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Old 01-08-18 | 04:54 PM
  #23  
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dddd
Ride, Wrench, Swap, Race
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Joined: Jan 2010
Posts: 9,805
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From: Northern California

Bikes: Cheltenham-Pedersen racer, Boulder F/S Paris-Roubaix, Varsity racer, '52 Christophe, '62 Continental, '92 Merckx, '75 Limongi, '76 Presto, '72 Gitane SC, '71 Schwinn SS, etc.

I've been in the same boat a few times, where I went for the limits of a shorter bb while having to respect both chainring clearance with the chainstay and the ability of the front derailer to still shift to the smallest chainring with authority.

I have a preference for using the biggest chainring as much as practically possible.
The bigger ring has the chain moving faster and under less tension, so shifting is faster and can be completed under a higher level of sustained power without slippage.
As well, the big ring keeps the chain better under control when off-roading, or when crossing railroad tracks at speed for instance, so there will be less slapping of the chain onto the chainstay.

And then there is the consideration of drivetrain reactivity lost to elasticity of the entire complex load path from chain to chainstay. Did you know that a 10% reduction in chainring tooth count actually causes a 22% increase in drive elasticity between the pedal and the road? I'm betting that you heard it here first!

Lastly, many of us, as mentioned, end up using bikes for riding where the smallest ring just doesn't get much use, and a chainline modification can be the cheapest fix as long as there is still chainring clearance and the front derailer can still pull inward far enough to shift to the smallest ring.

Last edited by dddd; 01-08-18 at 05:34 PM.
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