Bicycle Mechanics - FSA MegaExo chainrings have broke-off tips, with 500 miles

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md009003
03-23-09, 12:51 AM
Hi,

I have a new road bike the came with an FSA MegaExo crank set, 50/39/32T, 130mm. Recently I noticed that about 1/3 of the teeth on the 50/30 rings have their tips broken off. The amount of broke off is a bout 1/4 - 1/3 of the tooth height. The bike has about 500 miles on it. The rest of the rings do not show much wear off, cogs (Shimano Ultegra) look good too. The chain, a Shimano 105 CN5600 looks fine as well.

Does this have to do with shifting gears while climbing/starting? Most of my riding is on flat roads and I do not do much hard starting. Has this happened to any of you? What could have caused such a quick wear off? Do I need to replace the rings now?

Thanks,
-md009003

AEO
03-23-09, 01:29 AM
those are shaped and ramped teeth to aid in shifting, yes.
md009003
03-23-09, 01:45 AM
those are shaped and ramped teeth to aid in shifting, yes.

The teeth are made that way? In other words, what I saw now is what I always had from the beginning? That sounds plausible, even though the little ring (30T) doesn't appear to have such teeth arrangement.

MadBuddha1
03-23-09, 04:22 AM
maybe bad shifting habits.?
Wordbiker
03-23-09, 05:07 AM
maybe bad shifting habits.?

No, AEO has it right.

The small ring doesn't need engineered ramps and pickup teeth as the chain doesn't shift up to it, nor does the chain need release gates to shift down. On a triple setup only the middle and large rings will have shifting aids.
md009003
03-23-09, 02:35 PM
No, AEO has it right.

The small ring doesn't need engineered ramps and pickup teeth as the chain doesn't shift up to it, nor does the chain need release gates to shift down. On a triple setup only the middle and large rings will have shifting aids.

Thanks for confirming AEO's statement.