Originally Posted by
awesomejack
Why have a crank set like 24-34-44? Why not have something like 24-36-50? It gives you the low gears and the high gears. Nothing is gained by having a 44 big ring rather than a 50. You use low gears in the little rings and high gears in the big ring. So why this choice?
The question should be "why do most cyclist have such large rings". Most road bikes are seriously over geared for the average rider. They have the same gearing as professional cyclists and, let's be honest, not many weekend cyclists can average 27mph. If you want to do 60mph plus on downhills, or a 50mph sprint, then there is an argument for big rings, but most non competition cyclists would do well to adopt the gearing used by tourists. As an example I run 42/26 rings with an 11/34 cassette giving me 21" to 103" gearing. I can climb anything in the 21" gear and 103" lets me sustain 24.5mph at 80rpm.
Also when designing gearing it's important to minimize replication of gear ratios and to get suitable step sizes. Of course rear and front derailleur capacity limitations must also be met (within reason), hence my use of 42/26 instead of 42/24 to stay within the 16t range of a compact FD.
http://wheelsofchance.org/2009/08/28...-the-question/