Gear efficiency question

Pocket Rocket
Pocket Rocket Posts: 47
edited December 2009 in Workshop
On a 12-23 (10spd) cassette, which gear is more efficient for sprinting uphill 53/19 or 39/14? (both 75 inches), both gears are have a large chain cross over.
http://www.finchleyracingteam.com/

Comments

  • TornadoTom
    TornadoTom Posts: 129
    Bigger Sprocket + Bigger Chainring is mechanically more efficient.
  • rake
    rake Posts: 3,204
    +1 less tension in the chain and linear pull on bearings.
  • dennisn
    dennisn Posts: 10,601
    They both take the same amount of work / effort to get to the top. This holds true with ANY gearing. It doesn't matter what gear you're in, YOU must expend the same amount of energy to get to the top. Tornado Tom may be correct in what he says but only to the extent that a chain going around smaller gears is NOT as efficient as a chain wrapping around large ones, but only very, very, very slightly so. Nothing you would notice on a bike.
  • ride_whenever
    ride_whenever Posts: 13,279
    a very very slight difference is still a difference.
    Neeermad
    Carbon 456
    456 lefty
    Pompino
    White Inbred
  • dennisn
    dennisn Posts: 10,601
    ride_whenever wrote:
    a very very slight difference is still a difference.

    I got the impression that the OP thought that by using different gears HE HIMSELF would
    have to expend less effort to get to the top, in one set of gears as opposed to another.
    I didn't think he was referring to the science of chain wrap, cog sizes, and their effect on
    power transmission. Which I would GUESS would be very, very, very slight(3 verys)
    on bike gearing.


    Anyone?????
  • rake
    rake Posts: 3,204
    the chain and block would probably last a bit longer less stress on the drive. were not talking big power saving?
  • chrisw12
    chrisw12 Posts: 1,246
    If you want an answer from people who've tried measuring it then have a look here:-

    http://wattagetraining.com/forum/viewto ... 9ee07ce89a

    and

    http://wattagetraining.com/forum/viewtopic.php?f=2&t=87

    The 'myths' above may or may not be busted, I can't really remember, good luck. :)
  • Bill D
    Bill D Posts: 62
    If you get knackered after the sprint and you've still got uphill to do, the 39 - 14 gives you more gear options without using the front changer....
  • Pocket Rocket
    Pocket Rocket Posts: 47
    Bill D wrote:
    If you get knackered after the sprint and you've still got uphill to do, the 39 - 14 gives you more gear options without using the front changer....
    That's what I was thinking. The hill in question is part of a circuit that I race on during the season and the finishing climb (every lap climb) is steep, I personally have never gone up it in the big ring, as I am more of a spinner, whereas others grind up it. For the last lap however, when everyone is a big edgy and the speed increases, I was wondering if its best just to keep it in the larger chaining and be done with it.
    http://www.finchleyracingteam.com/
  • balthazar
    balthazar Posts: 1,565
    Pocket Rocket wrote:
    Bill D wrote:
    If you get knackered after the sprint and you've still got uphill to do, the 39 - 14 gives you more gear options without using the front changer....
    That's what I was thinking. The hill in question is part of a circuit that I race on during the season and the finishing climb (every lap climb) is steep, I personally have never gone up it in the big ring, as I am more of a spinner, whereas others grind up it. For the last lap however, when everyone is a big edgy and the speed increases, I was wondering if its best just to keep it in the larger chaining and be done with it.
    So, there it is. The variation in mechanical losses has no practical bearing on the matter. If the next gear you will want is higher, use the big ring; if it's going to be lower, use the small ring. Each will give you at least one cog each way if you misjudge, so it really doesn't matter much.

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