Rover I8 Questions about adding a 2 or 3 cog crankset.

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Comments

  • It's going to take a strong engine to maintain 19 mph @60rpm on a Rover.
  • @weldin4 -

    for a go-fast machine, sturmey is a better choice over the nexus hub because of its taller gearing.

    with the stock patterson up front and the usual 24-tooth sprocket on a sturmey xrf8w hub, 60 rpm in 16th gear should have you moving at 20 mph, and give you a 22-113 gear-inch range.

    change the sturmey sprocket to 22-teeth ($8) and you would have 24-134 g.i. with the patterson. in comparison, the terratrike sportster with its 30 gears and 26-inch wheel has a range of 23-120 g.i.
  • JamesR wrote: »
    @weldin4 -

    for a go-fast machine, sturmey is a better choice over the nexus hub because of its taller gearing.

    with the stock patterson up front and the usual 24-tooth sprocket on a sturmey xrf8w hub, 60 rpm in 16th gear should have you moving at 20 mph, and give you a 22-113 gear-inch range.

    change the sturmey sprocket to 22-teeth ($8) and you would have 24-134 g.i. with the patterson. in comparison, the terratrike sportster with its 30 gears and 26-inch wheel has a range of 23-120 g.i.

    There you go comparing two totally different models. Equal riders there is no way a Rover should be as fast as a Sportster. The Sportster has better tires, seating and pedal position plus it's appx. 10 lbs lighter. The Sportster is the sports car. The Rover is the Chevrolet or minivan, two totally different models. The older Sportster & Zoomer will beat any recent model also due to a much better seating position as it is lower and more reclined. The human body is the biggest drag followed by under inflated tires and gear line inefficiency.
    And last, engine, work on it.
  • TCEd wrote: »
    And last, engine, work on it.

    Actually, the single most important factor in the equation is the one you give the least weight to....

    If the engine is able to push the 134" gearing at the same RPM it is capable of spinning the 120" gearing at, guess which one is going to go faster?

    It's going to be the 134" gearing...

    More reclined or not, lower seats or not, tires and gearing inefficiencies or not, moving another 10% more chain through the system in the same amount of time is going to move the thing faster. You are putting more energy into the equation, and the losses aren't going to reduce the speed below something that has a lower potential top end turning at a lower energy output from the rider.

    Of all the factors involving speed in bicycling, the most important one always comes down to the putz on the pedals. Everything else is such a small amount of loss, very few of us on these forums would ever be able to tell the difference.

    But then again, very few of us on these forums could spin 134" at 90+RPM for more than a short period of time, anyway...
  • edited December 2017
    Equal engines with equal drive trains on different trike models will have different results. A Rover and Sportster are not equal.
  • I'm always more concerned with the granny gear GI
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