Mystery question: chain crossover at cruising speed?

Do the calcs again with a 12-23 10 speed cassette (it will have the 18t cog) and the 39t chainring, it should work out better. 🙂

This reminds me of the "Should I pedal with my toes down?" threads.

Dude, you are spending way too much time thinking about this stuff. Just get out and ride!

Bob

Just avoid the 53-25 and 39-12 gears and you'll be fine.

AmpedCycle said:

Countdown has begun until my new bike arrives this week. It turns out that I'm as broke as a joke after sinking the proverbial battleship, and I'm outta luck for getting a compact double. I'll be sticking with the stock ultegra double it comes with, which has a chainring combo of 53x39 and cassette combo of 12-25. For cruising around at 21-22 mph, which is what I do best, where does this put me as far as having a severe chain crossover angle in the big ring of the double? Or can I continue cruising in the 39 ring, like I cruise around in my triple now, which is a 42? I've done some gear inch calculations of my own given RPM matched with mph, and come up with this so far:
@85 RPM:
(windy days) 53 by 19= 19.47mph
(normal days) 53 by 17= 21.76mph

@90 RPM
(windy days) 53 by 19= 20.61 mph
(normal days) 53 by 17= 23.04 mph

I figure that in these combos at these RPM's, I'll find my optimum cruising speed. Compared to the 52x42x30 triple and 12-25 cassette I'm riding with now, I stay in the 42 chainring and in the 14-15-16 cassette combos, with no chain crossover angle.
So, does anyone know about the mystery of the chain crossover angle in a double? Or is it just my imagination? I don't know if it's a bad thing to have the chain making a diagonal line between the chainring and the cassette.

Just ride for awhile with the stock set-up. You will know soon enough if you really need a different crankset or cassette gear range.