Anonymous
Anonymous asked in SportsCycling · 6 months ago

Do bike wheels limit the top speed?

I have an MTB with 26 inch wheels and thick aluminum frame. Swapped the stock drivetrain to a bigger one with a 48 crankset. I topped out at 32 mph on a flat surface (an 0.5 mile road patch). Now, is it possible to get to 40 with more practice? I mean, aren’t the 26 wheels the limiting factor?

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  • 6 months ago

    Not so much the size, although you can make marginal gains with a 650b or 29er. Tyre choice If you want speed, then you want a low rolling resistance. So big balloon tyers are out. Panaracer, for example, do a 26" road tyre for an mtb wheel. Try that and you will find peddling smoother. The downside is that this will only work on road surfaces and will not be brilliant off road. So you might want to compromise and go for a 1.8 tyre with summer tread. This is very ;much an XC set up and will not allow you to do as much at a trail centre.

    Luck

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  • 6 months ago

    To hit 40 on flat ground, you're going to need to pay particular attention to aerodynamics. Eliminate all aero drag possible, including flappy clothes, wide handlebars, wheels with large spoke counts, tires, and especially body position.

    For gearing, you're going to need a bigger chainring. Rear cogs smaller than 13 teeth show increasingly large losses, so avoid going smaller and compensate by using large chainrings. A 56 or 58T ring should do it. Finally, going from 32 to 40 mph will probably require you to double your power output. I think you underestimate the magnitude of the goal, but good luck!

    • Bademus6 months agoReport

      Thank you!

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  • D50
    Lv 6
    6 months ago

    With high enough gearing and some way to avoid aerodynamic drag, bicyclists have topped 100 mph by a lot for years. I think the current record is 174 mph.

    • Land Rider Jerry
      Lv 6
      6 months agoReport

      It's now 184 mph. https://youtu.be/6CFTqHbgsKs

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  • 6 months ago

    Good wheels will help. Get advice from a good racing bike shop.

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  • David
    Lv 6
    6 months ago

    For a given cadence - pedaling pace - you’ve got three things deciding your top speed:

    - chainring tooth count

    - smallest sprocket tooth count

    - and wheel size

    In theory, it doesn’t matter which of these you change. Either can be tweaked to give greater speed.

    IRL, 11T sprockets is the most common smallest sprocket size. It takes an effort to go lower.

    Chainrings can easily be found up to 53T.

    If your bike started life as a MTB , you might not be able to fit a much bigger chainring

    For a 48/11 and 26” wheels, you’ll be pedaling ati just above 100 rpm to get to 35 mph. To hit 40 mph you need to pedal at 120 rpm. Doable with pedals with a foot-retention system, but not very efficient.

  • 6 months ago

    Wheel size has little to do with top speed. However, the type of tire you use can be a factor. Knobby off road tires will slow you down. As well, the position of the rider on a mountain bike isn't very aerodynamic making it much harder to push yourself through the air at higher speeds.

    Your top speed is only something you can hold for a very short time. On any bike you should also think about the speed you can hold over the duration of a ride, your average speed. However, if you want to look at making top speed attempts, you should probably look at trying out a road bike

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  • 6 months ago

    The rear gears & your own ability are also contributing factors. Easy solution. Find a bigger downhill run. You can easily surpass 40 mph.

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