bonsaibilly
Guest
Never.
Just a little advice needed..
- Thread starter Yantofullpelt
- Start date
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Never.
Congratulations. Your spoke breakage lies ahead of you rather than behind. It might never happen. But it probably will.
slowmotion
Quite dreadful
- Location
- lost somewhere
Is is usually OK to ride a few tens of miles with a broken spoke, or is that like asking the question " how far can I drive after I've crashed the car"?
Salty seadog
Space Cadet...(3rd Class...)
also never had one go ping in over 30 years and many bikes.
Yes. The FNRTTC before last featured a rider who broke a spoke at Nutfield who then made it to the end. I taped it to its neighbour to stop it getting in the way. FWIW I've also driven a car after I'd crashed it (into the railway bridge at Crianlarich ).
Shut Up Legs
Down Under Member
You go through bikes at that rate? What went wrong?
Salty seadog
Space Cadet...(3rd Class...)
You go through bikes at that rate? What went wrong?
???
Not sure what you're getting at old bean, most cyclists have had "many" bikes over a 30 year period, I have 3 right now.
Shut Up Legs
Down Under Member
Sorry, my mistake, I misread your post, and thought it said "as many bikes". I didn't mean to offend.
Personally, I've had 1 spoke break in the last 100,000km of cycling, so it's pretty rare for me, too.
Salty seadog
Space Cadet...(3rd Class...)
Yeah I did think you'd seen a non existent "as" in my post......certainly no offence.
gbb
Squire
- Location
- Peterborough
FWIW, I've never had a spoke ping or break in my 40 years or so of cycling,from some of the cheapest wheels I still use on an old hybrid to better fulcrum and shimano wheels..although all still of modest quality. I'd love to know how many miles I've done although I never will of course.
Just take the wheel to the LBS...I wouldn't lose any sleep over it. But I would avoid potholed.
Just take the wheel to the LBS...I wouldn't lose any sleep over it. But I would avoid potholed.
CanucksTraveller
Macho Business Donkey Wrestler
- Location
- Hertfordshire
As I said earlier in the thread, I once rode daily for many months on a wheel with a missing spoke. Not necessarily a good idea of course, I'd guess even less so on lightweight modern wheels with fewer spokes. This was a late 80s cheaper Mavic with about 200 of the buggers, some of them were loose too. I'd probably do it again for tens of miles, especially if the only other option was walking.
Yellow Saddle
Guru
- Location
- Loch side.
Spoke breakage.
The terminology is important here from an engineering standpoint and we don't say a spoke snapped but we do say it broke.
Snapping implies that it was subject to tensile (pulling) forces that stretched it beyond its limit, it elongated like a bit of toffee that's stretching and eventually it separated into two pieces. This is what happens to a tow rope or similar. But it is not what generally happens when spokes separate into two bits. I say "generally" because there are instances when a spoke snaps. A good example would be a broomstick thrown into a moving wheel. The stick would enter the spokes and get trapped between spoke and fork. The rotating wheel would then stretch the spoke as if someone is pulling very hard on a guitar string and it would snap. Snap is the layman's term for a tensile break and the mode of failure is tensile (pulling). The two sections at the break display a characteristic deformation called necking. The ends taper a little and then form a cup-and-cone end. The one end displays a little cup, the other a cone. Very distinctive.
Here's the photo of the cup side. Notice the necking as well as the cup. Unfortunately I can't find my cone photo but the other side looks similar but fits inside this view.
Such a break or "Snap" happens in the thinnest section of the spoke. On a typical double-butted spoke this is in the mid-span well clear of the ends where the spoke is typically thicker.
Now for the real "break". These breaks look different, happen for different reasons from the above and work by a different mode. Looks: The break is clean as if cut by a laser.
Have a look:
Notice how there is no necking and no cupping. Notice the row of lines and notice the shiny line at the inner end of the bend. This spoke broke from metal fatigue. Small movements in the spoke caused by each revolution of the wheel where the spoke relaxes (loaded) and tensions (unloaded) causes the elbow to bend in and out a tiny amount. These little movements eventually cause the metal to crack. The crack starts at the outer end of the end and travels inwards until it reaches a point where the remaining bit is too weak to hold the spoke in tension and then it "snaps" as in the previous mode. Hence the shiny last section and its sharp little lip.
This is the most common way a spoke breaks - metal fatigue. Here the spoke breaks at its thickest section - the bend, or at the first thread under the nipple. These are the two spots most vulnerable to metal fatigue. The thread is vulnerable because the valley (called a root) of the first thread is a sharp dent in the metal where stresses concentrate and start. The bend is vulnerable because the metal there is under tension from being forced around a bent (the metal on the inside is under compression and somewhat protected).
Ironically the solution to preventing spokes from breaking is not to make them thicker. That will just make them last a few hundred revolutions longer. The solution is to make the centre span of the spoke thinner so that all the strain (elongation and shortening) happens there rather than at the vulnerable end points. This is the reason for the double-butted spoke. It is not built stronger at the ends, it is built weaker at the midspan. Another way to prevent metal fatigue is to stress relieve the spokes. That's an entire story by itself.
Back to the pothole issue. When you hit a pothole, the spokes in the load affected zone (at the hole) relax, rather than tighten up. That's why I say the hole didn't break the spoke. Just riding along stresses the spokes with each revolution and your wheels go round and round far more often than you hit holes.
You did ask.
Ajax Bay
Guru
- Location
- East Devon
See my post #9 above. Distance 'OKness' will depend on number of spokes in the wheel: the more you had the less one will be missed. Would also depend on how heavily loaded / heavy you are.
pawl
Legendary Member
- Location
- Desford Leicestershire
