Comments on: Changing from a Triple to a Double

By: Tim Trogdon

Tim Trogdon — Tue, 02 Feb 2010 12:21:15 +0000

So it spins much better now which is how I ride the most – spinning.
In response also to “why not just stop using granny gear”. The second best way to improve performance/efficiency on long rides/time trials keeping the frame set your bike is built on – second only to changing the wheels – is to lighten the crank set and bottom bracket – the parts that spin and stay in motion. A properly operating chain (no stiff links) & light along with smooth derailleur pulleys all amount to an efficient smoother engine especially when changing speed, etc.
Also the triple cranks push your feet wider out – farther from the frame. for some body types they may need that – also prevents heel of shoe from coming to close to chain stays, etc. for such riders – but the 120 to 130 pound riders pedal more efficiently with a narrower foot placement. A double crank allows a rider to adjust their shoe/cleat on pedal a little further away from the crank arms so no nicking when spinning without widening natural stance as will happen to do that on a triple crank. Each system has to be evaluated, however, for proper fitting.

By: Tim Trogdon

Tim Trogdon — Tue, 02 Feb 2010 12:03:57 +0000

The triple crank I had was low quality & heavy. Also the bottom bracket had developed some play which can’t be adjusted on the sealed units. Also I rarely need to use the granny gear – I don’t live in the alps LOL.
The Shimano Ultegra double was a much better crank and I got it for a third of its normal retail price. Make sure you get the proper bottom bracket for certain crank models – the generic system does not match Shimano and when I used a bottom bracket for a triple it did not work with shifters. But when I got the proper Ultegra 600 bottom bracket to match crank arms & width I was able to have brake hood shifters work nicely with the double and adjusted the low & high stops as provided in the response. Fortunately, I did not need another front derailleur – just raised it up some on seat tube for the slightly larger (extra teeth) outer chain ring.
After doing this I follow procedure to determine proper chain length. I still have rear derailleur- shimano 105 with longer cage (for triple) which is ok, but it may be a little better if I go ahead and switch derailleur to a 105 with a shorter cage – designed for a double crank. My system – cassette is an 8 speed. The key was to have the proper narrower bottom bracket for a double crank, and the one that goes with your crank arms properly as well, which brings crank chain rings inward toward frame – second ring is where small granny ring used to be and outer ring on double is where the middle ring on triple crank was positioned. This placement allows the shifters to work properly – cable to be adjusted – and keeps tension off of cable/system when chain is on the small chainring.

By: David

David — Thu, 17 Dec 2009 07:43:13 +0000

HI,
Excuse my skeptics, but, why not just stop using the small
chainring ?