any to fit a Shimano XT bcd. A new, very cheap crank (that will have steel rings) might be a cheaper alternative.

Cablestein

Thanks for the input

I am indeed having chain skip problems. Mainly one problem that happens frequently. The chain falls off big ring, outwards. I haven't been able to consistently replicate it, or observe it happen (by looking down as I ride).

Next time it happens I'll try to take note of where my pedals are when the chain falls off, then I could narrow down at what point on the chain ring does the fall off happen (if it happens at the same spot, it might be one funky tooth to blame?).

I figured a new chainring wouldn't hurt anyways =P.

CHEERS!

HillRider

Do you have a front derailleur still on the bike? If so, tightening the outer limit screw a bit should stop the spilling problem. If there is no fd, adding one, even if it isn't cabled, it can be adjusted to do the same thing. Otherwise, there are guard plates that will fit outside the big ring and keep the chain in place.

Cablestein

I bought the FD but never installed it.

Good idea, about using it just as a general guide... although I feel like the chain may unnecessarily mangle it up.

The whole chain guide and bash ring idea fascinates me... because would eliminate the chain jumping off a single chain ring for good?

How much extra friction would roller chain guides make for the whole system?

HillRider

Don't bother with a roller chainguide. A bash plate or fd will accomplish the same thing with no friction downside. The chain can't "mangle" a front derailleur unless you leave so much clearance the chain can fall between the cage and the chainring.

JoebikerLa

Surly makes stainless steel rings in all bolt patterns. They don't have shifting ramps, so you don't want to try to shift with them. I have been very happy with them. I use a bash ring on the outside and a chain keeper on the inside, never a lost chain.

JohnDThompson 

Why not? Shifting ramps are a recent innovation; front derailleurs were used for decades on rings lacking them. The shift might not be as crisp or quick as a ramped ring, but there's no reason why it wouldn't work.

Sixty Fiver

The quickest way to wear out a chain ring is to let your chain get past it's maximum wear point and at 5000 km I will bet that chain has exceeded that and has started to wear the 44 tooth ring.

Like John said, ramps aid in shifting but they are not essential.