h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

When I was a kid it used to be a big thing having as many gears on your mountain bike as possible. Reading this entry has made me realise how absurd it all was, as we didn't really know how to use them (not to mention London is pretty flat). My bike at the moment has 21 gears, though lots of kids seem to be going for fixed-gear bmx-type-things now...

If you do mountain biking on trails that the bikes are designed to handle - ie. riding in mountains or woods off of nice flat road - you need a wide range of gears.

It is not so much the number of gears but the ease of shifting to accomodate varying terrain. For example if you are in a swampy wood land trail with many climbs, tree trunks and really tough bits you want to keep the front chain wheel small (I use 22 teeth down to 32 at the back). Then if you get a chance for a short burst of speed you can shift up somewhat at the rear (say down to 13 teeth over 8 gears if you could) if it is not worth changing the front gear because you have another tough bit coming up really soon.

These days you can get 9 speeds at the back - I still have my "old" 8 shifter to give me 24 - this is ample.

I agree - anymore then you have to have really strong springs in your derailleur to keep the spring tension, and besides it is physically impossible to stretch the shifting range beyong the minimum and maximum stretch you have in the chain. With the small gear in front and back the chain has to still be tight enough to not fall off and with the big wheel in front and back the chain has to have enough slack to shift - otherwise you get into very embarrasing situations with stuck or broken chains

My main problem is that I'm using my bike to get to college at the moment (well, before the holidays), which involves some woodland and some roads. on the roads though, my bike is very ineffecient, and takes huge amounts of energy compared to a road bike. i think this is partly down to tyres which never stay fully inflated, but also because the tyres are so thick and the bike is so heavy. still, it gets me fit!