Old and Slow

I recently purchased a Lemond Maillot Jaune on Ebay. (Dura Ace 9 speed) Overall, the bike is in excellent condition, but on close inspection the 53 t chainring appeared to be worn. The teeth are asymmetrical. I am not talking about the teeth with the tops cut off. I know why they are there. What I mean is the space between the teeth is not a U shape but more like a U shape. However, I have recently taken a close look at some new 9 speed (Ultegra and Dura Ace) chainrings and they are exactly the same. All of the teeth on the big ring have a different slope on the leading edge than they do on the trailing edge. The difference is slight. You have to look closely to see it, but it is definitely there. The 39 t ring is not like this.

Does anyone know the purpose of this? I have a much older Dura Ace bike (circa 1986) and it does not have this abnormality.

mtbikerinpa

If you have referred to a new sample and found it to be the same then there was a design purpose. Usually if there is a bias in the tooth profile it is to keep the rollers seated on the tooth more securely. That is my best guess, it may be the case here or it may not.

miamijim

Thats normal. Its to allow smoother shifting.

operator

It's called Hyperglide, it's to facilitate smoother shifting.

sydney

Well, actually it isn't. Hyperglide had been around looooooooooong before that tooth profile showed up.

operator

It isn't? What is it?

sydney

How about evolution of Shimano Total Integration?