New to 27.5: 26 vs 27.5 gearing and cadence- Mtbr.com
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  1. #1
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    New to 27.5: 26 vs 27.5 gearing and cadence

    I recently purchased a 27.5 Pivot Trail 429 coming from an Sworks Stumpjumper FSR 26.

    Both bike are geared the same. So, the gear ratios are the same. I know that it takes slightly more power to turn the 27.5 initially than the 26.

    I've been playing with the gearing on the new bike, and I'm finding that the 27.5 seems to like a slightly higher cadence with slightly lower gear ratios.

    Anyone else finding the same?

  2. #2
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    If they are geared the same, i.e. same size front chainring and same cassette, then they are not geared the same due to the wheel size differential. I'm guessing that to compensate, you are running (for example) in 3rd gear at a higher cadence to get the forward speed of 4th gear on the 26". Or, if both are in 4th gear, at the same cadence, the 27.5 will be 5 or 6% faster. Is that what you mean?

    It doesn't take any more power to turn a 27.5 inch wheel, once it's up to speed, but it would take marginally more to accelerate the wheel up to speed (given same rim/wheel mass). But, that is a small differential and only while accelerating.

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    Yeah; although you explained it much more precisely than I could of.

    Feels like the 27.5 runs about a half a gear taller all other things being the same.

  4. #4
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    Quote Originally Posted by rnitti1 View Post
    Yeah; although you explained it much more precisely than I could of.

    Feels like the 27.5 runs about a half a gear taller all other things being the same.
    Yeah, that's normal.
    You've probably seen something like this before:
    Berkshire Sports - Bicycle Gear Ratio Comparison Calculator
    It's a gear ratio calculator and can tell you the actual difference.

    I just realized you're running 27.5+ (rather than 27.5) so bigger tire as well. If it's say, 28.5" Vs. 26, it would be almost a 10% difference. Doesn't sound like much unless you're running at 90% effort and you go to 100%.

    You'll get used to it. I've gotten to where I now like running higher torque with lower cadence, but everyone is different.

  5. #5
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    Exactly! At 80% effort all is equal. At 90%+, I can really feel the difference. More time and getting stronger should help.

  6. #6
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    Update for anyone who cares: Changed from the 34t up front to the 32t. The 34t was just to tall a gear when I needed a bailout on the 27.5 vs the 26. I actually climb faster overall with the 32t (27.5), and my heart doesn't feel like it's going to explode...which is nice.

    My personal riding style just doesn't generate enough power / can't generate enough torque to keep the 34t spinning at the cadence I need to keep the pace I want without spiking my heart rate causing me to slow down.

  7. #7
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    If you went from a 26" tire to a 27.5+ tire, it will definitely require more power to move the bike.

    I am all about the smaller ring to suit your needs. That's important regardless of what a spec sheet indicates is ideal. Good for you.

    I use easier gears on my 27.5+ to hold a cadence that is acceptable to me relative to the 29'er.

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