Advertise on Bikeforums.net



User Tag List

Results 1 to 14 of 14
  1. #1
    Junior Member
    Join Date
    Apr 2006
    Location
    Sammamish, WA
    My Bikes
    '73 Frejus TdF
    Posts
    22
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)

    wheel building question

    I recently built a new rear wheel for my road bike. I used the following components -- Speedcific sealed rear hub (Campy 9 speed cassette compatible), Velocity Aerohead 36 hole rim. and 2.0/1.7 mm double butted Wheelsmith steeel spokes. I have a truing stand, dishing tool and a Park tensionmeter. I have read Brandt's book and Sheldon Brown's article on wheelbuilding.

    When I finished building the wheel, I thought the tension measurements looked pretty good. On the right hand side the average tension was 133 kg, with all measurements within +/- 15%. On the left hand side the average tension was 82 kg with a +/- 20% tolerance.

    I put the wheel on my bicycle and went for a single 20 mile ride. There was nothing special about the ride, but afterwards the wheel was badly out of true. I measured the tension as soon as I removed the rear wheel. The spoke tension on the right hand side seemed to have decreased fairly uniformly by about 15%. The spoke tension on the left hand also seemed to decrease by about 15%, but there were three spokes that lost a lot of tension. I adjusted the tension and re-trued the wheel fairly easily.

    My question is why did the tension in these spokes change so much in one ride? My guess is that I did not adequately stress relieve the spokes (although, I tried) during the build process. I don't have a lot of experience building wheels so I would appreciate any comments.

    Thanks,
    David

    '73 Frejus TdF
    '06 Rodriguez Sport (Veloce)

  2. #2
    cyclist/gearhead/cycli... moxfyre's Avatar
    Join Date
    Oct 2004
    Location
    DC / Maryland suburbs
    My Bikes
    Homebuilt tourer/commuter, modified-beyond-recognition 1990 Trek 1100, reasonably stock 2002-ish Gary Fisher Hoo Koo E Koo
    Posts
    4,172
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Yeah, sounds like not enough stress relief, definitely. The main thing that stress relieving does is it forces the elbow of the spoke to fit tightly to the shape of the hub flange.

    You have to put *a lot* of force on brand new spokes to stress-relieve them! Grab neighboring spokes and pull them towards each other with pretty much all your might. Do that all the way around the wheel. Do it again After that go back and touch up the truing. I've even seen people who WALK on top of their newly-built wheels to stress-relieve them.
    My bikes | Linux and Python stuff | Photo gallery

    Sheldon Brown, I miss you. Thanks for the advice, ideas, humor, and infectious enthusiasm for everything bikes...

  3. #3
    Junior Member
    Join Date
    Jun 2006
    Location
    Memphis, TN
    My Bikes
    Serotta Atlanta, Specialized Hardrock, Peugeot fixed-gear
    Posts
    10
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Another great way to pre-stress the wheel is to use the palm of your hand and apply as much pressure as possible, pushing in on both the right and left sides of the wheel, moving through each spoke intersection until you've done all of the intersections 4 or 5 times. You can add tremendous lateral pressure to the wheel this way without having to step on it.

  4. #4
    Senior Member
    Join Date
    Sep 2001
    Location
    Montreal
    My Bikes
    Peugeot Hybrid, Minelli Hybrid
    Posts
    6,521
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Did you measure the tension after the ride with air pressure in the tire, because that reduces spoke tension.

  5. #5
    la vache fantôme phantomcow2's Avatar
    Join Date
    Aug 2004
    Location
    NH
    Posts
    6,266
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    I never found grabbing pairs of spokes to be very efficient. I put the hub axle against the floor, and push on the edges of the rims. Work the wheel around until you get it all. Do it with both sides, you will eventually stop hearing that pop. Just keep truing it after this.

  6. #6
    cyclist/gearhead/cycli... moxfyre's Avatar
    Join Date
    Oct 2004
    Location
    DC / Maryland suburbs
    My Bikes
    Homebuilt tourer/commuter, modified-beyond-recognition 1990 Trek 1100, reasonably stock 2002-ish Gary Fisher Hoo Koo E Koo
    Posts
    4,172
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by AndrewP
    Did you measure the tension after the ride with air pressure in the tire, because that reduces spoke tension.
    How can air pressure affect spoke tension???
    My bikes | Linux and Python stuff | Photo gallery

    Sheldon Brown, I miss you. Thanks for the advice, ideas, humor, and infectious enthusiasm for everything bikes...

  7. #7
    la vache fantôme phantomcow2's Avatar
    Join Date
    Aug 2004
    Location
    NH
    Posts
    6,266
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by moxfyre
    How can air pressure affect spoke tension???
    I had a hard time believing that one too...
    The only thing I could think of to justify this would be the idea that the tire does not really flex outward when you pump up that tube. So what else must? The rim must flex inward.
    A metal rim is stronger tahn the tire, it's not going to flex anywhere .

  8. #8
    cyclist/gearhead/cycli... moxfyre's Avatar
    Join Date
    Oct 2004
    Location
    DC / Maryland suburbs
    My Bikes
    Homebuilt tourer/commuter, modified-beyond-recognition 1990 Trek 1100, reasonably stock 2002-ish Gary Fisher Hoo Koo E Koo
    Posts
    4,172
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by phantomcow2
    I had a hard time believing that one too...
    The only thing I could think of to justify this would be the idea that the tire does not really flex outward when you pump up that tube. So what else must? The rim must flex inward.
    A metal rim is stronger tahn the tire, it's not going to flex anywhere .
    Agreed. It's ESPECIALLY not going to flex anywhere when pressure is evenly applied all around its circumference. In the same way, an eggshell will not break if you squeeze it very hard but very evenly.
    My bikes | Linux and Python stuff | Photo gallery

    Sheldon Brown, I miss you. Thanks for the advice, ideas, humor, and infectious enthusiasm for everything bikes...

