Worn teeth on Shimano 105

[carolonabike]

Hi,

I've only done a couple of hundred miles on my Trek Lexa but when I was cleaning it yesterday I noticed that some of the teeth on the chainring look as if they have been damaged, sort of blunted, if that makes sense.
It's not every one and seems to be quite random, about a dozen in all.

Is this something I should be worried about and has this happened to anyone else?

I had it back at my LBS last week for it's first service but they didn't mention it.

 

[fossyant]

No, some of the teeth are profiled for assisting shifting.

Only worry when the teeth become 'shark fin shaped' - which won't happen for some time !

 

[TheDoctor]

Hello and

The teeth are shaped to help the chain on and off the sprockets.
Some of them are shorter, funny shapes and so on, so they're meant to be like that.

 

[carolonabike]

Ah, thanks for that. I'm feeling rather embarrased now

Thanks for the welcome though

 

[e-rider]

the teeth are designed like that! I workded in a bike shop 15 years ago when shimano started making these and we got quite a few customers back saying that the teeth were damaged - so you are clearly not the first to make this mistake.

 

[carolonabike]

I'm glad I asked on here, otherwise I would have asked at my LBS and they would definitely have laughed at me.

I had Shimano Dura Ace on my old bike but that's 25 years old and all the teeth looked the same in those days

 

[MartinC]

I had Shimano Dura Ace on my old bike but that's 25 years old and all the teeth looked the same in those days

Well everything is designed for convenience now - they sell you sprockets and chainwheels that are part worn to save you having to cycle thousands of miles to wear them out!

 

[carolonabike]