Advertise on Bikeforums.net



User Tag List

Results 1 to 5 of 5
  1. #1
    Senior Member Allen's Avatar
    Join Date
    Sep 2005
    Posts
    4,757
    Mentioned
    6 Post(s)
    Tagged
    0 Thread(s)

    Bottom Bracket Height

    I've done my reading and am ready to loft my first set of plans, a 29er project. Before I put pencil to paper, and since it's my starting point, I want to exhaust all my resources; how do y'all determine your bottom bracket height? The radius of my wheel with the tire is 14 3/4 inches.

    Many thanks,

    --A
    Last edited by Allen; 06-13-07 at 11:49 PM.

  2. #2
    Senior Member
    Join Date
    Feb 2001
    Location
    England
    Posts
    12,421
    Mentioned
    3 Post(s)
    Tagged
    0 Thread(s)
    What size crank are you using?
    This determines how much clearance you need to the ground and the front wheel.
    See http://www.zinncycles.com/bikes.aspx

  3. #3
    Senior Member Allen's Avatar
    Join Date
    Sep 2005
    Posts
    4,757
    Mentioned
    6 Post(s)
    Tagged
    0 Thread(s)
    180mm arms. Thanks for the link.
    Last edited by Allen; 06-14-07 at 09:17 PM.

  4. #4
    Banned
    Join Date
    Aug 2005
    Posts
    5,117
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Honestly by looking at other designs I have experience with. I also look at BB height as a design issue. I look at similar bikes made by famous builders or companies and get a lot of data points. I figure out whether I was comfortable riding these bikes, I am overall quite tall but marginally short legged, so BB height is an issue for standover. I also look at technical factors like clearance and how the ride feel is affected. Then I just guess.

    I did once try to measure the me on the bike tire deflected height of my tires and was surprised how little change there was, even given my weight.

  5. #5
    Senior Member
    Join Date
    Jan 2005
    Posts
    131
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    I was wondering the same thing about 29ers, so I looked around at what the best 29er custom builders were dong. I found that most often they were doing 6-8cm of BB drop. I just finished one with a 7cm drop and 175mm cranks, the customer has taken on the roughest trails we have and had no pedal strike issues at all.

Posting Permissions

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