Going from the small chainring to the large and vice versa!

wacka
wacka Posts: 169
edited April 2013 in Road general
Hi,

What is the best rear sprocket to be in to change from the small front chainring the the large when on the flat, and vice versa when you hit a climb?

Comments

  • slowbike
    slowbike Posts: 8,498
    For me it's anything in the middle of the cassette.
    But the decision to change depends on the route and the likelyhood of needing the new range of gears. I do cross chain if its only a short hill and I can climb it in the big ring.
  • rolf_f
    rolf_f Posts: 16,015
    There isn't one - it depends on what the terrain is doing. Chainring selection is more about the gradient that you'll be cycling on in a few moments and the cassette about where you are now. For example, a small dip on a climb might see me get to virtually small - small to maximise speed in the short dip to carry through to the following climb without wasting speed on a pointless shift to the big chainring and back to small within a few seconds.
    Faster than a tent.......
  • sungod
    sungod Posts: 17,496
    as long as the chain is the correct length and the rear mech is not being used with a cassette beyond it's specified limit, you can shift anywhere

    but generally it's best to avoid the two largest sprockets when on the big ring, and the two smallest sprockets when on the small ring, among other things this avoids having the chain run at too much of an angle (which would waste energy and also increase wear if you did it a lot)
    my bike - faster than god's and twice as shiny
  • Mikey23
    Mikey23 Posts: 5,306
    An interesting question and one that I haven't fully mastered. When I change from big to small I seem to be frantically clicking down 2 or 3 to get in the right gearing and cadence and I'm wondering if I'm doing it tight? Standard compact 105 here...
  • davem399
    davem399 Posts: 269
    Like Sungod, I avoid the two biggest sprockets with the large chainring, and the two smallest with the inner chainring. I l have a compact chain set on a couple of bikes and when dropping onto the small chainring, I often need to move to a smaller cog at the rear to keep the cadence down to a sensible level. This is not usually a problem with the 39/53 bike, as it seems the slightly closer (2 teeth) gap means a change of rear sprocket is not always needed.

    At the end of the day, I try to read the road ahead and anticipate chainring changes in good time.

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