Join Date: Apr 2010
Location: Warwick, UK
Bikes: 2000-something 3 speed commuter, 1990-something Raleigh Scorpion
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Standard triple or short arm double?
My bike currently has a fairly standard 28-38-48 crankset with 170mm cranks. I'm finding it difficult however to maintain a high enough cadence on the road, and almost never use the extreme low or high gears. In my pile of bits in the garage, I have the double crankset from a kids bike which has 28-38 chainrings and 140mm crank arms.
I've done some number crunching, and it works out that, accounting for the short cranks, the highest gear available (using gain ratios) is 12.8 for the double and 13.3 for the triple, or thereabouts. The lowest gear is 4.7 for the double and 3.9 for the triple. I don't think I've ever had to use the triple's extreme low gear on the road, and in any case the lowest gear on the double works out similar to the second lowest on the triple
My question is whether it's better for me to continue using the standard cranks or switch to the shorter ones. I realise 140mm is very short, but so also are my legs. My reasoning is that the shorter cranks will allow me to maintain a higher cadence, so I may end up faster despite the slightly lower gearing.
Last edited by Monster Pete; 08-03-10 at 12:14 PM.
Reason: copy/paste error