Originally Posted by
Mr. DNA
Can anyone tell me what the advantage is to having a 9, or even an 8 speed bike is? Likewise with a triple chainring in the front? I'm assuming I'm missing out on something really basic about gearing, but I don't quite understand the need for so many cogs, or especially for 3 chain rings.
Thanks for the feedback
Wider range and/or closer spacing which feels better.
The professional peloton opted for closer spacing between gears over more range until 9 speed 12-13-14-15-16-17-19-21-23. With 10 cogs some extended the range, and a few added an 18.
We can assume recreational riders are no more tolerant of lower cadence climbing or big jumps between gears.
The average pro has 6W/kg of functional threshold power.
It takes about 200W to average 20 MPH on flat terrain which is faster than most recreational riders over an hour. The average US male weighs 90 kg which is 2.2W/kg.
Extrapolating, the average rider should have a 64T large cog. Maintaining the same spacing that is a
12-13-14-15-16-17-19-21-23-25-28-31-34-37-41-45-50-55-61-66 20 cogs.
In the 9 speed era, the pros used 53-39 doubles. We could keep the cog count more reasonable with 50-34-24 triples; which would reduce the large cog requirement to 40 teeth cutting our gearing needs to 3x15.
I find cassettes with a two tooth jump before the 19 cog inappropriate for road riding, and have opted for a larger starting cog (13, with 52x13 ample for Eddy Merckx to dominate the pro peloton) or triple crank to make that work. 30x21 yields a low gear like 42x28, and allowed 13-14-15-16-17-18-19-21 in the 8 speed era.