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  1. #1
    Senior Member Plainsman's Avatar
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    REAL newbie question: crank for a sprint tri

    Okay, I'm totally green when it comes to triathlons and I want to do my first sprint in the spring. That means I'm already behind in training. I'm curious about which crank I should use on my bike. I recently replaced my Ultegra 53/39 with an FSA 50/34 (but I've held on to the Ultegra). The compact is great for the hills I typically ride in this area, but would the 53/39 be better suited for the 20-something mile long rides you usually see in sprints?

  2. #2
    Body by Guinness cjbruin's Avatar
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    Since we know very little about you, this is a tough call but I am willing to make a guess that you will be fine with the 50/34. I assume you are using a 9-speed 12-25 cassette.

    By the way, the bike leg will acutally be 10-15 mi for the spint.

    Anyway...here are the mph calcs for your gearing assuming 80 rpms

    50-12 - 26.1
    50-13 - 24.1
    50-14 - 22.3
    50-15 - 20.8
    50-17 - 18.4
    50-19 - 16.5
    50-21 - 14.9
    50-23 - 13.6
    50-25 - 12.5

    34-12 - 17.7
    34-13 - 16.4
    34-14 - 15.2
    34-15 - 14.2
    34-17 - 12.5
    34-19 - 11.2
    34-21 - 10.1
    34-23 - 9.2
    34-25 - 8.5

    Look this over and I think you will agree that you will be fine.
    Fredo, you're my older brother and I love you...but don't ever take sides, with anyone, against the family again...ever.

  3. #3
    Senior Member Plainsman's Avatar
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    Thanks for the calcs. I didn't realize that the bike legs were 10-15 miles for sprints. I guess that's good news. Sorry for the lack of info. I'm 32, and have been road biking for about a year. Pretty decent hills in the area I'm from. I was a competative swimmer as a youth (doesn't say anything for my conditioning now) and I'm still pretty comfortable with distance swimming. Ran a bit (recreationally) in HS, but still think the run will be my biggest hurdle. As I read my own post it occurs to me that my "credentials" off the bike are all at least 15+ years old! Anyway, I'm in decent shape at about 6'-1" and around 175+ pounds. I switched to the compact (10 speed 12-25) because there are some pretty severe grades in the North and South Carolina mountain/hill country, although I really enjoyed my 39/53 on the flats. At my skill level right now, I see a 50-12 as plenty on a 10-15 mile ride. Thanks!

  4. #4
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    use the compact & spin it faster

    It will help your running.

  5. #5
    Senior Member Plainsman's Avatar
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    Quote Originally Posted by LBonney
    use the compact & spin it faster

    It will help your running.
    Really? Sounds good, but how exactly does it help? (Any help is good help though)

  6. #6
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    Usually in a triathlon I find that spinning faster uses your cardio system more, leaving more strength in you legs. Hammering on the ride exhausts your legs too much for effective running after. (IMHO)

  7. #7
    Senior Member Plainsman's Avatar
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    That makes sense. Thanks!

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