Bicycle Mechanics - Drive side lacing
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At the risk of igniting debate I wanted to offer an observation. I act as the "wrench" for an annual WI bike trip and see broken spokes every year (22 yrs and counting). 80% are drive side spokes broken as a result of chain damage between cassette cluster and spokes. Almost always they are on wheels laced with the pattern shown in the second photo (black freehub) --presumably because the chain wedges in very tightly. I rarely see the same thing on spokes laced as shown in the first photo (silver freewheel hub) --where the outside spokes don't tend to wedge the chain deeper into greater damage. For this reason I always lace as shown in first photo. It seems like most of the photos I see here choose the opposite from me. I'm aware of the argument suggesting the outside spokes can bow out and intercept the derailer but have only seen one case of that --and those spokes had been allowed to get way too loose. I have seen dozens of cases of the chain destruction however.
oops, ignore those IGH photos. They are meant for another post.
02-19-12, 08:45 AM
FWIW, when I build wheels for derailleur bikes, I prefer to put the pulling spokes on the inside as in your first picture.
I tend to put the trailing spokes on the outside. I thought it was better that way, because drive forces would 'tuck' the spokes inward. I guess there's more than that to the story.
(Forgot to point out that the second photo comes from a wheel recently given to me for repair for this exact problem. Two spokes were broken but the whole group was so badly mangled that I replaced all 8.)
02-19-12, 09:35 AM
The much-maligned spoke protector a.k.a. "dork disc" might have prevented some or all of the damage, for a weight penalty of a few grams.
02-19-12, 09:44 AM
that is how i do it
Your photos and data are interesting, but I'm not sure of your reasoning unless you somehow got the captions reversed.
When lacing pulling spoke out (left photo) the spokes would tend to lift the chain away from the hub when the wheel turns. With the outer spokes going to the right, they'd slip over a chain and push it down toward the hub jamming it tighter.
Mr. Brandt advocates lacing as per your left photo, and this is the more common pattern in the USA. Mt. Brandt's thinking is that unter high torque, like when climbing in low gear, the transfer in tension between pulling and forward spokes moves the point of cross, and his way moves it in rather than out.
I don't disagree with Mr. Brandt, but feel the amount of movement isn't enough to be decisive, and prefer to weigh the "ramping or trapping of the chain higher and lace pulling out, as do most European builders.
This brings up why the post is so interesting. It seems to say the opposite of what I predict is happening. I'm not sure if the OP has his data or photos or analysis reversed, and ask that he confirm or correct. If the data is correct and spoke nicking is more on pulling outside wheels, it could also because these are more common, though I have no idea of the ratio between the two patterns in use.
I'm certainly not immune to being confused. My assumption had been that the left photo is not what Brandt suggests. But, reviewing the process in his book "The Bicycle Wheel", I think you're right about that point. He doesn't appear to discuss it there, but his process on 1st, 2nd, 3rd, and 4th sets do seem to create a wheel like the left photo (my own process was ingrained before acquiring his book so I only read it lightly looking for additional info).
However, the chain damage, in my observations, apparently results from the chain slipping inside while being pedaled. The pedaler experiences a sudden slip and the chain gets wedged deeper by the angle of the outside spokes as they continue to try to pedal their way out of the problem. I'm reluctant to take a bike out and force it to happen and observe, but maybe that's the best way to learn details. Bottom line I'm just observing that most of my chain-carved broken spokes seem to occur on wheels laced as in the right photo.
I'm certainly not immune to being confused. My assumption had been that the left photo is not what Brandt suggests. But, reviewing the process in his book "The Bicycle Wheel", ...
... Bottom line I'm just observing that most of my chain-carved broken spokes seem to occur on wheels laced as in the right photo.
Thanks for confirming. As i said, this is contrary to what I expect, and why I build opposite to how Mr. B. does. It's an intriguing data set. To make it useful would require the fleet mix of Mr. B and Euro so the data can be adjusted accordingly. If for example 90% of OEM wheels are pulling outside, then your data is simply reflecting that.
It's an interesting point and warrants further thought.
And it IS a good question about which lacing is more common.
If for example 90% of OEM wheels are pulling outside, then your data is simply reflecting that.
It's an interesting point and warrants further thought.
I'm thinking this is probably the case. I'm reacting to the pattern because it's not the way I build, but as I look at the few wheels I have laying around not built by me, most of them are like the right side pic. Several no-name wheels and a ritchie and an alex are laced as in right photo. My 3 bontrager are all laced as the left photo, however. (I think I'm beating this topic to death. I'm done.)
When I reach wheel building, I cover the pulling/out vs pulling/in question, by explaining Mr. B's logic, and my own. then I summarize that whatever difference it makes is probably small enough that it doesn't matter anyway. At which time I pass out quarters and tell anyone still unsure to trust it to fate. (if the quarter lands on it's edge, build radial)
02-19-12, 01:45 PM
Lacing pattern aside, if you aren't confident in your RD adjustment throw a spoke protector between the cassette and spokes. Forever made fun of but not a bad idea especially on a MTB that will get its RD bonked sooner or later.
Though I don't use one on any of my bikes, I list spoke protectors among the many "can't hurt, but might help" items.
If you're attuned to your bike, and attentive to any change in RD shifting, you'll probably never need a spoke protector as the change in trim and shift response will flag an bent hanger.
However many aren't, as evidenced by the number of times RD's or chains get snagged by spokes. So if unsure of your maintenance habits a spoke protector could save you serious grief and expense.
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