new rings or just buy a new crankset?
blur classic with older 180mm XT hollowtech and splined BB.
LBS replaced middle ring and small ring for me.....$55.
also had BB replaced about two months ago...$25.
anyway, after replacing the new rings (went out tonight) for the first time, been riding other bike quite a bit....anyway, about 1/4 mile into run drop the chain between the small ring and frame....the chain is REALLY stuck in there. it take me about ten minutes, take off rear tire, get some spare chain, wiggle, torque and it finally pops out. start rolling again and notice the chain is clicking, sure enough, I but a dent (bent) into one of the links. turn around and start heading to the car (mostly downhill) and on a short uphill pedaled a bit and bang, chain breaks, rips off rear derailer (x-9)! dang.
anyway, I noticed that my middle ring is now missing a tooth! brand new ring and somehow I managed to completely remove a tooth in the first 1/4 mile....wtf.
anyway, my question is should I try to replace the middle ring and keep my crankset or should I just get a new crank (LX at Jenson for $80)? If I keep my crank, I think it will drop a chain again and there I'm stuck. BTW, my LBS put a race face small ring on and I never had the chain suck issue with a small shimano ring......If I keep my crank, then I will need to stick (2) more rings on it for another $50...
i should just get the new crank (and new X9 rear der.), eh?
Usually when replacing a single ring, just doing that comes out cheapest, but when replacing multiple rings, or in some cases just the outer alone, it's cheaper to buy a complete crankset. Even if it isn't, the difference is so low that you might as well.
Whether you replace just the ring, or the crankset, you need to know what caused the problem. I doubt is was related to the crankset. It sounds more like an extreme example of chainsuck, and if you don't find out what went wrong, you have no assurance that it won't happen again.
The key to solving any problem is to understand and address the underlying cause.
how broken does the missing tooth look? I ask because many newer rings have a few teeth that are made a good bit shorter (and some brands do it more drastically than others). It is supposedly for quicker and smoother shifting up into that ring.
You can get the SLX double from Competitive cyclist for $99. Don't know how long the sale would last but it's a great deal for a great crank.
you shouldn't have to replace the ring because of a broken tooth. Check and make sure the rings not bent and it will work fine. You need to see why it dropped the chain. When you replaced the 2 rings did you install a new chain. Using the same chain that was with the worn rings could be the answer to your problem. If your LBS put it all together I'd ask their opinion on why you had this problem.
Do you still have the small Shimano ring? See if it sits differently on the crank from how the Race Face ring does. Many Shimano rings are made to stand off a little bit, so they sit closer to the centerline of the bike. If the Race Face ring isn't offset, there could be a little more room inboard of the ring - maybe enough to grab your chain and screw up your ride.
Regardless, maybe try screwing the "low" limit screw in a little further.
"Don't buy upgrades; ride up grades." -Eddy Merckx