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My kingdom for a spoke
a.k.a. a precautionary tale. I broke a spoke on the rear of the Gazelle a few days ago. I'm pretty sure I know why, in fact knew right away after I noticed it.
A year or so ago, when this wheel was on a different bike, the RD threw the chain off the FW to the inside between the FW and spokes. I figured at the time that it might have damaged the spokes, and in retrospect I'm surprised they lasted this long. Fortunately I don't weigh very much and prefer to spin instead of mash uphill. http://world.std.com/~muller/pics/BadSpokes.jpg It's time to replace all eight of them. It's just one more thing to think about if it ever happens to you. |
That could really, really hurt, Jim.
Scott (the guy above) knows of what he speaks, with a close call last summer. |
Chain suckers...
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One positive aspect of the dork disks we all remove (including me). I've seen this spoke damage on several bikes I have picked up.
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Sounds like you got good mileage after the initial injury.
A few years ago I had the odd misfortune of having a squirrel trying to jump through my front wheel at about 20 mph. Fortunately no crash, but ended up with a bent spoke and squirrel parts all over me and the bike. The Campy Proton wheel otherwise weathered the incident like a champ, stayed in true, and I finished the ride, albeit without any more drinks from my water bottle. The spoke is a weird straight pull spoke so while waiting for the new one to arrive I went for a ride a couple of days later and the spoke broke. Lesson learned. Even back then I had extra bikes and wheels and I still don't know why I just didn't ride another. |
wow. squirrel trying to jump through your spokes. that is a new one. bet your brakes didn't work so good after tha..
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Originally Posted by jetboy
(Post 18241040)
wow. squirrel trying to jump through your spokes. that is a new one. bet your brakes didn't work so good after tha..
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On looking at that photo I realized that the broken spoke was a leading spoke (as are all the outer spokes - it's something I rarely think about except when I'm building a wheel). So it carries no driving load from pedaling. That means it wouldn't matter whether I mash or spin up hills, and in any case the driving load is determined by the acceleration (combined inertial and against gravity) at any given time regardless of the gearing and spin rate which accomplishes it. This spoke broke from its share of the vertical load. (How that mechanism works is a different discussion.)
This leads me to wonder whether the trailing spokes should be strung head-in or head-out. I've been stringing them head-out because that's how I've seen it said and done. But since trailing spokes are more likely to break, putting them head-in makes them easier to replace because there is no problem feeding them through the other spokes. (I recall reading that Faliero Masi always wanted them head-in. Maybe that's why.) On the other hand, the difference in lateral offset between the inside and the outside of the flange means the outer spokes provide subtly more triangulation for wheel stability. Head-in would mean adding the driving load to that triangulation load. It would also mean that when one breaks the wheel's stability suffers slightly more. That's two good arguments for having the trailing spokes head-out. FWIW, earlier this week I replaced all eight outer DS spokes on that wheel with the same type (Wheelsmith DB14 which are 2.0mm x 1.7mm x 2.0mm) and rode it to work today. One section of the route has been ground up for repaving so the the ride was, shall we say, buzzy. The wheel seems to have held up nicely. |
^Weird squirrel incidents.
I've had a squirrel run under me while riding at a decent clip. He cleared my feet and both wheels as he ran between them - lucky bastid. I did brake ahead of time when I saw the squirrel bouncing between decisions on where to run to, that surely helped us both. I'm glad he didn't try to chew my spokes. |
You must be an engineer, Jim. I never ever think about leading or trailing spokes, especially when I'm building a wheel. Pulling spokes, pushing spokes, etc. I also use spoke protectors on all my bikes and a noggin protector on my head. Mistakes happen. But then I'm a bit of a contrarian, a fred if you will.
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Do the pulling spokes really suffer from more fatigue? Fatigue comes from the tightening-loosening cycle, right? Don't the two types of spokes suffer from the same cycle but in reverse order?
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[QUOTE=jimmuller;18241128]On looking at that photo I realized that the broken spoke was a leading spoke (as are all the outer spokes - it's something I rarely think about except when I'm building a wheel). So it carries no driving load from pedaling. That means it wouldn't matter whether I mash or spin up hills, and in any case the driving load is determined by the acceleration (combined inertial and against gravity) at any given time regardless of the gearing and spin rate which accomplishes it. This spoke broke from its share of the vertical load. (How that mechanism works is a different discussion.)
