Yellow Saddle
Guru
- Location
- Loch side.
OK, it was a bit naughty. I should have been frank and stated the truth by saying: "This is getting worse and worse."
Why do my spokes keep breaking? - Bike wheel science.
- Thread starter united4ever
- Start date
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(please 
)Hey i’ve just bought the trek roscoe 6 19, and i’ve had it for a day been on it maybe 4/5 hours and i do admit i do wheelies and i like swerve stuff and i’ve noticed the wheel is a little buckled not a lot but a little and i don’t know if i’m being para but does wheelie damage the back wheel to a point of not being able to ride it and is it possible to do it so soon?? please i need answers
Yellow Saddle
Guru
- Location
- Loch side.
No and no.
Cheers mate
overmind
My other bike is a Pinarello
- Location
- Reading, Berkshire
Does that mean that the buckle was there to begin with? Otherwise what would have caused the buckle (if it was not doing wheelies)?
Ming the Merciless
There is no mercy
- Location
- Inside my skull
Jumping off kerbs
overmind
My other bike is a Pinarello
- Location
- Reading, Berkshire
I was looking at some wheels in the bike shop yesterday and noticed that the more expensive high-end wheels have much higher spoke tension. What is the reason for this? I've noticed the spokes on my bike (BTwin Triban 3) are tight but not as tight as this.
Would there be any benefit in tightening my spokes? Say, 1/4-1/2 turn all round the wheel and then re-true?
Would there be any benefit in tightening my spokes? Say, 1/4-1/2 turn all round the wheel and then re-true?
More expensive wheels often have fewer spokes so require increased tension. If you think about the wheel as a system and the total tension of all the spokes required to keep a wheel circular and true then divide by the number of spokes and you will immediately see the need for greater tension. This is a bit of a simplification of what's happening and there are reasons to increase spoke tension in certain circumstances but unless your wheel is out of true or some of the spokes are loose I would avoid messing with them.
Ajax Bay
Guru
- Location
- East Devon
How did 'looking at the wheels' allow you to 'notice' that the spoke tension was higher, please? I'll go for a 'no'.
Why does the total tension (presumably you mean adding the tension of all the spokes together) need to be the same? This implies that a 16 spoke wheel wIll have twice the spoke tension of a 32 spoke wheel. I pity the rim of that 16 spoke wheel. If this question is too simple, please share the complexities with us.
It doesn't need to be be the same in the way you are implying but for a given rider weight there needs to be enough strength in the system to counteract the load (Force) on the wheels. Reducing the number of spokes increases the amount of load that each spoke will account for - this is complicated by the fact that not all spokes are evenly loaded as the wheel goes around.
I do have a rudimentary understanding of how this works, but I'm not an engineer and I know what I don't know, so at this point I'm going to bail and page @Yellow Saddle who will no doubt point out where I've gone wrong above anyway
Spoked Wheels
Legendary Member
- Location
- Bournemouth
Cheap factory wheels tend to come with under tension straight spokes. Higher end wheels tend to come with better spokes, more spokes tension and fewer spokes too.
It's possible that it was there and it got worse. My guess is that your spokes were under tension and made the wheel weak.
My son's mate rode his new bike down a mountain and the rear wheel was unridible afterwards, I was with them and with my spoke key I straightened the wheel enough for him to ride home... but the spokes were very under tension.
Ajax Bay
Guru
- Location
- East Devon
1. Agreed but. Assuming a 100kg load (rider and bike) and an even split rear/front (it's not) that means the load on the wheel is 490N (50kg x g).
2. Even (in a notional very low spoke wheel) if only one spoke is taking the reduction in load (tension) the reasonable spoke tension of 1000N will only reduce by 490N. So that spoke is still at 500+N tension. In practice in a 16 spoke wheel the spokes adjacent to the 'lowest' one are sharing some reduction in load (equal in total to the load on the wheel). (See also the quote below.) If a the spokes in a wheel are 'under-tensioned' (as @Spoked Wheels has described) then there's a danger of the the force on the wheel over-matching the spoke tension, with adverse effect (potential for spoke nipples to loosen and the wheel to lose true).
3. If you have not read pages 3 and 4 of this thread, the discussion there tries to consider and understand the way tension in spokes vary as the wheel (under load) rotates.
This Wjeelfanatyk article seemed relevant to me, to help inform the answer to @overmind 's question.
ETA this image: https://www.wheelfanatyk.com/wp-content/uploads/2014/01/tension-crank.jpg
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Ming the Merciless
There is no mercy
- Location
- Inside my skull
No, there's quite a wide range of spoke tension under which a wheel will remain strong and true. Once you are in this range, increasing the tension does not make the wheel stronger.
Yellow Saddle
Guru
- Location
- Loch side.
I think your understanding is correct except for the concept of "total tension doubled". The total tension in a 16-spoke wheel is not as high as that of a 32-spoke wheel, It simply cannot be because spokes are already loaded at the upper end of their tensile strength and, that would put an enormous amount of tension on sparsely-spaced spots on the rim. In short, it is just about impossible to double the tension of some spokes in a wheel. Typically, I'd build a 32-spoke wheel with about 1500N on the right hand spokes. To double it would imply 3000N. At that tension the nipples will not turn, the spoke will rotate with the nipple, the rim will burst and your fingers will fall off.It doesn't need to be be the same in the way you are implying but for a given rider weight there needs to be enough strength in the system to counteract the load (Force) on the wheels. Reducing the number of spokes increases the amount of load that each spoke will account for - this is complicated by the fact that not all spokes are evenly loaded as the wheel goes around.
I do have a rudimentary understanding of how this works, but I'm not an engineer and I know what I don't know, so at this point I'm going to bail and page @Yellow Saddle who will no doubt point out where I've gone wrong above anyway
A 16-spoke wheel does require higher tension, but not double. It makes up for the lack of "double tension" at a spoke by spreading the load-affected zone wider, through the use of a sturdier rim. Some rims, especially deep section rims are super stiff compared to box section rims. I used to sit on deep sections (35mm and up) and bounce, with no ill effect, whereas I once sat on a Mavic MA 2 with, lets say, I'll effects. This demonstrates how a deep section employs a very large load effected zone that can accommodate enough spokes to make up for loss of individual tension.
That's a bit long-winded and inelegant, but the best I can squeeze out now.
