cassette question - number of rivets

bubbaho

Hi guys. Sorry for dumb question, but I have a compact (50/34). I have a 9 speed cassette (11-25 speed). Theoretically, if the cog increasing by two rivet on each cog (11 to 25, would equal 18, which doesn't work out). So how does it work, with the number of rivets on a 9 speed (11-25). Are the one-rivet increments on the bigger cogs, so toward the bigger cogs 22, 23, 24, 25? And two-rivet increments on the smaller cogs, say going 11, 13, 15, etc?

Thx. I'm trying to understand my gears, and what combination I use to get up some hills.

Harry

dennisn

bubbaho wrote:

Hi guys. Sorry for dumb question, but I have a compact (50/34). I have a 9 speed cassette (11-25 speed). Theoretically, if the cog increasing by two rivet on each cog (11 to 25, would equal 18, which doesn't work out). So how does it work, with the number of rivets on a 9 speed (11-25). Are the one-rivet increments on the bigger cogs, so toward the bigger cogs 22, 23, 24, 25? And two-rivet increments on the smaller cogs, say going 11, 13, 15, etc?

Thx. I'm trying to understand my gears, and what combination I use to get up some hills.

Harry

The number of rivets(never heard them called that - teeth?) on each cog varies with different manufacturers. Try the companies technical web page for a complete listing.
As for gears to get up hills - Small ring in front and large cog on the back(34-27). A 12-27 or 11-28 cassette should do you just fine, along with your compact 50-34.

sungod

they're normally called teeth

the smaller cogs differ from each other by one tooth

the larger ones by two (or more in some cases)

what counts is the % difference, so the spacing is selected to make the difference as even as practical across the range of the cassette

so as you change gear up/down you get a similar increase/decrease in effort (all else being equal), with each shift

i.e. 11 to 12 is about 9% difference

23 to 25, also about 9% difference

bubbaho

Hi dennisn. :oops: teeth is what I mean. Yes lol

I checked the Shimano website and my cassette has the following:
11--12 --13 --15 -- 17 --19 -- 21 -- 23 -- 25

So this is different than I thought. This means I mostly use 34/ 21-23 for the steep hills I ride. So now I understand, as I thought maybe my gears went 23, 24, 25, but not so.

Sungod, you explain why I was wrong in my thinking. Because you wisely suggest it is the %, so now I understand how it works

thx a lot

cougie

The number of teeth is usually stamped on the sprocket anyway.