This leads me to wonder whether the trailing spokes should be strung head-in or head-out. I've been stringing them head-out because that's how I've seen it said and done. But since trailing spokes are more likely to break, putting them head-in makes them easier to replace because there is no problem feeding them through the other spokes. (I recall reading that Faliero Masi always wanted them head-in. Maybe that's why.) On the other hand, the difference in lateral offset between the inside and the outside of the flange means the outer spokes provide subtly more triangulation for wheel stability. Head-in would mean adding the driving load to that triangulation load. It would also mean that when one breaks the wheel's stability suffers slightly more. That's two good arguments for having the trailing spokes head-out.[QUOTE] My thoughts exactly when I saw the picture! :) |
Not
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Originally Posted by noglider
(Post 18241615)
Do the pulling spokes really suffer from more fatigue?
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Originally Posted by jimmuller
(Post 18241128)
On looking at that photo I realized that the broken spoke was a leading spoke (as are all the outer spokes - it's something I rarely think about except when I'm building a wheel). So it carries no driving load from pedaling.
This leads me to wonder whether the trailing spokes should be strung head-in or head-out. I've been stringing them head-out because that's how I've seen it said and done. But since trailing spokes are more likely to break, putting them head-in makes them easier to replace because there is no problem feeding them through the other spokes. (I recall reading that Faliero Masi always wanted them head-in. Maybe that's why.) On the other hand, the difference in lateral offset between the inside and the outside of the flange means the outer spokes provide subtly more triangulation for wheel stability. Head-in would mean adding the driving load to that triangulation load. It would also mean that when one breaks the wheel's stability suffers slightly more. That's two good arguments for having the trailing spokes head-out. Disc brakes change the equation. |
Originally Posted by noglider
(Post 18241118)
I had a squirrel jump into my rear wheel and spin around and go thump-thump-thump against my frame before falling out. I was on my fixed gear, so it was really scary. He lay on the ground, and I thought he was dead, but then he got up after a minute and walked away. No blood.
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Originally Posted by Spaghetti Legs
(Post 18242018)
Yeah this one went around 3-4 times before getting spit out. I'm lucky it didn't get caught in the fork and throw me over. I went back and looked and he looked like a twisted, wrung out dishrag.
We have black mutant squirrels in the Bronx where I work and nearby in upper Manhattan. They look nice. |
This happened 7 or 8 years ago, but I'm still very jumpy around squirrels in the road. Squirrelly, you might say.
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Not on topic but I guess I'll throw in my squirrel story too. I had one run right into the side of my front wheel's rim when I was cruising along pretty fast a few years ago. He bounced off and ran the other way, but it scared me pretty good. I'm always on the lookout now for squirrels when I ride, lol. Of course you cant really predict/prevent things like that.
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re: post 9 ... here's sheldon on the subject:
Originally Posted by sheldon brown
Which Side of the Flange?
Derailer rear wheels should be laced with the trailing spokes running up along the inside of the flange. There are three reasons for this: 1. The spokes are bent around each other at the outermost crossing. Under drive torque, especially in low gear, the trailing spokes straighten out and the leading spokes bend even more. If the wheel is laced with the trailing spokes on the outside of the flange, the crossing gets pulled outward toward the derailer cage, and in some cases will actually hit against the derailer under load. 2. If the chain should overshoot the inner sprocket due to the derailer being mis-adjusted or bent, it is likely to get more seriously jammed between the spokes and the freewheel if the spokes slant so as to wedge the chain inward under load. 3. If the chain should overshoot the inner sprocket, it may damage and weaken the spokes it rubs against. Since the trailing spokes are more highly stressed than the leading spokes, it is better to protect them from this type of damage by keeping them inboard. It really doesn't matter which way you go on the left side, but if you have all the trailing spokes face inward it makes lacing the wheel a bit easier. * In the case of fixed-gear or coaster-brake wheels, it is better to lace the opposite way, because a derailed chain is more likely to get jammed by backpedaling in these cases. Note: This is not an important issue! There is a sizable minority of good wheelbuilders who prefer to go the other way around, and good wheels can be built either way. |
I guess it happens a lot;
Topic: A Noble Squirrel | MPLS Bike Love I once saw a squirrel fall about 75 feet out of a tree onto a sidewalk. We all stopped and walked over to it. After a minute it jumped up, flipped over, looked at us all and ran full tilt back up the tree. Tough lil buggars. |
A few months ago on my commute to work a squirrel ran under my bike between the front and rear wheels. Lucky little devil.
Of course it has little to do with those broken spokes other than that it might have caused a few. |
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