  9. #9
    Senior Member
    Join Date
    Feb 2005
    Location
    Oklahoma
    My Bikes
    Trek 5500, Colnago C-50
    Posts
    9,201
    Mentioned
    2 Post(s)
    Tagged
    0 Thread(s)
    Andrew is correct. The spoke tension can decrease after tire inflation, but probably not 15%. I've experimented with this a couple of times and definitely had decreases of 5% to 7% prior to riding the wheel. This was with DT RR 1.1 rims and Revolution spokes.
    I would also suspect not enough stress relieving.

    Al

  10. #10
    cyclist/gearhead/cycli... moxfyre's Avatar
    Join Date
    Oct 2004
    Location
    DC / Maryland suburbs
    My Bikes
    Homebuilt tourer/commuter, modified-beyond-recognition 1990 Trek 1100, reasonably stock 2002-ish Gary Fisher Hoo Koo E Koo
    Posts
    4,172
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by Al1943
    Andrew is correct. The spoke tension can decrease after tire inflation, but probably not 15%. I've experimented with this a couple of times and definitely had decreases of 5% to 7% prior to riding the wheel. This was with DT RR 1.1 rims and Revolution spokes.
    I would also suspect not enough stress relieving.

    Al
    Surprising, but good to know! I've not had this problem, so I've never tested spoke tension after inflating the tire. Any idea how this actually works? I still can't figure out how it would happen.
    My bikes | Linux and Python stuff | Photo gallery

    Sheldon Brown, I miss you. Thanks for the advice, ideas, humor, and infectious enthusiasm for everything bikes...

  11. #11
    Senior Member
    Join Date
    Feb 2005
    Location
    Oklahoma
    My Bikes
    Trek 5500, Colnago C-50
    Posts
    9,201
    Mentioned
    2 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by moxfyre
    Surprising, but good to know! I've not had this problem, so I've never tested spoke tension after inflating the tire. Any idea how this actually works? I still can't figure out how it would happen.
    I was surprised too. I assume that with really light weight rims and spokes the wheel can be compressed that much. I noticed that the wheel's dish changed slightly too, by a fraction of a mm. I supose that's due to the asymetrical tension.

    Al

  12. #12
    lurking nightrider LittleGinseng's Avatar
    Join Date
    Apr 2004
    Location
    NE Florida
    My Bikes
    1987 Centurion Dave Scott Ironman Expert, 1987 Maruishi Professional, mid-80's Titan Exklusiv, 1981 Panasonic Sport, 1985 Club Fuji
    Posts
    298
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by moxfyre
    Surprising, but good to know! I've not had this problem, so I've never tested spoke tension after inflating the tire. Any idea how this actually works? I still can't figure out how it would happen.
    A slight loss of spoke tension is caused by radial compression imparted onto the rim. It's a little more pronounced on a clincher rim due to the fact that the crochet hook acts as a fulcrum. As the tire's tube is filled with air, the increasing air pressure, with the resulting deformation of the tube and tire that follows, becomes the applied force as the hook bead on the tire becomes the lever. The crochet hook on the rim gives a solid support for the increasing pressure towards the rim. Simple(*) mechanics at work.

    *[edit] Perhaps not quite so simple. There are many dynamics at work here. Should we start another thread related to this issue? We can call it 'Brownsfan's Wheel Thread Continuance'
    Last edited by LittleGinseng; 08-21-06 at 03:41 AM.
    "If there hadn't been women we'd still be squatting in a cave eating raw meat, because we made civilization in order to impress our girl friends. And they tolerated it and let us go ahead and play with our toys."Orson Wells

  13. #13
    Senior Member
    Join Date
    Oct 2005
    Posts
    1,735
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by Al1943
    Andrew is correct. The spoke tension can decrease after tire inflation, but probably not 15%. I've experimented with this a couple of times and definitely had decreases of 5% to 7% prior to riding the wheel. This was with DT RR 1.1 rims and Revolution spokes.
    I would also suspect not enough stress relieving.

    Al
    Check out this thread. There were some practical measurements done. I thought there was a thread that had a website of someone who did a more thorough study of the affect to spoke tension from tire inflation.

  14. #14
    lurking nightrider LittleGinseng's Avatar
    Join Date
    Apr 2004
    Location
    NE Florida
    My Bikes
    1987 Centurion Dave Scott Ironman Expert, 1987 Maruishi Professional, mid-80's Titan Exklusiv, 1981 Panasonic Sport, 1985 Club Fuji
    Posts
    298
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by brownsfan
    My question is why did the tension in these spokes change so much in one ride? My guess is that I did not adequately stress relieve the spokes (although, I tried) during the build process. I don't have a lot of experience building wheels so I would appreciate any comments.

    Thanks,
    The responses to this question are all spot on. Stress relieving in one method or another is required during the build process. If you research the different ways to stress relieve a wheel,and find a technique that works for you personally, I'll bet your next attempt at building a wheel will be a success.
    "If there hadn't been women we'd still be squatting in a cave eating raw meat, because we made civilization in order to impress our girl friends. And they tolerated it and let us go ahead and play with our toys."Orson Wells

Posting Permissions

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