Rolling Resistance (RR) - Understanding Tires

Discussion in 'Electric Bicycles' started by DrkAngel, Oct 28, 2013.

  1. DrkAngel

    DrkAngel Member

    While at high speeds, Rolling Resistance (RR) is a minimal factor, but at speeds below 20mph, it is a major factor and well worthy of consideration!

    At 50mph the rolling resistance is approximately 3.5% of the energy required from "Mountain Bike".

    An alternate source (Schwalbe) demonstrates the transition between rolling resistance and air resistance as the major energy robbing factor as speed increases.

    [​IMG] "Speed" is in KPH.
    I removed "Gradient" factor-lines.

    As demonstrated, 18kph looks to be the transition point of RR being surpassed by AR (Air Resistance) as the primary resistance creating force.

    Please note that RR increases at a linear rate ... 1 - 2 - 3 - 4 - 5 - 6 - 7 - 8 etc.
    While AR increases at a geometric rate ... 1 - 2 - 4 - 8 - 16 - 32 - 64 - 128 etc.

    As speed increases, RR becomes an increasingly minimal factor-consideration.
    Last edited: Oct 28, 2013
    Fabian likes this.

  2. Fabian

    Fabian Well-Known Member

    I really like your graphical representation of these numbers. It's visually informative.
  3. DrkAngel

    DrkAngel Member

    eBike tires

    I did a lot of shopping for low RR, durable and affordable tires.
    These 2 look to be great bargains!

    Might have just found my new - Best Bargain Tire!

    Schwinn - 26" x 2.125" heavy ... and it doesn't look too impressive ...
    Kevlar Belted!
    Large size and nearly flat tread is ideal for my eTrike!
    Price: $15.38 & FREE Shipping on orders over $35. (I bought 2 & $5 gloves to get free shipping)


    I lucked into finding these tires that meet my requirement almost perfectly!
    Tread is a a nice compromise between the mountain bike tread and the smooth tires that came with the eZip.
    26" x 1.90"
    Pressure @65psi is acceptably "good".
    City/commuter sidewall protection.
    Kevlar reinforced for puncture resistance.
    Reflective sidewall.
    The reflective stripe, though a cheap add-on (under close inspection), is a nice bonus.

    [​IMG] - only $15.72 each.
    This is great bicycle parts source w/free shipping on $100 order (USA only).
    Last edited: Nov 13, 2013
    skweezit likes this.
  4. Fabian

    Fabian Well-Known Member

    The Schwinn - 26" x 2.125" heavy looks like a tyre that promises long tread life with improved puncture protection - in the league of the Schwalbe Marathon tyre range, but for $15 as opposed to $60 +
  5. LR Jerry

    LR Jerry Well-Known Member

    I use Kendra 838 26x1.95. You can get them at (D i c k's Sporting Goods) for $15. They are patterned after a motorcycle tire. The Rubena V99 City Hopper is another good tire; you can get these in different colors.