RoadBikeReview.com's Forum Archives - General


Archive Home >> General(1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 )


HELP!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!(broken spoke)(8 posts)

<b>HELP!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!</b>(broken spoke)GTRider
Jun 12, 2001 7:47 PM
I need to know what is the most common reason for sopke brakeage?Which is the most common side(Drive or non-drive side)I broke a 14 gauge straight spoke just riding home,spinning up a slight grade.One more thing i weight 235 and the wheelset is not even 3 weeks old yet.The are oem cxp21 with ritchy sport hubs(32 hole) 14G ss spokes and brass nipples.Thanks for any and all help
GTRider
re: &lt;b&gt;HELP!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!&lt;/b&gt;(broken spoke)In the Campy Camp
Jun 13, 2001 7:08 AM
Drive side - under the most tension due to dish of the wheel, and taking the greatest torsional strain.

No reason why that set-up should give you problems - think you were just unlucky, mebbe a bad spoke.
I think Campy is 180 degrees off.Spoke Wrench
Jun 13, 2001 7:44 AM
The advent of 8 and 9 speed cassettes has changed the patterns of spokes breaking. The most common spoke to break today, BY FAR, is one which radiates from the top of the hub toard the front on the non-drive side. The issue isn't spoke tension, but rather LACK of spoke tension which causes the spokes to fatigue at the bend.

Fixes include having the wheel retensioned by a wheel builder who understands the problem, using eyeletted rims which reduce nipple to rim friction and allow more tension to be used, and the novel approach, radial lacing the non-drive side of the rear wheel.
Just experienceIn the Campy Camp
Jun 13, 2001 9:35 AM
never had a non-drive go, but broke a bunch of drivers - go figure. Not sure I get why a spoke with less tension on is more likely to break though - it has a lot further to move before it gets to a strain tension?
Just experienceSpoke Wrench
Jun 13, 2001 9:57 AM
It's because everytime a spoke with inadequate tension is at the bottom of the wheel it goes slack. Every time it's at the top of the wheel it gets tensioned again. The result is the elbow bends repeatedly until it fatigues and fails.

Last summer I did tech support for a week long ride with 350 riders. After flat tires, broken spokes were the most common problem. Sometimes my memory is faulty, but I think almost every broken spoke was a rear non-drive spoke. Trashed bottom brackets were the next most common repair.
Fair enough, but..The Campy Camp
Jun 13, 2001 10:09 AM
Why not build bikes with a wider spread at the rear, so that dishing could be sufficient to facilitate adequate tightening of both sides of the wheel?

The is, I guess, the principle governing the building of 6mm lateral off-set (Sigma?) rear triangles to enable more equal dishing?
Exactly... also:Jofa
Jun 13, 2001 1:00 PM
This diagnosis is precisely right, in theory and in my experience. I'm sure that the cause is one thing only: the wheel has not been properly stress-relieved. A good wheelbuilder should know how to stress-relieve a wheel in a controlled manner, as described by dear old Jobst Brandt more or less anywhere you care to look. A rebuild with swaged spokes at the next convenient oppurtunity will make these breakages rarer also, as I think I've suggested to GTrider before.
ConfusionJofa
Jun 13, 2001 1:03 PM
The way that this board displays is odd; the diagnosis to which I was referring is Spokewrench's initial one.