Thanks in advance for reading this and/or replying.
OK, I may be a bit anal (I've been called one of the synonyms to this, just not to my face). Anyway, I'm kinda new to the bicycle scene since I got my drivers license. I'm now in my mid 50's. Two years ago I purchased an X-Mart Mtn bike, a 15 speed. Now I'm not the sharpest tool in the shed but I figured it was called a 15 speed because of the 5 cogs and the 3 chainrings. Now where I'm confused is from reading where you should not ride using the largest cog and the largest chainring or on the smallest cog and the smallest chainring due to chain having to stretch across too much. So according to my math it turns out that I can only use 13 cog and chainring combinations. Why isn't it called a 13 speed? Secondly, being done with X-Mart bikes and doing my own wrenching now, I purchased a Schwinn Sierra 10 speed for $25 at a swapmeet/flee market. It has 5 cogs and 2 chainrings but is it really only an 8 speed? Why is the sky blue, err that's another post, why are they called 21 speed, 15 speed or whatever when you shouldn't shift through all the gear combos? Is this some kind of Bicycle Manufacturers propoganda/conspirecy?