Advertise on Bikeforums.net



User Tag List

Results 1 to 6 of 6
  1. #1
    Senior Member
    Join Date
    Apr 2007
    Location
    Central Florida
    My Bikes
    Raleigh Passage 3.5
    Posts
    59
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)

    Too little tension?

    I broke a spoke on the rear of my Raliegh hybrid at about 800 miles. I don't know what caused it. I didn't hit anything, or run in a pot hole, but I am a solid 300lbs. The LBS replaced the spoke, and did a really bad job of truing(way over 1/2" lateral) it wasn't much better than when the spoke was broken. I straightened the wheel by loosening the high spots 1/4 turn, and tightening the low spots, to get it passably straight without changing the overall tension much. My question is: the rear wheel seems to have considerably less spoke tension than the front wheel. Could this be why the spoke failed in the first place?

    All opinions are greatly appreciated,

    John
    Slow but steady

  2. #2
    Senior Member
    Join Date
    Feb 2005
    Location
    Oklahoma
    My Bikes
    Trek 510, Trek 5500, Colnago C-50
    Posts
    8,851
    Mentioned
    2 Post(s)
    Tagged
    0 Thread(s)
    With geared bikes the rear driveside (right) spokes normally have the highest tension on the bike and the rear non-driveside spokes have the lowest tension. The front wheel spokes should be equal on both sides with tension a bit less that the driveside rear. The tension differential on the rear wheel is due to the asymetrical hub flanges to make room for the cassette or freewheel cogs. With conventional 8, 9, or 10-speed wheels the non-driveside spokes will have about 65% as much tension as the driveside spokes. This is necessary to center the rim.
    Loose spokes break due to excessive flexure, usually in the "J" bend at the hub.

    Al

  3. #3
    Senior Member
    Join Date
    Apr 2007
    Location
    Central Florida
    My Bikes
    Raleigh Passage 3.5
    Posts
    59
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Loose spokes break due to excessive flexure, usually in the "J" bend at the hub.

    That is what I suspected, that is where the break was.

    Thanks for the quick reply
    Slow but steady

  4. #4
    Soma Lover
    Join Date
    Dec 2004
    Location
    Logan, UT
    My Bikes
    one bike for every day of the week
    Posts
    765
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by Rumblejohn View Post
    Could this be why the spoke failed in the first place?
    Yes, yes, and yes. This is the usual failure mode. I'm hard on stuff but I've never had a wheel stay true with less than 500-600 Newtons on the non-drive side.

    You're LBS wheel man definitely sounds a little less than competent. Even when I'm being lazy I get things to within 0.05" laterally.

    Find someplace with a tensiometer. Assuming it's a basic 32-spoke wheel, get the wheel dished right and true with the drive side at 1200 Newtons. That will leave the non-drive side at 700-800 Newtons.

    Bri

  5. #5
    Senior Member Tapeworm21's Avatar
    Join Date
    Jan 2007
    Location
    Berkeley
    My Bikes
    2010 Tarmac SL, 2007 Specialized Langster, 2013 Fairdale Weekender, 2013 Fairdale Coaster, 1986 Bridgestone 600, 1972 Schwinn Heavy Duty, 2014 Surley Long Haul Trucker
    Posts
    2,256
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by cachehiker View Post
    Yes, yes, and yes. This is the usual failure mode. I'm hard on stuff but I've never had a wheel stay true with less than 500-600 Newtons on the non-drive side.

    You're LBS wheel man definitely sounds a little less than competent. Even when I'm being lazy I get things to within 0.05" laterally.

    Find someplace with a tensiometer. Assuming it's a basic 32-spoke wheel, get the wheel dished right and true with the drive side at 1200 Newtons. That will leave the non-drive side at 700-800 Newtons.

    Bri
    Broken spoke normally means the wheel is toast, unless something ran into your wheel. It's not a lazy wheel true, it's him not telling you what's wrong with it.

    Get it fixed, but after the 3rd broken spoke, lay the wheel to rest. At 300 pounds, I would suggest a 36h rim.

  6. #6
    Air
    Air is offline
    Destroyer of Wheels Air's Avatar
    Join Date
    May 2006
    Location
    Creating some FA-Qs
    My Bikes
    Nishiki Sport, Downtube IXNS, 1950's MMB3 Russian Folding Bike, MTB
    Posts
    3,564
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    That sounds familiar, unfortunately the rim is probably shot.

Posting Permissions

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