Michael Shaw

See these pictures, both of 5-sprocket cassettes.:

https://dl.dropbox.com/u/4370787/Sprock1.JPG

https://dl.dropbox.com/u/4370787/Sprock2.JPG

On one, the sprockets go from 14 to 24 teeth, and on the other they go from 14 to 34 teeth.

Is there a special purpose to having a really tight or a really wide spacing in the number of teeth ??

Mike

SweetLou

Those are freewheels, not cassettes. Wide ranges are good for hilly areas. That way you have a low enough gear to get up the hill and a high enough one when going down the hill. Tight ranges are good in not so hilly areas, that way you are less likely to be in-between gears. You can pick just the right gear. If you are a strong rider, a tight range can be good in hilly areas also, as long as it is geared low enough for you.

Michael Shaw

Thanks !! The tight freewheel is on a really old European Campagnolo Record wheel set and the wide freewheel is on a relatively new North American VeloSport.

Makes sense.

Drew Eckhardt 

It feels better for many people and limits the number of situations in which you're forced to ride at a more fatiguing cadence. For instance, I noticed that I could ride threshold intervals on consecutive days at 90-100 RPM but not somewhere around the 85 that I'd prefer to pedal.

I'd do whatever I needed to do to avoid riding cogs with jumps bigger than one tooth up to the 19 - triple crank, more cogs, 13 starting cog, etc. (I'm going to use an 18 cog every day, but there are few hills where I'd care that I could apply power at a reasonable cadence with an 11 or 12 but not a 13).

It gives you a low enough gear to make it up the hills you're likely to face with a pleasant non-fatiguing cadence without compromising on down-hill speed. At a good climbing weight I could spin a 42x28, 39x26, 34x23, or 30x21 up the vast majority of paved roads in the Colorado Rockies and still enjoy steeper rides (where 30x21 could come from 50-40-30 x 13-14-15-16-17-18-19-21 rear cogs that were also ideal on the plains to the east). _Training and Racing with a Power Meter_ includes an anecdote about a rider who got dropped every time his power output matched what he could otherwise maintain for an hour but his cadence dropped below 70 RPM for more than five minutes.