Advertise on Bikeforums.net



User Tag List

Results 1 to 9 of 9
  1. #1
    Senior Member
    Join Date
    Dec 2009
    Posts
    771
    Mentioned
    1 Post(s)
    Tagged
    0 Thread(s)

    Anyone's cycle computers have a selection for 650b wheel?

    Mine only has one size - 650b x 37mm. But I am going to run 33mm tires.
    Don't know if it is that much of a big deal to not be dead-on, but was wondering if anyone knows off hand of any computers that have more 650b sizes to select from.

    I see also that I can measure the tire and input that. I guess I will try that but was wundrin' if anyone's has 650b inputs.
    Last edited by lungimsam; 08-04-12 at 01:44 PM.

  2. #2
    rebmeM roineS JanMM's Avatar
    Join Date
    Jan 2006
    Location
    Indiana
    My Bikes
    RANS V3, RANS V-Rex, RANS Screamer
    Posts
    11,446
    Mentioned
    2 Post(s)
    Tagged
    0 Thread(s)
    I always enter the actual roll-out measurement.
    RANS V3 (steel), RANS V-Rex, RANS Screamer

  3. #3
    7-speed doomsday prepper ThermionicScott's Avatar
    Join Date
    Aug 2011
    Location
    CID
    My Bikes
    1991 Bianchi Eros, 1964 Armstrong, 1988 Diamondback Ascent, 1988 Bianchi Premio, 1987 Bianchi Sport SX
    Posts
    7,689
    Mentioned
    4 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by JanMM View Post
    I always enter the actual roll-out measurement.
    +1. This is the best option, even if the computer does have your tire size programmed into it.
    Quote Originally Posted by chandltp View Post
    There's no such thing as too far.. just lack of time
    RUSA #7498

  4. #4
    Senior Member DieselDan's Avatar
    Join Date
    Mar 2003
    Location
    Beaufort, South Carolina, USA and surrounding islands.
    My Bikes
    Cannondale R500, Motobecane Messenger
    Posts
    8,524
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Do a roll out or use a GPS.
    Bikes use brakes to stop.

    If your bike has breaks, don't ride it.

  5. #5
    Senior Member Retro Grouch's Avatar
    Join Date
    Feb 2004
    Location
    St Peters, Missouri
    My Bikes
    Rans Enduro Sport, Hase Kettweisel Tandem, Merin Bear Valley beater bike
    Posts
    23,602
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Doing a roll out isn't hard, it's just an inconvenience to do.

    When setting up computers for customers in a shop I'd just use the numbers in the manual or sometimes interpolate between two listed tire sizes. Those methods are accurate enough enough for me.

  6. #6
    Senior Member
    Join Date
    Dec 2009
    Posts
    771
    Mentioned
    1 Post(s)
    Tagged
    0 Thread(s)
    The manual said do roll out in mm's, or measure tire from floor to top. Those mm's x 3.14 = number to input for wheel size.
    This is a Sigma 1609 sts computer.

    I couldn't get a roll out good, so tried to measure tire, but couldn't eyeball it good, sometimes off by alot. So:

    I measured in mm from the floor to center of hub axle (easy to get it right on) x 2 (for overall wheel dimension) x 3.14 = my number.

  7. #7
    Senior Member
    Join Date
    Jun 2004
    Location
    Northern Nevada
    Posts
    3,728
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by JanMM View Post
    I always enter the actual roll-out measurement.
    +1. this is easy and it will give you an accurate reading. But since I quit being Too Serious, I swap my computer back and forth between a bike with 700x37 tires and one with 700x28s, and it's only off by a few yards per mile.

  8. #8
    Senior Member
    Join Date
    Mar 2012
    Posts
    59
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    shouldn't matter much,second number is width of tire.

  9. #9
    Senior Member Retro Grouch's Avatar
    Join Date
    Feb 2004
    Location
    St Peters, Missouri
    My Bikes
    Rans Enduro Sport, Hase Kettweisel Tandem, Merin Bear Valley beater bike
    Posts
    23,602
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by gabkr View Post
    shouldn't matter much,second number is width of tire.
    Yeah but.

    Try to visualize a bike tire as being circular in section. Wider tires also tend be a bit taller in section. The width of the rim will have an effect too.

    Even taking all of that into account, how much precision do you really need? Sometimes close enough is close enough.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •