J-bend vs straight-pull spokes

[mvrider]

I'm no wheel builder, but I found this video to be very clear:

http://velonews.competitor.com/2015/03/video/ask-a-mechanic-straight-pull-vs-j-bend-spokes_364520

[oldpotatoe]

I'm no wheel builder, but I found this video to be very clear:

http://velonews.competitor.com/2015/03/video/ask-a-mechanic-straight-pull-vs-j-bend-spokes_364520

In spite of 'assuming' some video from a 'big bike shop' would be crappy, I found their videos to be quite good. This one about straight pull spokes being very good and accurate.

[Mark McM]

I agree with the video's comment about the durability of straight pull spokes often being no better than J-bend spokes.

There are three points where most spoke failures occur - the head, the elbow, and the threads. And like a chain, a spoke is only as strong as its weakest link.

With elbow spokes, proper fitting and bedding of spokes to the flange can reduce stress concentrations at the elbow, reducing the chances of breakage there. On the other hand, while a straight pull spoke has no elbow, it concentrates all the load on another natural stress concentration feature, the transition at the head, sometimes making this the weakest link.

In my experience, with proper spoke head/elbow/flange fitting and bedding, the most likely failure point moves to the threads. This should be no surprise, as the sharp v-grooves for the threading create natural stress concentrations.

[peanutgallery]

I'm with you, they are generally pretty practical. Didn't pay attention to them for a while, my loss

In spite of 'assuming' some video from a 'big bike shop' would be crappy, I found their videos to be quite good. This one about straight pull spokes being very good and accurate.

[SpokeValley]

I'm no wheel builder, but I found this video to be very clear:

http://velonews.competitor.com/2015/03/video/ask-a-mechanic-straight-pull-vs-j-bend-spokes_364520

Thanks for sharing this.

I'm not a fan of SP spokes either but I have several friends who think they are mo' bettah. :)

[Cicli]

Arts does a good job. I like their stuff even if its review.

[fogrider]

they do a good job, but is arts now velonews' de facto tech video provider? I think I also saw a link to GCN...maybe Lennard Zinn has to start making videos for the site!

but straight pull is kind of a pain...I blew a straight pull spoke on a campy wheel last week. 24 spokes so I had do the best I could on the road to get back with minimal wheel rub on the chainstay. I had to tighten some other spokes as best I could and ended up rounding some nipples. The wheel is from some 15 or 20 years ago that used spokes that flared out into a flat triangle to engage the hub. I have never seen it before and didn't have a replacement. I had to use a j bend spoke...seems to work fine.

[Mark McM]

but straight pull is kind of a pain...I blew a straight pull spoke on a campy wheel last week.

Out of curiosity, where did the spoke break? At the head, or the threads, or elsewhere?

[fogrider]

Out of curiosity, where did the spoke break? At the head, or the threads, or elsewhere?

the head snapped off and it was on the drive side. all the spokes were tension to 25 pounds on the drive side and about 14 to 16 on the non drive side. the rim is a square section with eyelets. I ended up having to replace 6 nipples since some were rounding. its a strange campy hub with a 26.0 lockring. it's my understanding they only made it for a couple years in the late 90s. works for a training wheel.

[Jesper64]

they do a good job, but is arts now velonews' de facto tech video provider? I think I also saw a link to GCN...maybe Lennard Zinn has to start making videos for the site!



I like the Arts Cyclery video's, short and to the point. Whereas the GCN ones are very long for very little information. Don't think I've seen one <5min...

[Mark McM]

the head snapped off and it was on the drive side. all the spokes were tension to 25 pounds on the drive side and about 14 to 16 on the non drive side. the rim is a square section with eyelets. I ended up having to replace 6 nipples since some were rounding. its a strange campy hub with a 26.0 lockring. it's my understanding they only made it for a couple years in the late 90s. works for a training wheel.

Interesting - so the weak point of that particular straight pull spoke was the head.

I'm pretty sure that the spoke tensions were much higher than 14 to 25 pounds - the wheel wouldn't hold together with tensions that low. More typical tensions are about 220 lb (100 kgf) or more. Maybe you are referring to the numbers read from a tension meter scale? (tension meters usually require a calibration chart to convert readings to a tension force value.)

The first version of 9/10spd hubs (late '9s), which had a steel axle, used 26 mm thread lockrings. When hubs with oversized aluminum axles appeared, the thread size was increased to 27 mm.

[Bostic]

I like the Art's videos and have found them helpful. The GCN are more humorous than helpful but a pleasant few minute distraction while on break at work.

[fogrider]

Interesting - so the weak point of that particular straight pull spoke was the head.

I'm pretty sure that the spoke tensions were much higher than 14 to 25 pounds - the wheel wouldn't hold together with tensions that low. More typical tensions are about 220 lb (100 kgf) or more. Maybe you are referring to the numbers read from a tension meter scale? (tension meters usually require a calibration chart to convert readings to a tension force value.)
.

yeah I'm just putting the gauge on each spoke...I don't pretend to know how much tension is actually in the wheel but that's what it takes to keep everything straight and running true. but I realized that the j bend spoke is further out than the others and if I go into the last gear, the rd taps it...looks like I'm going to have to run this as a 9 speed!

[Mark McM]

but I realized that the j bend spoke is further out than the others and if I go into the last gear, the rd taps it...looks like I'm going to have to run this as a 9 speed!

What size cassette are you using? The spokes angle inward from the hub flange to the rim, making more derailleur clearance the further it is from the flange. If you use a cassette with a larger bottom sprocket, it will move the derailleur cage further from the flange, and you should get more spoke clearance.

[fogrider]

Correct, but the rd alignment is where it is. I'm running a 27 cog now, not sure if NY rear can handle much more.

[Mark McM]

Even Campagnolo short cage derailleurs can handle 30 tooth sprockets.