Bicycle Mechanics - Chainrings from Nashbar...Where's the teeth?

Hi Folks,
Got a good price on replacement chainrings from Nashbar for my Shimano Mega 9 Deore crank.

Don't quite know what to make of what I received (pic attached)- note the short teeth on the right and left sides.

Can someone explain what the deal is?

Thanks!
Scott

I haven't seen any that severe, but it is an aid to shifting. Shimano rings also have this. The short teeth are right after that lifting rivet.

... but it is an aid to shifting. Shimano rings also have this...

I also noticed the short teeth on my newer ('03) roadbike's chainring. Does anyone know when they started making the short teeth chainrings? I have a couple of older ('80s) road bike whose chainring teeth are perfect - both do not shift as quick on the biggest chainring.

Can someone explain what the deal is?


Yea....its perfectly normal.

I haven't seen any that severe, but it is an aid to shifting. Shimano rings also have this. The short teeth are right after that lifting rivet.
Huh. Is this more common on road bikes? I didn't notice such smaller teeth on my current rings.

Also, are the low-profile teeth supposed to line up in a certain location relative to the crankarm?

Pretty much all the Shimano stuff has this. It really does improve the shifting :)

"Also, are the low-profile teeth supposed to line up in a certain location relative to the crankarm?"

Yes, the little tab between two of the mounting points is supposed to line up with the crank arm. The other rings should have some similar reference.

Thanks for the replies!

I'm getting the sense that I should read up on proper shifting techniques, in that low profile teeth located at a particular location relative to the arm suggests you should shift when the arm's in the 12 or 3 o'clock position?

Thanks for the replies!

I'm getting the sense that I should read up on proper shifting techniques, in that low profile teeth located at a particular location relative to the arm suggests you should shift when the arm's in the 12 or 3 o'clock position?



No.......the ring spins fast enough that it will engage when it feels like. Just stop worrying about everything.

http://toyopc.phys.unsw.edu.au/toyozumi/Bike2002/0618images/chainring.jpg

Your chainring seems to be literally missing teeth instead of just having shorter teeth beveled at different angles, I can't imagine how the chain can possibly fit on that...