Grooves in rear sprockets

[lulubel]

I decided to clean between the sprockets on the rear cassette with baby wipes the other day (have just discovered the miracle of baby wipes for bike cleaning, and it's now the cleanest it's been since I bought it!) I've never looked at the cassette this closely before because I usually clean it by taking the wheel off and scrubbing it with warm water and car shampoo.

All the sprockets have an angled groove in them. If you position the sprocket so that the groove is at the top, it runs from the outside edge down and to the left. Are they meant to be there, or is it wear caused by a chain that should have been replaced some time ago?

 

[tyred]

They are meant to be there (assuming these are reasonably modern components). It is to aid gear shifting

 

[lulubel]

Thanks. Yes, the bike's only a few years old. I think it's a 9-sp Shimano Tiagra cassette.

Can't justify spending money on an upgrade yet, then

 

[jethro10]

Yeah, to help shifting.
called "Ramps" i think.
It lets the chain get closer to the centre line of the sprocket so it gets picked up by a tooth easier.

If you look at some front chainrings, it's much more accentuated, and also they usually have "pins" as well to help lift the chain.

J

 

[tyred]

Google hyperglide or Uniglide to read more.