Broken spokes -> NEAR DEATH EXPERIENCE!!!

[max]

Thanks for posting Alprider, that's very clear.

How's the new rx100 mk6 working for you?

[alprider]

i have the rx100 mk4.....this littel thing is something lightweight I always have to be careful so that I keep her calm.....and not shaky shake shake...smilee

this pics now i made with the nex5n look my avatar.

[pdedse]

Well, I went out to the garage and pinged all spokes on the '07 klr650 w/44k miles front and back...very musical sounding, although one spoke looked very slightly bent. Then the '17ex CB1100 w/5k miles...again, pure música, no dull sounding thuds.

Since I bought the klr in '08, I've read a bit on spoke maintenance, but still haven't done anything with them. By pulling on them, there doesn't appear to be any loose ones, so I leave it.

[max]

i have the rx100 mk4.....this littel thing is something lightweight I always have to be careful so that I keep her calm.....and not shaky shake shake...smilee

this pics now i made with the nex5n look my avatar.

Thanks, just now when i was laughing at your funny reply i thought;
isn't it neat that two people who have never met and are at the opposite end of the world can have a laugh, amuse and help each other over 2 copper phone wires? spectacular!

[pekingduck]

Well, I went out to the garage and pinged all spokes on the '07 klr650 w/44k miles front and back...very musical sounding, although one spoke looked very slightly bent. Then the '17ex CB1100 w/5k miles...again, pure música, no dull sounding thuds.

Since I bought the klr in '08, I've read a bit on spoke maintenance, but still haven't done anything with them. By pulling on them, there doesn't appear to be any loose ones, so I leave it.

And..are...the...spokes...stainless?

made any pics this afternoon

modell 2017:
https://onedrive.live.com/?authkey=%21AC...AD0BA4E55E

modell 2014

https://onedrive.live.com/?authkey=%21AI...AD0BA4E55E

better quality for zoom if you download it...

Yes, thanks Alprider for the pictures! I looked at them and saw several things of note.

Honda uses 4 different rear wheel spokes for early hubs - 2 insides of different length, and 2 "outside" of different lengths. Same on the 2017, but different length and material. (Triumph does the same on the Bonnies).

And as Max in NZ pointed out, on the original rear hub, acceleration pulls on the "outer" spoke, the one with the longer neck before the bend, which causes that spoke to flex as it tries to straighten out.

This seems like bad practice. The longer neck is needed to clear the other spoke as they cross by each other, so they don't force each other to bend and distort.

The holes drilled in the hubs for the inner and outer spokes are not not in the same diameter circle, so they clear each other without the outer spokes having the extra neck length. On the 2017 hub, drive side inner pulls, on the brake side, outer pulls (and that's normal for most spoked wheels). But now, both inner and outer have the same strength, no flexing, so no real difference.

The last thing of note is that on the original wheels (see the last picture of the front wheel), there are some spoke threads visible, which makes me wonder if they are only partially engaging the spoke nipple threads. The spoke nipple's internal threads start about 4-5 mm down from the top. That stepped section of the spokes should be hidden by the recess in the spoke nipples.

[attachment=9692]

[pdedse]

Not looking to rush our right away to purchase spoke wrench, but how to determine spoke size for the 17ex? Looked in service manuel and online, but I can't find it.

[pekingduck]

Not looking to rush our right away to purchase spoke wrench, but how to determine spoke size for the 17ex? Looked in service manuel and online, but I can't find it.

Depends. Are they steel or stainless?

[jtopiso_imp]

That's a shame that happened.

Spoke breakage is not common but not rare either. The early Bonnevilles 2000-2003 had the issue so often the forums were asking for a recall. It happened to my 2003 Centenial Edition Bonnie as well. I went around a left hander and felt a pop, then more pops and the back end got all wobbly. Had probably a dozen or so broken spokes all together. Triumph thankfully paid for a new wheel.

Right now there is a internet blog of a guy on a BMW GS who's front wheel spokes all disintegrated on him. More reports of similar problems followed. They are wanting a recall on BMW spoked wheels.

Spokes are like the span of a bridge. EAch spoke shares and spreads the pressure between them. If one spoke goes, that puts extra pressure on the remaining spokes, which end up flexing more than they are designed and then another breaks, putting even more pressure on the remaining spokes. pretty soon it's a lost cause and most break.

Spokes look good, they flex making the ride softer, but they also sometimes break.

Well... spokes are like "stay-cables" on a bridge. The work in tension only, so they don't flex: they just stretch.
Preload on them has to be high enough so load cycles are small and fatigue is minimized (load will be small compared to tension, so cycle amplitude is small). If load is to high, you could have metal yield (so tension becomes VERY low), ir it can just snap (this depends on the alloy). In any case: spoke preload is VERY important.

Without knowing this case, I'd point the probable causes to be:

-wrong servicing (i.e. bad preload on spokes) -> most probable
-bad batch of spokes -> unlikely: we would have heard of more.
-corrosion failure -> unlikely: we would have heard of more.
-bad design -> VERY unlikely: spoke rim design is not exactly a new unknown technology

This is just my opinion, but if I had to bet... this failure can be from something very simple like a unit conversion problem from [Nm] to [lb·ft].

I'm glad nothing irreversible happened!
Some interesting info I've just found regarding spoked wheels:

http://poehali.net/attach/Bicycle_Wheel_...Brandt.pdf

[peterbaron]

Wow Jtopiso, very professional link with condensed explanation. Thanks for this technical link

[kennyw]

That's a shame that happened.

Spoke breakage is not common but not rare either. The early Bonnevilles 2000-2003 had the issue so often the forums were asking for a recall. It happened to my 2003 Centenial Edition Bonnie as well. I went around a left hander and felt a pop, then more pops and the back end got all wobbly. Had probably a dozen or so broken spokes all together. Triumph thankfully paid for a new wheel.

Right now there is a internet blog of a guy on a BMW GS who's front wheel spokes all disintegrated on him. More reports of similar problems followed. They are wanting a recall on BMW spoked wheels.

Spokes are like the span of a bridge. EAch spoke shares and spreads the pressure between them. If one spoke goes, that puts extra pressure on the remaining spokes, which end up flexing more than they are designed and then another breaks, putting even more pressure on the remaining spokes. pretty soon it's a lost cause and most break.

Spokes look good, they flex making the ride softer, but they also sometimes break.

Well... spokes are like "stay-cables" on a bridge. The work in tension only, so they don't flex: they just stretch.
Preload on them has to be high enough so load cycles are small and fatigue is minimized (load will be small compared to tension, so cycle amplitude is small). If load is to high, you could have metal yield (so tension becomes VERY low), ir it can just snap (this depends on the alloy). In any case: spoke preload is VERY important.

Without knowing this case, I'd point the probable causes to be:

-wrong servicing (i.e. bad preload on spokes) -> most probable
-bad batch of spokes -> unlikely: we would have heard of more.
-corrosion failure -> unlikely: we would have heard of more.
-bad design -> VERY unlikely: spoke rim design is not exactly a new unknown technology

This is just my opinion, but if I had to bet... this failure can be from something very simple like a unit conversion problem from [Nm] to [lb·ft].

I'm glad nothing irreversible happened!
Some interesting info I've just found regarding spoked wheels:

http://poehali.net/attach/Bicycle_Wheel_...Brandt.pdf

You cannot rule the last three as unlikely without further investigation. I've seen all of these types of failures in my 20+ years as a mechanical engineer across many mature product lines and industries.

The fact Honda changed the spoke wheel design tells me they MAY have been aware of a design issue OR the change was to cut cost. However, since the materials used after the design change are more expensive, I doubt it was a cost cut.