mkwdrs

Give me a brief education on the speed differences on cassettes. While looking at touring bike recommendations, one site recommended a 9-speed. Some entry level tourer's have 8-speed. What's the advantae or disadvantage of the different speeds?

MichaelW

In terms of the gear selection, there really is no difference between 9, 9 and 10. All of them give you more than enough gears to handle any terrain with reasonable jumps in ratio.
If you are looking at the latest models of groupset, then expedition-touring quality transmissions would be mid-upper range (105 or LX) which are 9 speed, so thats what you ride. You can use lower grade groupsets for touring which happen to be 8speed. Really dont sweat it, but get the highest grade you can afford.
If you happen upon a new-old stock bike, with 8 speed XTR or Campy Chorus components, then just enjoy the high quality and you wont miss the extra cog.

Rich Clark

Don't confuse the number of gearss with the *range* of the gearing; it's the range that matters, especially on a touring bike.

At a given pedaling cadence, a cassette's smallest cog (11 or 12 teeth, occasionally 13) is used when going faster; its biggest cog is used when climbing. The bigger that cog is (all other things being equal) the less the rear wheel will turn per pedal revolution. This means you can climb steeper hills without grinding to a stop.

A road bike might have a biggest cog of 23 -27 teeth. Mountain bikes go up to 34 teeth. IMO a touring bike that's expected to climb steep grades with a full touring load will want a 32 or 34.

All of this is modified by what's up front, of course. Many touring bikes these days come with road triple cranksets -- 52/42/30 chainrings. A 30 - 34 combo on the low end not all that low when climbing a steep grade into a headwind with 50 pounds of gear. So many touring cyclists go with smaller chainrings as well (at least a 26 or 28 instead of the 30; or with a MTB crankset).

The point being that a 12-32 could be an 8-speed or a 9-speed cassette, and it wouldn't make much difference. The 9 speed gives you slightly smaller increments between gears, which can make it a little easier to find just the right gear for the conditions of the moment, but it's not a big deal IMO. I have an 8-speed 12-32 on one bike and a 9-speed 12-34 on another, and the difference between the 32 and the 34 is much more relevant than the difference between 8 speeds and 9 speeds.

RichC